1
|
Sim ZY, Goh KC, He Y, Gin KYH. Present and future potential role of toxin-producing Synechococcus in the tropical region. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 896:165230. [PMID: 37400026 DOI: 10.1016/j.scitotenv.2023.165230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/05/2023]
Abstract
As anthropogenic induced temperature rises and nutrient loadings increase in fresh and brackish environments, the ecological function of the phytoplankton community is expected to favour the picocyanobacteria, of the genus Synechococcus. Synechococcus is already a ubiquitous cyanobacterium found in both freshwater and marine environments, notwithstanding that the toxigenic species still remains unexplored in many freshwaters. Their fast growth rate and their ability to produce toxins make Synechococcus a potential dominant player in harmful algal blooms under climate change scenarios. This study examines the responses of a novel toxin-producing Synechococcus (i.e., one belonging to a freshwater clade; the other belonging to a brackish clade) to environmental changes that reflect climate change effects. We conducted a series of controlled experiments under present and predicted future temperatures, as well as under various N and P nutrients loadings. Our findings highlight how Synechococcus can be altered by the differing reactions to increasing temperature and nutrients, which resulted in considerable variations in cell abundance, growth rate, death rate, cellular stoichiometry and toxin production. Synechococcus had the highest growth observed at 28 °C, and further increases in temperature resulted in a decline for both fresh and brackish waters. Cellular stoichiometry was also altered, where more nitrogen (N) per cell was required, and the plasticity of N:P was more severe for the brackish clade. However, Synechococcus become more toxic under future scenario. Anatoxin-a (ATX) saw the greatest spike when temperature was at 34 °C especially under P-enrichment conditions. In contrast, Cylindrospermopsin (CYN) was promoted at the lowest tested temperature (25 °C) and under N-limitation. Overall, both temperature and external nutrients are the dominant control over Synechococcus toxins production. A model was also created to assess Synechococcus toxicity to zooplankton grazing. Zooplankton grazing was reduced by two folds under nutrient limitation, but temperature accounted for very insignificant change.
Collapse
Affiliation(s)
- Zhi Yang Sim
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore
| | - Kwan Chien Goh
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore
| | - Yiliang He
- National University of Singapore Center for Eco-Environment Research, Nanjing Hydraulic Research Institute, Nanjing 210098, China
| | - K Y H Gin
- National University of Singapore Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore 138602, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, Blk E1A-07-03, 1 Engineering Drive 2, Singapore 117576, Singapore.
| |
Collapse
|
2
|
Fernández-González C, Tarran GA, Schuback N, Woodward EMS, Arístegui J, Marañón E. Phytoplankton responses to changing temperature and nutrient availability are consistent across the tropical and subtropical Atlantic. Commun Biol 2022; 5:1035. [PMID: 36175608 PMCID: PMC9522883 DOI: 10.1038/s42003-022-03971-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
Temperature and nutrient supply interactively control phytoplankton growth and productivity, yet the role of these drivers together still has not been determined experimentally over large spatial scales in the oligotrophic ocean. We conducted four microcosm experiments in the tropical and subtropical Atlantic (29°N-27°S) in which surface plankton assemblages were exposed to all combinations of three temperatures (in situ, 3 °C warming and 3 °C cooling) and two nutrient treatments (unamended and enrichment with nitrogen and phosphorus). We found that chlorophyll a concentration and the biomass of picophytoplankton consistently increase in response to nutrient addition, whereas changes in temperature have a smaller and more variable effect. Nutrient enrichment leads to increased picoeukaryote abundance, depressed Prochlorococcus abundance, and increased contribution of small nanophytoplankton to total biomass. Warming and nutrient addition synergistically stimulate light-harvesting capacity, and accordingly the largest biomass response is observed in the warmed, nutrient-enriched treatment at the warmest and least oligotrophic location (12.7°N). While moderate nutrient increases have a much larger impact than varying temperature upon the growth and community structure of tropical phytoplankton, ocean warming may increase their ability to exploit events of enhanced nutrient availability. Microcosm experiments in the tropical and subtropical Atlantic reveal consistent responses of phytoplankton to changing temperature and nutrient availability, with implications for the impacts of ocean warming in oligotrophic ecosystems.
Collapse
Affiliation(s)
- Cristina Fernández-González
- Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo, Spain.,Centro de Investigacións Mariñas, Universidade de Vigo, Vigo, Spain
| | | | | | | | - Javier Arístegui
- Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Emilio Marañón
- Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo, Spain. .,Centro de Investigacións Mariñas, Universidade de Vigo, Vigo, Spain.
| |
Collapse
|
3
|
Wang T, Li J, Jing H, Qin S. Picocyanobacterial Synechococcus in marine ecosystem: Insights from genetic diversity, global distribution, and potential function. MARINE ENVIRONMENTAL RESEARCH 2022; 177:105622. [PMID: 35429822 DOI: 10.1016/j.marenvres.2022.105622] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/01/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Marine Synechococcus, a main group of picocyanobacteria, has been ubiquitously observed across the global oceans. Synechococcus exhibits high phylogenetical and phenotypical diversity, and horizontal gene transfer makes its genetic evolution much more intricate. With the development of measurement technologies and analysis methods, the genomic information and niche partition of each Synechococcus lineage tend to be precisely described, but the global analysis is still lacking. Therefore, it is necessary to summarize existing studies and integrate published data to gain a comprehensive understanding of Synechococcus on genetic variation, niche division, and potential functions. In this review, the maximum likelihood trees are constructed based on existing sequence data, including both phylogenetic and pigmentary gene markers. The global distribution characteristics of abundance, lineages, and pigment types are concluded through pooled analysis of more than 700 samples obtained from approximately 50 scientific research cruises. The potential functions of Synechococcus are explored in element cycles and biological interactions. Future work on Synechococcus is suggested to focus on not only elucidating the nature of Synechococcus biodiversity but also demonstrating its interactions with the ecosystem by combining bioinformatics and macroscopic isotope-labeled environmental parameters.
Collapse
Affiliation(s)
- Ting Wang
- Key Laboratory of Coastal Biology and Biological Resource Conservation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264000, China; CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jialin Li
- Key Laboratory of Coastal Biology and Biological Resource Conservation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264000, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Hongmei Jing
- CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Song Qin
- Key Laboratory of Coastal Biology and Biological Resource Conservation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264000, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| |
Collapse
|
4
|
Armin G, Inomura K. Modeled temperature dependencies of macromolecular allocation and elemental stoichiometry in phytoplankton. Comput Struct Biotechnol J 2021; 19:5421-5427. [PMID: 34712391 PMCID: PMC8515405 DOI: 10.1016/j.csbj.2021.09.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/20/2021] [Accepted: 09/26/2021] [Indexed: 11/23/2022] Open
Abstract
Warming oceans may affect how phytoplankton allocate nutrients to essential cellular processes. Despite the potential impact of such processes on future biogeochemical cycles, questions remain about how temperature affects macromolecular allocation and elemental stoichiometry within phytoplankton cells. Here, we present a macromolecular model of phytoplankton and the effect of increasing temperature on the intracellular allocation of nutrients at a constant growth rate. When temperature increases under nitrogen (N) and phosphorus (P) co-limitation, the model shows less investment in phosphorus-rich RNA molecules relative to nitrogen-rich proteins, leading to a more severe decrease in cellular P:C than N:C causing increased cellular N:P values. Under P limitation, the model shows a similar pattern, but when excess P is available under N limitation, we predict lowered N:P due to the effect of luxury uptake of P. We reflected our model result on the surface ocean showing similar latitudinal patterns in N:P and P:C to observation and other model predictions, suggesting a considerable impact of temperature on constraining the elemental stoichiometry in the ocean.
Collapse
Affiliation(s)
- Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States
| |
Collapse
|
5
|
Rillema R, Hoang Y, MacCready JS, Vecchiarelli AG. Carboxysome Mispositioning Alters Growth, Morphology, and Rubisco Level of the Cyanobacterium Synechococcus elongatus PCC 7942. mBio 2021; 12:e0269620. [PMID: 34340540 PMCID: PMC8406218 DOI: 10.1128/mbio.02696-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/01/2021] [Indexed: 12/23/2022] Open
Abstract
Cyanobacteria are the prokaryotic group of phytoplankton responsible for a significant fraction of global CO2 fixation. Like plants, cyanobacteria use the enzyme ribulose 1,5-bisphosphate carboxylase/oxidase (Rubisco) to fix CO2 into organic carbon molecules via the Calvin-Benson-Bassham cycle. Unlike plants, cyanobacteria evolved a carbon-concentrating organelle called the carboxysome-a proteinaceous compartment that encapsulates and concentrates Rubisco along with its CO2 substrate. In the rod-shaped cyanobacterium Synechococcus elongatus PCC 7942, we recently identified the McdAB system responsible for uniformly distributing carboxysomes along the cell length. It remains unknown what role carboxysome positioning plays with respect to cellular physiology. Here, we show that a failure to distribute carboxysomes leads to slower cell growth, cell elongation, asymmetric cell division, and elevated levels of cellular Rubisco. Unexpectedly, we also report that even wild-type S. elongatus undergoes cell elongation and asymmetric cell division when grown at the cool, but environmentally relevant, growth temperature of 20°C or when switched from a high- to ambient-CO2 environment. The findings suggest that carboxysome positioning by the McdAB system functions to maintain the carbon fixation efficiency of Rubisco by preventing carboxysome aggregation, which is particularly important under growth conditions where rod-shaped cyanobacteria adopt a filamentous morphology. IMPORTANCE Photosynthetic cyanobacteria are responsible for almost half of global CO2 fixation. Due to eutrophication, rising temperatures, and increasing atmospheric CO2 concentrations, cyanobacteria have gained notoriety for their ability to form massive blooms in both freshwater and marine ecosystems across the globe. Like plants, cyanobacteria use the most abundant enzyme on Earth, Rubisco, to provide the sole source of organic carbon required for its photosynthetic growth. Unlike plants, cyanobacteria have evolved a carbon-concentrating organelle called the carboxysome that encapsulates and concentrates Rubisco with its CO2 substrate to significantly increase carbon fixation efficiency and cell growth. We recently identified the positioning system that distributes carboxysomes in cyanobacteria. However, the physiological consequence of carboxysome mispositioning in the absence of this distribution system remains unknown. Here, we find that carboxysome mispositioning triggers changes in cell growth and morphology as well as elevated levels of cellular Rubisco.
Collapse
Affiliation(s)
- Rees Rillema
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Y Hoang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Joshua S. MacCready
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Anthony G. Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| |
Collapse
|
6
|
Kazama T, Hayakawa K, Kuwahara VS, Shimotori K, Imai A, Komatsu K. Development of photosynthetic carbon fixation model using multi-excitation wavelength fast repetition rate fluorometry in Lake Biwa. PLoS One 2021; 16:e0238013. [PMID: 33529253 PMCID: PMC7853527 DOI: 10.1371/journal.pone.0238013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 01/19/2021] [Indexed: 12/04/2022] Open
Abstract
Direct measurements of gross primary productivity (GPP) in the water column are essential, but can be spatially and temporally restrictive. Fast repetition rate fluorometry (FRRf) is a bio-optical technique based on chlorophyll a (Chl-a) fluorescence that can estimate the electron transport rate (ETRPSII) at photosystem II (PSII) of phytoplankton in real time. However, the derivation of phytoplankton GPP in carbon units from ETRPSII remains challenging because the electron requirement for carbon fixation (Фe,C), which is mechanistically 4 mol e− mol C−1 or above, can vary depending on multiple factors. In addition, FRRf studies are limited in freshwater lakes where phosphorus limitation and cyanobacterial blooms are common. The goal of the present study is to construct a robust Фe,C model for freshwater ecosystems using simultaneous measurements of ETRPSII by FRRf with multi-excitation wavelengths coupled with a traditional carbon fixation rate by the 13C method. The study was conducted in oligotrophic and mesotrophic parts of Lake Biwa from July 2018 to May 2019. The combination of excitation light at 444, 512 and 633 nm correctly estimated ETRPSII of cyanobacteria. The apparent range of Фe,C in the phytoplankton community was 1.1–31.0 mol e− mol C−1 during the study period. A generalised linear model showed that the best fit including 12 physicochemical and biological factors explained 67% of the variance in Фe,C. Among all factors, water temperature was the most significant, while photosynthetically active radiation intensity was not. This study quantifies the in situ FRRf method in a freshwater ecosystem, discusses core issues in the methodology to calculate Фe,C, and assesses the applicability of the method for lake GPP prediction.
Collapse
Affiliation(s)
- Takehiro Kazama
- Lake Biwa Branch Office, National Institute for Environmental Studies, Otsu, Shiga, Japan
- Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
- * E-mail:
| | | | - Victor S. Kuwahara
- Graduate School of Science & Engineering, Soka University, Hachioji, Tokyo, Japan
| | - Koichi Shimotori
- Lake Biwa Branch Office, National Institute for Environmental Studies, Otsu, Shiga, Japan
- Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
| | - Akio Imai
- Lake Biwa Branch Office, National Institute for Environmental Studies, Otsu, Shiga, Japan
| | - Kazuhiro Komatsu
- Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
| |
Collapse
|