1
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Zehr JP, Capone DG. Unsolved mysteries in marine nitrogen fixation. Trends Microbiol 2024; 32:532-545. [PMID: 37658011 DOI: 10.1016/j.tim.2023.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 09/03/2023]
Abstract
Biological nitrogen (N2) fixation is critical in global biogeochemical cycles and in sustaining the productivity of the oceans. There remain many unanswered questions, unresolved hypotheses, and unchallenged paradigms. The fundamental balance of N input and losses has not been fully resolved. One of the major N2-fixers, Trichodesmium, remains an enigma with intriguing biological and ecological secrets. Cyanobacterial N2 fixation, once thought to be primarily due to free-living cyanobacteria, now also appears to be dependent on microbial interactions, from microbiomes to unicellular symbioses, which remain poorly characterized. Nitrogenase genes associated with diverse non-cyanobacterial diazotrophs (NCDs) are prevalent, but their significance remains a huge knowledge gap. Answering questions, new and old, such as those discussed here, is needed to understand the ocean's N and C cycles and their responses to environmental change.
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Affiliation(s)
- Jonathan P Zehr
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA.
| | - Douglas G Capone
- Marine and Environmental Biology Section of Biological Sciences, University of Southern California, Los Angeles, CA, USA
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2
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Kang W, Mu L, Hu X. Marine Colloids Boost Nitrogen Fixation in Trichodesmium erythraeum by Photoelectrophy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9236-9249. [PMID: 38748855 DOI: 10.1021/acs.est.4c01849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Nitrogen fixation by the diazotrophic cyanobacterium Trichodesmium contributes up to 50% of the bioavailable nitrogen in the ocean. N2 fixation by Trichodesmium is limited by the availability of nutrients, such as iron (Fe) and phosphorus (P). Although colloids are ubiquitous in the ocean, the effects of Fe limitation on nitrogen fixation by marine colloids (MC) and the related mechanisms are largely unexplored. In this study, we found that MC exhibit photoelectrochemical properties that boost nitrogen fixation by photoelectrophy in Trichodesmium erythraeum. MC efficiently promote photosynthesis in T. erythraeum, thus enhancing its growth. Photoexcited electrons from MC are directly transferred to the photosynthetic electron transport chain and contribute to nitrogen fixation and ammonia assimilation. Transcriptomic analysis revealed that MC significantly upregulates genes related to the electron transport chain, photosystem, and photosynthesis, which is consistent with elevated photosynthetic capacities (e.g., Fv/Fm and carboxysomes). As a result, MC increase the N2 fixation rate by 67.5-89.3%. Our findings highlight a proof-of-concept electron transfer pathway by which MC boost nitrogen fixation, broadening our knowledge on the role of ubiquitous colloids in marine nitrogen biogeochemistry.
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Affiliation(s)
- Weilu Kang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Carbon Neutrality Interdisciplinary Science Centre, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Li Mu
- Tianjin Key Laboratory of Agro-Environment and Product Safety, Key Laboratory for Environmental Factors Controlling Agro-Product Quality Safety (Ministry of Agriculture and Rural Affairs), Institute of Agro-Environmental Protection, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Xiangang Hu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Carbon Neutrality Interdisciplinary Science Centre, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
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3
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Colussi A, Bokhari SNH, Mijovilovich A, Koník P, Küpper H. Acclimation to medium-level non-lethal iron limitation: Adjustment of electron flow around the PSII and metalloprotein expression in Trichodesmium erythraeum IMS101. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149015. [PMID: 37742749 DOI: 10.1016/j.bbabio.2023.149015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023]
Abstract
The aim of this study was to investigate how acclimation to medium-level, long-term, non-lethal iron limitation changes the electron flux around the Photosystem II of the oceanic diazotroph Trichodesmium erythraeum IMS101. Fe availability of about 5× and 100× lower than a replete level, i.e. conditions common in the natural environment of this cyanobacterium, were applied in chemostats. The response of the cells was studied not only in terms of growth, but also mechanistically, measuring the chlorophyll fluorescence of dark-adapted filaments via imaging fluorescence kinetic microscopy (FKM) with 0.3 ms time resolution. Combining these measurements with those of metal binding to proteins via online coupling of metal-free HPLC (size exclusion chromatography SEC) to sector-field ICP-MS allowed to track the fate of the photosystems, together with other metalloproteins. General increase of fluorescence has been observed, with the consequent decrease in the quantum yields φ of the PSII, while the efficiency ψ of the electron flux between PSII and the PSI remained surprisingly unchanged. This indicates the ability of Trichodesmium to cope with a situation that makes assembling the many iron clusters in Photosystem I a particular challenge, as shown by decreasing ratios of Fe to Mg in these proteins. The negative effect of Fe limitation on PSII may also be due to its fast turnover. A broader view was obtained from metalloproteomics via HPLC-ICP-MS, revealing a differential protein expression pattern under iron limitation with a drastic down-regulation especially of iron-containing proteins and some increase in low MW metal-binding complexes.
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Affiliation(s)
- Antonio Colussi
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Sciences, Department of Experimental Plant Biology, České Budějovice, Czech Republic
| | - Syed Nadeem Hussain Bokhari
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic
| | - Ana Mijovilovich
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic
| | - Peter Koník
- University of South Bohemia, Faculty of Sciences, Department of Chemistry, České Budějovice, Czech Republic
| | - Hendrik Küpper
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, Laboratory of Plant Biophysics and Biochemistry, České Budějovice, Czech Republic; University of South Bohemia, Faculty of Sciences, Department of Experimental Plant Biology, České Budějovice, Czech Republic.
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4
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Eichner M, Inomura K, Pierella Karlusich JJ, Shaked Y. Better together? Lessons on sociality from Trichodesmium. Trends Microbiol 2023; 31:1072-1084. [PMID: 37244772 DOI: 10.1016/j.tim.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 04/30/2023] [Accepted: 05/01/2023] [Indexed: 05/29/2023]
Abstract
The N2-fixing cyanobacterium Trichodesmium is an important player in the oceanic nitrogen and carbon cycles. Trichodesmium occurs both as single trichomes and as colonies containing hundreds of trichomes. In this review, we explore the benefits and disadvantages of colony formation, considering physical, chemical, and biological effects from nanometer to kilometer scale. Showing that all major life challenges are affected by colony formation, we claim that Trichodesmium's ecological success is tightly linked to its colonial lifestyle. Microbial interactions in the microbiome, chemical gradients within the colony, interactions with particles, and elevated mobility in the water column shape a highly dynamic microenvironment. We postulate that these dynamics are key to the resilience of Trichodesmium and other colony formers in our changing environment.
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Affiliation(s)
- Meri Eichner
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic.
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | | | - Yeala Shaked
- Freddy and Nadine Herrmann Institute of Earth Sciences, Hebrew University, Jerusalem, Israel; Interuniversity Institute for Marine Sciences, Eilat, Israel
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5
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Sarkar S, Bhowmick TK, Gayen K. Enhancement for the synthesis of bio-energy molecules (carbohydrates and lipids) in Desmodesmus subspicatus: experiments and optimization techniques. Prep Biochem Biotechnol 2023; 54:343-357. [PMID: 37531084 DOI: 10.1080/10826068.2023.2241898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
Microalgae are regarded as renewable resources of energy, foods and high-valued compounds using a biorefinery approach. In the present study, we explored isolated microalgae (Desmodesmus subspicatus) for the production of bio-energy molecules (carbohydrate and lipid). Optimizations of media (BG-11) components have been made using the Taguchi orthogonal array (TOA) technique to maximize biomass, carbohydrate and lipid production. Optimized results showed that biomass, carbohydrates and lipid productivity increased by 1.3 times at optimal combinations of media components than standard BG-11 media. Further, the influence of various carbon and nitrogen sources as nutritional supplement with optimum media composition under different light intensities was investigated for productivity of carbohydrate and lipid. Results demonstrated that 1.5 times higher productivity of carbohydrate and lipids were achieved in the presence optimum BG-11 under a broad range of light intensities (84-504 µmol m-2 s-1). Among different nitrogen sources, glycine was found to give higher productivity (1.5 times) followed by urea. Use of the cellulose as a carbon source in the media significantly increases biomass (2.4 times), carbohydrates (2.3 times) and lipids (2.3 times) productivity. Investigations revealed that cultivating Desmodesmus subspicatus under optimum culture conditions has the potential for large-scale bio-ethanol and bio-diesel production.
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Affiliation(s)
- Sreya Sarkar
- Department of Chemical Engineering, National Institute of Technology Agartala, West Tripura, Tripura, India
| | - Tridib Kumar Bhowmick
- Department of Bioengineering, National Institute of Technology Agartala, West Tripura, Tripura, India
| | - Kalyan Gayen
- Department of Chemical Engineering, National Institute of Technology Agartala, West Tripura, Tripura, India
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Luo W, Luo YW. Diurnally dynamic iron allocation promotes N 2 fixation in marine dominant diazotroph Trichodesmium. Comput Struct Biotechnol J 2023; 21:3503-3512. [PMID: 37484493 PMCID: PMC10362294 DOI: 10.1016/j.csbj.2023.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/15/2023] [Accepted: 07/04/2023] [Indexed: 07/25/2023] Open
Abstract
Trichodesmium is the dominant photoautotrophic dinitrogen (N2) fixer (diazotroph) in the ocean. Iron is an important factor limiting growth of marine diazotrophs including Trichodesmium mainly because of high iron content of its N2-fixing enzyme, nitrogenase. However, it still lacks a quantitative understanding of how dynamic iron allocation among physiological processes acts to regulate growth and N2 fixation in Trichodesmium. Here, we constructed a model of Trichodesmium trichome in which intracellular iron could be dynamically re-allocated in photosystems and nitrogenase during the daytime. The results demonstrate that the dynamic iron allocation enhances modeled N2 fixation and growth rates of Trichodesmium, especially in iron-limited conditions, albeit having a marginal impact under high iron concentrations. Although the reuse of iron during a day is an apparent cause that dynamic iron allocation can benefit Trichodesmium under iron limitation, our model reveals two important mechanisms. First, the release of iron from photosystems downregulates the intracellular oxygen (O2) production and reduces the demand of respiratory protection, a process that Trichodesmium wastefully respires carbohydrates to create a lower O2 window for N2 fixation. Hence, more carbohydrates can be used in growth. Second, lower allocation of iron to nitrogenase during early daytime, a period when photosynthesis is active and intracellular O2 is high, reduces the amount of iron that is trapped in the inactivated nitrogenase induced by O2. This mechanism further increases the iron use efficiency in Trichodesmium. Overall, our study provides mechanistic and quantitative insight into the diurnal iron allocation that can alleviate iron limitation to Trichodesmium.
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Alam I, Zhang H, Du H, Rehman NU, Manghwar H, Lei X, Batool K, Ge L. Bioengineering Techniques to Improve Nitrogen Transformation and Utilization: Implications for Nitrogen Use Efficiency and Future Sustainable Crop Production. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:3921-3938. [PMID: 36842151 DOI: 10.1021/acs.jafc.2c08051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nitrogen (N) is crucial for plant growth and development, especially in physiological and biochemical processes such as component of different proteins, enzymes, nucleic acids, and plant growth regulators. Six categories, such as transporters, nitrate absorption, signal molecules, amino acid biosynthesis, transcription factors, and miscellaneous genes, broadly encompass the genes regulating NUE in various cereal crops. Herein, we outline detailed research on bioengineering modifications of N metabolism to improve the different crop yields and biomass. We emphasize effective and precise molecular approaches and technologies, including N transporters, transgenics, omics, etc., which are opening up fascinating opportunities for a complete analysis of the molecular elements that contribute to NUE. Moreover, the detection of various types of N compounds and associated signaling pathways within plant organs have been discussed. Finally, we highlight the broader impacts of increasing NUE in crops, crucial for better agricultural yield and in the greater context of global climate change.
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Affiliation(s)
- Intikhab Alam
- College of Forestry and Landscape Architecture, Department of Grassland Science, South China Agricultural University (SCAU), Guangzhou 510642, China
- College of Life Sciences, SCAU, Guangzhou 510642, China
- Guangdong Subcenter of the National Center for Soybean Improvement, SCAU, Guangzhou 510642, China
| | - Hanyin Zhang
- College of Forestry and Landscape Architecture, Department of Grassland Science, South China Agricultural University (SCAU), Guangzhou 510642, China
- Guangdong Subcenter of the National Center for Soybean Improvement, SCAU, Guangzhou 510642, China
| | - Huan Du
- College of Forestry and Landscape Architecture, Department of Grassland Science, South China Agricultural University (SCAU), Guangzhou 510642, China
- College of Life Sciences, SCAU, Guangzhou 510642, China
- Guangdong Subcenter of the National Center for Soybean Improvement, SCAU, Guangzhou 510642, China
| | - Naveed Ur Rehman
- Guangdong Subcenter of the National Center for Soybean Improvement, SCAU, Guangzhou 510642, China
| | - Hakim Manghwar
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry and Landscape Architecture, SCAU, Guangzhou 510642, China
| | - Xiao Lei
- College of Forestry and Landscape Architecture, Department of Grassland Science, South China Agricultural University (SCAU), Guangzhou 510642, China
- Guangdong Subcenter of the National Center for Soybean Improvement, SCAU, Guangzhou 510642, China
| | - Khadija Batool
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Liangfa Ge
- College of Forestry and Landscape Architecture, Department of Grassland Science, South China Agricultural University (SCAU), Guangzhou 510642, China
- Guangdong Subcenter of the National Center for Soybean Improvement, SCAU, Guangzhou 510642, China
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8
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Khetkorn W, Raksajit W, Maneeruttanarungroj C, Lindblad P. Photobiohydrogen Production and Strategies for H 2 Yield Improvements in Cyanobacteria. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:253-279. [PMID: 37009974 DOI: 10.1007/10_2023_216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
Hydrogen gas (H2) is one of the potential future sustainable and clean energy carriers that may substitute the use of fossil resources including fuels since it has a high energy content (heating value of 141.65 MJ/kg) when compared to traditional hydrocarbon fuels [1]. Water is a primary product of combustion being a most significant advantage of H2 being environmentally friendly with the capacity to reduce global greenhouse gas emissions. H2 is used in various applications. It generates electricity in fuel cells, including applications in transportation, and can be applied as fuel in rocket engines [2]. Moreover, H2 is an important gas and raw material in many industrial applications. However, the high cost of the H2 production processes requiring the use of other energy sources is a significant disadvantage. At present, H2 can be prepared in many conventional ways, such as steam reforming, electrolysis, and biohydrogen production processes. Steam reforming uses high-temperature steam to produce hydrogen gas from fossil resources including natural gas. Electrolysis is an electrolytic process to decompose water molecules into O2 and H2. However, both these two methods are energy-intensive and producing hydrogen from natural gas, which is mostly methane (CH4) and in steam reforming generates CO2 and pollutants as by-products. On the other hand, biological hydrogen production is more environmentally sustainable and less energy intensive than thermochemical and electrochemical processes [3], but most concepts are not yet developed to production scale.
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Affiliation(s)
- Wanthanee Khetkorn
- Division of Biology, Faculty of Science and Technology, Rajamangala University of Technology, Thanyaburi, Pathum Thani, Thailand
| | - Wuttinun Raksajit
- Faculty of Veterinary Technology, Program of Animal Health Technology, Kasetsart University, Bangkok, Thailand
| | - Cherdsak Maneeruttanarungroj
- Department of Biology, School of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand
- Bioenergy Research Unit, School of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand
| | - Peter Lindblad
- Microbial Chemistry, Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden.
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9
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Li H, Gao K. Deoxygenation enhances photosynthetic performance and increases N 2 fixation in the marine cyanobacterium Trichodesmium under elevated pCO 2. Front Microbiol 2023; 14:1102909. [PMID: 36876059 PMCID: PMC9975739 DOI: 10.3389/fmicb.2023.1102909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/27/2023] [Indexed: 02/17/2023] Open
Abstract
Effects of changed levels of dissolved O2 and CO2 on marine primary producers are of general concern with respect to ecological effects of ongoing ocean deoxygenation and acidification as well as upwelled seawaters. We investigated the response of the diazotroph Trichodesmium erythraeum IMS 101 after it had acclimated to lowered pO2 (~60 μM O2) and/or elevated pCO2 levels (HC, ~32 μM CO2) for about 20 generations. Our results showed that reduced O2 levels decreased dark respiration significantly, and increased the net photosynthetic rate by 66 and 89% under the ambient (AC, ~13 μM CO2) and the HC, respectively. The reduced pO2 enhanced the N2 fixation rate by ~139% under AC and only by 44% under HC, respectively. The N2 fixation quotient, the ratio of N2 fixed per O2 evolved, increased by 143% when pO2 decreased by 75% under the elevated pCO2. Meanwhile, particulate organic carbon and nitrogen quota increased simultaneously under reduced O2 levels, regardless of the pCO2 treatments. Nevertheless, changed levels of O2 and CO2 did not bring about significant changes in the specific growth rate of the diazotroph. Such inconsistency was attributed to the daytime positive and nighttime negative effects of both lowered pO2 and elevated pCO2 on the energy supply for growth. Our results suggest that Trichodesmium decrease its dark respiration by 5% and increase its N2-fixation by 49% and N2-fixation quotient by 30% under future ocean deoxygenation and acidification with 16% decline of pO2 and 138% rise of pCO2 by the end of this century.
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Affiliation(s)
- He Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China.,Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
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10
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Photosynthetic modulation during the diurnal cycle in a unicellular diazotrophic cyanobacterium grown under nitrogen-replete and nitrogen-fixing conditions. Sci Rep 2022; 12:18939. [PMID: 36344535 PMCID: PMC9640542 DOI: 10.1038/s41598-022-21829-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/04/2022] [Indexed: 11/09/2022] Open
Abstract
Cyanobacteria are the only oxygenic photosynthetic organisms that can fix nitrogen. In diazotrophic cyanobacteria, the regulation of photosynthesis during the diurnal cycle is hypothesized to be linked with nitrogen fixation and involve the D1 protein isoform PsbA4. The amount of bioavailable nitrogen has a major impact on productivity in aqueous environments. In contrast to low- or nitrogen-fixing (-N) conditions, little data on photosynthetic regulation under nitrogen-replete (+ N) conditions are available. We compared the regulation of photosynthesis under -N and + N conditions during the diurnal cycle in wild type and a psbA4 deletion strain of the unicellular diazotrophic cyanobacterium Cyanothece sp. ATCC 51142. We observed common changes to light harvesting and photosynthetic electron transport during the dark in + N and -N conditions and found that these modifications occur in both diazotrophic and non-diazotrophic cyanobacteria. Nitrogen availability increased PSII titer when cells transitioned from dark to light and promoted growth. Under -N conditions, deletion of PsbA4 modified charge recombination in dark and regulation of PSII titer during dark to light transition. We conclude that darkness impacts the acceptor-side modifications to PSII and photosynthetic electron transport in cyanobacteria independently of the nitrogen-fixing status and the presence of PsbA4.
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Shlosberg Y, Spungin D, Schuster G, Berman-Frank I, Adir N. Trichodesmium erythraeum produces a higher photocurrent than other cyanobacterial species in bio-photo electrochemical cells. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148910. [PMID: 35944660 DOI: 10.1016/j.bbabio.2022.148910] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 07/26/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
The increase in world energy consumption, and the worries from potential future disasters that may derive from climate change have stimulated the development of renewable energy technologies. One promising method is the utilization of whole photosynthetic cyanobacterial cells to produce photocurrent in a bio-photo electrochemical cell (BPEC). The photocurrent can be derived from either the respiratory or photosynthetic pathways, via the redox couple NADP+/NADPH mediating cyclic electron transport between photosystem I inside the cells, and the anode. In the past, most studies have utilized the fresh-water cyanobacterium Synechocystis sp. PCC 6803 (Syn). Here, we show that the globally important marine cyanobacterium Trichodesmium erythraeum flourishing in the subtropical oceans can provide improved currents as compared to Syn. We applied 2D-fluorescence measurements to detect the secretion of NADPH and show that the resulting photocurrent production is enhanced by increasing the electrolyte salinity, Further enhancement of the photocurrent can be obtained by the addition of electron mediators such as NAD+, NADP+, cytochrome C, vitamin B1, or potassium ferricyanide. Finally, we produce photocurrent from additional cyanobacterial species: Synechocystis sp. PCC6803, Synechococcus elongatus PCC7942, Acaryochloris marina MBIC 11017, and Spirulina, using their cultivation media as electrolytes for the BPEC.
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Affiliation(s)
- Yaniv Shlosberg
- Grand Technion Energy Program, Technion, Haifa 32000, Israel; Schulich Faculty of Chemistry, Technion, Haifa 320000, Israel
| | - Dina Spungin
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Gadi Schuster
- Grand Technion Energy Program, Technion, Haifa 32000, Israel; Faculty of Biology, Technion, Haifa 32000, Israel
| | - Ilana Berman-Frank
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Noam Adir
- Grand Technion Energy Program, Technion, Haifa 32000, Israel; Schulich Faculty of Chemistry, Technion, Haifa 320000, Israel.
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12
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Benavides M, Bonnet S, Le Moigne FAC, Armin G, Inomura K, Hallstrøm S, Riemann L, Berman-Frank I, Poletti E, Garel M, Grosso O, Leblanc K, Guigue C, Tedetti M, Dupouy C. Sinking Trichodesmium fixes nitrogen in the dark ocean. THE ISME JOURNAL 2022; 16:2398-2405. [PMID: 35835942 PMCID: PMC9478103 DOI: 10.1038/s41396-022-01289-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/29/2022] [Accepted: 07/05/2022] [Indexed: 01/04/2023]
Abstract
The photosynthetic cyanobacterium Trichodesmium is widely distributed in the surface low latitude ocean where it contributes significantly to N2 fixation and primary productivity. Previous studies found nifH genes and intact Trichodesmium colonies in the sunlight-deprived meso- and bathypelagic layers of the ocean (200-4000 m depth). Yet, the ability of Trichodesmium to fix N2 in the dark ocean has not been explored. We performed 15N2 incubations in sediment traps at 170, 270 and 1000 m at two locations in the South Pacific. Sinking Trichodesmium colonies fixed N2 at similar rates than previously observed in the surface ocean (36-214 fmol N cell-1 d-1). This activity accounted for 40 ± 28% of the bulk N2 fixation rates measured in the traps, indicating that other diazotrophs were also active in the mesopelagic zone. Accordingly, cDNA nifH amplicon sequencing revealed that while Trichodesmium accounted for most of the expressed nifH genes in the traps, other diazotrophs such as Chlorobium and Deltaproteobacteria were also active. Laboratory experiments simulating mesopelagic conditions confirmed that increasing hydrostatic pressure and decreasing temperature reduced but did not completely inhibit N2 fixation in Trichodesmium. Finally, using a cell metabolism model we predict that Trichodesmium uses photosynthesis-derived stored carbon to sustain N2 fixation while sinking into the mesopelagic. We conclude that sinking Trichodesmium provides ammonium, dissolved organic matter and biomass to mesopelagic prokaryotes.
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Affiliation(s)
- Mar Benavides
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France.
- Turing Center for Living Systems, Aix-Marseille University, 13009, Marseille, France.
| | - Sophie Bonnet
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Frédéric A C Le Moigne
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
- LEMAR, Laboratoire des Sciences de l'Environnement Marin, UMR6539, CNRS, UBO, IFREMER, IRD, 29280, Plouzané, Technopôle Brest-Iroise, France
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, South Kingstown, RI, USA
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, South Kingstown, RI, USA
| | - Søren Hallstrøm
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Ilana Berman-Frank
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Mt, Carmel, Haifa, Israel
| | - Emilie Poletti
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Marc Garel
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Olivier Grosso
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Karine Leblanc
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Catherine Guigue
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Marc Tedetti
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Cécile Dupouy
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
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13
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Sarkar S, Sarkar S, Bhowmick TK, Gayen K. Process intensification for the enhancement of growth and chlorophyll molecules of isolated Chlorella thermophila: A systematic experimental and optimization approach. Prep Biochem Biotechnol 2022:1-19. [DOI: 10.1080/10826068.2022.2119578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- Sreya Sarkar
- Department of Chemical engineering, National Institute of Technology Agartala, Agartala, India
| | - Sambit Sarkar
- Department of Chemical engineering, National Institute of Technology Agartala, Agartala, India
| | - Tridib Kumar Bhowmick
- Department of Bioengineering, National Institute of Technology Agartala, Agartala, India
| | - Kalyan Gayen
- Department of Chemical engineering, National Institute of Technology Agartala, Agartala, India
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14
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Abstract
The dominant marine filamentous N2 fixer, Trichodesmium, conducts photosynthesis and N2 fixation during the daytime. Because N2 fixation is sensitive to O2, some previous studies suggested that spatial segregation of N2 fixation and photosynthesis is essential in Trichodesmium. However, this hypothesis conflicts with some observations where all the cells contain both photosystems and the N2-fixing enzyme nitrogenase. Here, we construct a systematic model simulating Trichodesmium metabolism, showing that the hypothetical spatial segregation is probably useless in increasing the Trichodesmium growth and N2 fixation, unless substances can efficiently transfer among cells with low loss to the environment. The model suggests that Trichodesmium accumulates fixed carbon in the morning and uses that in respiratory protection to reduce intracellular O2 during the mid-daytime, when photosynthesis is downregulated, allowing the occurrence of N2 fixation. A cell membrane barrier against O2 and alternative non-O2 evolving electron transfer also contribute to maintaining low intracellular O2. Our study provides a mechanism enabling N2 fixation despite the presence of photosynthesis across Trichodesmium. IMPORTANCE The filamentous Trichodesmium is a globally prominent marine nitrogen fixer. A long-standing paradox is that the nitrogen-fixing enzyme nitrogenase is sensitive to oxygen, but Trichodesmium conducts both nitrogen fixation and oxygen-evolving photosynthesis during the daytime. Previous studies using immunoassays reported that nitrogenase was limited in some specialized Trichodesmium cells (termed diazocytes), suggesting the necessity of spatial segregation of nitrogen fixation and photosynthesis. However, attempts using other methods failed to find diazocytes in Trichodesmium, causing controversy on the existence of the spatial segregation. Here, our physiological model shows that Trichodesmium can maintain low intracellular O2 in mid-daytime and achieve feasible nitrogen fixation and growth rates even without the spatial segregation, while the hypothetical spatial segregation might not be useful if substantial loss of substances to the environment occurs when they transfer among the Trichodesmium cells. Our study then suggests a possible mechanism by which Trichodesmium can survive without the spatial segregation.
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15
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Cell death responses to acute high light mediated by non-photochemical quenching in the dinoflagellate Karenia brevis. Sci Rep 2022; 12:14081. [PMID: 35982058 PMCID: PMC9388518 DOI: 10.1038/s41598-022-18056-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/04/2022] [Indexed: 11/09/2022] Open
Abstract
Programmed cell death (PCD) can be induced in microalgae by many abiotic challenges via generation of reactive oxygen species (ROS). Marine phytoplankton live in a highly variable light environment, yet the potential for excess photosynthetically available radiation to trigger PCD has not been examined. On the other hand, photoprotective non-photochemical quenching (NPQ) is hypothesized to counteract intracellular ROS, potentially preventing cell death. The main objective of this study is to investigate high-light-induced death processes and their relationship with photosynthesis in bloom-forming dinoflagellate Karenia brevis. Here, we characterized the prevalence of ROS, caspase-like enzyme activity and cell death as well as photosynthetic status under acute irradiance of 500, 750 or 1000 µmol m-2 s-1. PCD only occurred at the largest light shift. Although depressed photosynthetic capacities and oxidative stress were apparent across the stress gradient, they did not necessarily lead to cell death. NPQ exhibited dose-dependent activation with increasing light stress, which enabled cells to resist or delay PCD. These results highlight the important role of the balance between ROS generation and NPQ activation on determining cell fates in Karenia under acute irradiance stress. This research also provides insights into potential survival strategies and mechanisms of cell loss under a changeable light environment.
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16
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Bourrat P, Doulcier G, Rose CJ, Rainey PB, Hammerschmidt K. Tradeoff breaking as model of evolutionary transitions in individuality and the limits of the fitness-decoupling metaphor. eLife 2022; 11:73715. [PMID: 35975712 PMCID: PMC9470156 DOI: 10.7554/elife.73715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 06/28/2022] [Indexed: 11/22/2022] Open
Abstract
Evolutionary transitions in individuality (ETIs) involve the formation of Darwinian collectives from Darwinian particles. The transition from cells to multicellular life is a prime example. During an ETI, collectives become units of selection in their own right. However, the underlying processes are poorly understood. One observation used to identify the completion of an ETI is an increase in collective-level performance accompanied by a decrease in particle-level performance, for example measured by growth rate. This seemingly counterintuitive dynamic has been referred to as fitness decoupling and has been used to interpret both models and experimental data. Extending and unifying results from the literature, we show that fitness of particles and collectives can never decouple because calculations of fitness performed over appropriate and equivalent time intervals are necessarily the same provided the population reaches a stable collective size distribution. By way of solution, we draw attention to the value of mechanistic approaches that emphasise traits, and tradeoffs among traits, as opposed to fitness. This trait-based approach is sufficient to capture dynamics that underpin evolutionary transitions. In addition, drawing upon both experimental and theoretical studies, we show that while early stages of transitions might often involve tradeoffs among particle traits, later—and critical—stages are likely to involve the rupture of such tradeoffs. Thus, when observed in the context of ETIs, tradeoff-breaking events stand as a useful marker of these transitions.
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Affiliation(s)
| | | | - Caroline J Rose
- Centre d'Écologie Fonctionnelle et Évolutive, CNRS, Montpellier, France
| | - Paul B Rainey
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
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17
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Chen M, Teng W, Zhao L, Han B, Song L, Shu W. Phylogenomics uncovers evolutionary trajectory of nitrogen fixation in Cyanobacteria. Mol Biol Evol 2022; 39:6659242. [PMID: 35946347 PMCID: PMC9435057 DOI: 10.1093/molbev/msac171] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Biological nitrogen fixation (BNF) by cyanobacteria is of significant importance for the Earth’s biogeochemical nitrogen cycle but is restricted to a few genera that do not form monophyletic group. To explore the evolutionary trajectory of BNF and investigate the driving forces of its evolution, we analyze 650 cyanobacterial genomes and compile the database of diazotrophic cyanobacteria based on the presence of nitrogen fixation gene clusters (NFGCs). We report that 266 of 650 examined genomes are NFGC-carrying members, and these potentially diazotrophic cyanobacteria are unevenly distributed across the phylogeny of Cyanobacteria, that multiple independent losses shaped the scattered distribution. Among the diazotrophic cyanobacteria, two types of NFGC exist, with one being ancestral and abundant, which have descended from diazotrophic ancestors, and the other being anaerobe-like and sparse, possibly being acquired from anaerobic microbes through horizontal gene transfer. Interestingly, we illustrate that the origin of BNF in Cyanobacteria coincide with two major evolutionary events. One is the origin of multicellularity of cyanobacteria, and the other is concurrent genetic innovations with massive gene gains and expansions, implicating their key roles in triggering the evolutionary transition from nondiazotrophic to diazotrophic cyanobacteria. Additionally, we reveal that genes involved in accelerating respiratory electron transport (coxABC), anoxygenic photosynthetic electron transport (sqr), as well as anaerobic metabolisms (pfor, hemN, nrdG, adhE) are enriched in diazotrophic cyanobacteria, representing adaptive genetic signatures that underpin the diazotrophic lifestyle. Collectively, our study suggests that multicellularity, together with concurrent genetic adaptations contribute to the evolution of diazotrophic cyanobacteria.
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Affiliation(s)
- Mengyun Chen
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
| | - Wenkai Teng
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, PR China
| | - Liang Zhao
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
| | - Boping Han
- Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou 510632, PR China
| | - Lirong Song
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Science, Hubei 430072, PR China
| | - Wensheng Shu
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
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18
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Limnospira fusiformis harbors dinitrogenase reductase (nifH)-like genes, but does not show N2 fixation activity. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Abstract
Heterocyst differentiation that occurs in some filamentous cyanobacteria, such as Anabaena sp. PCC 7120, provides a unique model for prokaryotic developmental biology. Heterocyst cells are formed in response to combined-nitrogen deprivation and possess a microoxic environment suitable for nitrogen fixation following extensive morphological and physiological reorganization. A filament of Anabaena is a true multicellular organism, as nitrogen and carbon sources are exchanged among different cells and cell types through septal junctions to ensure filament growth. Because heterocysts are terminally differentiated cells and unable to divide, their activity is an altruistic behavior dedicated to providing fixed nitrogen for neighboring vegetative cells. Heterocyst development is also a process of one-dimensional pattern formation, as heterocysts are semiregularly intercalated among vegetative cells. Morphogens form gradients along the filament and interact with each other in a fashion that fits well into the Turing model, a mathematical framework to explain biological pattern formation. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Xiaoli Zeng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China; ,
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China; , .,Institut WUT-AMU, Aix-Marseille Université and Wuhan University of Technology, Wuhan, Hubei, China.,Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
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20
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Twining BS, Baines SB. Luxury iron uptake and storage in pennate diatoms from the equatorial Pacific Ocean. Metallomics 2022; 14:6596291. [PMID: 35641175 DOI: 10.1093/mtomcs/mfac035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/08/2022] [Indexed: 11/13/2022]
Abstract
Iron is a key micronutrient for ocean phytoplankton, and the availability of iron controls primary production and community composition in large regions of the ocean. Pennate diatoms, a phytoplankton group that responds to iron additions in low-iron areas, can have highly variable iron contents, and some groups such as Pseudo-nitzschia are known to use ferritin to store iron for later use. We quantified and mapped the intracellular accumulation of iron by a natural population of Pseudo-nitzschia from the Fe-limited equatorial Pacific Ocean. Forty-eight hours after iron addition, nearly half of accumulated iron was localized in storage bodies adjacent to chloroplasts believed to represent ferritin. Over the subsequent 48 h, stored iron was distributed to the rest of the cell through subsequent growth and division, partially supporting the iron contents of the daughter cells. This study provides a first quantitative view into the cellular trafficking of iron in a globally relevant phytoplankton group and demonstrates the unique capabilities of synchrotron-based element imaging approaches.
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Affiliation(s)
| | - Stephen B Baines
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY
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21
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Zhu Y, Feng Y, Browning TJ, Wen Z, Hughes DJ, Hao Q, Zhang R, Meng Q, Wells ML, Jiang Z, Dissanayake PAKN, Priyadarshani WNC, Shou L, Zeng J, Chai F. Exploring Variability of Trichodesmium Photophysiology Using Multi-Excitation Wavelength Fast Repetition Rate Fluorometry. Front Microbiol 2022; 13:813573. [PMID: 35464918 PMCID: PMC9026164 DOI: 10.3389/fmicb.2022.813573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Fast repetition rate fluorometry (FRRf) allows for rapid non-destructive assessment of phytoplankton photophysiology in situ yet has rarely been applied to Trichodesmium. This gap reflects long-standing concerns that Trichodesmium (and other cyanobacteria) contain pigments that are less effective at absorbing blue light which is often used as the sole excitation source in FRR fluorometers-potentially leading to underestimation of key fluorescence parameters. In this study, we use a multi-excitation FRR fluorometer (equipped with blue, green, and orange LEDs) to investigate photophysiological variability in Trichodesmium assemblages from two sites. Using a multi-LED measurement protocol (447+519+634 nm combined), we assessed maximum photochemical efficiency (F v /F m ), functional absorption cross section of PSII (σ PSII ), and electron transport rates (ETRs) for Trichodesmium assemblages in both the Northwest Pacific (NWP) and North Indian Ocean in the vicinity of Sri Lanka (NIO-SL). Evaluating fluorometer performance, we showed that use of a multi-LED measuring protocol yields a significant increase of F v /F m for Trichodesmium compared to blue-only excitation. We found distinct photophysiological differences for Trichodesmium at both locations with higher average F v /F m as well as lower σ PSII and non-photochemical quenching (NPQ NSV ) observed in the NWP compared to the NIO-SL (Kruskal-Wallis t-test df = 1, p < 0.05). Fluorescence light response curves (FLCs) further revealed differences in ETR response with a lower initial slope (α ETR ) and higher maximum electron turnover rate ( E T R P S I I m a x ) observed for Trichodesmium in the NWP compared to the NIO-SL, translating to a higher averaged light saturation E K (= E T R P S I I m a x /α ETR ) for cells at this location. Spatial variations in physiological parameters were both observed between and within regions, likely linked to nutrient supply and physiological stress. Finally, we applied an algorithm to estimate primary productivity of Trichodesmium using FRRf-derived fluorescence parameters, yielding an estimated carbon-fixation rate ranging from 7.8 to 21.1 mgC mg Chl-a-1 h-1 across this dataset. Overall, our findings demonstrate that capacity of multi-excitation FRRf to advance the application of Chl-a fluorescence techniques in phytoplankton assemblages dominated by cyanobacteria and reveals novel insight into environmental regulation of photoacclimation in natural Trichodesmium populations.
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Affiliation(s)
- Yuanli Zhu
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Yuanyuan Feng
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Thomas J. Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Zuozhu Wen
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - David J. Hughes
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Qiang Hao
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Ruifeng Zhang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Qicheng Meng
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Mark L. Wells
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Darling Marine Center, University of Maine, Walpole, ME, United States
| | - Zhibing Jiang
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - P. A. K. N. Dissanayake
- Department of Oceanography and Marine Geology, Faculty of Fisheries and Marine Sciences and Technology, University of Ruhuna, Matara, Sri Lanka
| | - W. N. C. Priyadarshani
- National Institute of Oceanography and Marine Sciences, National Aquatic Resources Research and Development Agency, Colombo, Sri Lanka
| | - Lu Shou
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Jiangning Zeng
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Fei Chai
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
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22
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Cerdan-Garcia E, Baylay A, Polyviou D, Woodward EMS, Wrightson L, Mahaffey C, Lohan MC, Moore CM, Bibby TS, Robidart JC. Transcriptional responses of Trichodesmium to natural inverse gradients of Fe and P availability. THE ISME JOURNAL 2022; 16:1055-1064. [PMID: 34819612 PMCID: PMC8941076 DOI: 10.1038/s41396-021-01151-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 10/28/2021] [Accepted: 11/01/2021] [Indexed: 12/28/2022]
Abstract
The filamentous diazotrophic cyanobacterium Trichodesmium is responsible for a significant fraction of marine di-nitrogen (N2) fixation. Growth and distribution of Trichodesmium and other diazotrophs in the vast oligotrophic subtropical gyres is influenced by iron (Fe) and phosphorus (P) availability, while reciprocally influencing the biogeochemistry of these nutrients. Here we use observations across natural inverse gradients in Fe and P in the North Atlantic subtropical gyre (NASG) to demonstrate how Trichodesmium acclimates in situ to resource availability. Transcriptomic analysis identified progressive upregulation of known iron-stress biomarker genes with decreasing Fe availability, and progressive upregulation of genes involved in the acquisition of diverse P sources with decreasing P availability, while genes involved in N2 fixation were upregulated at the intersection under moderate Fe and P availability. Enhanced N2 fixation within the Fe and P co-stressed transition region was also associated with a distinct, consistent metabolic profile, including the expression of alternative photosynthetic pathways that potentially facilitate ATP generation required for N2 fixation with reduced net oxygen production. The observed response of Trichodesmium to availability of both Fe and P supports suggestions that these biogeochemically significant organisms employ unique molecular, and thus physiological responses as adaptations to specifically exploit the Fe and P co-limited niche they construct.
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Affiliation(s)
- E Cerdan-Garcia
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK.
| | - A Baylay
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - D Polyviou
- National Oceanography Centre, Southampton, SO14 3ZH, UK
| | | | - L Wrightson
- Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, L69 3BX, UK
| | - C Mahaffey
- Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, L69 3BX, UK
| | - M C Lohan
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - C M Moore
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - T S Bibby
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - J C Robidart
- National Oceanography Centre, Southampton, SO14 3ZH, UK.
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23
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Sarkar S, Mankad J, Padhihar N, Manna MS, Bhowmick TK, Gayen K. Enhancement of growth and biomolecules (carbohydrates, proteins, and chlorophylls) of isolated Chlorella thermophila using optimization tools. Prep Biochem Biotechnol 2022; 52:1173-1189. [PMID: 35234575 DOI: 10.1080/10826068.2022.2033995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The production of multiple products from microalgae is essential for economic sustainability and the knowledge of optimum cultivation conditions for high growth and biomolecule synthesis of a microalgal strain is the prerequisite for its commercial production. In this work, optimization of nutrient concentrations for the cultivation of isolated Chlorella thermophila was performed by manipulating nine nutrients with the objectives of maximization of growth, carbohydrate, protein, and chlorophyll contents. Experiments were designed and effects of the parameters were studied using Taguchi orthogonal array (TOA). Experimental results of TOA were used for modeling artificial neural networks (ANN) followed by the optimization using genetic algorithm (GA) to find global optimal solutions. Results showed an increase of 36, 88, 36, and 88% for growth, carbohydrates, proteins, and chlorophylls, respectively, at optimal combinations of parameters given by TOA. Results obtained through the ANN-GA optimization were 9, 10, and 3% more compared to the TOA for biomass, carbohydrates, and chlorophylls, respectively with experimental verification. Nitrates and bicarbonate were found to play the most pivotal role in biomass and biomolecule synthesis of the isolated microalgal strain. Results of the current investigation can be used in the industrial scale-up for the production of multiple products using the biorefinery approach.
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Affiliation(s)
- Sambit Sarkar
- Department of Chemical Engineering, National Institute of Technology Agartala, Agartala, India
| | - Jaivik Mankad
- Department of Chemical Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| | - Nitin Padhihar
- Department of Chemical Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| | - Mriganka Sekhar Manna
- Department of Chemical Engineering, National Institute of Technology Agartala, Agartala, India
| | - Tridib Kumar Bhowmick
- Department of Bioengineering, National Institute of Technology Agartala, Agartala, India
| | - Kalyan Gayen
- Department of Chemical Engineering, National Institute of Technology Agartala, Agartala, India
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24
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Held NA, Waterbury JB, Webb EA, Kellogg RM, McIlvin MR, Jakuba M, Valois FW, Moran DM, Sutherland KM, Saito MA. Dynamic diel proteome and daytime nitrogenase activity supports buoyancy in the cyanobacterium Trichodesmium. Nat Microbiol 2022; 7:300-311. [PMID: 35013592 PMCID: PMC10288448 DOI: 10.1038/s41564-021-01028-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 11/17/2021] [Indexed: 12/13/2022]
Abstract
Cyanobacteria of the genus Trichodesmium provide about 80 Tg of fixed nitrogen to the surface ocean per year and contribute to marine biogeochemistry, including the sequestration of carbon dioxide. Trichodesmium fixes nitrogen in the daylight, despite the incompatibility of the nitrogenase enzyme with oxygen produced during photosynthesis. While the mechanisms protecting nitrogenase remain unclear, all proposed strategies require considerable resource investment. Here we identify a crucial benefit of daytime nitrogen fixation in Trichodesmium spp. that may counteract these costs. We analysed diel proteomes of cultured and field populations of Trichodesmium in comparison with the marine diazotroph Crocosphaera watsonii WH8501, which fixes nitrogen at night. Trichodesmium's proteome is extraordinarily dynamic and demonstrates simultaneous photosynthesis and nitrogen fixation, resulting in balanced particulate organic carbon and particulate organic nitrogen production. Unlike Crocosphaera, which produces large quantities of glycogen as an energy store for nitrogenase, proteomic evidence is consistent with the idea that Trichodesmium reduces the need to produce glycogen by supplying energy directly to nitrogenase via soluble ferredoxin charged by the photosynthesis protein PsaC. This minimizes ballast associated with glycogen, reducing cell density and decreasing sinking velocity, thus supporting Trichodesmium's niche as a buoyant, high-light-adapted colony forming cyanobacterium. To occupy its niche of simultaneous nitrogen fixation and photosynthesis, Trichodesmium appears to be a conspicuous consumer of iron, and has therefore developed unique iron-acquisition strategies, including the use of iron-rich dust. Particle capture by buoyant Trichodesmium colonies may increase the residence time and degradation of mineral iron in the euphotic zone. These findings describe how cellular biochemistry defines and reinforces the ecological and biogeochemical function of these keystone marine diazotrophs.
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Affiliation(s)
- Noelle A Held
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Environmental Systems Science, ETH, Zurich, Switzerland
| | - John B Waterbury
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Eric A Webb
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Riss M Kellogg
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew R McIlvin
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Michael Jakuba
- Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Frederica W Valois
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Dawn M Moran
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Kevin M Sutherland
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
| | - Mak A Saito
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
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25
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Wang S, Koedooder C, Zhang F, Kessler N, Eichner M, Shi D, Shaked Y. Colonies of the marine cyanobacterium Trichodesmium optimize dust utilization by selective collection and retention of nutrient-rich particles. iScience 2022; 25:103587. [PMID: 35005537 PMCID: PMC8718973 DOI: 10.1016/j.isci.2021.103587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 10/01/2021] [Accepted: 12/06/2021] [Indexed: 12/11/2022] Open
Abstract
Trichodesmium, a globally important, N2-fixing, and colony-forming cyanobacterium, employs multiple pathways for acquiring nutrients from air-borne dust, including active dust collection. Once concentrated within the colony core, dust can supply Trichodesmium with nutrients. Recently, we reported a selectivity in particle collection enabling Trichodesmium to center iron-rich minerals and optimize its nutrient utilization. In this follow-up study we examined if colonies select Phosphorus (P) minerals. We incubated 1,200 Trichodesmium colonies from the Red Sea with P-free CaCO3, P-coated CaCO3, and dust, over an entire bloom season. These colonies preferably interacted, centered, and retained P-coated CaCO3 compared with P-free CaCO3. In both studies, Trichodesmium clearly favored dust over all other particles tested, whereas nutrient-free particles were barely collected or retained, indicating that the colonies sense the particle composition and preferably collect nutrient-rich particles. This unique ability contributes to Trichodesmium's current ecological success and may assist it to flourish in future warmer oceans. Natural Trichodesmium colonies collect and maintain dust within their colony core Using synthetic particles we tested if colonies select the particles they collect Colonies selectively collect and retain nutrient-rich over nutrient-free particles Selective collection of particles optimizes their nutrient acquisition from dust
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Affiliation(s)
- Siyuan Wang
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Coco Koedooder
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel.,Israel Limnology and Oceanography Research, Haifa, Israel
| | - Futing Zhang
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel.,State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Nivi Kessler
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Meri Eichner
- Laboratory of Photosynthesis, Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
| | - Dalin Shi
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Yeala Shaked
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
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26
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Coming full circle on diazotrophy in the marine cyanobacterium Trichodesmium. Proc Natl Acad Sci U S A 2021; 118:2117967118. [PMID: 34785598 DOI: 10.1073/pnas.2117967118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2021] [Indexed: 11/18/2022] Open
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27
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Landolfi A, Prowe AEF, Pahlow M, Somes CJ, Chien CT, Schartau M, Koeve W, Oschlies A. Can Top-Down Controls Expand the Ecological Niche of Marine N 2 Fixers? Front Microbiol 2021; 12:690200. [PMID: 34489886 PMCID: PMC8416505 DOI: 10.3389/fmicb.2021.690200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/05/2021] [Indexed: 01/12/2023] Open
Abstract
The ability of marine diazotrophs to fix dinitrogen gas (N2) is one of the most influential yet enigmatic processes in the ocean. With their activity diazotrophs support biological production by fixing about 100–200 Tg N/year and turning otherwise unavailable dinitrogen into bioavailable nitrogen (N), an essential limiting nutrient. Despite their important role, the factors that control the distribution of diazotrophs and their ability to fix N2 are not fully elucidated. We discuss insights that can be gained from the emerging picture of a wide geographical distribution of marine diazotrophs and provide a critical assessment of environmental (bottom-up) versus trophic (top-down) controls. We expand a simplified theoretical framework to understand how top-down control affects competition for resources that determine ecological niches. Selective mortality, mediated by grazing or viral-lysis, on non-fixing phytoplankton is identified as a critical process that can broaden the ability of diazotrophs to compete for resources in top-down controlled systems and explain an expanded ecological niche for diazotrophs. Our simplified analysis predicts a larger importance of top-down control on competition patterns as resource levels increase. As grazing controls the faster growing phytoplankton, coexistence of the slower growing diazotrophs can be established. However, these predictions require corroboration by experimental and field data, together with the identification of specific traits of organisms and associated trade-offs related to selective top-down control. Elucidation of these factors could greatly improve our predictive capability for patterns and rates of marine N2 fixation. The susceptibility of this key biogeochemical process to future changes may not only be determined by changes in environmental conditions but also via changes in the ecological interactions.
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Affiliation(s)
- Angela Landolfi
- Institute of Marine Sciences, National Research Council, Rome, Italy.,Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - A E Friederike Prowe
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Markus Pahlow
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Christopher J Somes
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Chia-Te Chien
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Markus Schartau
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Wolfgang Koeve
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Andreas Oschlies
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
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28
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Gradoville MR, Cabello AM, Wilson ST, Turk-Kubo KA, Karl DM, Zehr JP. Light and depth dependency of nitrogen fixation by the non-photosynthetic, symbiotic cyanobacterium UCYN-A. Environ Microbiol 2021; 23:4518-4531. [PMID: 34227720 PMCID: PMC9291983 DOI: 10.1111/1462-2920.15645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/28/2022]
Abstract
The symbiotic cyanobacterium UCYN‐A is one of the most globally abundant marine dinitrogen (N2)‐fixers, but cultures have not been available and its biology and ecology are poorly understood. We used cultivation‐independent approaches to investigate how UCYN‐A single‐cell N2 fixation rates (NFRs) and nifH gene expression vary as a function of depth and photoperiod. Twelve‐hour day/night incubations showed that UCYN‐A only fixed N2 during the day. Experiments conducted using in situ arrays showed a light‐dependence of NFRs by the UCYN‐A symbiosis, with the highest rates in surface waters (5–45 m) and lower rates at depth (≥ 75 m). Analysis of NFRs versus in situ light intensity yielded a light saturation parameter (Ik) for UCYN‐A of 44 μmol quanta m−2 s−1. This is low compared with other marine diazotrophs, suggesting an ecological advantage for the UCYN‐A symbiosis under low‐light conditions. In contrast to cell‐specific NFRs, nifH gene‐specific expression levels did not vary with depth, indicating that light regulates N2 fixation by UCYN‐A through processes other than transcription, likely including host–symbiont interactions. These results offer new insights into the physiology of the UCYN‐A symbiosis in the subtropical North Pacific Ocean and provide clues to the environmental drivers of its global distributions.
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Affiliation(s)
- Mary R Gradoville
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Ana M Cabello
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA.,Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, Fuengirola, Málaga, Spain
| | - Samuel T Wilson
- Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Kendra A Turk-Kubo
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - David M Karl
- Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
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29
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Elucidation of trophic interactions in an unusual single-cell nitrogen-fixing symbiosis using metabolic modeling. PLoS Comput Biol 2021; 17:e1008983. [PMID: 33961619 PMCID: PMC8143392 DOI: 10.1371/journal.pcbi.1008983] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 05/24/2021] [Accepted: 04/20/2021] [Indexed: 12/15/2022] Open
Abstract
Marine nitrogen-fixing microorganisms are an important source of fixed nitrogen in oceanic ecosystems. The colonial cyanobacterium Trichodesmium and diatom symbionts were thought to be the primary contributors to oceanic N2 fixation until the discovery of the unusual uncultivated symbiotic cyanobacterium UCYN-A (Candidatus Atelocyanobacterium thalassa). UCYN-A has atypical metabolic characteristics lacking the oxygen-evolving photosystem II, the tricarboxylic acid cycle, the carbon-fixation enzyme RuBisCo and de novo biosynthetic pathways for a number of amino acids and nucleotides. Therefore, it is obligately symbiotic with its single-celled haptophyte algal host. UCYN-A receives fixed carbon from its host and returns fixed nitrogen, but further insights into this symbiosis are precluded by both UCYN-A and its host being uncultured. In order to investigate how this syntrophy is coordinated, we reconstructed bottom-up genome-scale metabolic models of UCYN-A and its algal partner to explore possible trophic scenarios, focusing on nitrogen fixation and biomass synthesis. Since both partners are uncultivated and only the genome sequence of UCYN-A is available, we used the phylogenetically related Chrysochromulina tobin as a proxy for the host. Through the use of flux balance analysis (FBA), we determined the minimal set of metabolites and biochemical functions that must be shared between the two organisms to ensure viability and growth. We quantitatively investigated the metabolic characteristics that facilitate daytime N2 fixation in UCYN-A and possible oxygen-scavenging mechanisms needed to create an anaerobic environment to allow nitrogenase to function. This is the first application of an FBA framework to examine the tight metabolic coupling between uncultivated microbes in marine symbiotic communities and provides a roadmap for future efforts focusing on such specialized systems. Reduction of dinitrogen gas to biologically useful forms via nitrogen fixation is a key component of the biogeochemical cycle. In the marine environment, the cyanobacteria UCYN-A (Candidatus Atelocyanobacterium thalassa) has been found to be a primary contributor to biological nitrogen fixation at a global scale. UCYN-A exhibits a highly streamlined genome which lacks genes coding for essential cyanobacterial processes such as the energy-generating TCA cycle, oxygen-producing photosystem II, the carbon-fixing RuBisCo and de novo production pathways for numerous amino acids and nucleotides. Thus, it exists in a symbiosis with unicellular planktonic algae where it exchanges fixed nitrogen for fixed carbon with its host. However, both UCYN-A and its symbiotic partner remain uncultured under laboratory conditions. This necessitates implementing a computational approach to glean insights into UCYN-A’s unique physiology and metabolic processes governing the symbiotic association. To this end, we develop a constraints-based framework that infers all possible trophic scenarios consistent with the observed data. Possible mechanisms employed by UCYN-A to accommodate diazotrophy with daytime carbon fixation by the host (i.e., two mutually incompatible processes) are also elucidated. We envision that the developed framework using UCYN-A and its algal host will be used as a roadmap and motivate the study of similarly unique microbial systems in the future.
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30
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He H, Miao R, Huang L, Jiang H, Cheng Y. Vegetative cells may perform nitrogen fixation function under nitrogen deprivation in Anabaena sp. strain PCC 7120 based on genome-wide differential expression analysis. PLoS One 2021; 16:e0248155. [PMID: 33662009 PMCID: PMC7932525 DOI: 10.1371/journal.pone.0248155] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 02/20/2021] [Indexed: 11/25/2022] Open
Abstract
Nitrogen assimilation is strictly regulated in cyanobacteria. In an inorganic nitrogen-deficient environment, some vegetative cells of the cyanobacterium Anabaena differentiate into heterocysts. We assessed the photosynthesis and nitrogen-fixing capacities of heterocysts and vegetative cells, respectively, at the transcriptome level. RNA extracted from nitrogen-replete vegetative cells (NVs), nitrogen-deprived vegetative cells (NDVs), and nitrogen-deprived heterocysts (NDHs) in Anabaena sp. strain PCC 7120 was evaluated by transcriptome sequencing. Paired comparisons of NVs vs. NDHs, NVs vs. NDVs, and NDVs vs. NDHs revealed 2,044 differentially expressed genes (DEGs). Kyoto Encyclopedia of Genes and Genomes enrichment analysis of the DEGs showed that carbon fixation in photosynthetic organisms and several nitrogen metabolism-related pathways were significantly enriched. Synthesis of Gvp (Gas vesicle synthesis protein gene) in NVs was blocked by nitrogen deprivation, which may cause Anabaena cells to sink and promote nitrogen fixation under anaerobic conditions; in contrast, heterocysts may perform photosynthesis under nitrogen deprivation conditions, whereas the nitrogen fixation capability of vegetative cells was promoted by nitrogen deprivation. Immunofluorescence analysis of nitrogenase iron protein suggested that the nitrogen fixation capability of vegetative cells was promoted by nitrogen deprivation. Our findings provide insight into the molecular mechanisms underlying nitrogen fixation and photosynthesis in vegetative cells and heterocysts at the transcriptome level. This study provides a foundation for further functional verification of heterocyst growth, differentiation, and water bloom control.
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Affiliation(s)
- Hongli He
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Runyu Miao
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Lilong Huang
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Hongshan Jiang
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
| | - Yunqing Cheng
- Jilin Provincial Key Laboratory of Plant Resource Science and Green Production, Jilin Normal University, Siping, Jilin Province, China
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31
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Circadian clock-controlled gene expression in co-cultured, mat-forming cyanobacteria. Sci Rep 2020; 10:14095. [PMID: 32839512 PMCID: PMC7445270 DOI: 10.1038/s41598-020-69294-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 05/11/2020] [Indexed: 11/08/2022] Open
Abstract
Natural coastal microbial mat communities are multi-species assemblages that experience fluctuating environmental conditions and are shaped by resource competition as well as by cooperation. Laboratory studies rarely address the natural complexity of microbial communities but are usually limited to homogeneous mono-cultures of key species grown in liquid media. The mat-forming filamentous cyanobacteria Lyngbya aestuarii and Coleofasciculus chthonoplastes were cultured under different conditions to investigate the expression of circadian clock genes and genes that are under their control. The cyanobacteria were grown in liquid medium or on a solid substrate (glass beads) as mono- or as co-cultures under a light-dark regime and subsequently transferred to continuous light. TaqMan-probe based qPCR assays were used to quantify the expression of the circadian clock genes kaiA, kaiB, and kaiC, and of four genes that are under control of the circadian clock: psbA, nifH, ftsZ, and prx. Expression of kaiABC was influenced by co-culturing the cyanobacteria and whether grown in liquid media or on a solid substrate. Free-running (i.e. under continuous light) expression cycle of the circadian clock genes was observed in L. aestuarii but not in C. chthonoplastes. In the former organism, maximum expression of psbA and nifH occurred temporally separated and independent of the light regime, although the peak shifted in time when the culture was transferred to continuous illumination. Although functionally similar, both species of cyanobacteria displayed different 24-h transcriptional patterns in response to the experimental treatments, suggesting that their circadian clocks have adapted to different life strategies adopted by these mat-forming cyanobacteria.
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32
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Soumare A, Diedhiou AG, Thuita M, Hafidi M, Ouhdouch Y, Gopalakrishnan S, Kouisni L. Exploiting Biological Nitrogen Fixation: A Route Towards a Sustainable Agriculture. PLANTS 2020; 9:plants9081011. [PMID: 32796519 PMCID: PMC7464700 DOI: 10.3390/plants9081011] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/08/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022]
Abstract
For all living organisms, nitrogen is an essential element, while being the most limiting in ecosystems and for crop production. Despite the significant contribution of synthetic fertilizers, nitrogen requirements for food production increase from year to year, while the overuse of agrochemicals compromise soil health and agricultural sustainability. One alternative to overcome this problem is biological nitrogen fixation (BNF). Indeed, more than 60% of the fixed N on Earth results from BNF. Therefore, optimizing BNF in agriculture is more and more urgent to help meet the demand of the food production needs for the growing world population. This optimization will require a good knowledge of the diversity of nitrogen-fixing microorganisms, the mechanisms of fixation, and the selection and formulation of efficient N-fixing microorganisms as biofertilizers. Good understanding of BNF process may allow the transfer of this ability to other non-fixing microorganisms or to non-leguminous plants with high added value. This minireview covers a brief history on BNF, cycle and mechanisms of nitrogen fixation, biofertilizers market value, and use of biofertilizers in agriculture. The minireview focuses particularly on some of the most effective microbial products marketed to date, their efficiency, and success-limiting in agriculture. It also highlights opportunities and difficulties of transferring nitrogen fixation capacity in cereals.
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Affiliation(s)
- Abdoulaye Soumare
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
- Laboratoire Commun de Microbiologie (LCM) IRD/ISRA/UCAD, Centre de Recherche de Bel Air, Dakar 1386, Senegal
- Correspondence: (A.S.); (A.G.D.)
| | - Abdala G. Diedhiou
- Laboratoire Commun de Microbiologie (LCM) IRD/ISRA/UCAD, Centre de Recherche de Bel Air, Dakar 1386, Senegal
- Département de Biologie Végétale, Faculté des Sciences et Techniques, Université Cheikh Anta Diop (UCAD) de Dakar, Dakar 1386, Senegal
- Centre d’Excellence Africain en Agriculture pour la Sécurité Alimentaire et Nutritionnelle (CEA-AGRISAN), UCAD, Dakar 18524, Senegal
- Correspondence: (A.S.); (A.G.D.)
| | - Moses Thuita
- International Institute of Tropical Agriculture, Nairobi PO BOX 30772-00100, Kenya;
| | - Mohamed Hafidi
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
- Laboratory of Microbial Biotechnologies, Agrosciences and Environment, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco
| | - Yedir Ouhdouch
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
- Laboratory of Microbial Biotechnologies, Agrosciences and Environment, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco
| | | | - Lamfeddal Kouisni
- AgroBioSciences Program, Mohammed VI Polytechnic University (UM6P), Benguerir 43150, Morocco; (M.H.); (Y.O.); (L.K.)
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33
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Zhang X, Ward BB, Sigman DM. Global Nitrogen Cycle: Critical Enzymes, Organisms, and Processes for Nitrogen Budgets and Dynamics. Chem Rev 2020; 120:5308-5351. [DOI: 10.1021/acs.chemrev.9b00613] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xinning Zhang
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Bess B. Ward
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Daniel M. Sigman
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
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34
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Wang L, Xing P, Li H, Zhou L, Wu QL. Distinct Intra-lake Heterogeneity of Diazotrophs in a Deep Oligotrophic Mountain Lake. MICROBIAL ECOLOGY 2020; 79:840-852. [PMID: 31811330 DOI: 10.1007/s00248-019-01461-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
To date, little is known about the diazotrophs in freshwater ecosystems. In this study, we examined the diversity, abundance, and distribution of the diazotrophic community in the deep oligotrophic Lake Fuxian using high-throughput sequencing and quantitative polymerase chain reaction of nifH genes. Our results showed that the diazotrophs in Lake Fuxian were diverse and were distributed among Proteobacteria, Planctomycetes, Cyanobacteria, Verrucomicrobia, Bacteroidetes, Chloroflexi, and other unclassified environmental sequences. For the first time, it is found that Bacteroidetes and Planctomycetes harbor diazotrophs in freshwater ecosystems. The diazotrophic community compositions were significantly different between the littoral and pelagic zones in the surface layer, and they also changed dramatically along the vertical profile. High diazotrophic abundance and diversity were mostly observed in the surface littoral zone, and overall, a significant relationship between nifH gene richness and abundance was observed. The water turbidity, nitrite, and phosphorus were the most important factors explaining the spatial changes in diversity and abundances of this important functional group. The two most dominant operational taxonomic units belonging to Betaroproteobacteria and Planctomycetes demonstrated opposite distribution patterns in abundance that were driven by non-overlapping environmental factors. This study is by far the first to uncover the high diversity and intra-lake heterogeneity of diazotrophs in a freshwater lake and illuminate the controlling factors. It provides the probability of the co-occurrence of N2 fixation and N-loss in particles.
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Affiliation(s)
- Lina Wang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Peng Xing
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China.
| | - Huabing Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
| | - Lijun Zhou
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
| | - Qinglong L Wu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China.
- Sino-Danish Center for Science and Education, University of Chinese Academy of Sciences, Beijing, China.
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35
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Heterogeneous nitrogen fixation rates confer energetic advantage and expanded ecological niche of unicellular diazotroph populations. Commun Biol 2020; 3:172. [PMID: 32286494 PMCID: PMC7156374 DOI: 10.1038/s42003-020-0894-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/13/2020] [Indexed: 11/23/2022] Open
Abstract
Nitrogen fixing plankton provide nitrogen to fuel marine ecosystems and biogeochemical cycles but the factors that constrain their growth and habitat remain poorly understood. Here we investigate the importance of metabolic specialization in unicellular diazotroph populations, using laboratory experiments and model simulations. In clonal cultures of Crocosphaera watsonii and Cyanothece sp. spiked with 15N2, cellular 15N enrichment developed a bimodal distribution within colonies, indicating that N2 fixation was confined to a subpopulation. In a model of population metabolism, heterogeneous nitrogen (N2) fixation rates substantially reduce the respiration rate required to protect nitrogenase from O2. The energy savings from metabolic specialization is highest at slow growth rates, allowing populations to survive in deeper waters where light is low but nutrients are high. Our results suggest that heterogeneous N2 fixation in colonies of unicellular diazotrophs confers an energetic advantage that expands the ecological niche and may have facilitated the evolution of multicellular diazotrophs. Takako Masuda et al. show that individual cells in clonal populations of Crocosphaera watsonii and Cyanothece sp exhibit varied nitrogen fixation rates. This heterogeneity within the population decreases the energetic cost of respiration and expands the viable habitats for these unicellular diazotrophs.
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36
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Tilstra A, El-Khaled YC, Roth F, Rädecker N, Pogoreutz C, Voolstra CR, Wild C. Denitrification Aligns with N 2 Fixation in Red Sea Corals. Sci Rep 2019; 9:19460. [PMID: 31857601 PMCID: PMC6923481 DOI: 10.1038/s41598-019-55408-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 11/26/2019] [Indexed: 12/27/2022] Open
Abstract
Denitrification may potentially alleviate excess nitrogen (N) availability in coral holobionts to maintain a favourable N to phosphorous ratio in the coral tissue. However, little is known about the abundance and activity of denitrifiers in the coral holobiont. The present study used the nirS marker gene as a proxy for denitrification potential along with measurements of denitrification rates in a comparative coral taxonomic framework from the Red Sea: Acropora hemprichii, Millepora dichotoma, and Pleuractis granulosa. Relative nirS gene copy numbers associated with the tissues of these common corals were assessed and compared with denitrification rates on the holobiont level. In addition, dinitrogen (N2) fixation rates, Symbiodiniaceae cell density, and oxygen evolution were assessed to provide an environmental context for denitrification. We found that relative abundances of the nirS gene were 16- and 17-fold higher in A. hemprichii compared to M. dichotoma and P. granulosa, respectively. In concordance, highest denitrification rates were measured in A. hemprichii, followed by M. dichotoma and P. granulosa. Denitrification rates were positively correlated with N2 fixation rates and Symbiodiniaceae cell densities. Our results suggest that denitrification may counterbalance the N input from N2 fixation in the coral holobiont, and we hypothesize that these processes may be limited by photosynthates released by the Symbiodiniaceae.
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Affiliation(s)
- Arjen Tilstra
- Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, 28359, Germany.
| | - Yusuf C El-Khaled
- Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, 28359, Germany
| | - Florian Roth
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Nils Rädecker
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Claudia Pogoreutz
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Christian R Voolstra
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
- Department of Biology, University of Konstanz, Konstanz, 78464, Germany
| | - Christian Wild
- Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, 28359, Germany
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37
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Gardner JJ, Hodge BMS, Boyle NR. Multiscale Multiobjective Systems Analysis (MiMoSA): an advanced metabolic modeling framework for complex systems. Sci Rep 2019; 9:16948. [PMID: 31740694 PMCID: PMC6861322 DOI: 10.1038/s41598-019-53188-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/29/2019] [Indexed: 12/11/2022] Open
Abstract
In natural environments, cells live in complex communities and experience a high degree of heterogeneity internally and in the environment. Even in 'ideal' laboratory environments, cells can experience a high degree of heterogeneity in their environments. Unfortunately, most of the metabolic modeling approaches that are currently used assume ideal conditions and that each cell is identical, limiting their application to pure cultures in well-mixed vessels. Here we describe our development of Multiscale Multiobjective Systems Analysis (MiMoSA), a metabolic modeling approach that can track individual cells in both space and time, track the diffusion of nutrients and light and the interaction of cells with each other and the environment. As a proof-of concept study, we used MiMoSA to model the growth of Trichodesmium erythraeum, a filamentous diazotrophic cyanobacterium which has cells with two distinct metabolic modes. The use of MiMoSA significantly improves our ability to predictively model metabolic changes and phenotype in more complex cell cultures.
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Affiliation(s)
- Joseph J Gardner
- Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois St., Golden, CO, 80403, USA
| | - Bri-Mathias S Hodge
- Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois St., Golden, CO, 80403, USA.,National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA.,Electrical, Computer and Energy Engineering, 425 UCB, University of Colorado, Boulder, CO, 80309, USA
| | - Nanette R Boyle
- Chemical & Biological Engineering, Colorado School of Mines, 1613 Illinois St., Golden, CO, 80403, USA.
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Allen JF, Thake B, Martin WF. Nitrogenase Inhibition Limited Oxygenation of Earth's Proterozoic Atmosphere. TRENDS IN PLANT SCIENCE 2019; 24:1022-1031. [PMID: 31447302 DOI: 10.1016/j.tplants.2019.07.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/10/2019] [Accepted: 07/10/2019] [Indexed: 05/24/2023]
Abstract
Cyanobacteria produced the oxygen that began to accumulate on Earth 2.5 billion years ago, at the dawn of the Proterozoic Eon. By 2.4 billion years ago, the Great Oxidation Event (GOE) marked the onset of an atmosphere containing oxygen. The oxygen content of the atmosphere then remained low for almost 2 billion years. Why? Nitrogenase, the sole nitrogen-fixing enzyme on Earth, controls the entry of molecular nitrogen into the biosphere. Nitrogenase is inhibited in air containing more than 2% oxygen: the concentration of oxygen in the Proterozoic atmosphere. We propose that oxygen inhibition of nitrogenase limited Proterozoic global primary production. Oxygen levels increased when upright terrestrial plants isolated nitrogen fixation in soil from photosynthetic oxygen production in shoots and leaves.
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Affiliation(s)
- John F Allen
- Research Department of Genetics, Evolution and Environment, Darwin Building, University College London, Gower Street, London WC1E 6BT, UK.
| | - Brenda Thake
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - William F Martin
- Institute of Molecular Evolution, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany
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Zhang F, Hong H, Kranz SA, Shen R, Lin W, Shi D. Proteomic responses to ocean acidification of the marine diazotroph Trichodesmium under iron-replete and iron-limited conditions. PHOTOSYNTHESIS RESEARCH 2019; 142:17-34. [PMID: 31077001 DOI: 10.1007/s11120-019-00643-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/30/2019] [Indexed: 05/19/2023]
Abstract
Growth and dinitrogen (N2) fixation of the globally important diazotrophic cyanobacteria Trichodesmium are often limited by iron (Fe) availability in surface seawaters. To systematically examine the combined effects of Fe limitation and ocean acidification (OA), T. erythraeum strain IMS101 was acclimated to both Fe-replete and Fe-limited concentrations under ambient and acidified conditions. Proteomic analysis showed that OA affected a wider range of proteins under Fe-limited conditions compared to Fe-replete conditions. OA also led to an intensification of Fe deficiency in key cellular processes (e.g., photosystem I and chlorophyll a synthesis) in already Fe-limited T. erythraeum. This is a result of reallocating Fe from these processes to Fe-rich nitrogenase to compensate for the suppressed N2 fixation. To alleviate the Fe shortage, the diazotroph adopts a series of Fe-based economic strategies (e.g., upregulating Fe acquisition systems for organically complexed Fe and particulate Fe, replacing ferredoxin by flavodoxin, and using alternative electron flow pathways to produce ATP). This was more pronounced under Fe-limited-OA conditions than under Fe limitation only. Consequently, OA resulted in a further decrease of N2- and carbon-fixation rates in Fe-limited T. erythraeum. In contrast, Fe-replete T. erythraeum induced photosystem I (PSI) expression to potentially enhance the PSI cyclic flow for ATP production to meet the higher demand for energy to cope with the stress caused by OA. Our study provides mechanistic insight into the holistic response of the globally important N2-fixing marine cyanobacteria Trichodesmium to acidified and Fe-limited conditions of future oceans.
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Affiliation(s)
- Futing Zhang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Haizheng Hong
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, Fujian, People's Republic of China
- College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Sven A Kranz
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Rong Shen
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Wenfang Lin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Dalin Shi
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China.
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, Fujian, People's Republic of China.
- College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People's Republic of China.
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Mechanistic Model for the Coexistence of Nitrogen Fixation and Photosynthesis in Marine Trichodesmium. mSystems 2019; 4:4/4/e00210-19. [PMID: 31387928 PMCID: PMC6687940 DOI: 10.1128/msystems.00210-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trichodesmium is a major nitrogen-fixing cyanobacterium and exerts a significant influence on the oceanic nitrogen cycle. It is also a widely used model organism in laboratory studies. Since the nitrogen-fixing enzyme nitrogenase is extremely sensitive to oxygen, how these surface-dwelling plankton manage the two conflicting processes of nitrogen fixation and photosynthesis has been a long-standing question. In this study, we developed a simple model of metabolic fluxes of Trichodesmium capturing observed daily cycles of photosynthesis, nitrogen fixation, and boundary layer oxygen concentrations. The model suggests that forming a chain of cells for spatially segregating nitrogen fixation and photosynthesis is essential but not sufficient. It also requires a barrier against oxygen diffusion and high rates of oxygen scavenging by respiration. Finally, the model indicates that the life span of intracellular oxygen is extremely short, thus enabling cells to instantly create a low-oxygen environment upon deactivation of photosynthesis. The cyanobacterium Trichodesmium is an important contributor of new nitrogen (N) to the surface ocean, but its strategies for protecting the nitrogenase enzyme from inhibition by oxygen (O2) remain poorly understood. We present a dynamic physiological model to evaluate hypothesized conditions that would allow Trichodesmium to carry out its two conflicting metabolic processes of N2 fixation and photosynthesis. First, the model indicates that managing cellular O2 to permit N2 fixation requires high rates of respiratory O2 consumption. The energetic cost amounts to ∼80% of daily C fixation, comparable to the observed diminution of the growth rate of Trichodesmium relative to other phytoplankton. Second, by forming a trichome of connected cells, Trichodesmium can segregate N2 fixation from photosynthesis. The transfer of stored C to N-fixing cells fuels the respiratory O2 consumption that protects nitrogenase, while the reciprocal transfer of newly fixed N to C-fixing cells supports cellular growth. Third, despite Trichodesmium lacking the structural barrier found in heterocystous species, the model predicts low diffusivity of cell membranes, a function that may be explained by the presence of Gram-negative membrane, production of extracellular polysaccharide substances (EPS), and “buffer cells” that intervene between N2-fixing and photosynthetic cells. Our results suggest that all three factors—respiratory protection, trichome formation, and diffusion barriers—represent essential strategies that, despite their energetic costs, facilitate the growth of Trichodesmium in the oligotrophic aerobic ocean and permit it to be a major source of new reactive nitrogen. IMPORTANCETrichodesmium is a major nitrogen-fixing cyanobacterium and exerts a significant influence on the oceanic nitrogen cycle. It is also a widely used model organism in laboratory studies. Since the nitrogen-fixing enzyme nitrogenase is extremely sensitive to oxygen, how these surface-dwelling plankton manage the two conflicting processes of nitrogen fixation and photosynthesis has been a long-standing question. In this study, we developed a simple model of metabolic fluxes of Trichodesmium capturing observed daily cycles of photosynthesis, nitrogen fixation, and boundary layer oxygen concentrations. The model suggests that forming a chain of cells for spatially segregating nitrogen fixation and photosynthesis is essential but not sufficient. It also requires a barrier against oxygen diffusion and high rates of oxygen scavenging by respiration. Finally, the model indicates that the life span of intracellular oxygen is extremely short, thus enabling cells to instantly create a low-oxygen environment upon deactivation of photosynthesis.
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Eichner M, Basu S, Gledhill M, de Beer D, Shaked Y. Hydrogen Dynamics in Trichodesmium Colonies and Their Potential Role in Mineral Iron Acquisition. Front Microbiol 2019; 10:1565. [PMID: 31354665 PMCID: PMC6636555 DOI: 10.3389/fmicb.2019.01565] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 06/24/2019] [Indexed: 12/14/2022] Open
Abstract
N2-fixing cyanobacteria mediate H2 fluxes through the opposing processes of H2 evolution, which is a by-product of the N2 fixation reaction, and H2 uptake, which is driven by uptake hydrogenases. Here, we used microelectrodes to characterize H2 and O2 dynamics in single natural colonies of the globally important N2 fixer Trichodesmium collected from the Gulf of Eilat. We observed gradually changing H2 dynamics over the course of the day, including both net H2 evolution and net H2 uptake, as well as large differences in H2 fluxes between individual colonies. Net H2 uptake was observed in colonies amended with H2 in both light and dark. Net H2 evolution was recorded in the light only, reflecting light-dependent N2 fixation coupled to H2 evolution. Both net H2 evolution and H2 uptake rates were higher before 2 pm than later in the day. These pronounced H2 dynamics in the morning coincided with strong net O2 uptake and the previously reported diel peak in N2 fixation. Later in the afternoon, when photosynthesis rates determined by O2 measurements were highest, and N2 fixation rates decrease according to previous studies, the H2 dynamics were also less pronounced. Thus, the observed diel variations in H2 dynamics reflect diel changes in the rates of O2 consumption and N2 fixation. Remarkably, the presence of H2 strongly stimulated the uptake of mineral iron by natural colonies. The magnitude of this effect was dependent on the time of day, with the strongest response in incubations that started before 2 pm, i.e., the period that covered the time of highest uptake hydrogenase activity. Based on these findings, we propose that by providing an electron source for mineral iron reduction in N2-fixing cells, H2 may contribute to iron uptake in Trichodesmium colonies.
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Affiliation(s)
- Meri Eichner
- Microsensor Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Subhajit Basu
- The Freddy & Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Martha Gledhill
- GEOMAR Helmholtz Center for Ocean Research Kiel, Kiel, Germany
| | - Dirk de Beer
- Microsensor Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Yeala Shaked
- The Freddy & Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
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Luo YW, Shi D, Kranz SA, Hopkinson BM, Hong H, Shen R, Zhang F. Reduced nitrogenase efficiency dominates response of the globally important nitrogen fixer Trichodesmium to ocean acidification. Nat Commun 2019; 10:1521. [PMID: 30944323 PMCID: PMC6447586 DOI: 10.1038/s41467-019-09554-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 03/19/2019] [Indexed: 12/25/2022] Open
Abstract
The response of the prominent marine dinitrogen (N2)-fixing cyanobacteria Trichodesmium to ocean acidification (OA) is critical to understanding future oceanic biogeochemical cycles. Recent studies have reported conflicting findings on the effect of OA on growth and N2 fixation of Trichodesmium. Here, we quantitatively analyzed experimental data on how Trichodesmium reallocated intracellular iron and energy among key cellular processes in response to OA, and integrated the findings to construct an optimality-based cellular model. The model results indicate that Trichodesmium growth rate decreases under OA primarily due to reduced nitrogenase efficiency. The downregulation of the carbon dioxide (CO2)-concentrating mechanism under OA has little impact on Trichodesmium, and the energy demand of anti-stress responses to OA has a moderate negative effect. We predict that if anthropogenic CO2 emissions continue to rise, OA could reduce global N2 fixation potential of Trichodesmium by 27% in this century, with the largest decrease in iron-limiting regions.
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Affiliation(s)
- Ya-Wei Luo
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, 361102, Xiamen, Fujian, China.
| | - Dalin Shi
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China.
| | - Sven A Kranz
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Brian M Hopkinson
- Department of Marine Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Haizheng Hong
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China
| | - Rong Shen
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China
| | - Futing Zhang
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China
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Eichner M, Thoms S, Rost B, Mohr W, Ahmerkamp S, Ploug H, Kuypers MMM, de Beer D. N 2 fixation in free-floating filaments of Trichodesmium is higher than in transiently suboxic colony microenvironments. THE NEW PHYTOLOGIST 2019; 222:852-863. [PMID: 30507001 PMCID: PMC6590460 DOI: 10.1111/nph.15621] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/22/2018] [Indexed: 05/31/2023]
Abstract
To understand the role of micrometer-scale oxygen (O2 ) gradients in facilitating dinitrogen (N2 ) fixation, we characterized O2 dynamics in the microenvironment around free-floating trichomes and colonies of Trichodesmium erythraeum IMS101. Diurnal and spatial variability in O2 concentrations in the bulk medium, within colonies, along trichomes and within single cells were determined using O2 optodes, microsensors and model calculations. Carbon (C) and N2 fixation as well as O2 evolution and uptake under different O2 concentrations were analyzed by stable isotope incubations and membrane inlet mass spectrometry. We observed a pronounced diel rhythm in O2 fluxes, with net O2 evolution restricted to short periods in the morning and evening, and net O2 uptake driven by dark respiration and light-dependent O2 uptake during the major part of the light period. Remarkably, colonies showed lower N2 fixation and C fixation rates than free-floating trichomes despite the long period of O2 undersaturation in the colony microenvironment. Model calculations demonstrate that low permeability of the cell wall in combination with metabolic heterogeneity between single cells allows for anoxic intracellular conditions in colonies but also free-floating trichomes of Trichodesmium. Therefore, whereas colony formation must have benefits for Trichodesmium, it does not favor N2 fixation.
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Affiliation(s)
- Meri Eichner
- Max Planck Institute for Marine MicrobiologyCelsiusstr. 1Bremen28359Germany
| | - Silke Thoms
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine ResearchAm Handelshafen 12Bremerhaven27570Germany
| | - Björn Rost
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine ResearchAm Handelshafen 12Bremerhaven27570Germany
| | - Wiebke Mohr
- Max Planck Institute for Marine MicrobiologyCelsiusstr. 1Bremen28359Germany
| | - Soeren Ahmerkamp
- Max Planck Institute for Marine MicrobiologyCelsiusstr. 1Bremen28359Germany
| | - Helle Ploug
- Department of Marine SciencesUniversity of GothenburgCarl Skottbergsgata 22 BGöteborg41319Sweden
| | | | - Dirk de Beer
- Max Planck Institute for Marine MicrobiologyCelsiusstr. 1Bremen28359Germany
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Piché-Choquette S, Constant P. Molecular Hydrogen, a Neglected Key Driver of Soil Biogeochemical Processes. Appl Environ Microbiol 2019; 85:e02418-18. [PMID: 30658976 PMCID: PMC6414374 DOI: 10.1128/aem.02418-18] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The atmosphere of the early Earth is hypothesized to have been rich in reducing gases such as hydrogen (H2). H2 has been proposed as the first electron donor leading to ATP synthesis due to its ubiquity throughout the biosphere as well as its ability to easily diffuse through microbial cells and its low activation energy requirement. Even today, hydrogenase enzymes enabling the production and oxidation of H2 are found in thousands of genomes spanning the three domains of life across aquatic, terrestrial, and even host-associated ecosystems. Even though H2 has already been proposed as a universal growth and maintenance energy source, its potential contribution as a driver of biogeochemical cycles has received little attention. Here, we bridge this knowledge gap by providing an overview of the classification, distribution, and physiological role of hydrogenases. Distribution of these enzymes in various microbial functional groups and recent experimental evidence are finally integrated to support the hypothesis that H2-oxidizing microbes are keystone species driving C cycling along O2 concentration gradients found in H2-rich soil ecosystems. In conclusion, we suggest focusing on the metabolic flexibility of H2-oxidizing microbes by combining community-level and individual-level approaches aiming to decipher the impact of H2 on C cycling and the C-cycling potential of H2-oxidizing microbes, via both culture-dependent and culture-independent methods, to give us more insight into the role of H2 as a driver of biogeochemical processes.
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45
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Vedalankar P, Tripathy BC. Evolution of light-independent protochlorophyllide oxidoreductase. PROTOPLASMA 2019; 256:293-312. [PMID: 30291443 DOI: 10.1007/s00709-018-1317-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 09/27/2018] [Indexed: 06/08/2023]
Abstract
The nonhomologous enzymes, the light-independent protochlorophyllide reductase (DPOR) and the light-dependent protochlorophyllide oxidoreductase (LPOR), catalyze the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide) in the penultimate step of biosynthesis of chlorophyll (Chl) required for photosynthetic light absorption and energy conversion. The two enzymes differ with respect to the requirement of light for catalysis and oxygen sensitivity. DPOR and LPOR initially evolved in the ancestral prokaryotic genome perhaps at different times. DPOR originated in the anoxygenic environment of the Earth from nitrogenase-like enzyme of methanogenic archaea. Due to the transition from anoxygenic to oxygenic photosynthesis in the prokaryote, the DPOR was mostly inactivated in the daytime by photosynthetic O2 leading to the evolution of oxygen-insensitive LPOR that could function in the light. The primary endosymbiotic event transferred the DPOR and LPOR genes to the eukaryotic phototroph; the DPOR remained in the genome of the ancestor that turned into the plastid, whereas LPOR was transferred to the host nuclear genome. From an evolutionary point of view, several compelling theories that explain the disappearance of DPOR from several species cutting across different phyla are as follows: (i) pressure of the oxygenic environment; (ii) change in the light conditions and temperature; and (iii) lineage-specific gene losses, RNA editing, and nonsynonymous substitution. Certain primary amino acid sequence and the physiochemical properties of the ChlL subunit of DPOR have similarity with that of LPOR suggesting a convergence of these two enzymes in certain evolutionary event. The newly obtained sequence data from different phototrophs will further enhance the width of the phylogenetic information on DPOR.
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Affiliation(s)
| | - Baishnab C Tripathy
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Boatman TG, Davey PA, Lawson T, Geider RJ. CO2 modulation of the rates of photosynthesis and light-dependent O2 consumption in Trichodesmium. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:589-597. [PMID: 30380078 PMCID: PMC6322564 DOI: 10.1093/jxb/ery368] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 10/15/2018] [Indexed: 05/28/2023]
Abstract
As atmospheric CO2 concentrations increase, so too does the dissolved CO2 and HCO3- concentrations in the world's oceans. There are still many uncertainties regarding the biological response of key groups of organisms to these changing conditions, which is crucial for predicting future species distributions, primary productivity rates, and biogeochemical cycling. In this study, we established the relationship between gross photosynthetic O2 evolution and light-dependent O2 consumption in Trichodesmium erythraeum IMS101 acclimated to three targeted pCO2 concentrations (180 µmol mol-1=low-CO2, 380 µmol mol-1=mid-CO2, and 720 µmol mol-1=high-CO2). We found that biomass- (carbon) specific, light-saturated maximum net O2 evolution rates (PnC,max) and acclimated growth rates increased from low- to mid-CO2, but did not differ significantly between mid- and high-CO2. Dark respiration rates were five times higher than required to maintain cellular metabolism, suggesting that respiration provides a substantial proportion of the ATP and reductant for N2 fixation. Oxygen uptake increased linearly with gross O2 evolution across light intensities ranging from darkness to 1100 µmol photons m-2 s-1. The slope of this relationship decreased with increasing CO2, which we attribute to the increased energetic cost of operating the carbon-concentrating mechanism at lower CO2 concentrations. Our results indicate that net photosynthesis and growth of T. erythraeum IMS101 would have been severely CO2 limited at the last glacial maximum, but that the direct effect of future increases of CO2 may only cause marginal increases in growth.
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Affiliation(s)
- Tobias G Boatman
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
- Department of Chemical Engineering, Imperial College London, South Kensington, London, UK
| | - Phillip A Davey
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Tracy Lawson
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Richard J Geider
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
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Phenology of Trichodesmium spp. blooms in the Great Barrier Reef lagoon, Australia, from the ESA-MERIS 10-year mission. PLoS One 2018; 13:e0208010. [PMID: 30550568 PMCID: PMC6294392 DOI: 10.1371/journal.pone.0208010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 11/09/2018] [Indexed: 11/19/2022] Open
Abstract
Trichodesmium, a filamentous bloom-forming marine cyanobacterium, plays a key role in the biogeochemistry of oligotrophic ocean regions because of the ability to fix nitrogen. Naturally occurring in the Great Barrier Reef (GBR), the contribution of Trichodesmium to the nutrient budget may be of the same order as that entering the system via catchment runoff. However, the cyclicity of Trichodesmium in the GBR is poorly understood and sparsely documented because of the lack of sufficient observations. This study provides the first systematic analysis of Trichodesmium spatial and temporal occurrences in the GBR over the decade-long MERIS ocean color mission (2002–2012). Trichodesmium surface expressions were detected using the Maximum Chlorophyll Index (MCI) applied to MERIS satellite imagery of the GBR lagoonal waters. The MCI performed well (76%), albeit tested on a limited set of images (N = 25) coincident with field measurements. A north (Cape York) to south (Fitzroy) increase in the extent, frequency and timing of the surface expressions characterized the GBR, with surface expressions extending over several hundreds of kilometers. The two southernmost subregions Mackay and Fitzroy accounted for the most (70%) bloom events. The bloom timing of Trichodesmium varied from May in the north to November in the south, with wet season conditions less favorable to Trichodesmium aggregations. MODIS-Aqua Sea Surface Temperature (SST) datasets, wind speed and field measurements of nutrient concentrations were used in combination with MCI positive instances to assess the blooms’ driving factors. Low wind speed (<6 m.s-1) and SST > 24°C were associated with the largest surface aggregations. Generalized additive models (GAM) indicated an increase in bloom occurrences over the 10-year period with seasonal bloom patterns regionally distinct. Interannual variability in SST partially (14%) explained bloom occurrences, and other drivers, such as the subregion and the nutrient budget, likely regulate Trichodesmium surface aggregations in the GBR.
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Zacchetti B, Wösten HA, Claessen D. Multiscale heterogeneity in filamentous microbes. Biotechnol Adv 2018; 36:2138-2149. [DOI: 10.1016/j.biotechadv.2018.10.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 09/15/2018] [Accepted: 10/01/2018] [Indexed: 12/20/2022]
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Inomura K, Bragg J, Riemann L, Follows MJ. A quantitative model of nitrogen fixation in the presence of ammonium. PLoS One 2018; 13:e0208282. [PMID: 30496286 PMCID: PMC6264846 DOI: 10.1371/journal.pone.0208282] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/29/2018] [Indexed: 11/29/2022] Open
Abstract
Nitrogen fixation provides bioavailable nitrogen, supporting global ecosystems and influencing global cycles of other elements. It provides an additional source of nitrogen to organisms at a cost of lower growth efficiency, largely due to respiratory control of intra-cellular oxygen. Nitrogen-fixing bacteria can, however, utilize both dinitrogen gas and fixed nitrogen, decreasing energetic costs. Here we present an idealized metabolic model of the heterotrophic nitrogen fixer Azotobacter vinelandii which, constrained by laboratory data, provides quantitative predictions for conditions under which the organism uses either ammonium or nitrogen fixation, or both, as a function of the relative supply rates of carbohydrate, fixed nitrogen as well as the ambient oxygen concentration. The model reveals that the organism respires carbohydrate in excess of energetic requirements even when nitrogen fixation is inhibited and respiratory protection is not essential. The use of multiple nitrogen source expands the potential niche and range for nitrogen fixation. The model provides a quantitative framework which can be employed in ecosystem and biogeochemistry models.
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Affiliation(s)
- Keisuke Inomura
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- * E-mail:
| | - Jason Bragg
- National Herbarium of New South Wales, The Royal Botanic Gardens and Domain Trust, Sydney, NSW, Australia
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Michael J. Follows
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States of America
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Liu H, Ni J, Xu P, Tao F. Enhancing Light-Driven 1,3-Propanediol Production by Using Natural Compartmentalization of Differentiated Cells. ACS Synth Biol 2018; 7:2436-2446. [PMID: 30234972 DOI: 10.1021/acssynbio.8b00239] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Synthetic biology emerges as a powerful approach for unlocking the potential of cyanobacteria to produce various chemicals. However, the highly oxidative intracellular environment of cyanobacteria is incompatible to numerous introduced enzymes from anaerobes. In this study, we explore a strategy based on natural compartmentalization of cyanobacterial heterocysts to overcome the incompatibility. Hence, the oxygen-sensitive 1,3-propanediol (1,3-PDO) biosynthetic pathway was selected as a model and insulated in heterocysts to evaluate the proposed strategy. Thus, the genes from different sources for 1,3-PDO production were tandemly arrayed with promoter, resulting the assembled 1,3-PDO synthetic cassettes. Then the synthetic cassettes were integrated into the chromosome of Anabaena sp. strain PCC7120 by homologous recombination, respectively. The engineered strain P11 containing the genes from facultative anaerobe Klebsiella pneumoniae (cassette KP) accumulated 46.0 mg L-1 of 1,3-PDO when heterocysts were present, which is approximately 1.7-fold higher than that of no heterocysts. As for the strains (P12, P13, and P14) containing the genes from strictly anaerobic bacterium Clostridium butyricum (cassette CB), the product 1,3-PDO could only be detected when heterocysts were present. These results indicate that insulation of the oxygen-sensitive 1,3-PDO pathway with heterocysts is an effective way to protect these enzymes in cyanobacteria. The strategy may have the potential of serving as a universal strategy to overcome the incompatibility of oxygen-sensitivity in synthetic biology.
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Affiliation(s)
- Hongyu Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Jun Ni
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
| | - Fei Tao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
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