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Kujawinski EB, Braakman R, Longnecker K, Becker JW, Chisholm SW, Dooley K, Kido Soule MC, Swarr GJ, Halloran K. Metabolite diversity among representatives of divergent Prochlorococcus ecotypes. mSystems 2023; 8:e0126122. [PMID: 37815355 PMCID: PMC10654061 DOI: 10.1128/msystems.01261-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 08/31/2023] [Indexed: 10/11/2023] Open
Abstract
IMPORTANCE Approximately half of the annual carbon fixation on Earth occurs in the surface ocean through the photosynthetic activities of phytoplankton such as the ubiquitous picocyanobacterium Prochlorococcus. Ecologically distinct subpopulations (or ecotypes) of Prochlorococcus are central conduits of organic substrates into the ocean microbiome, thus playing important roles in surface ocean production. We measured the chemical profile of three cultured ecotype strains, observing striking differences among them that have implications for the likely chemical impact of Prochlorococcus subpopulations on their surroundings in the wild. Subpopulations differ in abundance along gradients of temperature, light, and nutrient concentrations, suggesting that these chemical differences could affect carbon cycling in different ocean strata and should be considered in models of Prochlorococcus physiology and marine carbon dynamics.
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Affiliation(s)
- Elizabeth B. Kujawinski
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Rogier Braakman
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Krista Longnecker
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Jamie W. Becker
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Science Department, Alvernia University, Reading, Pennsylvania, USA
| | - Sallie W. Chisholm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Keven Dooley
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, USA
| | - Melissa C. Kido Soule
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Gretchen J. Swarr
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Kathryn Halloran
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- MIT/WHOI Joint Program in Oceanography/Applied Ocean Sciences and Engineering, Department of Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
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2
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Martín-Rodríguez AJ. Respiration-induced biofilm formation as a driver for bacterial niche colonization. Trends Microbiol 2023; 31:120-134. [PMID: 36075785 DOI: 10.1016/j.tim.2022.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 01/27/2023]
Abstract
Depending on their physiology and metabolism, bacteria can carry out diverse redox processes for energy acquisition, which facilitates adaptation to environmental or host-associated niches. Of these processes, respiration, using oxygen or alternative terminal electron acceptors, is energetically the most favorable in heterotrophic bacteria. The biofilm lifestyle, a coordinated multicellular behavior, is ubiquitous in bacteria and is regulated by a variety of intrinsic and extrinsic cues. Respiration of distinct electron acceptors has been shown to induce biofilm formation or dispersal. The notion of biofilm formation regulation by electron acceptor availability and respiration has often been considered species-specific. However, recent evidence suggests that this phenomenon can be strain-specific, even in strains sharing the same functional respiratory pathways, thereby implying subtle regulatory mechanisms. On this basis, I argue that induction of biofilm formation by sensing and respiration of electron acceptors might direct subgroups of redox-specialized strains to occupy certain niches. A palette of respiration and electron-transfer-mediated microbial social interactions within biofilms may broaden ecological opportunities. The strain specificity of this phenomenon represents an important opportunity to identify key molecular mechanisms and their ecophysiological significance, which in turn may lay the ground for applications in areas ranging from biotechnology to the prevention of antimicrobial resistance.
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3
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Díez J, López-Lozano A, Domínguez-Martín MA, Gómez-Baena G, Muñoz-Marín MC, Melero-Rubio Y, García-Fernández JM. Regulatory and metabolic adaptations in the nitrogen assimilation of marine picocyanobacteria. FEMS Microbiol Rev 2023; 47:6794272. [PMID: 36323406 DOI: 10.1093/femsre/fuac043] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 10/25/2022] [Accepted: 10/28/2022] [Indexed: 11/17/2022] Open
Abstract
Prochlorococcus and Synechococcus are the two most abundant photosynthetic organisms on Earth, with a strong influence on the biogeochemical carbon and nitrogen cycles. Early reports demonstrated the streamlining of regulatory mechanisms in nitrogen metabolism and the removal of genes not strictly essential. The availability of a large series of genomes, and the utilization of latest generation molecular techniques have allowed elucidating the main mechanisms developed by marine picocyanobacteria to adapt to the environments where they thrive, with a particular interest in the strains inhabiting oligotrophic oceans. Given that nitrogen is often limited in those environments, a series of studies have explored the strategies utilized by Prochlorococcus and Synechococcus to exploit the low concentrations of nitrogen-containing molecules available in large areas of the oceans. These strategies include the reduction in the GC and the cellular protein contents; the utilization of truncated proteins; a reduced average amount of N in the proteome; the development of metabolic mechanisms to perceive and utilize nanomolar nitrate concentrations; and the reduced responsiveness of key molecular regulatory systems such as NtcA to 2-oxoglutarate. These findings are in sharp contrast with the large body of knowledge obtained in freshwater cyanobacteria. We will outline the main discoveries, stressing their relevance to the ecological success of these important microorganisms.
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Affiliation(s)
- J Díez
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
| | - A López-Lozano
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
| | - M A Domínguez-Martín
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
| | - G Gómez-Baena
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
| | - M C Muñoz-Marín
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
| | - Y Melero-Rubio
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
| | - J M García-Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, Córdoba,14001, Spain
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4
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Labban A, Shibl AA, Calleja ML, Hong PY, Morán XAG. Growth dynamics and transcriptional responses of a Red Sea Prochlorococcus strain to varying temperatures. Environ Microbiol 2022; 25:1007-1021. [PMID: 36567447 DOI: 10.1111/1462-2920.16326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/11/2022] [Indexed: 12/27/2022]
Abstract
Prochlorococcus play a crucial role in the ocean's biogeochemical cycling, but it remains controversial how they will respond to global warming. Here we assessed the response to temperature (22-30°C) of the growth dynamics and gene expression profiles of a Red Sea Prochlorococcus strain (RSP50) in a non-axenic culture. Both the specific growth rate (0.55-0.80 day-1 ) and cell size (0.04-0.07 μm3 ) of Prochlorococcus increased significantly with temperature. The primary production released extracellularly ranged from 20% to 34%, with humic-like fluorescent compounds increasing up to fivefold as Prochlorococcus reached its maximum abundance. At 30°C, genes involved in carbon fixation such as CsoS2 and CsoS3 and photosynthetic electron transport including PTOX were downregulated, suggesting a cellular homeostasis and energy saving mechanism response. In contrast, PTOX was found upregulated at 22°C and 24°C. Similar results were found for transaldolase, related to carbon metabolism, and citrate synthase, an important enzyme in the TCA cycle. Our data suggest that in spite of the currently warm temperatures of the Red Sea, Prochlorococcus can modulate its gene expression profiles to permit growth at temperatures lower than its optimum temperature (28°C) but is unable to cope with temperatures exceeding 30°C.
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Affiliation(s)
- Abbrar Labban
- Marine Science, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia.,Environmental Science and Engineering, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Ahmed A Shibl
- Genetic Heritage Group, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.,Public Health Research Center, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Maria Ll Calleja
- Climate Geochemistry Department, Max Plank Institute for Chemistry, Mainz, Germany
| | - Pei-Ying Hong
- Environmental Science and Engineering, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Xosé Anxelu G Morán
- Marine Science, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia.,Centro Oceanográfico de Gijón/Xixón, Instituto Español de Oceanografía (IEO-CSIC), Gijón/Xixón, Spain
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5
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Yang N, Lin YA, Merkel CA, DeMers MA, Qu PP, Webb EA, Fu FX, Hutchins DA. Molecular mechanisms underlying iron and phosphorus co-limitation responses in the nitrogen-fixing cyanobacterium Crocosphaera. THE ISME JOURNAL 2022; 16:2702-2711. [PMID: 36008474 PMCID: PMC9666452 DOI: 10.1038/s41396-022-01307-7] [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: 02/27/2022] [Revised: 08/04/2022] [Accepted: 08/09/2022] [Indexed: 12/15/2022]
Abstract
In the nitrogen-limited subtropical gyres, diazotrophic cyanobacteria, including Crocosphaera, provide an essential ecosystem service by converting dinitrogen (N2) gas into ammonia to support primary production in these oligotrophic regimes. Natural gradients of phosphorus (P) and iron (Fe) availability in the low-latitude oceans constrain the biogeography and activity of diazotrophs with important implications for marine biogeochemical cycling. Much remains unknown regarding Crocosphaera's physiological and molecular responses to multiple nutrient limitations. We cultured C. watsonii under Fe, P, and Fe/P (co)-limiting scenarios to link cellular physiology with diel gene expression and observed unique physiological and transcriptional profiles for each treatment. Counterintuitively, reduced growth and N2 fixation resource use efficiencies (RUEs) for Fe or P under P limitation were alleviated under Fe/P co-limitation. Differential gene expression analyses show that Fe/P co-limited cells employ the same responses as single-nutrient limited cells that reduce cellular nutrient requirements and increase responsiveness to environmental change including smaller cell size, protein turnover (Fe-limited), and upregulation of environmental sense-and-respond systems (P-limited). Combined, these mechanisms enhance growth and RUEs in Fe/P co-limited cells. These findings are important to our understanding of nutrient controls on N2 fixation and the implications for primary productivity and microbial dynamics in a changing ocean.
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Affiliation(s)
- Nina Yang
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Yu-An Lin
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Carlin A Merkel
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Michelle A DeMers
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Ping-Ping Qu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Eric A Webb
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Fei-Xue Fu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - David A Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
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6
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Li W, Yang M, Wang B, Liu CQ. Regulation strategy for nutrient-dependent carbon and nitrogen stoichiometric homeostasis in freshwater phytoplankton. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 823:153797. [PMID: 35150673 DOI: 10.1016/j.scitotenv.2022.153797] [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: 11/07/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
Phytoplankton carbon (C) and nitrogen (N) stoichiometric homeostasis plays an important role in aquatic ecosystems. Their C:N ratio is a result of cellular metabolic balance, and the relevant regulatory strategy for its plasticity is still unclear. Therefore, a field survey of seven reservoirs in Tianjin, North China, was conducted to understand variations in phytoplankton C:N ratios, and a laboratory culture of Chlamydomonas reinhardtii was performed to understand the relevant regulation strategy for cellular C-N stoichiometric homeostasis under different C and N availability by using transcriptome sequencing and Nano SIMS and C stable isotope analyses. The results indicated that CO2 limitation had no significant effect on the phytoplankton C:N ratio in either scene, whereas limitation of dissolved inorganic N induced a 35% higher ratio in the field and a 138% higher ratio in the laboratory. Under CO2 limitation, algal CO2-concentrating mechanisms were operated to ensure a C supply, and coupled C-N molecular regulation remained the cellular C:N ratio stable. Under nitrate limitation, differentially expressed gene-regulated intensities increase enormously, and their increasing proportion was comparable to that of the algal C:N ratio; cellular metabolism was reorganized to form a "subhealthy" C-N stoichiometric state with high C:N ratios. In addition, the N transport system had a specific role under CO2 and nitrate limitations. Our study implies that algal stoichiometric homeostasis depends on the involved limitation element and will help to deepen the understanding of C-N stoichiometric homeostasis in freshwater phytoplankton.
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Affiliation(s)
- Wanzhu Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
| | - Meiling Yang
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
| | - Baoli Wang
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
| | - Cong-Qiang Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
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7
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Chowdhury NB, Schroeder WL, Sarkar D, Amiour N, Quilleré I, Hirel B, Maranas CD, Saha R. Dissecting the metabolic reprogramming of maize root under nitrogen-deficient stress conditions. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:275-291. [PMID: 34554248 DOI: 10.1093/jxb/erab435] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
The growth and development of maize (Zea mays L.) largely depends on its nutrient uptake through the root. Hence, studying its growth, response, and associated metabolic reprogramming to stress conditions is becoming an important research direction. A genome-scale metabolic model (GSM) for the maize root was developed to study its metabolic reprogramming under nitrogen stress conditions. The model was reconstructed based on the available information from KEGG, UniProt, and MaizeCyc. Transcriptomics data derived from the roots of hydroponically grown maize plants were used to incorporate regulatory constraints in the model and simulate nitrogen-non-limiting (N+) and nitrogen-deficient (N-) condition. Model-predicted flux-sum variability analysis achieved 70% accuracy compared with the experimental change of metabolite levels. In addition to predicting important metabolic reprogramming in central carbon, fatty acid, amino acid, and other secondary metabolism, maize root GSM predicted several metabolites (l-methionine, l-asparagine, l-lysine, cholesterol, and l-pipecolate) playing a regulatory role in the root biomass growth. Furthermore, this study revealed eight phosphatidylcholine and phosphatidylglycerol metabolites which, even though not coupled with biomass production, played a key role in the increased biomass production under N-deficient conditions. Overall, the omics-integrated GSM provides a promising tool to facilitate stress condition analysis for maize root and engineer better stress-tolerant maize genotypes.
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Affiliation(s)
- Niaz Bahar Chowdhury
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Wheaton L Schroeder
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Debolina Sarkar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Nardjis Amiour
- Institut National de Recherche pour l'Agriculure, l'Alimentation et l'Envionnement (INRAE), Centre de Versailles-Grignon, Versailles cedex, France
| | - Isabelle Quilleré
- Institut National de Recherche pour l'Agriculure, l'Alimentation et l'Envionnement (INRAE), Centre de Versailles-Grignon, Versailles cedex, France
| | - Bertrand Hirel
- Institut National de Recherche pour l'Agriculure, l'Alimentation et l'Envionnement (INRAE), Centre de Versailles-Grignon, Versailles cedex, France
| | - Costas D Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Rajib Saha
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
- Center for Root and Rhizobiome Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
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8
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Behrenfeld MJ, O'Malley R, Boss E, Karp-Boss L, Mundt C. Phytoplankton biodiversity and the inverted paradox. ISME COMMUNICATIONS 2021; 1:52. [PMID: 36750580 PMCID: PMC9723737 DOI: 10.1038/s43705-021-00056-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/15/2021] [Accepted: 09/20/2021] [Indexed: 11/08/2022]
Abstract
Earth's aquatic food webs are overwhelmingly supported by planktonic microalgae that live in the sunlit water column where only a minimum number of physical niches are readily identifiable. Despite this paucity of environmental differentiation, these "phytoplankton" populations exhibit a rich biodiversity, an observation not easily reconciled with broadly accepted rules of resource-based competitive exclusion. This conundrum is referred to as the "Paradox of the Plankton". Consideration of physical distancing between nutrient depletion zones around individual phytoplankton, however, suggests a competition-neutral resource landscape. Application of neutral theory to the sheer number of phytoplankton in physically-mixed water masses yields a prediction of astronomical biodiversity, suggesting the inverted paradox: Why are there so few phytoplankton species? Here, we introduce a trophic constraint on phytoplankton that, when combined with stochastic principals of ecological drift, predicts only modest levels of diversity in an otherwise competition-neutral landscape. Our "trophic exclusion" principle predicts diversity to be independent of population size and yields a species richness across cell-size classes that is consistent with broad oceanographic survey observations.
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Affiliation(s)
- Michael J Behrenfeld
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
| | - Robert O'Malley
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Emmanuel Boss
- School of Marine Sciences, University of Maine, Orono, ME, USA
| | - Lee Karp-Boss
- School of Marine Sciences, University of Maine, Orono, ME, USA
| | - Christopher Mundt
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
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9
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Glucosidase Inhibitors Screening in Microalgae and Cyanobacteria Isolated from the Amazon and Proteomic Analysis of Inhibitor Producing Synechococcus sp. GFB01. Microorganisms 2021; 9:microorganisms9081593. [PMID: 34442672 PMCID: PMC8402191 DOI: 10.3390/microorganisms9081593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 11/17/2022] Open
Abstract
Microalgae and cyanobacteria are good sources for prospecting metabolites of biotechnological interest, including glucosidase inhibitors. These inhibitors act on enzymes related to various biochemical processes; they are involved in metabolic diseases, such as diabetes and Gaucher disease, tumors and viral infections, thus, they are interesting hubs for the development of new drugs and therapies. In this work, the screening of 63 environmental samples collected in the Brazilian Amazon found activity against β-glucosidase, of at least 60 min, in 13.85% of the tested extracts, with Synechococcus sp. GFB01 showing inhibitory activity of 90.2% for α-glucosidase and 96.9% against β-glucosidase. It was found that the nutritional limitation due to a reduction in the concentration of sodium nitrate, despite not being sufficient to cause changes in cell growth and photosynthetic apparatus, resulted in reduced production of α and β-glucosidase inhibitors and differential protein expression. The proteomic analysis of cyanobacteria isolated from the Amazon is unprecedented, with this being the first work to evaluate the protein expression of Synechococcus sp. GFB01 subjected to nutritional stress. This evaluation helps to better understand the metabolic responses of this organism, especially related to the production of inhibitors, adding knowledge to the industrial potential of these cyanobacterial compounds.
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Ustick LJ, Larkin AA, Garcia CA, Garcia NS, Brock ML, Lee JA, Wiseman NA, Moore JK, Martiny AC. Metagenomic analysis reveals global-scale patterns of ocean nutrient limitation. Science 2021; 372:287-291. [DOI: 10.1126/science.abe6301] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 03/01/2021] [Indexed: 12/23/2022]
Abstract
Nutrient supply regulates the activity of phytoplankton, but the global biogeography of nutrient limitation and co-limitation is poorly understood. Prochlorococcus adapt to local environments by gene gains and losses, and we used genomic changes as an indicator of adaptation to nutrient stress. We collected metagenomes from all major ocean regions as part of the Global Ocean Ship-based Hydrographic Investigations Program (Bio-GO-SHIP) and quantified shifts in genes involved in nitrogen, phosphorus, and iron assimilation. We found regional transitions in stress type and severity as well as widespread co-stress. Prochlorococcus stress genes, bottle experiments, and Earth system model predictions were correlated. We propose that the biogeography of multinutrient stress is stoichiometrically linked by controls on nitrogen fixation. Our omics-based description of phytoplankton resource use provides a nuanced and highly resolved description of nutrient stress in the global ocean.
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Affiliation(s)
- Lucas J. Ustick
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697, USA
| | - Alyse A. Larkin
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
| | - Catherine A. Garcia
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
| | - Nathan S. Garcia
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
| | - Melissa L. Brock
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697, USA
| | - Jenna A. Lee
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
| | - Nicola A. Wiseman
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
| | - J. Keith Moore
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
| | - Adam C. Martiny
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697, USA
- Department of Earth System Science, University of California Irvine, Irvine, CA 92697, USA
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11
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Gazitúa MC, Vik DR, Roux S, Gregory AC, Bolduc B, Widner B, Mulholland MR, Hallam SJ, Ulloa O, Sullivan MB. Potential virus-mediated nitrogen cycling in oxygen-depleted oceanic waters. THE ISME JOURNAL 2021; 15:981-998. [PMID: 33199808 PMCID: PMC8115048 DOI: 10.1038/s41396-020-00825-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 09/30/2020] [Accepted: 10/27/2020] [Indexed: 01/29/2023]
Abstract
Viruses play an important role in the ecology and biogeochemistry of marine ecosystems. Beyond mortality and gene transfer, viruses can reprogram microbial metabolism during infection by expressing auxiliary metabolic genes (AMGs) involved in photosynthesis, central carbon metabolism, and nutrient cycling. While previous studies have focused on AMG diversity in the sunlit and dark ocean, less is known about the role of viruses in shaping metabolic networks along redox gradients associated with marine oxygen minimum zones (OMZs). Here, we analyzed relatively quantitative viral metagenomic datasets that profiled the oxygen gradient across Eastern Tropical South Pacific (ETSP) OMZ waters, assessing whether OMZ viruses might impact nitrogen (N) cycling via AMGs. Identified viral genomes encoded six N-cycle AMGs associated with denitrification, nitrification, assimilatory nitrate reduction, and nitrite transport. The majority of these AMGs (80%) were identified in T4-like Myoviridae phages, predicted to infect Cyanobacteria and Proteobacteria, or in unclassified archaeal viruses predicted to infect Thaumarchaeota. Four AMGs were exclusive to anoxic waters and had distributions that paralleled homologous microbial genes. Together, these findings suggest viruses modulate N-cycling processes within the ETSP OMZ and may contribute to nitrogen loss throughout the global oceans thus providing a baseline for their inclusion in the ecosystem and geochemical models.
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Affiliation(s)
- M. Consuelo Gazitúa
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA ,Viromica Consulting, Santiago, Chile
| | - Dean R. Vik
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA
| | - Simon Roux
- grid.451309.a0000 0004 0449 479XDOE Joint Genome Institute, Berkeley, CA USA
| | - Ann C. Gregory
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA
| | - Benjamin Bolduc
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA
| | - Brittany Widner
- grid.261368.80000 0001 2164 3177Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA USA ,grid.56466.370000 0004 0504 7510Woods Hole Oceanographic Institution, Woods Hole, MA USA
| | - Margaret R. Mulholland
- grid.261368.80000 0001 2164 3177Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA USA
| | - Steven J. Hallam
- grid.17091.3e0000 0001 2288 9830Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC Canada
| | - Osvaldo Ulloa
- grid.5380.e0000 0001 2298 9663Departamento de Oceanografía & Instituto Milenio de Oceanografía, Universidad de Concepción, Concepción, Chile
| | - Matthew B. Sullivan
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA ,grid.261331.40000 0001 2285 7943Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH USA
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12
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Ip YK, Teng GCY, Boo MV, Poo JST, Hiong KC, Kim H, Wong WP, Chew SF. Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination. JOURNAL OF PHYCOLOGY 2020; 56:1696-1711. [PMID: 32725784 DOI: 10.1111/jpy.13053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
Giant clams harbor three genera of symbiotic dinoflagellates (Symbiodinium, Cladocopium, and Durusdinium) as extracellular symbionts (zooxanthellae). While symbiotic dinoflagellates can synthesize amino acids to benefit the host, they are nitrogen-deficient. Hence, the host must supply them with nitrogen including urea, which can be degraded to ammonia and carbon dioxide by urease (URE). Here, we report three complete coding cDNA sequences of URE, one for each genus of dinoflagellate, obtained from the colorful outer mantle of the giant clam, Tridacna squamosa. The outer mantle had higher transcript level of Tridacna squamosa zooxanthellae URE (TSZURE) than the whitish inner mantle, foot muscle, hepatopancreas, and ctenidium. TSZURE was immunolocalized strongly and atypically in the plastid, moderately in the cytoplasm, and weakly in the cell wall and plasma membrane of symbiotic dinoflagellates. In the outer mantle, illumination upregulated the protein abundance of TSZURE, which could enhance urea degradation in photosynthesizing dinoflagellates. The urea-nitrogen released could then augment synthesis of amino acids to be shared with the host for its general needs. Illumination also enhanced gene and protein expression levels of TSZURE/TSZURE in the inner mantle and foot muscle, which contain only small quantities of symbiotic dinoflagellate, have no iridocyte, and lack direct exposure to light. With low phototrophic potential, dinoflagellates in the inner mantle and foot muscle might need to absorb carbohydrates in order to assimilate the urea-nitrogen into amino acids. Amino acids donated by dinoflagellates to the inner mantle and the foot muscle could be used especially for synthesis of organic matrix needed for light-enhanced shell formation and muscle protein, respectively.
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Affiliation(s)
- Yuen Kwong Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Germaine Ching Yun Teng
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Mel Veen Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Jeslyn Shi Ting Poo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Kum Chew Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Hyoju Kim
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Wai Peng Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543
| | - Shit Fun Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore, 637616
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13
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Prochlorococcus Cells Rely on Microbial Interactions Rather than on Chlorotic Resting Stages To Survive Long-Term Nutrient Starvation. mBio 2020; 11:mBio.01846-20. [PMID: 32788385 PMCID: PMC7439483 DOI: 10.1128/mbio.01846-20] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The ability of microorganisms to withstand long periods of nutrient starvation is key to their survival and success under highly fluctuating conditions that are common in nature. Therefore, one would expect this trait to be prevalent among organisms in the nutrient-poor open ocean. Here, we show that this is not the case for Prochlorococcus, a globally abundant and ecologically important marine cyanobacterium. Instead, Prochlorococcus relies on co-occurring heterotrophic bacteria to survive extended phases of nutrient and light starvation. Our results highlight the power of microbial interactions to drive major biogeochemical cycles in the ocean and elsewhere with consequences at the global scale. Many microorganisms produce resting cells with very low metabolic activity that allow them to survive phases of prolonged nutrient or energy stress. In cyanobacteria and some eukaryotic phytoplankton, the production of resting stages is accompanied by a loss of photosynthetic pigments, a process termed chlorosis. Here, we show that a chlorosis-like process occurs under multiple stress conditions in axenic laboratory cultures of Prochlorococcus, the dominant phytoplankton linage in large regions of the oligotrophic ocean and a global key player in ocean biogeochemical cycles. In Prochlorococcus strain MIT9313, chlorotic cells show reduced metabolic activity, measured as C and N uptake by Nanoscale secondary ion mass spectrometry (NanoSIMS). However, unlike many other cyanobacteria, chlorotic Prochlorococcus cells are not viable and do not regrow under axenic conditions when transferred to new media. Nevertheless, cocultures with a heterotrophic bacterium, Alteromonas macleodii HOT1A3, allowed Prochlorococcus to survive nutrient starvation for months. We propose that reliance on co-occurring heterotrophic bacteria, rather than the ability to survive extended starvation as resting cells, underlies the ecological success of Prochlorococcus.
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14
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Lott SC, Voigt K, Lambrecht SJ, Hess WR, Steglich C. A framework for the computational prediction and analysis of non-coding RNAs in microbial environmental populations and their experimental validation. THE ISME JOURNAL 2020; 14:1955-1965. [PMID: 32346084 PMCID: PMC7368042 DOI: 10.1038/s41396-020-0658-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 03/22/2020] [Accepted: 04/07/2020] [Indexed: 11/09/2022]
Abstract
Small regulatory RNAs and antisense RNAs play important roles in the regulation of gene expression in bacteria but are underexplored, especially in natural populations. While environmentally relevant microbes often are not amenable to genetic manipulation or cannot be cultivated in the laboratory, extensive metagenomic and metatranscriptomic datasets for these organisms might be available. Hence, dedicated workflows for specific analyses are needed to fully benefit from this information. Here, we identified abundant sRNAs from oceanic environmental populations of the ecologically important primary producer Prochlorococcus starting from a metatranscriptomic differential RNA-Seq (mdRNA-Seq) dataset. We tracked their homologs in laboratory isolates, and we provide a framework for their further detailed characterization. Several of the experimentally validated sRNAs responded to ecologically relevant changes in cultivation conditions. The expression of the here newly discovered sRNA Yfr28 was highly stimulated in low-nitrogen conditions. Its predicted top targets include mRNAs encoding cell division proteins, a sigma factor, and several enzymes and transporters, suggesting a pivotal role of Yfr28 in the coordination of primary metabolism and cell division. A cis-encoded antisense RNA was identified as a possible positive regulator of atpF encoding subunit b' of the ATP synthase complex. The presented workflow will also be useful for other environmentally relevant microorganisms for which experimental validation abilities are frequently limiting although there is wealth of sequence information available.
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Affiliation(s)
- Steffen C Lott
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany
| | - Karsten Voigt
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany
| | - S Joke Lambrecht
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany
| | - Wolfgang R Hess
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany
| | - Claudia Steglich
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany.
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15
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Guyet U, Nguyen NA, Doré H, Haguait J, Pittera J, Conan M, Ratin M, Corre E, Le Corguillé G, Brillet-Guéguen L, Hoebeke M, Six C, Steglich C, Siegel A, Eveillard D, Partensky F, Garczarek L. Synergic Effects of Temperature and Irradiance on the Physiology of the Marine Synechococcus Strain WH7803. Front Microbiol 2020; 11:1707. [PMID: 32793165 PMCID: PMC7393227 DOI: 10.3389/fmicb.2020.01707] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/29/2020] [Indexed: 11/18/2022] Open
Abstract
Understanding how microorganisms adjust their metabolism to maintain their ability to cope with short-term environmental variations constitutes one of the major current challenges in microbial ecology. Here, the best physiologically characterized marine Synechococcus strain, WH7803, was exposed to modulated light/dark cycles or acclimated to continuous high-light (HL) or low-light (LL), then shifted to various stress conditions, including low (LT) or high temperature (HT), HL and ultraviolet (UV) radiations. Physiological responses were analyzed by measuring time courses of photosystem (PS) II quantum yield, PSII repair rate, pigment ratios and global changes in gene expression. Previously published membrane lipid composition were also used for correlation analyses. These data revealed that cells previously acclimated to HL are better prepared than LL-acclimated cells to sustain an additional light or UV stress, but not a LT stress. Indeed, LT seems to induce a synergic effect with the HL treatment, as previously observed with oxidative stress. While all tested shift conditions induced the downregulation of many photosynthetic genes, notably those encoding PSI, cytochrome b6/f and phycobilisomes, UV stress proved to be more deleterious for PSII than the other treatments, and full recovery of damaged PSII from UV stress seemed to involve the neo-synthesis of a fairly large number of PSII subunits and not just the reassembly of pre-existing subunits after D1 replacement. In contrast, genes involved in glycogen degradation and carotenoid biosynthesis pathways were more particularly upregulated in response to LT. Altogether, these experiments allowed us to identify responses common to all stresses and those more specific to a given stress, thus highlighting genes potentially involved in niche acclimation of a key member of marine ecosystems. Our data also revealed important specific features of the stress responses compared to model freshwater cyanobacteria.
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Affiliation(s)
- Ulysse Guyet
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Ngoc A Nguyen
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Hugo Doré
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Julie Haguait
- LS2N, UMR CNRS 6004, IMT Atlantique, ECN, Université de Nantes, Nantes, France
| | - Justine Pittera
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Maël Conan
- DYLISS (INRIA-IRISA)-INRIA, CNRS UMR 6074, Université de Rennes 1, Rennes, France
| | - Morgane Ratin
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Erwan Corre
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France
| | - Gildas Le Corguillé
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France
| | - Loraine Brillet-Guéguen
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France.,CNRS, UMR 8227 Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Mark Hoebeke
- CNRS, FR2424, ABiMS, Station Biologique, Sorbonne Université, Roscoff, France
| | - Christophe Six
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | | | - Anne Siegel
- DYLISS (INRIA-IRISA)-INRIA, CNRS UMR 6074, Université de Rennes 1, Rennes, France
| | - Damien Eveillard
- LS2N, UMR CNRS 6004, IMT Atlantique, ECN, Université de Nantes, Nantes, France
| | - Frédéric Partensky
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Laurence Garczarek
- CNRS, UMR 7144 Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
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16
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Shilova IN, Magasin JD, Mills MM, Robidart JC, Turk-Kubo KA, Zehr JP. Phytoplankton transcriptomic and physiological responses to fixed nitrogen in the California current system. PLoS One 2020; 15:e0231771. [PMID: 32310982 PMCID: PMC7170224 DOI: 10.1371/journal.pone.0231771] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 03/31/2020] [Indexed: 11/18/2022] Open
Abstract
Marine phytoplankton are responsible for approximately half of photosynthesis on Earth. However, their ability to drive ocean productivity depends on critical nutrients, especially bioavailable nitrogen (N) which is scarce over vast areas of the ocean. Phytoplankton differ in their preferences for N substrates as well as uptake efficiencies and minimal N requirements relative to other critical nutrients, including iron (Fe) and phosphorus. In this study, we used the MicroTOOLs high-resolution environmental microarray to examine transcriptomic responses of phytoplankton communities in the California Current System (CCS) transition zone to added urea, ammonium, nitrate, and also Fe in the late summer when N depletion is common. Transcript level changes of photosynthetic, carbon fixation, and nutrient stress genes indicated relief of N limitation in many strains of Prochlorococcus, Synechococcus, and eukaryotic phytoplankton. The transcriptomic responses helped explain shifts in physiological and growth responses observed later. All three phytoplankton groups had increased transcript levels of photosynthesis and/or carbon fixation genes in response to all N substrates. However, only Prochlorococcus had decreased transcript levels of N stress genes and grew substantially, specifically after urea and ammonium additions, suggesting that Prochlorococcus outcompeted other community members in these treatments. Diatom transcript levels of carbon fixation genes increased in response to Fe but not to Fe with N which might have favored phytoplankton that were co-limited by N and Fe. Moreover, transcription patterns of closely related strains indicated variability in N utilization, including nitrate utilization by some high-light adapted Prochlorococcus. Finally, up-regulation of urea transporter genes by both Prochlorococcus and Synechococcus in response to filtered deep water suggested a regulatory mechanism other than classic control via the global N regulator NtcA. This study indicated that co-existing phytoplankton strains experience distinct nutrient stresses in the transition zone of the CCS, an understudied region where oligotrophic and coastal communities naturally mix.
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Affiliation(s)
- Irina N. Shilova
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, California, United States of America
- * E-mail: (INS); (JPZ)
| | - Jonathan D. Magasin
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Matthew M. Mills
- Department of Earth System Science, Stanford University, Stanford, California, United States of America
| | - Julie C. Robidart
- Ocean Technology and Engineering, National Oceanography Centre, Southampton, England, United Kingdom
| | - Kendra A. Turk-Kubo
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Jonathan P. Zehr
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, California, United States of America
- * E-mail: (INS); (JPZ)
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17
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Weber L, Apprill A. Diel, daily, and spatial variation of coral reef seawater microbial communities. PLoS One 2020; 15:e0229442. [PMID: 32160233 PMCID: PMC7065756 DOI: 10.1371/journal.pone.0229442] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 02/06/2020] [Indexed: 01/02/2023] Open
Abstract
Reef organisms influence microorganisms within the surrounding seawater, yet the spatial and temporal dynamics of seawater microbial communities located in proximity to corals are rarely investigated. To better understand reef seawater microbial community dynamics over time and space, we collected small-volume seawater samples during the day and night over a 72 hour period from three locations that differed in spatial distance from 5 Porites astreoides coral colonies on a shallow reef in St. John, U.S. Virgin Islands: near-coral (sampled 5 cm horizontally from each colony), reef-depth (sampled 2 m above each colony) and surface seawater (sampled 1 m from the seawater surface). At all time points and locations, we quantified abundances of microbial cells, sequenced small subunit rRNA genes of bacterial and archaeal communities, and measured inorganic nutrient concentrations. Prochlorococcus and Synechococcus cells were consistently elevated at night compared to day and these abundances changed over time, corresponding with temperature, nitrite, and silicate concentrations. During the day, bacterial and archaeal alpha diversity was significantly higher in reef-depth and near-coral seawater compared to the surface seawater, signifying that the reef influences the diversity of the seawater microorganisms. At night, alpha diversity decreased across all samples, suggesting that photosynthesis may favor a more taxonomically diverse community. While Prochlorococcus exhibited consistent temporal rhythmicity, additional taxa were enriched in reef seawater at night compared to day or in reef-depth compared to surface seawater based on their normalized sequence counts. There were some significant differences in nutrient concentrations and cell abundances between reef-depth and near-coral seawater but no clear trends. This study demonstrates that temporal variation supersedes small-scale spatial variation in proximity to corals in reef seawater microbial communities. As coral reefs continue to change in benthic composition worldwide, monitoring microbial composition in response to temporal changes and environmental fluctuations will help discern normal variability from longer lasting changes attributed to anthropogenic stressors and global climate change.
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Affiliation(s)
- Laura Weber
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States of America
- MIT-WHOI Joint PhD Program in Biological Oceanography, Woods Hole, MA, United States of America
| | - Amy Apprill
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States of America
- * E-mail:
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18
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Lambrecht SJ, Steglich C, Hess WR. A minimum set of regulators to thrive in the ocean. FEMS Microbiol Rev 2020; 44:232-252. [DOI: 10.1093/femsre/fuaa005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 02/19/2020] [Indexed: 12/25/2022] Open
Abstract
ABSTRACT
Marine cyanobacteria of the genus Prochlorococcus thrive in high cell numbers throughout the euphotic zones of the world's subtropical and tropical oligotrophic oceans, making them some of the most ecologically relevant photosynthetic microorganisms on Earth. The ecological success of these free-living phototrophs suggests that they are equipped with a regulatory system competent to address many different stress situations. However, Prochlorococcus genomes are compact and streamlined, with the majority encoding only five different sigma factors, five to six two-component systems and eight types of other transcriptional regulators. Here, we summarize the existing information about the functions of these protein regulators, about transcriptomic responses to defined stress conditions, and discuss the current knowledge about riboswitches, RNA-based regulation and the roles of certain metabolites as co-regulators. We focus on the best-studied isolate, Prochlorococcus MED4, but extend to other strains and ecotypes when appropriate, and we include some information gained from metagenomic and metatranscriptomic analyses.
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Affiliation(s)
- S Joke Lambrecht
- Genetics and Experimental Bioinformatics, Institute of Biology III, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany
| | - Claudia Steglich
- Genetics and Experimental Bioinformatics, Institute of Biology III, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany
| | - Wolfgang R Hess
- Genetics and Experimental Bioinformatics, Institute of Biology III, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany
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19
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Lambrecht SJ, Kanesaki Y, Fuss J, Huettel B, Reinhardt R, Steglich C. Interplay and Targetome of the Two Conserved Cyanobacterial sRNAs Yfr1 and Yfr2 in Prochlorococcus MED4. Sci Rep 2019; 9:14331. [PMID: 31586076 PMCID: PMC6778093 DOI: 10.1038/s41598-019-49881-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 09/02/2019] [Indexed: 01/22/2023] Open
Abstract
The sRNA Yfr1 and members of the Yfr2 sRNA family are almost universally present within cyanobacteria. The conserved motifs of these sRNAs are nearly complementary to each other, suggesting their ability to participate in crosstalk. The conserved motif of Yfr1 is shared by members of the Yfr10 sRNA family, members of which are otherwise less conserved in sequence, structure, and synteny compared to Yfr1. The different structural properties enable the discrimination of unique targets of Yfr1 and Yfr10. Unlike most studied regulatory sRNAs, Yfr1 gene expression only slightly changes under the tested stress conditions and is present at high levels at all times. In contrast, cellular levels of Yfr10 increase during the course of acclimation to darkness, and levels of Yfr2 increase when cells are shifted to high light or nitrogen limitation conditions. In this study, we investigated the targetomes of Yfr2, Yfr1, and Yfr10 in Prochlorococcus MED4, establishing CRAFD-Seq as a new method for identifying direct targets of these sRNAs that is applicable to all bacteria, including those that are not amenable to genetic modification. The results suggest that these sRNAs are integrated within a regulatory network of unprecedented complexity in the adjustment of carbon and nitrogen-related primary metabolism.
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Affiliation(s)
- S Joke Lambrecht
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany
| | - Yu Kanesaki
- NODAI Genome Research Center, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan.,Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Janina Fuss
- Max Planck-Genome-Centre Cologne, Max Planck Institute for Plant Breeding Research, D-50829, Köln, Germany
| | - Bruno Huettel
- Max Planck-Genome-Centre Cologne, Max Planck Institute for Plant Breeding Research, D-50829, Köln, Germany
| | - Richard Reinhardt
- Max Planck-Genome-Centre Cologne, Max Planck Institute for Plant Breeding Research, D-50829, Köln, Germany
| | - Claudia Steglich
- University of Freiburg, Faculty of Biology, D-79104, Freiburg, Germany.
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20
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Veaudor T, Cassier-Chauvat C, Chauvat F. Genomics of Urea Transport and Catabolism in Cyanobacteria: Biotechnological Implications. Front Microbiol 2019; 10:2052. [PMID: 31551986 PMCID: PMC6737895 DOI: 10.3389/fmicb.2019.02052] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/20/2019] [Indexed: 11/13/2022] Open
Abstract
Cyanobacteria are widely-diverse prokaryotes that colonize our planet. They use solar energy to assimilate huge amounts of atmospheric CO2 and produce a large part of the biomass and oxygen that sustain most life forms. Cyanobacteria are therefore increasingly studied for basic research objectives, as well as for the photosynthetic production of chemicals with industrial interests. One potential approach to reduce the cost of future bioproduction processes is to couple them with wastewater treatment, often polluted with urea, which in any case is cheaper than nitrate. As of yet, however, research has mostly focused on a very small number of model cyanobacteria growing on nitrate. Thus, the genetic inventory of the cyanobacterial phylum is still insufficiently employed to meaningfully select the right host for the right purpose. This review reports what is known about urea transport and catabolism in cyanobacteria, and what can be inferred from the comparative analysis of the publicly available genome sequence of the 308 cyanobacteria. We found that most cyanobacteria mostly harbor the genes encoding the urea catabolytic enzymes urease (ureABCDEFG), but not systematically, together with the urea transport (urtABCDE). These findings are consistent with the capacity of the few tested cyanobacteria that grow on urea as the sole nitrogen source. They also indicate that urease is important for the detoxification of internally generated urea (re-cycling its carbon and nitrogen). In contrast, several cyanobacteria have urtABCDE but not ureABCDEFG, suggesting that urtABCDE could operate in the transport of not only urea but also of other nutrients. Only four cyanobacteria appeared to have the genes encoding the urea carboxylase (uc) and allophanate hydrolase (ah) enzymes that sequentially catabolize urea. Three of these cyanobacteria belongs to the genera Gloeobacter and Gloeomargarita that have likely diverged early from other cyanobacteria, suggesting that the urea carboxylase and allophanate hydrolase enzymes appeared in cyanobacteria before urease.
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Affiliation(s)
- Théo Veaudor
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Corinne Cassier-Chauvat
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Franck Chauvat
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
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21
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Li YY, Chen XH, Xue C, Zhang H, Sun G, Xie ZX, Lin L, Wang DZ. Proteomic Response to Rising Temperature in the Marine Cyanobacterium Synechococcus Grown in Different Nitrogen Sources. Front Microbiol 2019; 10:1976. [PMID: 31507578 PMCID: PMC6716455 DOI: 10.3389/fmicb.2019.01976] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 08/12/2019] [Indexed: 11/16/2022] Open
Abstract
Synechococcus is one of the most important contributors to global primary productivity, and ocean warming is predicted to increase abundance and distribution of Synechococcus in the ocean. Here, we investigated molecular response of an oceanic Synechococcus strain WH8102 grown in two nitrogen sources (nitrate and urea) under present (25°C) and predicted future (28°C) temperature conditions using an isobaric tag (IBT)-based quantitative proteomic approach. Rising temperature decreased growth rate, contents of chlorophyll a, protein and sugar in the nitrate-grown cells, but only decreased protein content and significantly increased zeaxanthin content of the urea-grown cells. Expressions of CsoS2 protein involved in carboxysome formation and ribosomal subunits in both nitrate- and urea-grown cells were significantly decreased in rising temperature, whereas carbohydrate selective porin and sucrose-phosphate synthase (SPS) were remarkably up-regulated, and carbohydrate degradation associated proteins, i.e., glycogen phosphorylase kinase, fructokinase and glucose-6-phosphate dehydrogenase, were down-regulated in the urea-grown cells. Rising temperature also increased expressions of three redox-sensitive enzymes (peroxiredoxin, thioredoxin, and CP12) in both nitrate- and urea-grown cells. Our results indicated that rising temperature did not enhance cell growth of Synechococcus; on the contrary, it impaired cell functions, and this might influence cell abundance and distribution of Synechococcus in a future ocean.
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Affiliation(s)
- Yuan-Yuan Li
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Xiao-Huang Chen
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Cheng Xue
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Hao Zhang
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Geng Sun
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Zhang-Xian Xie
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Lin Lin
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
- Key Laboratory of Marine Ecology and Environmental Sciences, Chinese Academy of Sciences, Qingdao, China
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22
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Yu XZ, Lei SY, Lin YJ, Zhang Q. Interaction of cyanate uptake by rice seedlings with nitrate assimilation: gene expression analysis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:20208-20218. [PMID: 31098903 DOI: 10.1007/s11356-019-05407-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/06/2019] [Indexed: 06/09/2023]
Abstract
Cyanate (CNO-) has been produced in the environment through either natural or anthropogenic sources. However, due to industrialization, it has been led more over-loads. In this study, interaction of CNO- uptake by rice seedlings with nitrate assimilation was investigated using gene expression analysis after an acute phytotoxicity assay. Our results showed that CNO- exposure caused inhibition on relative growth rates of plants. CNO- analysis demonstrated that rice seedlings had higher potential for CNO- uptake and the removal rates showed a zero-order kinetic. PCR analysis exposed that OsCYN transcript was not significantly induced by CNO- treatments in rice tissues and CNO- exposure also repressed gene expression of the collaborative enzyme carbonic anhydrase (CA), suggesting that assimilation of CNO- initiated by the enzyme cyanase (CYN) in rice seedlings was an enzyme-limitation reaction. Gene expression of other enzymes involved in nitrate metabolism was tissue-specific under CNO- exposure, suggesting that rice seedlings were able to trigger its intrinsic regulative and responsive mechanisms to cope up with uneven N conditions. Significant upregulation of three OsGDH isogenes, except for OsGDH1 in roots, was detected in both rice materials with enhancing CNO- concentrations, suggesting that GDH may play a primary role to maintain the balance of C and N in plants under CNO- exposure. In conclusion, because the innate pool of CYN activity was non-sufficient to degrade exogenous CNO- by rice seedlings, CNO-derived ammonium only can serve as a supporting N source to support growth of rice seedling under non-effective doses of CNO- exposure.
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Affiliation(s)
- Xiao-Zhang Yu
- College of Environmental Science & Engineering, Guilin University of Technology, Guilin, 541004, People's Republic of China.
| | - Sheng-Yu Lei
- College of Environmental Science & Engineering, Guilin University of Technology, Guilin, 541004, People's Republic of China
| | - Yu-Juan Lin
- College of Environmental Science & Engineering, Guilin University of Technology, Guilin, 541004, People's Republic of China
| | - Qing Zhang
- College of Environmental Science & Engineering, Guilin University of Technology, Guilin, 541004, People's Republic of China
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23
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Thangaraj S, Shang X, Sun J, Liu H. Quantitative Proteomic Analysis Reveals Novel Insights into Intracellular Silicate Stress-Responsive Mechanisms in the Diatom Skeletonema dohrnii. Int J Mol Sci 2019; 20:E2540. [PMID: 31126124 PMCID: PMC6566588 DOI: 10.3390/ijms20102540] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/19/2019] [Accepted: 05/20/2019] [Indexed: 01/04/2023] Open
Abstract
Diatoms are a successful group of marine phytoplankton that often thrives under adverse environmental stress conditions. Members of the Skeletonema genus are ecologically important which may subsist during silicate stress and form a dense bloom following higher silicate concentration. However, our understanding of diatoms' underlying molecular mechanism involved in these intracellular silicate stress-responses are limited. Here an iTRAQ-based proteomic method was coupled with multiple physiological techniques to explore distinct cellular responses associated with oxidative stress in the diatom Skeletonema dohrnii to the silicate limitation. In total, 1768 proteins were detected; 594 proteins were identified as differentially expressed (greater than a two-fold change; p < 0.05). In Si-limited cells, downregulated proteins were mainly related to photosynthesis metabolism, light-harvesting complex, and oxidative phosphorylation, corresponding to inducing oxidative stress, and ROS accumulation. None of these responses were identified in Si-limited cells; in comparing with other literature, Si-stress cells showed that ATP-limited diatoms are unable to rely on photosynthesis, which will break down and reshuffle carbon metabolism to compensate for photosynthetic carbon fixation losses. Our findings have a good correlation with earlier reports and provides a new molecular level insight into the systematic intracellular responses employed by diatoms in response to silicate stress in the marine environment.
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Affiliation(s)
- Satheeswaran Thangaraj
- Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
- Research Center for Indian Ocean Ecosystem, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
- Faculty of Food Engineering and Biotechnology, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
| | - Xiaomei Shang
- Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
- Research Center for Indian Ocean Ecosystem, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
| | - Jun Sun
- Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
- Research Center for Indian Ocean Ecosystem, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
| | - Haijiao Liu
- Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
- Research Center for Indian Ocean Ecosystem, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin 300457, China.
- Institute of Marine Science and Technology, Shandong University, No 27, Shanda Nan Road, Jinan 250110, China.
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24
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Carbon Fate and Flux in Prochlorococcus under Nitrogen Limitation. mSystems 2019; 4:mSystems00254-18. [PMID: 30834330 PMCID: PMC6392094 DOI: 10.1128/msystems.00254-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/28/2019] [Indexed: 11/20/2022] Open
Abstract
Primary production by Prochlorococcus, the smallest known free-living photosynthetic organism in terms of both physical and genomic size, is thought to have a significant role in global carbon cycles. Despite its small size and low growth rate, Prochlorococcus numerically dominates the phytoplankton community in the nutrient-poor oligotrophic ocean, the largest biome of the Earth's surface. How nutrient limitation, and nitrogen limitation in particular, affects the fate and flux of carbon fixed by Prochlorococcus is currently unknown. To address this gap in knowledge, we compared the bulk rates of photosynthesis and organic carbon release, the concentrations of intracellular metabolites, and the rates of assimilated carbon into the metabolite pools between replete and N-limited chemostat cultures. Total photosynthesis of our N-limited cultures was less than half of those observed in replete cultures, and nitrogen limitation also appears to cause a larger proportion of total fixed carbon to be released to the environment. Our data suggest this occurs in concert with the maintenance of large slow-moving pools of metabolites, including nitrogen-rich molecules such as glutamate. Additionally, we report field data suggesting metabolisms of Prochlorococcus are comparable to results we observe in our laboratory studies. Accounting for these observations, potential metabolic mechanisms utilized by Prochlorococcus are discussed as we build upon our understanding of nutrient-limited photosynthesis and carbon metabolism. IMPORTANCE Photosynthetic microbes are the predominant sources of organic carbon in the sunlit regions of the ocean. During photosynthesis, nitrogen and carbon metabolism are coordinated to synthesize nitrogen-containing organics such as amino acids and nucleic acids. In large regions of the ocean, nitrogen is thought to limit the growth of phytoplankton. The impact of nitrogen limitation on the synthesis of organic carbon is not well understood, especially for the most abundant photosynthetic organism in the nitrogen-limited regions of the ocean, Prochlorococcus. This study compares the carbon metabolism of nitrogen-replete and nitrogen-limited Prochlorococcus spp. to determine how nitrogen availability influences inorganic carbon assimilation into an organic form. Metabolomics and physiological data revealed that cells under nitrogen limitation have reduced metabolic flux and total carbon fixation rates while maintaining elevated metabolite pool levels and releasing a larger proportion of total fixed carbon to the environment.
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25
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Fang X, Liu Y, Zhao Y, Chen Y, Liu R, Qin QL, Li G, Zhang YZ, Chan W, Hess WR, Zeng Q. Transcriptomic responses of the marine cyanobacterium Prochlorococcus to viral lysis products. Environ Microbiol 2019; 21:2015-2028. [PMID: 30585375 DOI: 10.1111/1462-2920.14513] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/19/2018] [Indexed: 01/27/2023]
Abstract
Viral infection of marine phytoplankton releases a variety of dissolved organic matter (DOM). The impact of viral DOM (vDOM) on the uninfected co-occurring phytoplankton remains largely unknown. Here, we conducted transcriptomic analyses to study the effects of vDOM on the cyanobacterium Prochlorococcus, which is the most abundant photosynthetic organism on Earth. Using Prochlorococcus MIT9313, we showed that its growth was not affected by vDOM, but many tRNAs increased in abundance. We tested tRNA-gly and found that its abundance increased upon addition of glycine. The decreased transcript abundances of N metabolism genes also suggested that Prochlorococcus responded to organic N compounds in vDOM. Addition of vDOM to Prochlorococcus reduced the maximum photochemical efficiency of photosystem II and CO2 fixation while increasing its respiration rate, consistent with differentially abundant transcripts related to photosynthesis and respiration. One of the highest positive fold-changes was observed for the 6S RNA, a noncoding RNA functioning as a global transcriptional regulator in bacteria. The high level of 6S RNA might be responsible for some of the observed transcriptional responses. Taken together, our results revealed the transcriptional regulation of Prochlorococcus in response to viral lysis products and suggested its metabolic potential to utilize organic N compounds.
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Affiliation(s)
- Xiaoting Fang
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yaxin Liu
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yao Zhao
- Department of Chemistry, 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
| | - Riyue Liu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Qi-Long Qin
- State Key Lab of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan, China
| | - Gang Li
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology (CAS), Guangzhou, China
| | - Yu-Zhong Zhang
- State Key Lab of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan, China.,College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Wan Chan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Wolfgang R Hess
- Genetics & Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Germany
| | - Qinglu Zeng
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.,HKUST Shenzhen Research Institute, Shenzhen, China
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26
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Lambrecht SJ, Wahlig JML, Steglich C. The GntR family transcriptional regulator PMM1637 regulates the highly conserved cyanobacterial sRNA Yfr2 in marine picocyanobacteria. DNA Res 2019; 25:489-497. [PMID: 29901694 PMCID: PMC6191309 DOI: 10.1093/dnares/dsy019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 05/14/2018] [Indexed: 11/21/2022] Open
Abstract
Prochlorococcus is a marine picocyanobacterium with a streamlined genome that is adapted to different ecological niches in the oligotrophic oceans. There are currently >20 regulatory small RNAs (sRNAs) that have been identified in the model strain Prochlorococcus MED4. While most of these sRNAs are ecotype-specific, sRNA homologs of Yfr1 and of the Yfr2 family are widely found throughout the cyanobacterial phylum. Although they were identified 13 yrs ago, the functions of Yfr1 and Yfr2 have remained unknown. We observed a strong induction of two Yfr2 sRNA homologs of Prochlorococcus MED4 during high light stress and nitrogen starvation. Several Prochlorococcus and marine Synechococcus yfr2 promoter regions contain a conserved motif we named CGRE1 (cyanobacterial GntR family transcriptional regulator responsive element 1). Using the conserved promoter region as bait in a DNA affinity pull-down assay we identified the GntR family transcriptional regulator PMM1637 as a binding partner. Similar to Yfr2, homologs of PMM1637 are universally and exclusively found in cyanobacteria. We suggest that PMM1637 governs the induction of gene expression of Yfr2 homologs containing CGRE1 in their promoters under nitrogen-depleted and high-light stress conditions.
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Affiliation(s)
- S Joke Lambrecht
- Faculty of Biology, Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg, Germany
| | - J Mascha L Wahlig
- Faculty of Biology, Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg, Germany
| | - Claudia Steglich
- Faculty of Biology, Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg, Germany
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27
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Bolay P, Muro-Pastor MI, Florencio FJ, Klähn S. The Distinctive Regulation of Cyanobacterial Glutamine Synthetase. Life (Basel) 2018; 8:E52. [PMID: 30373240 PMCID: PMC6316151 DOI: 10.3390/life8040052] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/23/2018] [Accepted: 10/25/2018] [Indexed: 12/02/2022] Open
Abstract
Glutamine synthetase (GS) features prominently in bacterial nitrogen assimilation as it catalyzes the entry of bioavailable nitrogen in form of ammonium into cellular metabolism. The classic example, the comprehensively characterized GS of enterobacteria, is subject to exquisite regulation at multiple levels, among them gene expression regulation to control GS abundance, as well as feedback inhibition and covalent modifications to control enzyme activity. Intriguingly, the GS of the ecologically important clade of cyanobacteria features fundamentally different regulatory systems to those of most prokaryotes. These include the interaction with small proteins, the so-called inactivating factors (IFs) that inhibit GS linearly with their abundance. In addition to this protein interaction-based regulation of GS activity, cyanobacteria use alternative elements to control the synthesis of GS and IFs at the transcriptional level. Moreover, cyanobacteria evolved unique RNA-based regulatory mechanisms such as glutamine riboswitches to tightly tune IF abundance. In this review, we aim to outline the current knowledge on the distinctive features of the cyanobacterial GS encompassing the overall control of its activity, sensing the nitrogen status, transcriptional and post-transcriptional regulation, as well as strain-specific differences.
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Affiliation(s)
- Paul Bolay
- Helmholtz Centre for Environmental Research, Department of Solar Materials, Permoserstrasse 15, D-04318 Leipzig, Germany.
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, E-41092 Seville, Spain.
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Américo Vespucio 49, E-41092 Seville, Spain.
| | - Stephan Klähn
- Helmholtz Centre for Environmental Research, Department of Solar Materials, Permoserstrasse 15, D-04318 Leipzig, Germany.
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28
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Robidart JC, Magasin JD, Shilova IN, Turk-Kubo KA, Wilson ST, Karl DM, Scholin CA, Zehr JP. Effects of nutrient enrichment on surface microbial community gene expression in the oligotrophic North Pacific Subtropical Gyre. ISME JOURNAL 2018; 13:374-387. [PMID: 30254320 DOI: 10.1038/s41396-018-0280-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 07/26/2018] [Accepted: 08/26/2018] [Indexed: 11/09/2022]
Abstract
Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity in the surface ocean is constrained by nutrients which are supplied, in part, by mixing with deeper water. Little is known about the time scales, frequency, or impact of mixing on microbial communities. We combined in situ sampling using the Environmental Sample Processor and a small-scale mixing experiment with lower euphotic zone water to determine how individual populations respond to mixing. Transcriptional responses were measured using the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) microarray, which targets all three domains of life and viruses. The experiment showed that mixing substantially affects photosynthetic taxa as expected, but surprisingly also showed that populations respond differently to unfiltered deep water which contains particles (organisms and detritus) compared to filtered deep water that only contains nutrients and viruses, pointing to the impact of biological interactions associated with these events. Comparison between experimental and in situ population transcription patterns indicated that manipulated populations can serve as analogs for natural populations, and that natural populations may be frequently or continuously responding to nutrients from deeper waters. Finally, this study also shows that the microarray approach, which is complementary to metatranscriptomic sequencing, is useful for determining the physiological status of in situ microbial communities.
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Affiliation(s)
- J C Robidart
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA.,National Oceanography Centre, Southampton, UK
| | - J D Magasin
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - I N Shilova
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA.,Second Genome, South San Francisco, CA, USA
| | - K A Turk-Kubo
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - S T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA.,Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - D M Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA.,Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - C A Scholin
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - J P Zehr
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA.
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29
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Li YY, Chen XH, Xie ZX, Li DX, Wu PF, Kong LF, Lin L, Kao SJ, Wang DZ. Bacterial Diversity and Nitrogen Utilization Strategies in the Upper Layer of the Northwestern Pacific Ocean. Front Microbiol 2018; 9:797. [PMID: 29922238 PMCID: PMC5996900 DOI: 10.3389/fmicb.2018.00797] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 04/10/2018] [Indexed: 11/13/2022] Open
Abstract
Nitrogen (N) is a primary limiting nutrient for bacterial growth and productivity in the ocean. To better understand bacterial community and their N utilization strategy in different N regimes of the ocean, we examined bacterial diversity, diazotrophic diversity, and N utilization gene expressions in the northwestern Pacific Ocean (NWPO) using a combination of high-throughput sequencing and real-time qPCR methods. 521 and 204 different operational taxonomic units (OTUs) were identified in the 16s rRNA and nifH libraries from nine surface samples. Of the 16s rRNA gene OTUs, 11.9% were observed in all samples while 3.5 and 15.9% were detected only in N-sufficient and N-deficient samples. Proteobacteria, Cyanobacteria and Bacteroidetes dominated the bacterial community. Prochlorococcus and Pseudoalteromonas were the most abundant at the genus level in N-deficient regimes, while SAR86, Synechococcus and SAR92 were predominant in the Kuroshio-Oyashio confluence region. The distribution of the nifH gene presented great divergence among sampling stations: Cyanobacterium_UCYN-A dominated the N-deficient stations, while clusters related to the Alpha-, Beta-, and Gamma-Proteobacteria were abundant in other stations. Temperature was the main factor that determined bacterial community structure and diversity while concentration of NOX-N was significantly correlated with structure and distribution of N2-fixing microorganisms. Expression of the ammonium transporter was much higher than that of urea transporter subunit A (urtA) and ferredoxin-nitrate reductase, while urtA had an increased expression in N-deficient surface water. The predicted ammonium transporter and ammonium assimilation enzymes were most abundant in surface samples while urease and nitrogenase were more abundant in the N-deficient regions. These findings underscore the fact that marine bacteria have evolved diverse N utilization strategies to adapt to different N habitats, and that urea metabolism is of vital ecological importance in N-deficient regimes.
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Affiliation(s)
- Yuan-Yuan Li
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Xiao-Huang Chen
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Zhang-Xian Xie
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Dong-Xu Li
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Peng-Fei Wu
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Ling-Fen Kong
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Lin Lin
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Shuh-Ji Kao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
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30
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Domínguez-Martín MA, López-Lozano A, Clavería-Gimeno R, Velázquez-Campoy A, Seidel G, Burkovski A, Díez J, García-Fernández JM. Differential NtcA Responsiveness to 2-Oxoglutarate Underlies the Diversity of C/N Balance Regulation in Prochlorococcus. Front Microbiol 2018; 8:2641. [PMID: 29375510 PMCID: PMC5767323 DOI: 10.3389/fmicb.2017.02641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 12/19/2017] [Indexed: 11/29/2022] Open
Abstract
Previous studies showed differences in the regulatory response to C/N balance in Prochlorococcus with respect to other cyanobacteria, but no information was available about its causes, or the ecological advantages conferred to thrive in oligotrophic environments. We addressed the changes in key enzymes (glutamine synthetase, isocitrate dehydrogenase) and the ntcA gene (the global nitrogen regulator) involved in C/N metabolism and its regulation, in three model Prochlorococcus strains: MED4, SS120, and MIT9313. We observed a remarkable level of diversity in their response to azaserine, a glutamate synthase inhibitor which increases the concentration of the key metabolite 2-oxoglutarate, used to sense the C/N balance by cyanobacteria. Besides, we studied the binding between the global nitrogen regulator (NtcA) and the promoter of the glnA gene in the same Prochlorococcus strains, and its dependence on the 2-oxoglutarate concentration, by using isothermal titration calorimetry, surface plasmon resonance, and electrophoretic mobility shift. Our results show a reduction in the responsiveness of NtcA to 2-oxoglutarate in Prochlorococcus, especially in the MED4 and SS120 strains. This suggests a trend to streamline the regulation of C/N metabolism in late-branching Prochlorococcus strains (MED4 and SS120), in adaptation to the rather stable conditions found in the oligotrophic ocean gyres where this microorganism is most abundant.
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Affiliation(s)
- María A Domínguez-Martín
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
| | - Antonio López-Lozano
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
| | - Rafael Clavería-Gimeno
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Units BIFI-IQFR-CSIC and GBsC-BIFI-CSIC, Universidad de Zaragoza, Zaragoza, Spain.,Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain.,Instituto Aragonés de Ciencias de la Salud, Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Units BIFI-IQFR-CSIC and GBsC-BIFI-CSIC, Universidad de Zaragoza, Zaragoza, Spain.,Aragon Institute for Health Research (IIS Aragon), Zaragoza, Spain.,Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Barcelona, Spain.,Fundación ARAID, Gobierno de Aragón, Zaragoza, Spain
| | - Gerald Seidel
- Professur für Mikrobiologie, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Burkovski
- Professur für Mikrobiologie, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jesús Díez
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
| | - José M García-Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain
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31
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Abstract
Marine plankton elemental stoichiometric ratios can deviate from the Redfield ratio (106C:16N:1P); here, we examine physiological and biogeochemical mechanisms that lead to the observed variation across lineages, regions, and seasons. Many models of ecological stoichiometry blend together acclimative and adaptive responses to environmental conditions. These two pathways can have unique molecular mechanisms and stoichiometric outcomes, and we attempt to disentangle the two processes. We find that interactions between environmental conditions and cellular growth are key to understanding stoichiometric regulation, but the growth rates of most marine plankton populations are poorly constrained. We propose that specific physiological mechanisms have a strong impact on plankton and community stoichiometry in nutrient-rich environments, whereas biogeochemical interactions are important for the stoichiometry of the oligotrophic gyres. Finally, we outline key areas with missing information that is needed to advance understanding of the present and future ecological stoichiometry of ocean plankton.
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Affiliation(s)
- Allison R Moreno
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697;
| | - Adam C Martiny
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697;
- Department of Earth System Science, University of California, Irvine, California 92697
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32
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Domínguez-Martín MA, López-Lozano A, Rangel-Zúñiga OA, Díez J, García-Fernández JM. Distinct features of C/N balance regulation in Prochlorococcus sp. strain MIT9313. FEMS Microbiol Lett 2017; 365:4757061. [DOI: 10.1093/femsle/fnx278] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/17/2017] [Indexed: 11/13/2022] Open
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33
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Estimating Population Turnover Rates by Relative Quantification Methods Reveals Microbial Dynamics in Marine Sediment. Appl Environ Microbiol 2017; 84:AEM.01443-17. [PMID: 29054869 DOI: 10.1128/aem.01443-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 10/09/2017] [Indexed: 11/20/2022] Open
Abstract
The difficulty involved in quantifying biogeochemically significant microbes in marine sediments limits our ability to assess interspecific interactions, population turnover times, and niches of uncultured taxa. We incubated surface sediments from Cape Lookout Bight, North Carolina, USA, anoxically at 21°C for 122 days. Sulfate decreased until day 68, after which methane increased, with hydrogen concentrations consistent with the predicted values of an electron donor exerting thermodynamic control. We measured turnover times using two relative quantification methods, quantitative PCR (qPCR) and the product of 16S gene read abundance and total cell abundance (FRAxC, which stands for "fraction of read abundance times cells"), to estimate the population turnover rates of uncultured clades. Most 16S rRNA reads were from deeply branching uncultured groups, and ∼98% of 16S rRNA genes did not abruptly shift in relative abundance when sulfate reduction gave way to methanogenesis. Uncultured Methanomicrobiales and Methanosarcinales increased at the onset of methanogenesis with population turnover times estimated from qPCR at 9.7 ± 3.9 and 12.6 ± 4.1 days, respectively. These were consistent with FRAxC turnover times of 9.4 ± 5.8 and 9.2 ± 3.5 days, respectively. Uncultured Syntrophaceae, which are possibly fermentative syntrophs of methanogens, and uncultured Kazan-3A-21 archaea also increased at the onset of methanogenesis, with FRAxC turnover times of 14.7 ± 6.9 and 10.6 ± 3.6 days. Kazan-3A-21 may therefore either perform methanogenesis or form a fermentative syntrophy with methanogens. Three genera of sulfate-reducing bacteria, Desulfovibrio, Desulfobacter, and Desulfobacterium, increased in the first 19 days before declining rapidly during sulfate reduction. We conclude that population turnover times on the order of days can be measured robustly in organic-rich marine sediment, and the transition from sulfate-reducing to methanogenic conditions stimulates growth only in a few clades directly involved in methanogenesis, rather than in the whole microbial community.IMPORTANCE Many microbes cannot be isolated in pure culture to determine their preferential growth conditions and predict their response to changing environmental conditions. We created a microcosm of marine sediments that allowed us to simulate a diagenetic profile using a temporal analog for depth. This allowed for the observation of the microbial community population dynamics caused by the natural shift from sulfate reduction to methanogenesis. Our research provides evidence for the population dynamics of uncultured microbes as well as the application of a novel method of turnover rate analysis for individual taxa within a mixed incubation, FRAxC, which stands for "fraction of read abundance times cells," which was verified by quantitative PCR. This allows for the calculation of population turnover times for microbes in a natural setting and the identification of uncultured clades involved in geochemical processes.
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Jing X, Lin S, Zhang H, Koerting C, Yu Z. Utilization of urea and expression profiles of related genes in the dinoflagellate Prorocentrum donghaiense. PLoS One 2017; 12:e0187837. [PMID: 29117255 PMCID: PMC5678928 DOI: 10.1371/journal.pone.0187837] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 10/26/2017] [Indexed: 01/23/2023] Open
Abstract
Urea has been shown to contribute more than half of total nitrogen (N) required by phytoplankton in some estuaries and coastal waters and to provide a substantial portion of the N demand for many harmful algal blooms (HABs) of dinoflagellates. In this study, we investigated the physiological and transcriptional responses in Prorocentrum donghaiense to changes in nitrate and urea availability. We found that this species could efficiently utilize urea as sole N source and achieve comparable growth rate and photosynthesis capability as it did under nitrate. These physiological parameters were markedly lower in cultures grown under nitrate- or urea-limited conditions. P. donghaiense N content was similarly low under nitrate- or urea-limited culture condition, but was markedly higher under urea-replete condition than under nitrate-replete condition. Carbon (C) content was consistently elevated under N-limited condition. Consequently, the C:N ratio was as high as 21:1 under nitrate- or urea-limitation, but 7:1 under urea-replete condition and 9:1 to 10:1 under nitrate-replete condition. Using quantitative reverse transcription PCR, we investigated the expression pattern for four genes involved in N transport and assimilation. The results indicated that genes encoding nitrate transport, urea hydrolysis, and nickel transporter gene were sensitive to changes in general N nutrient availability whereas the urea transporter gene responded much more strongly to changes in urea concentration. Taken together, our study shows the high bioavailability of urea, its impact on C:N stoichiometry, and the sensitivity of urea transporter gene expression to urea availability.
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Affiliation(s)
- Xiaoli Jing
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Department of Marine Sciences, University of Connecticut, Groton, United States of America
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Senjie Lin
- Department of Marine Sciences, University of Connecticut, Groton, United States of America
| | - Huan Zhang
- Department of Marine Sciences, University of Connecticut, Groton, United States of America
| | - Claudia Koerting
- Department of Marine Sciences, University of Connecticut, Groton, United States of America
| | - Zhigang Yu
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Chemical Theory and Technology, Ministry of Education, Qingdao, China
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Ehira S, Shimmori Y, Watanabe S, Kato H, Yoshikawa H, Ohmori M. The nitrogen-regulated response regulator NrrA is a conserved regulator of glycogen catabolism in β-cyanobacteria. Microbiology (Reading) 2017; 163:1711-1719. [DOI: 10.1099/mic.0.000549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Shigeki Ehira
- Department of Biological Science, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Yuka Shimmori
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Satoru Watanabe
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | - Hiroaki Kato
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | - Hirofumi Yoshikawa
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
| | - Masayuki Ohmori
- Department of Biological Science, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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Harke MJ, Juhl AR, Haley ST, Alexander H, Dyhrman ST. Conserved Transcriptional Responses to Nutrient Stress in Bloom-Forming Algae. Front Microbiol 2017; 8:1279. [PMID: 28769884 PMCID: PMC5513979 DOI: 10.3389/fmicb.2017.01279] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 06/26/2017] [Indexed: 11/13/2022] Open
Abstract
The concentration and composition of bioavailable nitrogen (N) and phosphorus (P) in the upper ocean shape eukaryotic phytoplankton communities and influence their physiological responses. Phytoplankton are known to exhibit similar physiological responses to limiting N and P conditions such as decreased growth rates, chlorosis, and increased assimilation of N and P. Are these responses similar at the molecular level across multiple species? To interrogate this question, five species from biogeochemically important, bloom-forming taxa (Bacillariophyta, Dinophyta, and Haptophyta) were grown under similar low N, low P, and replete nutrient conditions to identify transcriptional patterns and associated changes in biochemical pools related to N and P stress. Metabolic profiles, revealed through the transcriptomes of these taxa, clustered together based on species rather than nutrient stressor, suggesting that the global metabolic response to nutrient stresses was largely, but not exclusively, species-specific. Nutrient stress led to few transcriptional changes in the two dinoflagellates, consistent with other research. An orthologous group analysis examined functionally conserved (i.e., similarly changed) responses to nutrient stress and therefore focused on the diatom and haptophytes. Most conserved ortholog changes were specific to a single nutrient treatment, but a small number of orthologs were similarly changed under both N and P stress in 2 or more species. Many of these orthologs were related to photosynthesis and may represent generalized stress responses. A greater number of orthologs were conserved across more than one species under low P compared to low N. Screening the conserved orthologs for functions related to N and P metabolism revealed increased relative abundance of orthologs for nitrate, nitrite, ammonium, and amino acid transporters under N stress, and increased relative abundance of orthologs related to acquisition of inorganic and organic P substrates under P stress. Although the global transcriptional responses were dominated by species-specific changes, the analysis of conserved responses revealed functional similarities in resource acquisition pathways among different phytoplankton taxa. This overlap in nutrient stress responses observed among species may be useful for tracking the physiological ecology of phytoplankton field populations.
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Affiliation(s)
- Matthew J Harke
- Lamont-Doherty Earth Observatory, Columbia UniversityPalisades, NY, United States
| | - Andrew R Juhl
- Lamont-Doherty Earth Observatory, Columbia UniversityPalisades, NY, United States.,Department of Earth and Environmental Sciences, Columbia UniversityPalisades, NY, United States
| | - Sheean T Haley
- Lamont-Doherty Earth Observatory, Columbia UniversityPalisades, NY, United States
| | - Harriet Alexander
- Department of Population Health and Reproduction, University of California, DavisDavis, CA, United States
| | - Sonya T Dyhrman
- Lamont-Doherty Earth Observatory, Columbia UniversityPalisades, NY, United States.,Department of Earth and Environmental Sciences, Columbia UniversityPalisades, NY, United States
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Nitrogen cost minimization is promoted by structural changes in the transcriptome of N-deprived Prochlorococcus cells. ISME JOURNAL 2017; 11:2267-2278. [PMID: 28585937 PMCID: PMC5607370 DOI: 10.1038/ismej.2017.88] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 04/20/2017] [Accepted: 04/28/2017] [Indexed: 01/17/2023]
Abstract
Prochlorococcus is a globally abundant marine cyanobacterium with many adaptations that reduce cellular nutrient requirements, facilitating growth in its nutrient-poor environment. One such genomic adaptation is the preferential utilization of amino acids containing fewer N-atoms, which minimizes cellular nitrogen requirements. We predicted that transcriptional regulation might further reduce cellular N budgets during transient N limitation. To explore this, we compared transcription start sites (TSSs) in Prochlorococcus MED4 under N-deprived and N-replete conditions. Of 64 genes with primary and internal TSSs in both conditions, N-deprived cells initiated transcription downstream of primary TSSs more frequently than N-replete cells. Additionally, 117 genes with only an internal TSS demonstrated increased internal transcription under N-deprivation. These shortened transcripts encode predicted proteins with an average of 21% less N content compared to full-length transcripts. We hypothesized that low translation rates, which afford greater control over protein abundances, would be beneficial to relatively slow-growing organisms like Prochlorococcus. Consistent with this idea, we found that Prochlorococcus exhibits greater usage of glycine–glycine motifs, which causes translational pausing, when compared to faster growing microbes. Our findings indicate that structural changes occur within the Prochlorococcus MED4 transcriptome during N-deprivation, potentially altering the size and structure of proteins expressed under nutrient limitation.
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Quantitative Proteomics Shows Extensive Remodeling Induced by Nitrogen Limitation in Prochlorococcusmarinus SS120. mSystems 2017; 2:mSystems00008-17. [PMID: 28593196 PMCID: PMC5451487 DOI: 10.1128/msystems.00008-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 04/26/2017] [Indexed: 12/27/2022] Open
Abstract
Prochlorococcus requires the capability to accommodate to environmental changes in order to proliferate in oligotrophic oceans, in particular regarding nitrogen availability. A precise knowledge of the composition and changes in the proteome can yield fundamental insights into such a response. Here we report a detailed proteome analysis of the important model cyanobacterium Prochlorococcus marinus SS120 after treatment with azaserine, an inhibitor of ferredoxin-dependent glutamate synthase (GOGAT), to simulate extreme nitrogen starvation. In total, 1,072 proteins, corresponding to 57% of the theoretical proteome, were identified-the maximum proteome coverage obtained for any Prochlorococcus strain thus far. Spectral intensity, calibrated quantification by the Hi3 method, was obtained for 1,007 proteins. Statistically significant changes (P value of <0.05) were observed for 408 proteins, with the majority of proteins (92.4%) downregulated after 8 h of treatment. There was a strong decrease in ribosomal proteins upon azaserine addition, while many transporters were increased. The regulatory proteins PII and PipX were decreased, and the global nitrogen regulator NtcA was upregulated. Furthermore, our data for Prochlorococcus indicate that NtcA also participates in the regulation of photosynthesis. Prochlorococcus responds to the lack of nitrogen by slowing down translation, while inducing photosynthetic cyclic electron flow and biosynthesis of proteins involved in nitrogen uptake and assimilation. IMPORTANCEProchlorococcus is the most abundant photosynthetic organism on Earth, contributing significantly to global primary production and playing a prominent role in biogeochemical cycles. Here we study the effects of extreme nitrogen limitation, a feature of the oligotrophic oceans inhabited by this organism. Quantitative proteomics allowed an accurate quantification of the Prochlorococcus proteome, finding three main responses to nitrogen limitation: upregulation of nitrogen assimilation-related proteins, including transporters; downregulation of ribosome proteins; and induction of the photosystem II cyclic electron flow. This suggests that nitrogen limitation affects a range of metabolic processes far wider than initially believed, with the ultimate goal of saving nitrogen and maximizing the nitrogen uptake and assimilation capabilities of the cell.
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Larkin AA, Martiny AC. Microdiversity shapes the traits, niche space, and biogeography of microbial taxa. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:55-70. [PMID: 28185400 DOI: 10.1111/1758-2229.12523] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/31/2017] [Accepted: 02/01/2017] [Indexed: 06/06/2023]
Abstract
With rapidly improving sequencing technologies, scientists have recently gained the ability to examine diverse microbial communities at high genomic resolution, revealing that both free-living and host-associated microbes partition their environment at fine phylogenetic scales. This 'microdiversity,' or closely related (> 97% similar 16S rRNA gene) but ecologically and physiologically distinct sub-taxonomic groups, appears to be an intrinsic property of microorganisms. However, the functional implications of microdiversity as well as its effects on microbial biogeography are poorly understood. Here, we present two theoretical models outlining the evolutionary mechanisms that drive the formation of microdiverse 'sub-taxa.' Additionally, we review recent literature and reveal that microdiversity influences a wide range of functional traits across diverse ecosystems and microbes. Moving to higher levels of organization, we use laboratory data from marine, soil, and host-associated bacteria to demonstrate that the aggregated trait-based response of microdiverse sub-taxa modifies the fundamental niche of microbes. The correspondence between microdiversity and niche space represents a critical tool for future studies of microbial ecology. By combining growth experiments on diverse isolates with examinations of environmental abundance patterns, researchers can better quantify the fundamental and realized niches of microbes and improve understanding of microbial biogeography and response to future environmental change.
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Affiliation(s)
- Alyse A Larkin
- Department of Earth System Science, University of California, Irvine, CA, 92697, USA
| | - Adam C Martiny
- Department of Earth System Science, University of California, Irvine, CA, 92697, USA
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, 92697, USA
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Aharonovich D, Sher D. Transcriptional response of Prochlorococcus to co-culture with a marine Alteromonas: differences between strains and the involvement of putative infochemicals. THE ISME JOURNAL 2016; 10:2892-2906. [PMID: 27128996 PMCID: PMC5148192 DOI: 10.1038/ismej.2016.70] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 11/08/2022]
Abstract
Interactions between marine microorganisms may determine the dynamics of microbial communities. Here, we show that two strains of the globally abundant marine cyanobacterium Prochlorococcus, MED4 and MIT9313, which belong to two different ecotypes, differ markedly in their response to co-culture with a marine heterotrophic bacterium, Alteromonas macleodii strain HOT1A3. HOT1A3 enhanced the growth of MIT9313 at low cell densities, yet inhibited it at a higher concentration, whereas it had no effect on MED4 growth. The early transcriptomic responses of Prochlorococcus cells after 20 h in co-culture showed no evidence of nutrient starvation, whereas the expression of genes involved in photosynthesis, protein synthesis and stress responses typically decreased in MED4 and increased in MIT313. Differential expression of genes involved in outer membrane modification, efflux transporters and, in MIT9313, lanthipeptides (prochlorosins) suggests that Prochlorococcus mount a specific response to the presence of the heterotroph in the cultures. Intriguingly, many of the differentially-expressed genes encoded short proteins, including two new families of co-culture responsive genes: CCRG-1, which is found across the Prochlorococcus lineage and CCRG-2, which contains a sequence motif involved in the export of prochlorosins and other bacteriocin-like peptides, and are indeed released from the cells into the media.
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Affiliation(s)
- Dikla Aharonovich
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Daniel Sher
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
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Longworth J, Wu D, Huete-Ortega M, Wright PC, Vaidyanathan S. Proteome response of Phaeodactylum tricornutum, during lipid accumulation induced by nitrogen depletion. ALGAL RES 2016; 18:213-224. [PMID: 27812494 PMCID: PMC5070409 DOI: 10.1016/j.algal.2016.06.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 05/08/2016] [Accepted: 06/14/2016] [Indexed: 11/26/2022]
Abstract
Nitrogen stress is a common strategy employed to stimulate lipid accumulation in microalgae, a biofuel feedstock of topical interest. Although widely investigated, the underlying mechanism of this strategy is still poorly understood. We examined the proteome response of lipid accumulation in the model diatom, Phaeodactylum tricornutum (CCAP 1055/1), at an earlier stage of exposure to selective nitrogen exclusion than previously investigated, and at a time point when changes would reflect lipid accumulation more than carbohydrate accumulation. In total 1043 proteins were confidently identified (≥ 2 unique peptides) with 645 significant (p < 0.05) changes observed, in the LC-MS/MS based iTRAQ investigation. Analysis of significant changes in KEGG pathways and individual proteins showed that under nitrogen starvation P. tricornutum reorganizes its proteome in favour of nitrogen scavenging and reduced lipid degradation whilst rearranging the central energy metabolism that deprioritizes photosynthetic pathways. By doing this, this species appears to increase nitrogen availability inside the cell and limit its use to the pathways where it is needed most. Compared to previously published proteomic analysis of nitrogen starvation in Chlamydomonas reinhardtii, central energy metabolism and photosynthesis appear to be affected more in the diatom, whilst the green algae appears to invest its energy in reorganizing respiration and the cellular organization pathways.
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Domínguez-Martín MA, Díez J, García-Fernández JM. Physiological Studies of Glutamine Synthetases I and III from Synechococcus sp. WH7803 Reveal Differential Regulation. Front Microbiol 2016; 7:969. [PMID: 27446010 PMCID: PMC4923085 DOI: 10.3389/fmicb.2016.00969] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/03/2016] [Indexed: 11/18/2022] Open
Abstract
The marine picocyanobacterium Synechococcus sp. WH7803 possesses two glutamine synthetases (GSs; EC 6.3.1.2), GSI encoded by glnA and GSIII encoded by glnN. This is the first work addressing the physiological regulation of both enzymes in a marine cyanobacterial strain. The increase of GS activity upon nitrogen starvation was similar to that found in other model cyanobacteria. However, an unusual response was found when cells were grown under darkness: the GS activity was unaffected, reflecting adaptation to the environment where they thrive. On the other hand, we found that GSIII did not respond to nitrogen availability, in sharp contrast with the results observed for this enzyme in other cyanobacteria thus far studied. These features suggest that GS activities in Synechococcus sp. WH7803 represent an intermediate step in the evolution of cyanobacteria, in a process of regulatory streamlining where GSI lost the regulation by light, while GSIII lost its responsiveness to nitrogen. This is in good agreement with the phylogeny of Synechococcus sp. WH7803 in the context of the marine cyanobacterial radiation.
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Affiliation(s)
| | | | - José M. García-Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CEIA3, Universidad de CórdobaCórdoba, Spain
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Torn apart and reunited: impact of a heterotroph on the transcriptome of Prochlorococcus. ISME JOURNAL 2016; 10:2831-2843. [PMID: 27258949 DOI: 10.1038/ismej.2016.82] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 03/29/2016] [Accepted: 04/12/2016] [Indexed: 11/09/2022]
Abstract
Microbial interactions, whether direct or indirect, profoundly affect the physiology of individual cells and ultimately have the potential to shape the biogeochemistry of the Earth. For example, the growth of Prochlorococcus, the numerically dominant cyanobacterium in the oceans, can be improved by the activity of co-occurring heterotrophs. This effect has been largely attributed to the role of heterotrophs in detoxifying reactive oxygen species that Prochlorococcus, which lacks catalase, cannot. Here, we explore this phenomenon further by examining how the entire transcriptome of Prochlorococcus NATL2A changes in the presence of a naturally co-occurring heterotroph, Alteromonas macleodii MIT1002, with which it was co-cultured for years, separated and then reunited. Significant changes in the Prochlorococcus transcriptome were evident within 6 h of initiating co-culture, with groups of transcripts changing in different temporal waves. Many transcriptional changes persisted throughout the 48 h experiment, suggesting that the presence of the heterotroph affected a stable shift in Prochlorococcus physiology. These initial transcriptome changes largely corresponded to reduced stress conditions for Prochlorococcus, as inferred from the depletion of transcripts encoding DNA repair enzymes and many members of the 'high light inducible' family of stress-response proteins. Later, notable changes were seen in transcripts encoding components of the photosynthetic apparatus (particularly, an increase in PSI subunits and chlorophyll synthesis enzymes), ribosomal proteins and biosynthetic enzymes, suggesting that the introduction of the heterotroph may have induced increased production of reduced carbon compounds for export. Changes in secretion-related proteins and transporters also highlight the potential for metabolic exchange between the two strains.
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Komenda J, Sobotka R. Cyanobacterial high-light-inducible proteins — Protectors of chlorophyll–protein synthesis and assembly. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:288-95. [DOI: 10.1016/j.bbabio.2015.08.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/28/2015] [Accepted: 08/30/2015] [Indexed: 12/24/2022]
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Transcriptome dynamics of a broad host-range cyanophage and its hosts. ISME JOURNAL 2015; 10:1437-55. [PMID: 26623542 DOI: 10.1038/ismej.2015.210] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 09/17/2015] [Accepted: 10/07/2015] [Indexed: 01/21/2023]
Abstract
Cyanobacteria are highly abundant in the oceans and are constantly exposed to lytic viruses. The T4-like cyanomyoviruses are abundant in the marine environment and have broad host-ranges relative to other cyanophages. It is currently unknown whether broad host-range phages specifically tailor their infection program for each host, or employ the same program irrespective of the host infected. Also unknown is how different hosts respond to infection by the same phage. Here we used microarray and RNA-seq analyses to investigate the interaction between the Syn9 T4-like cyanophage and three phylogenetically, ecologically and genomically distinct marine Synechococcus strains: WH7803, WH8102 and WH8109. Strikingly, Syn9 led a nearly identical infection and transcriptional program in all three hosts. Different to previous assumptions for T4-like cyanophages, three temporally regulated gene expression classes were observed. Furthermore, a novel regulatory element controlled early-gene transcription, and host-like promoters drove middle gene transcription, different to the regulatory paradigm for T4. Similar results were found for the P-TIM40 phage during infection of Prochlorococcus NATL2A. Moreover, genomic and metagenomic analyses indicate that these regulatory elements are abundant and conserved among T4-like cyanophages. In contrast to the near-identical transcriptional program employed by Syn9, host responses to infection involved host-specific genes primarily located in hypervariable genomic islands, substantiating islands as a major axis of phage-cyanobacteria interactions. Our findings suggest that the ability of broad host-range phages to infect multiple hosts is more likely dependent on the effectiveness of host defense strategies than on differential tailoring of the infection process by the phage.
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Sachs JP, Kawka OE. The Influence of Growth Rate on 2H/1H Fractionation in Continuous Cultures of the Coccolithophorid Emiliania huxleyi and the Diatom Thalassiosira pseudonana. PLoS One 2015; 10:e0141643. [PMID: 26576007 PMCID: PMC4648508 DOI: 10.1371/journal.pone.0141643] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/12/2015] [Indexed: 11/24/2022] Open
Abstract
The hydrogen isotope (2H/1H) ratio of lipids from phytoplankton is a powerful new tool for reconstructing hydroclimate variations in the geologic past from marine and lacustrine sediments. Water 2H/1H changes are reflected in lipid 2H/1H changes with R2 > 0.99, and salinity variations have been shown to cause about a 1‰ change in lipid δ2H values per unit (ppt) change in salinity. Less understood are the effects of growth rate, nutrient limitation and light on 2H/1H fractionation in phytoplankton. Here we present the first published study of growth rate effects on 2H/1H fractionation in the lipids of coccolithophorids grown in continuous cultures. Emiliania huxleyi was cultivated in steady state at four growth rates and the δ2H value of individual alkenones (C37:2, C37:3, C38:2, C38:3), fatty acids (C14:0, C16:0, C18:0), and 24-methyl cholest-5,22-dien-3β-ol (brassicasterol) were measured. 2H/1H fractionation increased in all lipids as growth rate increased by 24‰ to 79‰ (div d-1)-1. We attribute this response to a proportional increase in the fraction of NADPH from Photosystem I (PS1) of photosynthesis relative to NADPH from the cytosolic oxidative pentose phosphate (OPP) pathway in the synthesis of lipids as growth rate increases. A 3-endmember model is presented in which lipid hydrogen comes from NADPH produced in PS1, NADPH produced by OPP, and intracellular water. With published values or best estimates of the fractionation factors for these sources (αPS1 = 0.4, αOPP = 0.75, and αH2O = 0) and half of the hydrogen in a lipid derived from water the model indicates αlipid = 0.79. This value is within the range measured for alkenones (αalkenone = 0.77 to 0.81) and fatty acids (αFA = 0.75 to 0.82) in the chemostat cultures, but is greater than the range for brassicasterol (αbrassicasterol = 0.68 to 0.72). The latter is attributed to a greater proportion of hydrogen from NADPH relative to water in isoprenoid lipids. The model successfully explains the increase in 2H/1H fractionation in the sterol 24-methyl-cholesta-5,24(28)-dien-3β-ol from marine centric diatom T. pseudonana chemostat cultures as growth rate increases. Insensitivity of αFA in those same cultures may be attributable to a larger fraction of hydrogen in fatty acids sourced from intracellular water at the expense of NADPH as growth rate increases. The high sensitivity of α to growth rate in E. huxleyi lipids and a T. pseudonana sterol implies that any change in growth rate larger than ~0.15 div d-1 can cause a change in δ2Hlipid that is larger than the analytical error of the measurement (~5‰), and needs to be considered when interpreting δ2Hlipid variations in sediments.
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Affiliation(s)
- Julian P. Sachs
- School of Oceanography, University of Washington, Seattle, Washington, 98195, United States of America
- * E-mail:
| | - Orest E. Kawka
- School of Oceanography, University of Washington, Seattle, Washington, 98195, United States of America
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Puxty RJ, Millard AD, Evans DJ, Scanlan DJ. Shedding new light on viral photosynthesis. PHOTOSYNTHESIS RESEARCH 2015; 126:71-97. [PMID: 25381655 DOI: 10.1007/s11120-014-0057-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 10/29/2014] [Indexed: 06/04/2023]
Abstract
Viruses infecting the environmentally important marine cyanobacteria Prochlorococcus and Synechococcus encode 'auxiliary metabolic genes' (AMGs) involved in the light and dark reactions of photosynthesis. Here, we discuss progress on the inventory of such AMGs in the ever-increasing number of viral genome sequences as well as in metagenomic datasets. We contextualise these gene acquisitions with reference to a hypothesised fitness gain to the phage. We also report new evidence with regard to the sequence and predicted structural properties of viral petE genes encoding the soluble electron carrier plastocyanin. Viral copies of PetE exhibit extensive modifications to the N-terminal signal peptide and possess several novel residues in a region responsible for interaction with redox partners. We also highlight potential knowledge gaps in this field and discuss future opportunities to discover novel phage-host interactions involved in the photosynthetic process.
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Affiliation(s)
- Richard J Puxty
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
- School of Biological Sciences, University of California, Irvine, CA 92697, USA
| | - Andrew D Millard
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | - David J Evans
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - David J Scanlan
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
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Bagby SC, Chisholm SW. Response of Prochlorococcus to varying CO2:O2 ratios. THE ISME JOURNAL 2015; 9:2232-45. [PMID: 25848872 PMCID: PMC4579476 DOI: 10.1038/ismej.2015.36] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 02/06/2015] [Accepted: 02/12/2015] [Indexed: 11/08/2022]
Abstract
Carbon fixation has a central role in determining cellular redox poise, increasingly understood to be a key parameter in cyanobacterial physiology. In the cyanobacterium Prochlorococcus-the most abundant phototroph in the oligotrophic oceans-the carbon-concentrating mechanism is reduced to the bare essentials. Given the ability of Prochlorococcus populations to grow under a wide range of oxygen concentrations in the ocean, we wondered how carbon and oxygen physiology intersect in this minimal phototroph. Thus, we examined how CO2:O2 gas balance influenced growth and chlorophyll fluorescence in Prochlorococcus strain MED4. Under O2 limitation, per-cell chlorophyll fluorescence fell at all CO2 levels, but still permitted substantial growth at moderate and high CO2. Under CO2 limitation, we observed little growth at any O2 level, although per-cell chlorophyll fluorescence fell less sharply when O2 was available. We explored this pattern further by monitoring genome-wide transcription in cells shocked with acute limitation of CO2, O2 or both. O2 limitation produced much smaller transcriptional changes than the broad suppression seen under CO2 limitation and CO2/O2 co-limitation. Strikingly, both CO2 limitation conditions initially evoked a transcriptional response that resembled the pattern previously seen in high-light stress, but at later timepoints we observed O2-dependent recovery of photosynthesis-related transcripts. These results suggest that oxygen has a protective role in Prochlorococcus when carbon fixation is not a sufficient sink for light energy.
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Affiliation(s)
- Sarah C Bagby
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sallie W Chisholm
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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49
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Gaudana SB, Zarzycki J, Moparthi VK, Kerfeld CA. Bioinformatic analysis of the distribution of inorganic carbon transporters and prospective targets for bioengineering to increase Ci uptake by cyanobacteria. PHOTOSYNTHESIS RESEARCH 2015; 126:99-109. [PMID: 25399051 DOI: 10.1007/s11120-014-0059-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 11/07/2014] [Indexed: 06/04/2023]
Abstract
Cyanobacteria have evolved a carbon-concentrating mechanism (CCM) which has enabled them to inhabit diverse environments encompassing a range of inorganic carbon (Ci: [Formula: see text] and CO2) concentrations. Several uptake systems facilitate inorganic carbon accumulation in the cell, which can in turn be fixed by ribulose 1,5-bisphosphate carboxylase/oxygenase. Here we survey the distribution of genes encoding known Ci uptake systems in cyanobacterial genomes and, using a pfam- and gene context-based approach, identify in the marine (alpha) cyanobacteria a heretofore unrecognized number of putative counterparts to the well-known Ci transporters of beta cyanobacteria. In addition, our analysis shows that there is a huge repertoire of transport systems in cyanobacteria of unknown function, many with homology to characterized Ci transporters. These can be viewed as prospective targets for conversion into ancillary Ci transporters through bioengineering. Increasing intracellular Ci concentration coupled with efforts to increase carbon fixation will be beneficial for the downstream conversion of fixed carbon into value-added products including biofuels. In addition to CCM transporter homologs, we also survey the occurrence of rhodopsin homologs in cyanobacteria, including bacteriorhodopsin, a class of retinal-binding, light-activated proton pumps. Because they are light driven and because of the apparent ease of altering their ion selectivity, we use this as an example of re-purposing an endogenous transporter for the augmentation of Ci uptake by cyanobacteria and potentially chloroplasts.
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Affiliation(s)
- Sandeep B Gaudana
- DOE Plant Research Laboratories, Department of Biochemistry and Molecular Biology, Michigan State University, 612 Wilson Road, East Lansing, MI, 48824, USA
| | - Jan Zarzycki
- DOE Plant Research Laboratories, Department of Biochemistry and Molecular Biology, Michigan State University, 612 Wilson Road, East Lansing, MI, 48824, USA
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Vamsi K Moparthi
- Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA
| | - Cheryl A Kerfeld
- DOE Plant Research Laboratories, Department of Biochemistry and Molecular Biology, Michigan State University, 612 Wilson Road, East Lansing, MI, 48824, USA.
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
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Gómez-Baena G, Domínguez-Martín MA, Donaldson RP, García-Fernández JM, Diez J. Glutamine Synthetase Sensitivity to Oxidative Modification during Nutrient Starvation in Prochlorococcus marinus PCC 9511. PLoS One 2015; 10:e0135322. [PMID: 26270653 PMCID: PMC4535847 DOI: 10.1371/journal.pone.0135322] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/21/2015] [Indexed: 11/19/2022] Open
Abstract
Glutamine synthetase plays a key role in nitrogen metabolism, thus the fine regulation of this enzyme in Prochlorococcus, which is especially important in the oligotrophic oceans where this marine cyanobacterium thrives. In this work, we studied the metal-catalyzed oxidation of glutamine synthetase in cultures of Prochlorococcus marinus strain PCC 9511 subjected to nutrient limitation. Nitrogen deprivation caused glutamine synthetase to be more sensitive to metal-catalyzed oxidation (a 36% increase compared to control, non starved samples). Nutrient starvation induced also a clear increase (three-fold in the case of nitrogen) in the concentration of carbonyl derivatives in cell extracts, which was also higher (22%) upon addition of the inhibitor of electron transport, DCMU, to cultures. Our results indicate that nutrient limitations, representative of the natural conditions in the Prochlorococcus habitat, affect the response of glutamine synthetase to oxidative inactivating systems. Implications of these results on the regulation of glutamine synthetase by oxidative alteration prior to degradation of the enzyme in Prochlorococcus are discussed.
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Affiliation(s)
- Guadalupe Gómez-Baena
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
- * E-mail:
| | | | - Robert P. Donaldson
- Department of Biological Sciences, The George Washington University, Washington, D.C., United States of America
| | | | - Jesús Diez
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
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