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Xu X, Wu X, Xu W, Sun Y, Zhang L, Yang Z. Water acidification weakens the carbon sink capacity of mixotrophic organisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 865:161120. [PMID: 36581282 DOI: 10.1016/j.scitotenv.2022.161120] [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: 10/21/2022] [Revised: 12/17/2022] [Accepted: 12/18/2022] [Indexed: 06/17/2023]
Abstract
Mixotrophs combine both autotrophic and heterotrophic cell structures, and their highly plastic nutritional modes can shape the structure of food web and affect the carbon sink capacity of aquatic ecosystems. As pH affects the growth of phytoplankton by altering the carbonate balance system, water acidification caused by environmental pollution and global climate change may affect the nutritional modes of mixotrophs and bring a serious environmental consequence. In this study, we cultured mixotrophic Ochromonas gloeopara under autotrophic, mixotrophic, and heterotrophic conditions at different pH levels to test the tendency of its nutritional model and the changes in photosynthetic carbon fixation capacity. Results showed that: (1) with decreasing pH, carbon uptake of Ochromonas through phagocytosis gradually replaced the carbon fixation of photosynthesis; (2) with increasing pH, Ochromonas grazing rate decreased, and the relative contribution of photosynthetic carbon fixation to total carbon acquisition increased for Ochromonas; (3) Ochromonas became more heterotrophic under water acidification, which was involved in the up-regulated expression of genes encoding key enzymes that regulate nutrient perception, movement ability, and cell repair. These findings suggested that acidification caused mixotrophic organisms to become more heterotrophic, which can change their functional role and weaken their carbon sink capacity.
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Affiliation(s)
- Xiaoqing Xu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China.
| | - Xiyi Wu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China.
| | - Wenjie Xu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China.
| | - Yunfei Sun
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China.
| | - Lu Zhang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China.
| | - Zhou Yang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China.
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2
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Jean N, Perié L, Dumont E, Bertheau L, Balliau T, Caruana AMN, Amzil Z, Laabir M, Masseret E. Metal stresses modify soluble proteomes and toxin profiles in two Mediterranean strains of the distributed dinoflagellate Alexandrium pacificum. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 818:151680. [PMID: 34793790 DOI: 10.1016/j.scitotenv.2021.151680] [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: 06/23/2021] [Revised: 10/25/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
HABs involving Alexandrium pacificum have been reported in metal-contaminated ecosystems, suggesting that this distributed species adapts to and/or can tolerate the effects of metals. Modifications in soluble proteomes and PST contents were characterized in two Mediterranean A. pacificum strains exposed to mono- or polymetallic stresses (zinc, lead, copper, cadmium). These strains were isolated from two anthropized locations: Santa Giusta Lagoon (Italy, SG C10-3) and the Tarragona seaport (Spain, TAR C5-4F). In both strains, metals primarily downregulated key photosynthesis proteins. Metals also upregulated other proteins involved in photosynthesis (PCP in both strains), the oxidative stress response (HSP 60, proteasome and SOD in SG C10-3; HSP 70 in TAR C5-4F), energy metabolism (AdK in TAR C5-4F), neoglucogenesis/glycolysis (GAPDH and PEP synthase in SG C10-3) and protein modification (PP in TAR C5-4F). These proteins, possibly involved in adaptive proteomic responses, may explain the development of these A. pacificum strains in metal-contaminated ecosystems. The two strains showed different proteomic responses to metals, with SG C10-3 upregulating more proteins, particularly PCP. Among the PSTs, regardless of the metal and the strain studied, C2 and GTX4 predominated, followed by GTX5. Under the polymetallic cocktail, (i) total PSTs, C2 and GTX4 reached the highest levels in SG C10-3 only, and (ii) total PSTs, C2, GTX5 and neoSTX were higher in SG C10-3 than in TAR C5-4F, whereas in SG C10-3 under copper stress, total PSTs, GTX5, GTX1 and C1 were higher than in the controls, revealing variability in PST biosynthesis between the two strains. Total PSTs, C2, GTX4 and GTX1 showed significant positive correlations with PCP, indicating that PST production may be positively related to photosynthesis. Our results showed that the A. pacificum strains adapt their proteomic and physiological responses to metals, which may contribute to their ecological success in highly anthropized areas.
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Affiliation(s)
- Natacha Jean
- Université de Toulon, Aix Marseille Univ, CNRS, IRD, MIO, Toulon, France.
| | - Luce Perié
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University, 30(th) St., New York, NY 10016, USA
| | - Estelle Dumont
- UMR_MD1, Aix-Marseille Univ, U-1261-INSERM, SSA, IRBA, MCT, Marseille, France
| | - Lucie Bertheau
- UMR PAM A 02.102 Procédés Alimentaires et Microbiologiques, Université de Bourgogne Franche-Comté, AgroSup Dijon, esplanade Erasme, 21 000 Dijon, France
| | - Thierry Balliau
- PAPPSO-GQE-Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91 190 Gif-sur-Yvette, France
| | - Amandine M N Caruana
- IFREMER, Phycotoxin Laboratory, rue de l'île d'Yeu, BP 21105, 44 311 Nantes, France
| | - Zouher Amzil
- IFREMER, Phycotoxin Laboratory, rue de l'île d'Yeu, BP 21105, 44 311 Nantes, France
| | - Mohamed Laabir
- Marbec, Univ Montpellier, IRD, Ifremer, CNRS, Montpellier, France
| | - Estelle Masseret
- Marbec, Univ Montpellier, IRD, Ifremer, CNRS, Montpellier, France
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3
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Abiusi F, Trompetter E, Pollio A, Wijffels RH, Janssen M. Acid Tolerant and Acidophilic Microalgae: An Underexplored World of Biotechnological Opportunities. Front Microbiol 2022; 13:820907. [PMID: 35154060 PMCID: PMC8829295 DOI: 10.3389/fmicb.2022.820907] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Despite their large number and diversity, microalgae from only four genera are currently cultivated at large-scale. Three of those share common characteristics: they are cultivated mainly autotrophically and are extremophiles or tolerate “extreme conditions.” Extreme growth conditions aid in preventing contamination and predation of microalgae, therefore facilitating outdoor cultivation. In search for new extremophilic algae suitable for large-scale production, we investigated six microalgal strains able to grow at pH below 3 and belonging to four genera; Stichococcus bacillaris ACUF158, Chlamydomonas acidophila SAG 2045, and Chlamydomonas pitschmannii ACUF238, Viridiella fridericiana ACUF035 and Galdieria sulphuraria ACUF064 and ACUF074. All strains were cultivated autotrophically at light intensity of 100 and 300 μmol m−2 s−1 and pH between 1.9 and 2.9. The autotrophic biomass productivities were compared with one of the most productive microalgae, Chlorella sorokiniana SAG 211-8K, grown at pH 6.8. The acid tolerant strains have their autotrophic biomass productivities reported for the first time. Mixotrophic and heterotrophic properties were investigated when possible. Five of the tested strains displayed autotrophic biomass productivities 10–39% lower than Chlorella sorokiniana but comparable with other commercially relevant neutrophilic microalgae, indicating the potential of these microalgae for autotrophic biomass production under acidic growth conditions. Two acid tolerant species, S. bacillaris and C. acidophila were able to grow mixotrophically with glucose. Chlamydomonas acidophila and the two Galdieria strains were also cultivated heterotrophically with glucose at various temperatures. Chlamydomonas acidophila failed to grow at 37°C, while G. sulphuraria ACUF64 showed a temperature optimum of 37°C and G. sulphuraria ACUF74 of 42°C. For each strain, the biomass yield on glucose decreased when cultivated above their optimal temperature. The possible biotechnological applications of our findings will be addressed.
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Affiliation(s)
- Fabian Abiusi
- Bioprocess Engineering, AlgaePARC, Wageningen University and Research, Wageningen, Netherlands
- *Correspondence: Fabian Abiusi,
| | - Egbert Trompetter
- Bioprocess Engineering, AlgaePARC, Wageningen University and Research, Wageningen, Netherlands
| | - Antonino Pollio
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Rene H. Wijffels
- Bioprocess Engineering, AlgaePARC, Wageningen University and Research, Wageningen, Netherlands
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Marcel Janssen
- Bioprocess Engineering, AlgaePARC, Wageningen University and Research, Wageningen, Netherlands
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Choi HI, Hwang SW, Kim J, Park B, Jin E, Choi IG, Sim SJ. Augmented CO 2 tolerance by expressing a single H +-pump enables microalgal valorization of industrial flue gas. Nat Commun 2021; 12:6049. [PMID: 34663809 PMCID: PMC8523702 DOI: 10.1038/s41467-021-26325-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 10/01/2021] [Indexed: 12/02/2022] Open
Abstract
Microalgae can accumulate various carbon-neutral products, but their real-world applications are hindered by their CO2 susceptibility. Herein, the transcriptomic changes in a model microalga, Chlamydomonas reinhardtii, in a high-CO2 milieu (20%) are evaluated. The primary toxicity mechanism consists of aberrantly low expression of plasma membrane H+-ATPases (PMAs) accompanied by intracellular acidification. Our results demonstrate that the expression of a universally expressible PMA in wild-type strains makes them capable of not only thriving in acidity levels that they usually cannot survive but also exhibiting 3.2-fold increased photoautotrophic production against high CO2 via maintenance of a higher cytoplasmic pH. A proof-of-concept experiment involving cultivation with toxic flue gas (13 vol% CO2, 20 ppm NOX, and 32 ppm SOX) shows that the production of CO2-based bioproducts by the strain is doubled compared with that by the wild-type, implying that this strategy potentially enables the microalgal valorization of CO2 in industrial exhaust.
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Affiliation(s)
- Hong Il Choi
- Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Sung-Won Hwang
- Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jongrae Kim
- Department of Life Science, Hanyang University, 206, Wangsimni-ro, Seongbuk-gu, Seoul, 04763, Republic of Korea
| | - Byeonghyeok Park
- Department of Biotechnology, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - EonSeon Jin
- Department of Life Science, Hanyang University, 206, Wangsimni-ro, Seongbuk-gu, Seoul, 04763, Republic of Korea
| | - In-Geol Choi
- Department of Biotechnology, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Sang Jun Sim
- Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.
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Lund PA, De Biase D, Liran O, Scheler O, Mira NP, Cetecioglu Z, Fernández EN, Bover-Cid S, Hall R, Sauer M, O'Byrne C. Understanding How Microorganisms Respond to Acid pH Is Central to Their Control and Successful Exploitation. Front Microbiol 2020; 11:556140. [PMID: 33117305 PMCID: PMC7553086 DOI: 10.3389/fmicb.2020.556140] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/21/2020] [Indexed: 12/20/2022] Open
Abstract
Microbes from the three domains of life, Bacteria, Archaea, and Eukarya, share the need to sense and respond to changes in the external and internal concentrations of protons. When the proton concentration is high, acidic conditions prevail and cells must respond appropriately to ensure that macromolecules and metabolic processes are sufficiently protected to sustain life. While, we have learned much in recent decades about the mechanisms that microbes use to cope with acid, including the unique challenges presented by organic acids, there is still much to be gained from developing a deeper understanding of the effects and responses to acid in microbes. In this perspective article, we survey the key molecular mechanisms known to be important for microbial survival during acid stress and discuss how this knowledge might be relevant to microbe-based applications and processes that are consequential for humans. We discuss the research approaches that have been taken to investigate the problem and highlight promising new avenues. We discuss the influence of acid on pathogens during the course of infections and highlight the potential of using organic acids in treatments for some types of infection. We explore the influence of acid stress on photosynthetic microbes, and on biotechnological and industrial processes, including those needed to produce organic acids. We highlight the importance of understanding acid stress in controlling spoilage and pathogenic microbes in the food chain. Finally, we invite colleagues with an interest in microbial responses to low pH to participate in the EU-funded COST Action network called EuroMicropH and contribute to a comprehensive database of literature on this topic that we are making publicly available.
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Affiliation(s)
- Peter A Lund
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Daniela De Biase
- Department of Medico-Surgical Sciences and Biotechnologies, Laboratory affiliated to the Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Sapienza University of Rome, Latina, Italy
| | - Oded Liran
- Department of Plant Sciences, MIGAL - Galilee Research Institute, Kiryat-Shemona, Israel
| | - Ott Scheler
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Nuno Pereira Mira
- Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Zeynep Cetecioglu
- Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
| | | | - Sara Bover-Cid
- IRTA, Food Safety Programme, Finca Camps i Armet, Monells, Spain
| | - Rebecca Hall
- School of Biosciences, Kent Fungal Group, University of Kent, Canterbury, United Kingdom
| | - Michael Sauer
- Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Conor O'Byrne
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, NUI Galway, Galway, Ireland
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6
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Toxicity, Physiological, and Ultrastructural Effects of Arsenic and Cadmium on the Extremophilic Microalga Chlamydomonas acidophila. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17051650. [PMID: 32138382 PMCID: PMC7084474 DOI: 10.3390/ijerph17051650] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 01/23/2023]
Abstract
The cytotoxicity of cadmium (Cd), arsenate (As(V)), and arsenite (As(III)) on a strain of Chlamydomonas acidophila, isolated from the Rio Tinto, an acidic environment containing high metal(l)oid concentrations, was analyzed. We used a broad array of methods to produce complementary information: cell viability and reactive oxygen species (ROS) generation measures, ultrastructural observations, transmission electron microscopy energy dispersive x-ray microanalysis (TEM-XEDS), and gene expression. This acidophilic microorganism was affected differently by the tested metal/metalloid: It showed high resistance to arsenic while Cd was the most toxic heavy metal, showing an LC50 = 1.94 µM. Arsenite was almost four-fold more toxic (LC50= 10.91 mM) than arsenate (LC50 = 41.63 mM). Assessment of ROS generation indicated that both arsenic oxidation states generate superoxide anions. Ultrastructural analysis of exposed cells revealed that stigma, chloroplast, nucleus, and mitochondria were the main toxicity targets. Intense vacuolization and accumulation of energy reserves (starch deposits and lipid droplets) were observed after treatments. Electron-dense intracellular nanoparticle-like formation appeared in two cellular locations: inside cytoplasmic vacuoles and entrapped into the capsule, around each cell. The chemical nature (Cd or As) of these intracellular deposits was confirmed by TEM-XEDS. Additionally, they also contained an unexpected high content in phosphorous, which might support an essential role of poly-phosphates in metal resistance.
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7
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Raven JA, Gobler CJ, Hansen PJ. Dynamic CO 2 and pH levels in coastal, estuarine, and inland waters: Theoretical and observed effects on harmful algal blooms. HARMFUL ALGAE 2020; 91:101594. [PMID: 32057340 DOI: 10.1016/j.hal.2019.03.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 06/10/2023]
Abstract
Rising concentrations of atmospheric CO2 results in higher equilibrium concentrations of dissolved CO2 in natural waters, with corresponding increases in hydrogen ion and bicarbonate concentrations and decreases in hydroxyl ion and carbonate concentrations. Superimposed on these climate change effects is the dynamic nature of carbon cycling in coastal zones, which can lead to seasonal and diel changes in pH and CO2 concentrations that can exceed changes expected for open ocean ecosystems by the end of the century. Among harmful algae, i.e. some species and/or strains of Cyanobacteria, Dinophyceae, Prymnesiophyceae, Bacillariophyceae, and Ulvophyceae, the occurrence of a CO2 concentrating mechanisms (CCMs) is the most frequent mechanism of inorganic carbon acquisition in natural waters in equilibrium with the present atmosphere (400 μmol CO2 mol-1 total gas), with varying phenotypic modification of the CCM. No data on CCMs are available for Raphidophyceae or the brown tide Pelagophyceae. Several HAB species and/or strains respond to increased CO2 concentrations with increases in growth rate and/or cellular toxin content, however, others are unaffected. Beyond the effects of altered C concentrations and speciation on HABs, changes in pH in natural waters are likely to have profound effects on algal physiology. This review outlines the implications of changes in inorganic cycling for HABs in coastal zones, and reviews the knowns and unknowns with regard to how HABs can be expected to ocean acidification. We further point to the large regions of uncertainty with regard to this evolving field.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK; Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, 2007, Australia; School of Biological Science, University of Western Australia, Crawley, WA, 6009, Australia.
| | - Christopher J Gobler
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton NY, 11968, USA.
| | - Per Juel Hansen
- University of Copenhagen, Marine Biological Section, Strandpromenaden 5, DK 3000 Helsingør, Denmark
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Removal of Manganese(II) from Acid Mine Wastewater: A Review of the Challenges and Opportunities with Special Emphasis on Mn-Oxidizing Bacteria and Microalgae. WATER 2019. [DOI: 10.3390/w11122493] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many global mining activities release large amounts of acidic mine drainage with high levels of manganese (Mn) having potentially detrimental effects on the environment. This review provides a comprehensive assessment of the main implications and challenges of Mn(II) removal from mine drainage. We first present the sources of contamination from mineral processing, as well as the adverse effects of Mn on mining ecosystems. Then the comparison of several techniques to remove Mn(II) from wastewater, as well as an assessment of the challenges associated with precipitation, adsorption, and oxidation/filtration are provided. We also critically analyze remediation options with special emphasis on Mn-oxidizing bacteria (MnOB) and microalgae. Recent literature demonstrates that MnOB can efficiently oxidize dissolved Mn(II) to Mn(III, IV) through enzymatic catalysis. Microalgae can also accelerate Mn(II) oxidation through indirect oxidation by increasing solution pH and dissolved oxygen production during its growth. Microbial oxidation and the removal of Mn(II) have been effective in treating artificial wastewater and groundwater under neutral conditions with adequate oxygen. Compared to physicochemical techniques, the bioremediation of manganese mine drainage without the addition of chemical reagents is relatively inexpensive. However, wastewater from manganese mines is acidic and has low-levels of dissolved oxygen, which inhibit the oxidizing ability of MnOB. We propose an alternative treatment for manganese mine drainage that focuses on the synergistic interactions of Mn in wastewater with co-immobilized MnOB/microalgae.
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9
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Calegario G, Freitas L, Santos E, Silva B, Oliveira L, Garcia G, Omachi C, Pereira R, Thompson C, Thompson F. Environmental modulation of the proteomic profiles from closely phylogenetically related populations of the red seaweed Plocamium brasiliense. PeerJ 2019; 7:e6469. [PMID: 30972241 PMCID: PMC6450377 DOI: 10.7717/peerj.6469] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/17/2019] [Indexed: 11/30/2022] Open
Abstract
The genus Plocamium encompasses seaweeds that are widely distributed throughout the world’s oceans, with Plocamium brasiliense found along the tropical and subtropical coasts of the Western Atlantic. This wide distribution can lead to structured populations due to environmental differences (e.g., light levels or temperature), restricted gene flow, and the presence of cryptic species. Abiotic variation can also affect gene expression, which consequently leads to differences in the seaweeds protein profile. This study aimed to analyze the genetic and proteomic profiles of P. brasiliense sampled in two geographically distinct sites on the coastline of Rio de Janeiro state, Brazil: Arraial do Cabo (P1) and Búzios (P2). The genetic profiles of macroalgal specimens from these two sites were indistinguishable as assessed by the markers UPA/23S, rbcL, and COI-5P; however, the protein profiles varied significantly between populations from the two sites. At both sites the ribulose-1,5-biphosphate carboxylase/oxygenase was the most abundant protein found in P. brasiliense specimens. The number of phycobiliproteins differed between both sites with the highest numbers being found at P1, possibly due to water depth. The differences in proteomic profiles of the two nearly identical populations of P. brasiliense suggest that environmental parameters such as light availability and desiccation might induce distinct protein expression, probably as a result of the phenotypic plasticity within this population of seaweed.
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Affiliation(s)
- Gabriela Calegario
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lucas Freitas
- Department of Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Genetics, Evolution, Microbiology and Immunology, State University of Campinas, Campinas, São Paulo, Brazil
| | - Eidy Santos
- Unit of Biology, State University of the West Zone, Rio de Janeiro, Brazil
| | - Bruno Silva
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Louisi Oliveira
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gizele Garcia
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Undergraduate Education, Federal University of Rio de Janeiro, Macaé, Brazil
| | - Cláudia Omachi
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renato Pereira
- Department of Marine Biology, Fluminense Federal University, Niterói, Brazil.,Rio de Janeiro Botanical Garden, Rio de Janeiro, Brazil
| | - Cristiane Thompson
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabiano Thompson
- Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,SAGE-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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10
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Dean AP, Hartley A, McIntosh OA, Smith A, Feord HK, Holmberg NH, King T, Yardley E, White KN, Pittman JK. Metabolic adaptation of a Chlamydomonas acidophila strain isolated from acid mine drainage ponds with low eukaryotic diversity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 647:75-87. [PMID: 30077857 DOI: 10.1016/j.scitotenv.2018.07.445] [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: 06/25/2018] [Revised: 07/30/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Abstract
The diversity and biological characteristics of eukaryotic communities within acid mine drainage (AMD) sites is less well studied than for prokaryotic communities. Furthermore, for many eukaryotic extremophiles the potential mechanisms of adaptation are unclear. This study describes an evaluation of eight highly acidic (pH 1.6-3.1) and one moderately acidic (pH 5.6) metal-rich acid mine drainage ponds at a disused copper mine. The severity of AMD pollution on eukaryote biodiversity was examined, and while the most species-rich site was less acidic, biodiversity did not only correlate with pH but also with the concentration of dissolved and particulate metals. Acid-tolerant microalgae were present in all ponds, including the species Chlamydomonas acidophila, abundance of which was high in one very metal-rich and highly acidic (pH 1.6) pond, which had a particularly high PO4-P concentration. The C. acidophila strain named PM01 had a broad-range pH tolerance and tolerance to high concentrations of Cd, Cu and Zn, with bioaccumulation of these metals within the cell. Comparison of metal tolerance between the isolated strain and other C. acidophila strains previously isolated from different acidic environments found that the new strain exhibited much higher Cu tolerance, suggesting adaptation by C. acidophila PM01 to excess Cu. An analysis of the metabolic profile of the strains in response to increasing concentrations of Cu suggests that this tolerance by PM01 is in part due to metabolic adaptation and changes in protein content and secondary structure.
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Affiliation(s)
- Andrew P Dean
- School of Science and the Environment, Manchester Metropolitan University, Oxford Road, Manchester M1 5GD, UK
| | - Antoni Hartley
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Owen A McIntosh
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Alyssa Smith
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Helen K Feord
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Nicolas H Holmberg
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Thomas King
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Ellen Yardley
- Department of Geography, University of Sheffield, Sheffield S10 2TN, UK
| | - Keith N White
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Jon K Pittman
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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Golda-VanEeckhoutte RL, Roof LT, Needoba JA, Peterson TD. Determination of intracellular pH in phytoplankton using the fluorescent probe, SNARF, with detection by fluorescence spectroscopy. J Microbiol Methods 2018; 152:109-118. [DOI: 10.1016/j.mimet.2018.07.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/30/2018] [Accepted: 07/31/2018] [Indexed: 02/04/2023]
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12
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Acidophilic green algal genome provides insights into adaptation to an acidic environment. Proc Natl Acad Sci U S A 2017; 114:E8304-E8313. [PMID: 28893987 DOI: 10.1073/pnas.1707072114] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Some microalgae are adapted to extremely acidic environments in which toxic metals are present at high levels. However, little is known about how acidophilic algae evolved from their respective neutrophilic ancestors by adapting to particular acidic environments. To gain insights into this issue, we determined the draft genome sequence of the acidophilic green alga Chlamydomonas eustigma and performed comparative genome and transcriptome analyses between Ceustigma and its neutrophilic relative Chlamydomonas reinhardtii The results revealed the following features in Ceustigma that probably contributed to the adaptation to an acidic environment. Genes encoding heat-shock proteins and plasma membrane H+-ATPase are highly expressed in Ceustigma This species has also lost fermentation pathways that acidify the cytosol and has acquired an energy shuttle and buffering system and arsenic detoxification genes through horizontal gene transfer. Moreover, the arsenic detoxification genes have been multiplied in the genome. These features have also been found in other acidophilic green and red algae, suggesting the existence of common mechanisms in the adaptation to acidic environments.
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Varshney P, Mikulic P, Vonshak A, Beardall J, Wangikar PP. Extremophilic micro-algae and their potential contribution in biotechnology. BIORESOURCE TECHNOLOGY 2015; 184:363-372. [PMID: 25443670 DOI: 10.1016/j.biortech.2014.11.040] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 11/05/2014] [Accepted: 11/07/2014] [Indexed: 05/18/2023]
Abstract
Micro-algae have potential as sustainable sources of energy and products and alternative mode of agriculture. However, their mass cultivation is challenging due to low survival under harsh outdoor conditions and competition from other, undesired, species. Extremophilic micro-algae have a role to play by virtue of their ability to grow under acidic or alkaline pH, high temperature, light, CO2 level and metal concentration. In this review, we provide several examples of potential biotechnological applications of extremophilic micro-algae and the ranges of tolerated extremes. We also discuss the adaptive mechanisms of tolerance to these extremes. Analysis of phylogenetic relationship of the reported extremophiles suggests certain groups of the Kingdom Protista to be more tolerant to extremophilic conditions than other taxa. While extremophilic microalgae are beginning to be explored, much needs to be done in terms of the physiology, molecular biology, metabolic engineering and outdoor cultivation trials before their true potential is realized.
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Affiliation(s)
- Prachi Varshney
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India; School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia; IIT Bombay Monash Research Academy, CSE Building, 2nd Floor, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Paulina Mikulic
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Avigad Vonshak
- Jacob Blaustein Institutes for Desert Research, Ben Gurion University, Sede Boqer Campus, 84990, Israel
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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Spijkerman E, Stojkovic S, Beardall J. CO2 acquisition in Chlamydomonas acidophila is influenced mainly by CO2, not phosphorus, availability. PHOTOSYNTHESIS RESEARCH 2014; 121:213-221. [PMID: 24906887 DOI: 10.1007/s11120-014-0016-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 05/19/2014] [Indexed: 06/03/2023]
Abstract
The extremophilic green microalga Chlamydomonas acidophila grows in very acidic waters (pH 2.3-3.4), where CO2 is the sole inorganic carbon source. Previous work has revealed that the species can accumulate inorganic carbon (Ci) and exhibits high affinity CO2 utilization under low-CO2 (air-equilibrium) conditions, similar to organisms with an active CO2 concentrating mechanism (CCM), whereas both processes are down-regulated under high CO2 (4.5 % CO2) conditions. Responses of this species to phosphorus (Pi)-limited conditions suggested a contrasting regulation of the CCM characteristics. Therefore, we measured external carbonic anhydrase (CAext) activities and protein expression (CAH1), the internal pH, Ci accumulation, and CO2-utilization in cells adapted to high or low CO2 under Pi-replete and Pi-limited conditions. Results reveal that C. acidophila expressed CAext activity and expressed a protein cross-reacting with CAH1 (the CAext from Chlamydomonas reinhardtii). Although the function of this CA remains unclear, CAext activity and high affinity CO2 utilization were the highest under low CO2 conditions. C. acidophila accumulated Ci and expressed the CAH1 protein under all conditions tested, and C. reinhardtii also contained substantial amounts of CAH1 protein under Pi-limitation. In conclusion, Ci utilization is optimized in C. acidophila under ecologically relevant conditions, which may enable optimal survival in its extreme Ci- and Pi-limited habitat. The exact physiological and biochemical acclimation remains to be further studied.
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Affiliation(s)
- Elly Spijkerman
- Universität Potsdam, Am Neuen Palais 10, 14469, Potsdam, Germany,
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15
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Escudero A, Blanco F, Lacalle A, Pinto M. Ammonium removal from anaerobically treated effluent by Chlamydomonas acidophila. BIORESOURCE TECHNOLOGY 2014; 153:62-68. [PMID: 24342946 DOI: 10.1016/j.biortech.2013.11.076] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 11/20/2013] [Accepted: 11/25/2013] [Indexed: 06/03/2023]
Abstract
Several batch culture studies were carried out to evaluate an anaerobically treated effluent as a low-cost growth medium for the microalga Chlamydomonas acidophila and to study the effectiveness of the microalga in removing NH4-N from the effluent. An initial decrease in the effluent pH to 3 was required for adequate growth of C. acidophila and removal of NH4-N. Growth of the microalgae was inhibited at high light intensity (224μmolphotonsm(-2)s(-1) at the surface of the vessels). However, the growth was not greatly affected by the high solid content and turbidity of the effluent. The microalga was able to grow in media containing NH4-N at concentrations of up to 1000mgL(-1) (50% of effluent) and to remove 88mg of NH4-NL(-1) in 10days. C. acidophila therefore appears a promising agent for the removal of NH4-N from anaerobically treated effluents.
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Affiliation(s)
| | | | | | - Miriam Pinto
- NEIKER-TECNALIA, Berreaga 1, E-48160 Derio, Spain
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16
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Skjånes K, Rebours C, Lindblad P. Potential for green microalgae to produce hydrogen, pharmaceuticals and other high value products in a combined process. Crit Rev Biotechnol 2013; 33:172-215. [PMID: 22765907 PMCID: PMC3665214 DOI: 10.3109/07388551.2012.681625] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 01/25/2012] [Accepted: 03/29/2012] [Indexed: 12/31/2022]
Abstract
Green microalgae for several decades have been produced for commercial exploitation, with applications ranging from health food for human consumption, aquaculture and animal feed, to coloring agents, cosmetics and others. Several products from green algae which are used today consist of secondary metabolites that can be extracted from the algal biomass. The best known examples are the carotenoids astaxanthin and β-carotene, which are used as coloring agents and for health-promoting purposes. Many species of green algae are able to produce valuable metabolites for different uses; examples are antioxidants, several different carotenoids, polyunsaturated fatty acids, vitamins, anticancer and antiviral drugs. In many cases, these substances are secondary metabolites that are produced when the algae are exposed to stress conditions linked to nutrient deprivation, light intensity, temperature, salinity and pH. In other cases, the metabolites have been detected in algae grown under optimal conditions, and little is known about optimization of the production of each product, or the effects of stress conditions on their production. Some green algae have shown the ability to produce significant amounts of hydrogen gas during sulfur deprivation, a process which is currently studied extensively worldwide. At the moment, the majority of research in this field has focused on the model organism, Chlamydomonas reinhardtii, but other species of green algae also have this ability. Currently there is little information available regarding the possibility for producing hydrogen and other valuable metabolites in the same process. This study aims to explore which stress conditions are known to induce the production of different valuable products in comparison to stress reactions leading to hydrogen production. Wild type species of green microalgae with known ability to produce high amounts of certain valuable metabolites are listed and linked to species with ability to produce hydrogen during general anaerobic conditions, and during sulfur deprivation. Species used today for commercial purposes are also described. This information is analyzed in order to form a basis for selection of wild type species for a future multi-step process, where hydrogen production from solar energy is combined with the production of valuable metabolites and other commercial uses of the algal biomass.
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Affiliation(s)
- Kari Skjånes
- Bioforsk - Norwegian Institute for Agricultural and Environmental Research, Fredrik A. Dahls vei 20, Ås, Norway.
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Qian Z, Liu X, Wang L, Wang X, Li Y, Xiang J, Wang P. Gene expression profiles of four heat shock proteins in response to different acute stresses in shrimp, Litopenaeus vannamei. Comp Biochem Physiol C Toxicol Pharmacol 2012; 156:211-20. [PMID: 22698717 DOI: 10.1016/j.cbpc.2012.06.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 06/01/2012] [Accepted: 06/04/2012] [Indexed: 10/28/2022]
Abstract
Heat shock proteins (HSPs) are a suite of highly conserved proteins well known for their quick responses to environmental stresses. However, the respective roles of different HSPs in response to a particular environmental stress have not received adequate scientific attentions to date. In this study, the expression profiles of four HSP genes (Lvhsp60, Lvhsp70, Lvhsc70, and Lvhsp90) of the Pacific white shrimp, Litopenaeus vannamei under acute thermal stress, pH challenge, and heavy metal exposure were investigated, respectively, using the quantitative real-time reverse transcription polymerase chain reaction technique. Results showed that the four genes exhibited quite different expression profiles when the shrimp were subjected to each of the above stressors. Under acute thermal stress, the messenger RNA (mRNA) levels of all the four genes were significantly induced, and the transcription level of Lvhsp70 was the most sensitive to temperature fluctuations. Under acute pH challenge, the relative mRNA expression of the four genes was shown to be time and pH dependent, and the strongest response occurred in Lvhsp60. Under acute heavy metal exposure, transcripts of each of the four genes varied depending on metal type and exposure time. Lvhsp60 displayed particularly high sensitivity to cadmium and manganese exposure, while Lvhsp70 showed the most sensitive response to iron and zinc treatments. The results obtained suggest that different LvHSP genes may play different roles in mediating cell stress caused by a specific environmental stressor. Given the response sensitivity and intensity of LvHSP genes to environmental stresses, Lvhsp70 may be most suitable to act as a biomarker indicating thermal stress, iron and zinc stimulation, while Lvhsp60 may be a promising candidate marker of pH stress, cadmium and manganese exposure in shrimp.
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Affiliation(s)
- Zhaoying Qian
- College of Animal Science and Technology, Northwest A & F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Shaanxi Yangling 712100, China
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Spijkerman E. The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations. PHOTOSYNTHESIS RESEARCH 2011; 109:179-189. [PMID: 21286811 DOI: 10.1007/s11120-010-9607-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 12/13/2010] [Indexed: 05/30/2023]
Abstract
The CO(2) acquisition was analyzed in Chlamydomonas acidophila at pH 2.4 in a range of medium P and Fe concentrations and at high and low CO(2) condition. The inorganic carbon concentrating factor (CCF) was related to cellular P quota (Q(p)), maximum CO(2)-uptake rate by photosynthesis (V(max,O2)), half saturation constant for CO(2) uptake (K(0.5)), and medium Fe concentration. There was no effect of the medium Fe concentration on the CCF. The CCF increased with increasing Q(p) in both high and low CO(2) grown algae, but maximum Q(p) was 6-fold higher in the low CO(2) cells. In high CO(2) conditions, the CCF was low, ranging between 0.8 and 3.5. High CCF values up to 9.1 were only observed in CO(2)-limited cells, but P- and CO(2)-colimited cells had a low CCF. High CCF did not relate with a low K(0.5) as all CO(2)-limited cells had a low K(0.5) (<4 μM CO(2)). High C(i)-pools in cells with high Q(p) suggested the presence of an active CO(2)-uptake mechanism. The CCF also increased with increasing V(max,O2) which reflect an adaptation to the nutrient in highest demand (CO(2)) under balanced growth conditions. It is proposed that the size of the CCF in C. acidophila is more strongly related to porter density for CO(2) uptake (reflected in V(max,O2)) and less- to high-affinity CO(2) uptake (low K(0.5)) at balanced growth. In addition, high CCF can only be realized with high Q(p).
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Affiliation(s)
- Elly Spijkerman
- Department of Ecology and Ecosystem Modelling, University of Potsdam, Potsdam, Germany.
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Moser M, Weisse T. Combined stress effect of pH and temperature narrows the niche width of flagellates in acid mining lakes. JOURNAL OF PLANKTON RESEARCH 2011; 33:1023-1032. [PMID: 21655470 PMCID: PMC3109992 DOI: 10.1093/plankt/fbr014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 01/20/2011] [Indexed: 05/14/2023]
Abstract
Strains of the green alga Chlamydomonas acidophila and two chrysomonads, Ochromonas spp., isolated from each of two similar acid mining lakes (AMLs) with extremely low pH (∼2.6) were investigated to consider a possible synergistic stress effect of low pH and unfavourable temperature. We measured flagellate growth rates over a combination of four pH (2.5, 3.5, 5.0 and 7.0) and three temperatures (10, 17.5 and 25°C) in the laboratory. Our hypothesis was that, under highly acidic conditions (pH <3), an obligate acidophil species (C. acidophila) would be less sensitive to the combined stress of pH and temperature than acidotolerant species (Ochromonas spp.). We expected that the difference of the fundamental vs. realized pH niche would be greater in the latter. Another chrysomonad, Poterioochromonas malhamensis strain DS, served as a reference for a closely related neutrophil species. Surprisingly, C. acidophila did not survive temperatures >27°C. The lowest temperature tested reduced growth rates of all three chrysomonad strains significantly. Since all chrysomonads were tolerant to high temperature, growth rate of one Ochromonas spp. strain was measured exemplarily at 35°C. Only at this high temperature was the realized pH niche significantly narrowed. We also recorded significant intraspecific differences within the C. acidophila strains from the two AML, illustrating that the niche width of a species is broader than that of individual clones.
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Spijkerman E. What physiological acclimation supports increased growth at high CO2 conditions? PHYSIOLOGIA PLANTARUM 2008; 133:41-48. [PMID: 18298410 DOI: 10.1111/j.1399-3054.2008.01062.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Chlamydomonas acidophila Negoro is a green algal species abundant in acidic waters (pH 2-3.5), in which inorganic carbon is present only as CO(2). Previous studies have shown that aeration with CO(2) increased its maximum growth rate, suggesting CO(2) limitation under natural conditions. To unravel the underlying physiological mechanisms at high CO(2) conditions that enables increased growth, several physiological characteristics from high- and low-CO(2)-acclimated cells were studied: maximum quantum yield, photosynthetic O(2) evolution (P(max)), affinity constant for CO(2) by photosynthesis (K(0.5,p)), a CO(2)-concentrating mechanism (CCM), cellular Rubisco content and the affinity constant of Rubisco for CO(2) (K(0.5,r)). The results show that at high CO(2) concentrations, C. acidophila had a higher K(0.5,p), P(max), maximum quantum yield, switched off its CCM and had a lower Rubisco content than at low CO(2) conditions. In contrast, the K(0.5,r) was comparable under high and low CO(2) conditions. It is calculated that the higher P(max) can already explain the increased growth rate in a high CO(2) environment. From an ecophysiological point of view, the increased maximum growth rate at high CO(2) will likely not be realised in the field because of other population regulating factors and should be seen as an acclimation to CO(2) and not as proof for a CO(2) limitation.
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Affiliation(s)
- Elly Spijkerman
- Department of Ecology and Ecosystem Modelling, University of Potsdam, Am Neuen Palais 10, D-14469 Potsdam, Germany.
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Spijkerman E. Phosphorus acquisition by Chlamydomonas acidophila under autotrophic and osmo-mixotrophic growth conditions. JOURNAL OF EXPERIMENTAL BOTANY 2007; 58:4195-4202. [PMID: 18039735 DOI: 10.1093/jxb/erm276] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Chlamydomonas acidophila Negoro is a green algal species abundant in acidic waters where inorganic phosphorus (P(i)) and carbon (CO(2)) are considered the most important growth-limiting nutrients for the phytoplankton. This paper describes the P(i) uptake and growth kinetics under varying carbon supply by cultivating the alga autotrophically, with and without CO(2) aeration, and osmo-mixotrophically with glucose under low P(i) conditions at pH 2.7. The low minimum cellular phosphorus quota (Q(0); ranging from 0.6 to 1.1 mmol P mol(-1) C) suggested P(i)-limiting conditions under all different modes of carbon supply, and was lowest under CO(2)-aerated conditions. The threshold P(i) concentration for growth did not vary from zero, suggesting no detectable metabolic costs. Maximum P(i)-uptake rates (V(max)) were a better indication of P(i) limitation when compared with the affinity constant for P(i) uptake (K(m)), as V(max) was only high under P(i)-limited conditions whereas K(m) was low under both P(i)-limited and P(i)-replete conditions. Osmo-mixotrophic growth conditions did not result in decreased extracellular phosphatase activity, but often resulted in physiological characteristics comparable with CO(2)-aerated cells, suggesting intracellular CO(2) production by glucose respiration. In addition, at low CO(2) and in autotrophic conditions, C. acidophila had a higher Q(0), lower dissolved organic carbon concentration, lower maximum P(i)-uptake rates, and lower phosphatase activity, suggesting that growth was co-limited by CO(2) and P(i). Furthermore, cells may respond physiologically to both nutrient limitations simultaneously.
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Affiliation(s)
- Elly Spijkerman
- Department of Ecology and Ecosystem Modelling, University of Potsdam, Am Neuen Palais 10, Potsdam, Germany.
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Spijkerman E, Barua D, Gerloff-Elias A, Kern J, Gaedke U, Heckathorn SA. Stress responses and metal tolerance of Chlamydomonas acidophila in metal-enriched lake water and artificial medium. Extremophiles 2007; 11:551-62. [PMID: 17429574 DOI: 10.1007/s00792-007-0067-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Accepted: 02/15/2007] [Indexed: 10/23/2022]
Abstract
Chlamydomonas acidophila faces high heavy-metal concentrations in acidic mining lakes, where it is a dominant phytoplankton species. To investigate the importance of metals to C. acidophila in these lakes, we examined the response of growth, photosynthesis, cell structure, heat-shock protein (Hsp) accumulation, and metal adsorption after incubation in metal-rich lake water and artificial growth medium enriched with metals (Fe, Zn). Incubation in both metal-rich lake water and medium caused large decreases in photosystem II function (though no differences among lakes), but no decrease in growth rate (except for medium + Fe). Concentrations of small Hsps were higher in algae incubated in metal-rich lake-water than in metal-enriched medium, whereas Hsp60 and Hsp70A were either less or equally expressed. Cellular Zn and Fe contents were lower, and metals adsorbed to the cell surface were higher, in lake-water-incubated algae than in medium-grown cells. The results indicate that high Zn or Fe levels are likely not the main or only contributor to the low primary production in mining lakes, and multiple adaptations of C. acidophila (e.g., high Hsp levels, decreased metal accumulation) increase its tolerance to metals and permit survival under such adverse environmental conditions. Supposedly, the main stress factor present in the lake water is an interaction between low P and high Fe concentrations.
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Affiliation(s)
- Elly Spijkerman
- Department of Ecology and Ecosystem Modelling, University of Potsdam, Am Neuen Palais 10, Potsdam, Germany.
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