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Manck LE, Coale TH, Stephens BM, Forsch KO, Aluwihare LI, Dupont CL, Allen AE, Barbeau KA. Iron limitation of heterotrophic bacteria in the California Current System tracks relative availability of organic carbon and iron. THE ISME JOURNAL 2024; 18:wrae061. [PMID: 38624181 PMCID: PMC11069385 DOI: 10.1093/ismejo/wrae061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/17/2024]
Abstract
Iron is an essential nutrient for all microorganisms of the marine environment. Iron limitation of primary production has been well documented across a significant portion of the global surface ocean, but much less is known regarding the potential for iron limitation of the marine heterotrophic microbial community. In this work, we characterize the transcriptomic response of the heterotrophic bacterial community to iron additions in the California Current System, an eastern boundary upwelling system, to detect in situ iron stress of heterotrophic bacteria. Changes in gene expression in response to iron availability by heterotrophic bacteria were detected under conditions of high productivity when carbon limitation was relieved but when iron availability remained low. The ratio of particulate organic carbon to dissolved iron emerged as a biogeochemical proxy for iron limitation of heterotrophic bacteria in this system. Iron stress was characterized by high expression levels of iron transport pathways and decreased expression of iron-containing enzymes involved in carbon metabolism, where a majority of the heterotrophic bacterial iron requirement resides. Expression of iron stress biomarkers, as identified in the iron-addition experiments, was also detected insitu. These results suggest iron availability will impact the processing of organic matter by heterotrophic bacteria with potential consequences for the marine biological carbon pump.
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Affiliation(s)
- Lauren E Manck
- Geosciences Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
- Flathead Lake Biological Station, University of Montana, Polson, MT 59860, United States
| | - Tyler H Coale
- Integrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA 95064, United States
- Department of Environment and Sustainability, J. Craig Venter Institute, La Jolla, CA 92037, United States
| | - Brandon M Stephens
- Geosciences Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
- Institute of Oceanography, National Taiwan University, Taipei, 106, Taiwan
| | - Kiefer O Forsch
- Geosciences Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
| | - Lihini I Aluwihare
- Geosciences Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
| | - Christopher L Dupont
- Department of Environment and Sustainability, J. Craig Venter Institute, La Jolla, CA 92037, United States
- Department of Human Health, J. Craig Venter Institute, La Jolla, CA 92037, United States
- Department of Synthetic Biology, J. Craig Venter Institute, La Jolla, CA 92037, United States
| | - Andrew E Allen
- Integrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
- Department of Environment and Sustainability, J. Craig Venter Institute, La Jolla, CA 92037, United States
| | - Katherine A Barbeau
- Geosciences Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, United States
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Andrew S, Wilson T, Smith S, Marchetti A, Septer AN. A tripartite model system for Southern Ocean diatom-bacterial interactions reveals the coexistence of competing symbiotic strategies. ISME COMMUNICATIONS 2022; 2:97. [PMID: 37938401 PMCID: PMC9723598 DOI: 10.1038/s43705-022-00181-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 09/06/2022] [Accepted: 09/15/2022] [Indexed: 09/24/2023]
Abstract
Southern Ocean (SO) diatoms play an important role in global carbon flux, and their influence on carbon export is directly linked to interactions with epiphytic bacteria. Bacterial symbionts that increase diatom growth promote atmospheric carbon uptake, while bacterial degraders divert diatom biomass into the microbial loop where it can then be released as carbon dioxide through respiration. To further explore SO diatom-bacterial associations, a natural model system is needed that is representative of these diverse and important interactions. Here, we use concurrent cultivation to isolate a species of the ecologically-important SO diatom, Pseudo-nitzschia subcurvata, and its co-occurring bacteria. Although vitamin-depleted, axenic Pseudo-nitzschia grew poorly in culture, addition of a co-isolated Roseobacter promoted diatom growth, while addition of a co-isolated Flavobacterium negatively impacted diatom growth. Microscopy revealed both bacterial isolates are physically associated with diatom cells and genome sequencing identified important predicted functions including vitamin synthesis, motility, cell attachment mechanisms, and diverse antimicrobial weapons that could be used for interbacterial competition. These findings revealed the natural coexistence of competing symbiotic strategies of diatom-associated bacteria in the SO, and the utility of this tripartite system, composed of a diatom and two bacterial strains, as a co-culture model to probe ecological-relevant interactions between diatoms and the bacteria that compete for access to the phycosphere.
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Affiliation(s)
- Sarah Andrew
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Travis Wilson
- Environment, Ecology & Energy Program, University of North Carolina, Chapel Hill, NC, USA
| | - Stephanie Smith
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Adrian Marchetti
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Alecia N Septer
- Department of Earth, Marine & Environmental Sciences, University of North Carolina, Chapel Hill, NC, USA.
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Mars Brisbin M, Mitarai S, Saito MA, Alexander H. Microbiomes of bloom-forming Phaeocystis algae are stable and consistently recruited, with both symbiotic and opportunistic modes. THE ISME JOURNAL 2022; 16:2255-2264. [PMID: 35764675 PMCID: PMC9381791 DOI: 10.1038/s41396-022-01263-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 05/11/2022] [Accepted: 05/31/2022] [Indexed: 05/29/2023]
Abstract
Phaeocystis is a cosmopolitan, bloom-forming phytoplankton genus that contributes significantly to global carbon and sulfur cycles. During blooms, Phaeocystis species produce large carbon-rich colonies, creating a unique interface for bacterial interactions. While bacteria are known to interact with phytoplankton-e.g., they promote growth by producing phytohormones and vitamins-such interactions have not been shown for Phaeocystis. Therefore, we investigated the composition and function of P. globosa microbiomes. Specifically, we tested whether microbiome compositions are consistent across individual colonies from four P. globosa strains, whether similar microbiomes are re-recruited after antibiotic treatment, and how microbiomes affect P. globosa growth under limiting conditions. Results illuminated a core colonial P. globosa microbiome-including bacteria from the orders Alteromonadales, Burkholderiales, and Rhizobiales-that was re-recruited after microbiome disruption. Consistent microbiome composition and recruitment is indicative that P. globosa microbiomes are stable-state systems undergoing deterministic community assembly and suggests there are specific, beneficial interactions between Phaeocystis and bacteria. Growth experiments with axenic and nonaxenic cultures demonstrated that microbiomes allowed continued growth when B-vitamins were withheld, but that microbiomes accelerated culture collapse when nitrogen was withheld. In sum, this study reveals symbiotic and opportunistic interactions between Phaeocystis colonies and microbiome bacteria that could influence large-scale phytoplankton bloom dynamics and biogeochemical cycles.
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Affiliation(s)
- Margaret Mars Brisbin
- Marine Biophysics Unit, Okinawa Institute of Science and Technology, Okinawa, Japan.
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
| | - Satoshi Mitarai
- Marine Biophysics Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
| | - Mak A Saito
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Harriet Alexander
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
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Fourquez M, Strzepek RF, Ellwood MJ, Hassler C, Cabanes D, Eggins S, Pearce I, Deppeler S, Trull TW, Boyd PW, Bressac M. Phytoplankton Responses to Bacterially Regenerated Iron in a Southern Ocean Eddy. Microorganisms 2022; 10:microorganisms10081655. [PMID: 36014073 PMCID: PMC9413495 DOI: 10.3390/microorganisms10081655] [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: 07/06/2022] [Revised: 08/07/2022] [Accepted: 08/09/2022] [Indexed: 11/16/2022] Open
Abstract
In the Subantarctic sector of the Southern Ocean, vertical entrainment of iron (Fe) triggers the seasonal productivity cycle but diminishing physical supply during the spring to summer transition forces microbial assemblages to rapidly acclimate. Here, we tested how phytoplankton and bacteria within an isolated eddy respond to different dissolved Fe (DFe)/ligand inputs. We used three treatments: one that mimicked the entrainment of new DFe (Fe-NEW), another in which DFe was supplied from bacterial regeneration of particles (Fe-REG), and a control with no addition of DFe (Fe-NO). After 6 days, 3.5 (Fe-NO, Fe-NEW) to 5-fold (Fe-REG) increases in Chlorophyll a were observed. These responses of the phytoplankton community were best explained by the differences between the treatments in the amount of DFe recycled during the incubation (Fe-REG, 15% recycled c.f. 40% Fe-NEW, 60% Fe-NO). This additional recycling was more likely mediated by bacteria. By day 6, bacterial production was comparable between Fe-NO and Fe-NEW but was approximately two-fold higher in Fe-REG. A preferential response of phytoplankton (haptophyte-dominated) relative to high nucleic acid (HNA) bacteria was also found in the Fe-REG treatment while the relative proportion of diatoms increased faster in the Fe-NEW and Fe-NO treatments. Comparisons between light and dark incubations further confirmed the competition between picophytoplankton and HNA for DFe. Overall, our results demonstrate great versatility by microorganisms to use different Fe sources that results in highly efficient Fe recycling within surface waters. This study also encourages future research to further investigate the interactions between functional groups of microbes (e.g. HNA and cyanobacteria) to better constraint modeling in Fe and carbon biogeochemical cycles.
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Affiliation(s)
- Marion Fourquez
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7004, Australia
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart 7004, Australia
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UMR 110, 13288 Marseille, France
- Correspondence:
| | - Robert F. Strzepek
- Australian Antarctic Program Partnership (AAPP), Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7004, Australia
| | - Michael J. Ellwood
- Research School of Earth Sciences, Australian National University, Canberra 2601, Australia
| | - Christel Hassler
- Marine and Lake Biogeochemistry, Department F.-A. Forel, University of Geneva, 1205 Geneva, Switzerland
- Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland
| | - Damien Cabanes
- Marine and Lake Biogeochemistry, Department F.-A. Forel, University of Geneva, 1205 Geneva, Switzerland
| | - Sam Eggins
- Research School of Earth Sciences, Australian National University, Canberra 2601, Australia
| | - Imojen Pearce
- Australian Antarctic Division (AAD), Kingston 7050, Australia
| | - Stacy Deppeler
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7004, Australia
- National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand
| | - Thomas W. Trull
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7004, Australia
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart 7004, Australia
- Climate Science Centre, Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organisation, Hobart 7004, Australia
| | - Philip W. Boyd
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7004, Australia
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart 7004, Australia
| | - Matthieu Bressac
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7004, Australia
- Laboratoire d’Océanographie de Villefranche, Sorbonne Université, CNRS, 06230 Villefranche-sur-Mer, France
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Spatial and Seasonal Variations of the Island Mass Effect at the Sub-Antarctic Prince Edward Islands Archipelago. REMOTE SENSING 2022. [DOI: 10.3390/rs14092140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
At the sub-Antarctic Prince Edward Islands (PEIs) in the Southern Ocean, the Island Mass Effect (IME) plays an important role in maintaining an ecosystem able to support diverse biological communities; however, limited in situ sampling has severely constrained our understanding of it. As such, our study used satellite chlorophyll a (chla) to provide the first detailed characterisation of the spatial extent and seasonal variability of the IME at the PEIs. Seasonal surface chla variations were remarkable, with localised increases observed from mid-austral spring to the end of autumn (October to May). In contrast, during June to September, there were no distinguishable differences between chla at the PEIs and that further afield. Seasonal chla changes were significantly correlated with higher light levels, warmer waters, and shallow upper mixed layer depths reflecting enhanced water column stability during summer and autumn, with the opposite pattern in winter and spring. The IME extended northeast of the islands and remained spatially distinct from elevated chla around the northern branch of the sub-Antarctic Front and the southern branch of the Antarctic Polar Front. From December to February, the IME was spatially connected to the island shelf. In contrast, during March–May and in October, higher chla was observed only to the northeast, some distance away from the islands, suggesting a delayed IME, which has not previously been observed at the PEIs. The clear association of this higher chla with the weak mean geostrophic circulation northeast of the islands suggested retention and accumulation of nutrients and phytoplankton biomass, which was likely aided by wind-driven northeastward transport of water from the shelf. Climatological mean chla to the northeast was generally higher than that on the PEI shelf, and further research is required to determine the importance of this region to ecosystem functioning at the islands.
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Mazzotta MG, McIlvin MR, Moran DM, Wang DT, Bidle KD, Lamborg CH, Saito MA. Characterization of the metalloproteome of Pseudoalteromonas (BB2-AT2): biogeochemical underpinnings for zinc, manganese, cobalt, and nickel cycling in a ubiquitous marine heterotroph. Metallomics 2021; 13:6409836. [PMID: 34694406 DOI: 10.1093/mtomcs/mfab060] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/14/2021] [Indexed: 11/13/2022]
Abstract
Pseudoalteromonas (BB2-AT2) is a ubiquitous marine heterotroph, often associated with labile organic carbon sources in the ocean (e.g. phytoplankton blooms and sinking particles). Heterotrophs hydrolyze exported photosynthetic materials, components of the biological carbon pump, with the use of diverse metalloenzymes containing zinc (Zn), manganese (Mn), cobalt (Co), and nickel (Ni). Studies on the metal requirements and cytosolic utilization of metals for marine heterotrophs are scarce, despite their relevance to global carbon cycling. Here, we characterized the Zn, Mn, Co, and Ni metallome of BB2-AT2. We found that the Zn metallome is complex and cytosolic Zn is associated with numerous proteins for transcription (47.2% of the metallome, obtained from singular value decomposition of the metalloproteomic data), translation (33.5%), proteolysis (12.8%), and alkaline phosphatase activity (6.4%). Numerous proteolytic enzymes also appear to be putatively associated with Mn, and to a lesser extent, Co. Putative identification of the Ni-associated proteins, phosphoglucomutase and a protein in the cupin superfamily, provides new insights for Ni utilization in marine heterotrophs. BB2-AT2 relies on numerous transition metals for proteolytic and phosphatase activities, inferring an adaptative potential to metal limitation. Our field observations of increased alkaline phosphatase activity upon addition of Zn in field incubations suggest that such metal limitation operates in sinking particulate material collected from sediment traps. Taken together, this study improves our understanding of the Zn, Mn, Co, and Ni metallome of marine heterotrophic bacteria and provides novel and mechanistic frameworks for understanding the influence of nutrient limitation on biogeochemical cycling.
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Affiliation(s)
- Michael G Mazzotta
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Matthew R McIlvin
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Dawn M Moran
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - David T Wang
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Kay D Bidle
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Carl H Lamborg
- Department of Ocean Sciences, University of California, Santa Cruz, CA 95064, USA
| | - Mak A Saito
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
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