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Reignier O, Bormans M, Hervé F, Robert E, Savar V, Tanniou S, Amzil Z, Noël C, Briand E. Spatio-temporal connectivity of a toxic cyanobacterial community and its associated microbiome along a freshwater-marine continuum. HARMFUL ALGAE 2024; 134:102627. [PMID: 38705620 DOI: 10.1016/j.hal.2024.102627] [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: 01/26/2024] [Revised: 03/22/2024] [Accepted: 04/10/2024] [Indexed: 05/07/2024]
Abstract
Due to climate changes and eutrophication, blooms of predominantly toxic freshwater cyanobacteria are intensifying and are likely to colonize estuaries, thus impacting benthic organisms and shellfish farming representing a major ecological, health and economic risk. In the natural environment, Microcystis form large mucilaginous colonies that influence the development of both cyanobacterial and embedded bacterial communities. However, little is known about the fate of natural colonies of Microcystis by salinity increase. In this study, we monitored the fate of a Microcystis dominated bloom and its microbiome along a French freshwater-marine gradient at different phases of a bloom. We demonstrated changes in the cyanobacterial genotypic composition, in the production of specific metabolites (toxins and compatible solutes) and in the heterotrophic bacteria structure in response to the salinity increase. In particular M. aeruginosa and M. wesenbergii survived salinities up to 20. Based on microcystin gene abundance, the cyanobacteria became more toxic during their estuarine transfer but with no selection of specific microcystin variants. An increase in compatible solutes occurred along the continuum with extensive trehalose and betaine accumulations. Salinity structured most the heterotrophic bacteria community, with an increased in the richness and diversity along the continuum. A core microbiome in the mucilage-associated attached fraction was highly abundant suggesting a strong interaction between Microcystis and its microbiome and a likely protecting role of the mucilage against an osmotic shock. These results underline the need to better determine the interactions between the Microcystis colonies and their microbiome as a likely key to their widespread success and adaptation to various environmental conditions.
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Affiliation(s)
| | - Myriam Bormans
- UMR CNRS 6553 ECOBIO, University of Rennes 1, Rennes F-35042, France
| | - Fabienne Hervé
- IFREMER, PHYTOX, Laboratoire METALG, Nantes F-44000, France
| | - Elise Robert
- IFREMER, PHYTOX, Laboratoire GENALG, Nantes F-44000, France
| | | | - Simon Tanniou
- IFREMER, PHYTOX, Laboratoire METALG, Nantes F-44000, France
| | - Zouher Amzil
- IFREMER, PHYTOX, Laboratoire METALG, Nantes F-44000, France
| | - Cyril Noël
- IFREMER, IRSI - Service de Bioinformatique (SeBiMER), Plouzané, France
| | - Enora Briand
- IFREMER, PHYTOX, Laboratoire GENALG, Nantes F-44000, France.
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Reignier O, Bormans M, Marchand L, Sinquin C, Amzil Z, Zykwinska A, Briand E. Production and composition of extracellular polymeric substances by a unicellular strain and natural colonies of Microcystis: Impact of salinity and nutrient stress. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023; 15:783-796. [PMID: 37697704 PMCID: PMC10667651 DOI: 10.1111/1758-2229.13200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/22/2023] [Indexed: 09/13/2023]
Abstract
The transfer of toxic cyanobacterial Microcystis blooms from freshwater to estuaries constitutes a serious environmental problem worldwide that is expected to expand in scale and intensity with anthropogenic and climate change. The formation and maintenance of Microcystis in colonial form is conditioned to the presence of extracellular polymeric substances (EPS). In this study, we attempted to better understand how the mucilaginous colonial form of Microcystis evolves under environmental stress conditions. In particular, we studied and compared the production and the composition of EPS fractions (attached and free) from natural colonies of a Microcystis bloom and from a unicellular M. aeruginosa strain under salinity and nutrient stress (representing a land-sea continuum). Our results highlighted a greater production of EPS from the natural colonies of Microcystis than the unicellular one under nutrient and combined stress conditions dominated by the attached form. In comparison to the unicellular Microcystis, EPS produced by the colonial form were characterized by high molecular weight polysaccharides which were enriched in uronic acids and hexosamines, notably for the free fraction in response to increased salinities. This complex extracellular matrix gives the cells the ability to aggregate and allows the colonial cyanobacterial population to cope with osmotic shock.
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Cai P, Xu L, Yang J, Tian C, Wu X, Wang C, Xiao B. Differences in survivability and toxic potential among Microcystis colonies of different sizes in sediment. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:118916-118927. [PMID: 37919509 DOI: 10.1007/s11356-023-30753-9] [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: 04/26/2023] [Accepted: 10/25/2023] [Indexed: 11/04/2023]
Abstract
Microcystis colonies have the ability to persist for extended periods in sediment and function as a "seed bank" for the succeeding summer bloom in water column. The colonial morphology and toxin production ability of Microcystis are important for their population maintenance and life history. However, it is unclear about the influence of the colony morphology and toxic potential of Microcystis colonies on their benthic process. To address this question, we classified field Microcystis samples into three groups based on their size (< 150 μm, 150-300 μm, and > 300 μm) and compared their survivability and toxic potential during culturing in sediment. The results showed that Microcystis colonies in sediments disappeared quickly at 25℃ but survived for long periods at 5℃. The survivability of smaller Microcystis colonies (< 300 μm) was significantly higher than that of larger ones (> 300 μm). The activities of catalase (CAT) were significantly increased in large colonies compared to small colonies at 15℃ and 25℃. Real-time PCR indicated that smaller colonies had higher proportion of potential toxic genotype, and Microcystis colonies cultured at 15℃ and 25℃ showed higher percentage of microcystin-producing genotype. These results indicate that Microcystis colonies survived longer at low temperature and that larger Microcystis colonies are more susceptible to oxidative stress in sediments. The difference of toxic potential of Microcystis colonies of different sizes in sediments may be related to their survival ability in sediments.
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Affiliation(s)
- Pei Cai
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lei Xu
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiaojiao Yang
- Dianchi Lake Ecosystem Observation and Research Station of Yunnan Province, Kunming Dianchi & Plateau Lakes Institute, Kunming, 650228, China
| | - Cuicui Tian
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Xingqiang Wu
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Chunbo Wang
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
| | - Bangding Xiao
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
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Bormans M, Legrand B, Waisbord N, Briand E. Morphological and physiological impacts of salinity on colonial strains of the cyanobacteria Microcystis aeruginosa. Microbiologyopen 2023; 12:e1367. [PMID: 37379426 PMCID: PMC10306157 DOI: 10.1002/mbo3.1367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/30/2023] Open
Abstract
In the context of global change and enhanced toxic cyanobacterial blooms, cyanobacterial transfer to estuaries is likely to increase in frequency and intensity and impact animal and human health. Therefore, it is important to evaluate the potential of their survival in estuaries. In particular, we tested if the colonial form generally observed in natural blooms enhanced the resistance to salinity shock compared to the unicellular form generally observed in isolated strains. We tested the impact of salinity on two colonial strains of Microcystis aeruginosa, producing different amounts of mucilage by combining classical batch methods with a novel microplate approach. We demonstrate that the collective organization of these pluricellular colonies improves their ability to cope with osmotic shock when compared to unicellular strains. The effect of a sudden high salinity increase (S ≥ 20) over 5 to 6 days had several impacts on the morphology of M. aeruginosa colonies. For both strains, we observed a gradual increase in colony size and a gradual decrease in intercellular spacing. For one strain, we also observed a decrease in cell diameter with an increase in mucilage extent. The pluricellular colonies formed by both strains could withstand higher salinities than unicellular strains studied previously. In particular, the strain producing more mucilage displayed a sustained autofluorescence even at S = 20, a limit that is higher than the most robust unicellular strain. These results imply survival and possible M. aeruginosa proliferation in mesohaline estuaries.
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Affiliation(s)
- Myriam Bormans
- UMR CNRS 6553 ECOBIOUniversity of RennesRennesCedexFrance
| | | | - Nicolas Waisbord
- UMR CNRS 6118 Géosciences RennesUniversity of RennesRennesCedexFrance
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Ma X, Li M, Jiang E, Pan B, Gao L. Humic acid inhibits colony formation of the cyanobacterium Microcystis at high level of iron. CHEMOSPHERE 2021; 281:130742. [PMID: 34000652 DOI: 10.1016/j.chemosphere.2021.130742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 04/19/2021] [Accepted: 04/24/2021] [Indexed: 06/12/2023]
Abstract
Colony formation is a key process for the occurrence of Microcystis blooms. In order to inhibit colony formation of Microcystis at high level of iron using humic acid, unicellular Microcystis aeruginosa was cultivated in laboratory treated with varying concentrations of iron and humic acid. Our results showed that the extracellular polysaccharides (EPS) content and average colony size increased from 0.57 pg cells-1 and 4.0 μm to 0.93 pg cells-1 and 26.1 μm, respectively, while iron concentration increased from 0.68 mg L-1 to 6.8 mg L-1, suggesting that high level of iron stimulated EPS secretion and induced unicellular Microcystis to form colonies. Transcriptome analysis showed that two genes described as glycosyltransferases (BH695-2217 and BH695-3696) were significantly up-regulated while EPS content increased with increasing iron concentration indicating that iron may regulate the expression of genes involved in polysaccharide synthesis. When treated with 10 mg C L-1 humic acid at high level of iron, the EPS content and average colony size decreased by 35.5% and 56.3%, respectively, revealing that humic acid inhibited EPS secretion under high level of iron condition, and ultimately inhibited colony formation of Microcystis. Our results suggested that humic acid could be used as an agentia inhibiting large colony formation of Microcystis and thereby reducing the occurrence of Microcystis blooms.
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Affiliation(s)
- Xiao Ma
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, PR China
| | - Ming Li
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, PR China.
| | - Enli Jiang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, PR China
| | - Baozhu Pan
- State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, 710048, Shaanxi, China
| | - Li Gao
- Institute for Sustainable Industries and Liveable Cities, Victoria University, PO Box 14428, Melbourne, Victoria, 8001, Australia
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Kruk C, Martínez A, Martínez de la Escalera G, Trinchin R, Manta G, Segura AM, Piccini C, Brena B, Yannicelli B, Fabiano G, Calliari D. Rapid freshwater discharge on the coastal ocean as a mean of long distance spreading of an unprecedented toxic cyanobacteria bloom. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:142362. [PMID: 33254935 DOI: 10.1016/j.scitotenv.2020.142362] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/21/2020] [Accepted: 09/12/2020] [Indexed: 06/12/2023]
Abstract
Cyanobacterial toxic blooms are a worldwide problem. The Río de la Plata (RdlP) basin makes up about one fourth of South America areal surface, second only to the Amazonian. Intensive agro-industrial land use and the construction of dams have led to generalized eutrophication of main tributaries and increased the intensity and duration of cyanobacteria blooms. Here we analyse the evolution of an exceptional bloom at the low RdlP basin and Atlantic coast during the summer of 2019. A large array of biological, genetic, meteorological, oceanographic and satellite data is combined to discuss the driving mechanisms. The bloom covered the whole stripe of the RdlP estuary and the Uruguayan Atlantic coasts (around 500 km) for approximately 4 months. It was caused by the Microcystis aeruginosa complex (MAC), which produces hepatotoxins (microcystin). Extreme precipitation in the upstream regions of Uruguay and Negro rivers' basins caused high water flows and discharges. The evolution of meteorological and oceanographic conditions as well as the similarity of organisms' traits in the affected area suggest that the bloom originated in eutrophic reservoirs at the lower RdlP basin, Salto Grande in the Uruguay river, and Negro river reservoirs. High temperatures and weak Eastern winds prompted the rapid dispersion of the bloom over the freshwater plume along the RdlP northern and Atlantic coasts. The long-distance rapid drift allowed active MAC organisms to inoculate freshwater bodies from the Atlantic basin, impacting environments relevant for biodiversity conservation. Climate projections for the RdlP basin suggest an increase in precipitation and river water flux, which, in conjunction with agriculture intensification and dams' construction, might turn this extraordinary event into an ordinary situation.
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Affiliation(s)
- Carla Kruk
- Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, UDELAR, Iguá 4225, 11400 Montevideo, Uruguay; Ecología Funcional de Sistemas Acuáticos, Centro Universitario Regional del Este (CURE), UdelaR, Ruta nacional 9 intersección con ruta 15, 27000 Rocha, Uruguay.
| | - Ana Martínez
- Dirección Nacional de Recursos Acuáticos, La Paloma, MGAP, Avenida del Puerto s/n, Puerto la Paloma, La Paloma, CP 27001, Rocha, Uruguay
| | - Gabriela Martínez de la Escalera
- Departamento de Microbiología, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Av Italia 3318, 11600 Montevideo, Uruguay
| | - Romina Trinchin
- Departamento de Ciencias de la Atmósfera, Facultad de Ciencias, UDELAR, Iguá 4225, 11400 Montevideo, Uruguay; Instituto Uruguayo de meteorología, Dr Javier Barrios Amorín 1488, 11200 Montevideo, Uruguay
| | - Gastón Manta
- Departamento de Ciencias de la Atmósfera, Facultad de Ciencias, UDELAR, Iguá 4225, 11400 Montevideo, Uruguay
| | - Angel M Segura
- Modelación y Análisis de Recursos Naturales, CURE, UDELAR, Ruta nacional 9 intersección con ruta 15, 27000 Rocha, Uruguay
| | - Claudia Piccini
- Departamento de Microbiología, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Av Italia 3318, 11600 Montevideo, Uruguay
| | - Beatriz Brena
- Bioquímica-DEPBIO, Facultad de Química, UDELAR, Av. Gral. Flores 2124, 11800 Montevideo, Uruguay
| | - Beatriz Yannicelli
- Ecología Funcional de Sistemas Acuáticos, Centro Universitario Regional del Este (CURE), UdelaR, Ruta nacional 9 intersección con ruta 15, 27000 Rocha, Uruguay
| | - Graciela Fabiano
- Instituto de Investigaciones Pesqueras, Facultad de Veterinaria, UDELAR, Tomás Basáñez 1160, Montevideo 11400, Uruguay
| | - Danilo Calliari
- Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, UDELAR, Iguá 4225, 11400 Montevideo, Uruguay; Ecología Funcional de Sistemas Acuáticos, Centro Universitario Regional del Este (CURE), UdelaR, Ruta nacional 9 intersección con ruta 15, 27000 Rocha, Uruguay
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