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Hu X, Zhao S, Li H, Pan Y, Fan Z, Lu J, Li Y, Song G, Zhang H, Liu Q, Bao M. N-alkane shape distinctive microbial patterns in Kuroshio Extension. ENVIRONMENT INTERNATIONAL 2024; 188:108757. [PMID: 38795659 DOI: 10.1016/j.envint.2024.108757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 05/15/2024] [Accepted: 05/15/2024] [Indexed: 05/28/2024]
Abstract
Marine microorganisms are primary drivers of the elemental cycling. The interaction between heterotrophic prokaryotes and biomarker (n-alkane) in Kuroshio Extension (KE) remains unclear. Here, we categorize KE into three characteristic areas based on ocean temperatures and nutrient conditions: Cold Water Area (CWA), Mixed Area (MA), and Warm Water Area (WWA). A total of 49 samples were collected during two-year voyage to identify the source of n-alkane and associated degrading microorganisms. Total n-alkane concentrations (Σn-Alk) in surface water (SW) spanned from 1,308 ng L-1 to 1,890 ng L-1, it was significantly higher (Tukey-Kramer test, p < 0.05) in MA than CWA and WWA. The Σn-Alk in surface sediments (SS) gradually increased from north to south, ranging from 5,982 ng g-1 to 37,857 ng g-1. Bacteria and algae were the primary sources of n-alkane in both SW and SS. Proteobacteria was the most widely distributed among three areas. The presence of Rhodobacteraceae with alkB was the primary reason affecting n-alkane concentrations in SW. The Gammaproteobacteria with alkB and alkR chiefly affected n-alkane concentrations in SS. In summary, n-alkane s serve as an energy source for particular microorganisms, shaping the unique oceanographic patterns.
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Affiliation(s)
- Xin Hu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Shanshan Zhao
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Haoshuai Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Yaping Pan
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Zhongxiang Fan
- Physical Oceanography Laboratory, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Jinren Lu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Yiming Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Guodong Song
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Honghai Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Qian Liu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China
| | - Mutai Bao
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China; College of Chemistry & Chemical Engineering, Ocean University of China, Qingdao, Shandong Province 266100, China.
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2
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Shen A, Gao S, Jiang J, Hu Q, Wang H, Yuan S. Oscillations of algal cell quota: Considering two-stage phosphate uptake kinetics. J Theor Biol 2024; 581:111739. [PMID: 38280542 DOI: 10.1016/j.jtbi.2024.111739] [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: 06/01/2023] [Accepted: 01/10/2024] [Indexed: 01/29/2024]
Abstract
Elucidating the mechanism of effect of phosphate (PO43-) uptake on the growth of algal cells helps understand the frequent outbreaks of algal blooms caused by eutrophication. In this study, we develop a comprehensive mathematical model that incorporates two stages of PO43- uptake and accounts for transport time delay. The model parameter values are determined by fitting experimental data of Prorocentrum donghaiense and the model is validated using experimental data of Karenia mikimotoi. The numerical results demonstrate that the model successfully captures the general characteristics of algal growth and PO43- uptake under PO43- sufficient conditions. Significantly, the experimental and mathematical findings suggest that the time delay associated with the transfer of PO43- from the surface-adsorbed PO43- (Ps) pool to the intracellular PO43- (Pi) pool may serve as a physiologically plausible mechanism leading to oscillations of algal cell quota. These results have important implications for resource managers, enabling them to predict and deepen their understanding of harmful algal blooms.
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Affiliation(s)
- Anglu Shen
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China
| | - Shufei Gao
- College of science, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Jie Jiang
- College of science, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Qingjing Hu
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China
| | - Hao Wang
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta T6G 2G1, Canada
| | - Sanling Yuan
- College of science, University of Shanghai for Science and Technology, Shanghai 200093, China.
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3
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Raven JA. Avoiding and allowing apatite precipitation in oxygenic photolithotrophs. THE NEW PHYTOLOGIST 2023; 238:1801-1812. [PMID: 36856343 DOI: 10.1111/nph.18849] [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: 12/06/2022] [Accepted: 02/24/2023] [Indexed: 05/04/2023]
Abstract
The essential elements Ca and P, taken up and used metabolically as Ca2+ and H2 PO4 - /HPO4 2- respectively, could precipitate as one or more of the insoluble forms calcium phosphate (mainly apatite) if the free ion concentrations and pH are high enough. In the cytosol, chloroplast stroma, and mitochondrial matrix, the very low free Ca2+ concentration avoids calcium phosphate precipitation, apart from occasionally in the mitochondrial matrix. The low free Ca2+ concentration in these compartments is commonly thought of in terms of the role of Ca2+ in signalling. However, it also helps avoids calcium phosphate precipitation, and this could be its earliest function in evolution. In vacuoles, cell walls, and xylem conduits, there can be relatively high concentrations of Ca2+ and inorganic orthophosphate, but pH and/or other ligands for Ca2+ , suggests that calcium phosphate precipitates are rare. However, apatite is precipitated under metabolic control in shoot trichomes, and by evaporative water loss in hydathodes, in some terrestrial flowering plants. In aquatic macrophytes that deposit CaCO3 on their cell walls or in their environment as a result of pH increase or removal of inhibitors of nucleation or crystal growth, phosphate is sometimes incorporated in the CaCO3 . Calcium phosphate precipitation also occurs in some stromatolites.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Climate Change Cluster, Faculty of Science, University of Technology, Sydney, Ultimo, NSW, 2007, Australia
- School of Biological Sciences, University of Western Australia, Crawley, WA, 6009, Australia
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4
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Lanclos VC, Rasmussen AN, Kojima CY, Cheng C, Henson MW, Faircloth BC, Francis CA, Thrash JC. Ecophysiology and genomics of the brackish water adapted SAR11 subclade IIIa. THE ISME JOURNAL 2023; 17:620-629. [PMID: 36739346 PMCID: PMC10030771 DOI: 10.1038/s41396-023-01376-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/06/2023] [Accepted: 01/20/2023] [Indexed: 02/05/2023]
Abstract
The Order Pelagibacterales (SAR11) is the most abundant group of heterotrophic bacterioplankton in global oceans and comprises multiple subclades with unique spatiotemporal distributions. Subclade IIIa is the primary SAR11 group in brackish waters and shares a common ancestor with the dominant freshwater IIIb (LD12) subclade. Despite its dominance in brackish environments, subclade IIIa lacks systematic genomic or ecological studies. Here, we combine closed genomes from new IIIa isolates, new IIIa MAGS from San Francisco Bay (SFB), and 460 highly complete publicly available SAR11 genomes for the most comprehensive pangenomic study of subclade IIIa to date. Subclade IIIa represents a taxonomic family containing three genera (denoted as subgroups IIIa.1, IIIa.2, and IIIa.3) that had distinct ecological distributions related to salinity. The expansion of taxon selection within subclade IIIa also established previously noted metabolic differentiation in subclade IIIa compared to other SAR11 subclades such as glycine/serine prototrophy, mosaic glyoxylate shunt presence, and polyhydroxyalkanoate synthesis potential. Our analysis further shows metabolic flexibility among subgroups within IIIa. Additionally, we find that subclade IIIa.3 bridges the marine and freshwater clades based on its potential for compatible solute transport, iron utilization, and bicarbonate management potential. Pure culture experimentation validated differential salinity ranges in IIIa.1 and IIIa.3 and provided detailed IIIa cell size and volume data. This study is an important step forward for understanding the genomic, ecological, and physiological differentiation of subclade IIIa and the overall evolutionary history of SAR11.
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Affiliation(s)
- V Celeste Lanclos
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Anna N Rasmussen
- Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA
| | - Conner Y Kojima
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Chuankai Cheng
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Michael W Henson
- Department of Geophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | - Brant C Faircloth
- Department of Biological Sciences and Museum of Natural Science, Louisiana State University, Baton Rouge, LA, 70803, USA
| | | | - J Cameron Thrash
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA.
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5
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Zhao F, Lin X, Cai K, Jiang Y, Ni T, Chen Y, Feng J, Dang S, Zhou CZ, Zeng Q. Biochemical and structural characterization of the cyanophage-encoded phosphate binding protein: implications for enhanced phosphate uptake of infected cyanobacteria. Environ Microbiol 2022; 24:3037-3050. [PMID: 35590460 DOI: 10.1111/1462-2920.16043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 05/07/2022] [Accepted: 05/08/2022] [Indexed: 12/01/2022]
Abstract
To acquire phosphorus, cyanobacteria use the typical bacterial ABC-type phosphate transporter, which is composed of a periplasmic high-affinity phosphate-binding protein PstS and a channel formed by two transmembrane proteins PstC and PstA. A putative pstS gene was identified in the genomes of cyanophages that infect the unicellular marine cyanobacteria Prochlorococcus and Synechococcus. However, it has not been determined whether the cyanophage PstS protein is functional during infection to enhance the phosphate uptake rate of host cells. Here we showed that the cyanophage P-SSM2 PstS protein was abundant in the infected Prochlorococcus NATL2A cells and the host phosphate uptake rate was enhanced after infection. This is consistent with our biochemical and structural analyses showing that the phage PstS protein is indeed a high-affinity phosphate-binding protein. We further modeled the complex structure of phage PstS with host PstCA and revealed three putative interfaces that may facilitate the formation of a chimeric ABC transporter. Our results provide insights into the molecular mechanism by which cyanophages enhance the phosphate uptake rate of cyanobacteria. Phosphate acquisition by infected bacteria can increase the phosphorus contents of released cellular debris and virus particles, which together constitute a significant proportion of the marine dissolved organic phosphorus pool. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Fangxin Zhao
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Xingqin Lin
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Kun Cai
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230027, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - YongLiang Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230027, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Tianchi Ni
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yue Chen
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jianrong Feng
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Shangyu Dang
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.,Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Cong-Zhao Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230027, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Qinglu Zeng
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.,Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China.,HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute, Futian, Shenzhen, China
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6
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Accumulation of ambient phosphate into the periplasm of marine bacteria is proton motive force dependent. Nat Commun 2020; 11:2642. [PMID: 32457313 PMCID: PMC7250820 DOI: 10.1038/s41467-020-16428-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/24/2020] [Indexed: 12/20/2022] Open
Abstract
Bacteria acquire phosphate (Pi) by maintaining a periplasmic concentration below environmental levels. We recently described an extracellular Pi buffer which appears to counteract the gradient required for Pi diffusion. Here, we demonstrate that various treatments to outer membrane (OM) constituents do not affect the buffered Pi because bacteria accumulate Pi in the periplasm, from which it can be removed hypo-osmotically. The periplasmic Pi can be gradually imported into the cytoplasm by ATP-powered transport, however, the proton motive force (PMF) is not required to keep Pi in the periplasm. In contrast, the accumulation of Pi into the periplasm across the OM is PMF-dependent and can be enhanced by light energy. Because the conventional mechanism of Pi-specific transport cannot explain Pi accumulation in the periplasm we propose that periplasmic Pi anions pair with chemiosmotic cations of the PMF and millions of accumulated Pi pairs could influence the periplasmic osmolarity of marine bacteria. The ubiquitous oceanic bacteria harbour an external phosphate buffer for modulating phosphate (Pi) uptake. Here, using both oceanic SAR11, Prochlorococcus and Synechococcus strains as a model, the authors show that the Pi buffer accumulation in the periplasm is proton motive force-dependent and can be enhanced by light energy.
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7
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Faithfull C, Goetze E. Copepod nauplii use phosphorus from bacteria, creating a short circuit in the microbial loop. Ecol Lett 2019; 22:1462-1471. [PMID: 31270952 DOI: 10.1111/ele.13332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 05/11/2019] [Accepted: 06/05/2019] [Indexed: 11/30/2022]
Abstract
In subtropical oceans phytoplankton carbon: phosphorus (C : P) ratios are high, and these ratios are predicted to increase further with rising ocean temperatures and stratification. Prey stoichiometry may pose a problem for copepod zooplankton nauplii, which have high phosphorus demands due to rapid growth. We hypothesised that nauplii meet this demand by consuming bacteria. Naupliar bacterial and phytoplankton carbon and phosphorus ingestion, assimilation and incorporation were traced using 33 P and 14 C radioisotopes. Bacterial carbon was incorporated four times less efficiently into biomass than phytoplankton carbon. In contrast, bacterial and phytoplankton phosphorus were incorporated at similar efficiencies, and bacteria could meet a substantial amount of naupliar phosphorus requirements. As parts of the ocean become more oligotrophic, bacteria could help sustain naupliar growth and survival under suboptimal stoichiometric conditions. Thus, nauplii may be a shortcut for phosphorus from the microbial loop to the classical food web.
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Affiliation(s)
- Carolyn Faithfull
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.,Department of Oceanography, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Erica Goetze
- Department of Oceanography, University of Hawaii at Manoa, Honolulu, Hawaii
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8
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Barreiro C, Martínez-Castro M. Regulation of the phosphate metabolism in Streptomyces genus: impact on the secondary metabolites. Appl Microbiol Biotechnol 2019; 103:1643-1658. [DOI: 10.1007/s00253-018-09600-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 12/30/2022]
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9
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The Transcriptional Cycle Is Suited to Daytime N 2 Fixation in the Unicellular Cyanobacterium " Candidatus Atelocyanobacterium thalassa" (UCYN-A). mBio 2019; 10:mBio.02495-18. [PMID: 30602582 PMCID: PMC6315102 DOI: 10.1128/mbio.02495-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The symbiotic N2-fixing cyanobacterium UCYN-A, which is closely related to Braarudosphaera bigelowii, and its eukaryotic algal host have been shown to be globally distributed and important in open-ocean N2 fixation. These unique cyanobacteria have reduced metabolic capabilities, even lacking genes for oxygenic photosynthesis and carbon fixation. Cyanobacteria generally use energy from photosynthesis for nitrogen fixation but require mechanisms for avoiding inactivation of the oxygen-sensitive nitrogenase enzyme by ambient oxygen (O2) or the O2 evolved through photosynthesis. This study showed that symbiosis between the N2-fixing cyanobacterium UCYN-A and its eukaryotic algal host has led to adaptation of its daily gene expression pattern in order to enable daytime aerobic N2 fixation, which is likely more energetically efficient than fixing N2 at night, as found in other unicellular marine cyanobacteria. Symbiosis between a marine alga and a N2-fixing cyanobacterium (Cyanobacterium UCYN-A) is geographically widespread in the oceans and is important in the marine N cycle. UCYN-A is uncultivated and is an unusual unicellular cyanobacterium because it lacks many metabolic functions, including oxygenic photosynthesis and carbon fixation, which are typical in cyanobacteria. It is now presumed to be an obligate symbiont of haptophytes closely related to Braarudosphaera bigelowii. N2-fixing cyanobacteria use different strategies to avoid inhibition of N2 fixation by the oxygen evolved in photosynthesis. Most unicellular cyanobacteria temporally separate the two incompatible activities by fixing N2 only at night, but, surprisingly, UCYN-A appears to fix N2 during the day. The goal of this study was to determine how the unicellular UCYN-A strain coordinates N2 fixation and general metabolism compared to other marine cyanobacteria. We found that UCYN-A has distinct daily cycles of many genes despite the fact that it lacks two of the three circadian clock genes found in most cyanobacteria. We also found that the transcription patterns in UCYN-A are more similar to those in marine cyanobacteria that are capable of aerobic N2 fixation in the light, such as Trichodesmium and heterocyst-forming cyanobacteria, than to those in Crocosphaera or Cyanothece species, which are more closely related to unicellular marine cyanobacteria evolutionarily. Our findings suggest that the symbiotic interaction has resulted in a shift of transcriptional regulation to coordinate UCYN-A metabolism with that of the phototrophic eukaryotic host, thus allowing efficient coupling of N2 fixation (by the cyanobacterium) to the energy obtained from photosynthesis (by the eukaryotic unicellular alga) in the light.
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10
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Duhamel S, Van Wambeke F, Lefevre D, Benavides M, Bonnet S. Mixotrophic metabolism by natural communities of unicellular cyanobacteria in the western tropical South Pacific Ocean. Environ Microbiol 2018; 20:2743-2756. [PMID: 29573372 DOI: 10.1111/1462-2920.14111] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 03/12/2018] [Accepted: 03/17/2018] [Indexed: 12/31/2022]
Abstract
Cyanobacteria are major contributors to ocean biogeochemical cycling. However, mixotrophic metabolism and the relative importance of inorganic and organic carbon assimilation within the most abundant cyanobacteria are still poorly understood. We explore the ability of Prochlorococcus and Synechococcus to assimilate organic molecules with variable C:N:P composition and its modulation by light availability and photosynthetic impairment. We used a combination of radiolabelled molecules incubations with flow cytometry cell sorting to separate picoplankton groups from the western tropical South Pacific Ocean. Prochlorococcus and Synechococcus assimilated glucose, leucine and ATP at all stations, but cell-specific assimilation rates of N and P containing molecules were significantly higher than glucose. Incubations in the dark or with an inhibitor of photosystem II resulted in reduced assimilation rates. Light-enhanced cell-specific glucose uptake was generally higher for cyanobacteria (∼50%) than for the low nucleic acid fraction of bacterioplankton (LNA, ∼35%). Our results confirm previous findings, based mainly on cultures and genomic potentials, showing that Prochlorococcus and Synechococcus have a flexible mixotrophic metabolism, but demonstrate that natural populations remain primarily photoautotrophs. Our findings indicate that mixotrophy by marine cyanobacteria is more likely to be an adaptation to low inorganic nutrient availability rather than a facultative pathway for carbon acquisition.
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Affiliation(s)
- Solange Duhamel
- Lamont Doherty Earth Observatory, Division of Biology and Paleo Environment, PO Box 1000, 61 Route 9W, Palisades, NY 10964, USA
| | - France Van Wambeke
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Dominique Lefevre
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Mar Benavides
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France.,Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 98848, Noumea, New Caledonia
| | - Sophie Bonnet
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France.,Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 98848, Noumea, New Caledonia
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11
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Abstract
SAR11 is a group of small, carbon-oxidizing bacteria that reach a global estimated population size of 2.4×1028 cells-approximately 25% of all plankton. They are found throughout the oceans but reach their largest numbers in stratified, oligotrophic gyres, which are an expanding habitat in the warming oceans. SAR11 likely had a Precambrian origin and, over geological time, evolved into the niche of harvesting labile, low-molecular-weight dissolved organic matter (DOM). SAR11 cells are minimal in size and complexity, a phenomenon known as streamlining that is thought to benefit them by lowering the material costs of replication and maximizing transport functions that are essential to competition at ultralow nutrient concentrations. One of the surprises in SAR11 metabolism is their ability to both oxidize and produce a variety of volatile organic compounds that can diffuse into the atmosphere. SAR11 cells divide slowly and lack many forms of regulation commonly used by bacterial cells to adjust to changing environmental conditions. As a result of genome reduction, they require an unusual range of nutrients, which leads to complex biochemical interactions with other plankton. The study of SAR11 is providing insight into the biogeochemistry of labile DOM and is affecting microbiology beyond marine science by providing a model for understanding the evolution and function of streamlined cells.
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12
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Manrique JM, Jones LR. Are ocean currents too slow to counteract SAR11 evolution? A next-generation sequencing, phylogeographic analysis. Mol Phylogenet Evol 2016; 107:324-337. [PMID: 27894996 DOI: 10.1016/j.ympev.2016.11.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 11/18/2016] [Accepted: 11/24/2016] [Indexed: 11/27/2022]
Abstract
This work set out to shed light on the phylogeography of the SAR11 clade of Alphaproteobacteria, which is probably the most abundant group of heterotrophic bacteria on Earth. In particular, we assessed the degree to which empirical evidence (environmental DNA sequences) supports the concept that SAR11 lineages evolve faster than they are dispersed thus generating vicariant distributions, as predicted by recent simulation efforts. We generated 16S rRNA gene sequences from surface seawater collected at the South West Atlantic Ocean and combined these data with previously published sequences from similar environments from elsewhere. Altogether, these data consisted in about 1e6 reads, from which we generated 355,306 high quality sequences of which 95,318 corresponded to SAR11. Quantitative phylogeographic analyses supported the existence of a spatially explicit distribution of SAR11 species and provided evidence in favor of the idea that dispersal limitations significantly contribute to SAR11 radiation throughout the world's oceans. Likewise, pairwise phylogenetic distances between the communities studied here were significantly correlated with the genetic divergences predicted by a previously proposed neutral model. As discussed in the paper, these findings are compatible with the concept that the ocean surface constitutes a homogeneous environment for SAR11, in agreement with previous experimental data. We discuss the implications of this hypothesis in a global change scenario. This is the first study combining high throughput sequencing and phylogenic analysis to study bacterial phylogeography and reporting a distance decay pattern of phylogenetic distances for bacteria.
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Affiliation(s)
- Julieta M Manrique
- Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, (C1083ACA) Buenos Aires, Argentina; Laboratorio de Virología y Genética Molecular, Facultad de Ciencias Naturales sede Trelew, Universidad Nacional de la Patagonia San Juan Bosco, Argentina
| | - Leandro R Jones
- Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, (C1083ACA) Buenos Aires, Argentina; Laboratorio de Virología y Genética Molecular, Facultad de Ciencias Naturales sede Trelew, Universidad Nacional de la Patagonia San Juan Bosco, Argentina.
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