Physiological and metabolic responses of freshwater and brackish strains of Microcystis aeruginosa acclimated to a salinity gradient: insight into salt tolerance

Proliferation of microcystin (MC) producing Microcystis aeruginosa in brackish waters 27 has been described in several locations and represents a new concern for public and 28 environmental health. While the impact of a sudden salinity increase on M. 29 aeruginosa physiology has been studied, less is known about the mechanisms 30 involved in salt tolerance after acclimation. This study aims to compare the 31 physiological responses of two strains of M. aeruginosa (PCC 7820 and PCC 7806), 32 isolated from contrasted environments, to increasing salinities. After acclimation, 33 growth, MC production and metabolomic analyses were conducted. For both strains, 34 salinity decreased the biovolume, the growth and MC production rates and induced 35 the accumulation of polyunsaturated lipids identified as monogalactosyldiacylglycerol. 36 The distinct salt tolerance (7.5 and 16.9) obtained between the freshwater (PCC 37 7820) and the brackish water (PCC 7806) strains suggested different strategies to 38 cope with the osmotic pressure, as revealed by targeted and untargeted metabolomic 39 analyses . Accumulation of trehalose as the main compatible solute was obtained in 40 the freshwater strain while sucrose was mainly accumulated in the brackish one. 41 Moreover, distinct levels of glycine betaine and proline accumulation were noted. 42 Altogether, metabolomic analysis illustrated a strain-specific response to salt 43 tolerance, involving compatible solutes production. 44 45 46 47 48 49 50 health. In order to better describe the mechanisms involved in 56 Microcystis proliferation in brackish water, this study used two M. aeruginosa strains 57 isolated from fresh and brackish waters. High salinity reduced the growth rate and 58 microcystin production rate of M. aeruginosa . In order to cope with higher salinities, 59 the strains accumulated different cyanobacterial compatible as well lipids, Factors influencing MC production as well as the inherent role of MCs are still under debate (43). With the exception of one study (44), reports on the impact of salinity variation concluded to a decrease of MC cellular quotas under higher salinity conditions (23, 24, 29, 30). A decrease in MC cellular quota is frequently associated 302 with an increase in dissolved MC because of cell lysis (19, 23, 29). Our study also showed that the MC cellular quota was decreased with increasing salinity for both strains. In addition, a linear correlation was found between growth rate and net production rate of MCs. This relation shows that MC cellular quotas in both strains 306 are strongly coupled to cell division, as already evidenced by Orr et al. (45). Furthermore, as explained by Orr et al. this correlation illustrates that salinity only indirectly influences the production of MCs through its effect on growth. Also, as a comparison, Amé and Wunderlin and showed that temperature and nutrients changed the MC congener ratios by up to a 82-fold 311 change. Our results suggested that salinity did not seem to alter the MC ratios in M. aeruginosa in the same order of range. The extracellular MC fractions decreased with time, indicating no significant cell lysis phenomenon. At high salinities, the higher proportion of extracellular MCs resulted from the larger volume of inoculum. These results suggest that no active excretion of MCs occurred in response to higher salinities. Thus, the growth conditions were convenient for cell membrane integrity, as well as showed by the stability of the maximum photochemical efficiency of photosystem II over time. As a comparison, an active release of saxitoxin and gonyautoxins 2 and 3 can be induced by sodium and potassium increase in Raphidiopsis another toxic bloom forming cyanobacteria (49). Based on previous 321 studies (29, 50) and our results, the MCs did not appear to be accumulated in M. 322 aeruginosa cells in response to higher salinity. Overall, the growth of the two M.

[1]  Z. Amzil,et al.  Demonstrated transfer of cyanobacteria and cyanotoxins along a freshwater-marine continuum in France. , 2019, Harmful algae.

[2]  E. M. Janssen,et al.  Cyanobacterial peptides beyond microcystins - A review on co-occurrence, toxicity, and challenges for risk assessment. , 2019, Water research.

[3]  Abraham Otero,et al.  CEU Mass Mediator 3.0: A Metabolite Annotation Tool. , 2019, Journal of proteome research.

[4]  H. Paerl,et al.  Cyanobacterial blooms , 2018, Nature Reviews Microbiology.

[5]  T. Sano,et al.  Adaptation of the Freshwater Bloom-Forming Cyanobacterium Microcystis aeruginosa to Brackish Water Is Driven by Recent Horizontal Transfer of Sucrose Genes , 2018, Front. Microbiol..

[6]  M. Burford,et al.  Application of first order rate kinetics to explain changes in bloom toxicity—the importance of understanding cell toxin quotas , 2018, Journal of Oceanology and Limnology.

[7]  H. Paerl,et al.  Mitigating the Expansion of Harmful Algal Blooms Across the Freshwater-to-Marine Continuum. , 2018, Environmental science & technology.

[8]  Lewis G. Spurgin,et al.  DSYB catalyses the key step of dimethylsulfoniopropionate biosynthesis in many phytoplankton , 2018, Nature Microbiology.

[9]  M. Steinke,et al.  Flux of the biogenic volatiles isoprene and dimethyl sulfide from an oligotrophic lake , 2018, Scientific Reports.

[10]  O. Burlet-Schiltz,et al.  Metabolome and proteome changes between biofilm and planktonic phenotypes of the marine bacterium Pseudoalteromonas lipolytica TC8 , 2018, Biofouling.

[11]  E. Testai,et al.  Cyanobacteria blooms in water: Italian guidelines to assess and manage the risk associated to bathing and recreational activities. , 2017, The Science of the total environment.

[12]  A. Segura,et al.  Dynamics of toxic genotypes of Microcystis aeruginosa complex (MAC) through a wide freshwater to marine environmental gradient. , 2017, Harmful algae.

[13]  D. Kaplan,et al.  Restore or retreat? saltwater intrusion and water management in coastal wetlands , 2017 .

[14]  Kristian Fog Nielsen,et al.  Sharing and community curation of mass spectrometry data with Global Natural Products Social Molecular Networking , 2016, Nature Biotechnology.

[15]  H. Paerl,et al.  A review of the global ecology, genomics, and biogeography of the toxic cyanobacterium, Microcystis spp. , 2016, Harmful algae.

[16]  E. Preece,et al.  Transfer of microcystin from freshwater lakes to Puget Sound, WA and toxin accumulation in marine mussels (Mytilus trossulus). , 2015, Ecotoxicology and environmental safety.

[17]  M. Manefield,et al.  Changes in metabolites, antioxidant system, and gene expression in Microcystis aeruginosa under sodium chloride stress. , 2015, Ecotoxicology and environmental safety.

[18]  E. Dittmann,et al.  Metabolomic analysis indicates a pivotal role of the hepatotoxin microcystin in high light adaptation of Microcystis. , 2015, Environmental microbiology.

[19]  Tohru Takahashi,et al.  Diffusion of microcystins (cyanobacteria hepatotoxins) from the reservoir of Isahaya Bay, Japan, into the marine and surrounding ecosystems as a result of large-scale drainage. , 2014, Marine pollution bulletin.

[20]  Hans W. Paerl,et al.  Mitigating Harmful Cyanobacterial Blooms in a Human- and Climatically-Impacted World , 2014, Life.

[21]  B. Xi,et al.  Effect of NaCl salinity on the growth, metabolites, and antioxidant system of Microcystis aeruginosa , 2013 .

[22]  W. Sunda,et al.  Increased intracellular concentrations of DMSP and DMSO in iron‐limited oceanic phytoplankton Thalassiosira oceanica and Trichodesmium erythraeum , 2013 .

[23]  A. Cembella,et al.  PSP toxin release from the cyanobacterium Raphidiopsis brookii D9 (Nostocales) can be induced by sodium and potassium ions. , 2012, Toxicon : official journal of the International Society on Toxinology.

[24]  Natalie I. Tasman,et al.  A Cross-platform Toolkit for Mass Spectrometry and Proteomics , 2012, Nature Biotechnology.

[25]  M. Bes,et al.  An active photosynthetic electron transfer chain required for mcyD transcription and microcystin synthesis in Microcystis aeruginosa PCC7806 , 2012, Ecotoxicology.

[26]  Leticia L. Torres,et al.  Sucrose synthase in unicellular cyanobacteria and its relationship with salt and hypoxic stress , 2011, Planta.

[27]  E. Phlips,et al.  Growth and Toxin Production by Microcystis Aeruginosa PCC 7806 (Kutzing) Lemmerman at Elevated Salt Concentrations , 2011 .

[28]  Age K. Smilde,et al.  Double-check: validation of diagnostic statistics for PLS-DA models in metabolomics studies , 2011, Metabolomics.

[29]  Philippe Besse,et al.  Sparse PLS discriminant analysis: biologically relevant feature selection and graphical displays for multiclass problems , 2011, BMC Bioinformatics.

[30]  M. Hagemann,et al.  Compatible solute biosynthesis in cyanobacteria. , 2011, Environmental microbiology.

[31]  H. Mazur-Marzec,et al.  Morphological, genetic, chemical and ecophysiological characterisation of two Microcystis aeruginosa isolates from the Vistula Lagoon, southern Baltic , 2010 .

[32]  J. Huisman,et al.  The ecological stoichiometry of toxins produced by harmful cyanobacteria: an experimental test of the carbon-nutrient balance hypothesis. , 2009, Ecology letters.

[33]  H. Paerl,et al.  Climate change: a catalyst for global expansion of harmful cyanobacterial blooms. , 2009, Environmental microbiology reports.

[34]  S. Sánchez-Fortún,et al.  Toxic effects induced by salt stress on selected freshwater prokaryotic and eukaryotic microalgal species , 2009, Ecotoxicology.

[35]  Nigel W. Hardy,et al.  Proposed minimum reporting standards for chemical analysis , 2007, Metabolomics.

[36]  J. Huisman,et al.  Salt tolerance of the harmful cyanobacterium Microcystis aeruginosa , 2007 .

[37]  J. Huisman,et al.  Water management strategies against toxic Microcystis blooms in the Dutch delta. , 2006, Ecological applications : a publication of the Ecological Society of America.

[38]  R. Abagyan,et al.  XCMS: processing mass spectrometry data for metabolite profiling using nonlinear peak alignment, matching, and identification. , 2006, Analytical chemistry.

[39]  D. Wunderlin,et al.  Effects of Iron, Ammonium and Temperature on Microcystin Content by a Natural Concentrated Microcystis Aeruginosa Population , 2005 .

[40]  P. Orr,et al.  Response of cultured Microcystis aeruginosa from the Swan river, Australia, to elevated salt concentration and consequences for bloom and toxin management in estuaries , 2004 .

[41]  D. Baldwin,et al.  Effects of increasing salinity on freshwater ecosystems in Australia , 2003 .

[42]  K. Mikami,et al.  Membrane fluidity and the perception of environmental signals in cyanobacteria and plants. , 2003, Progress in lipid research.

[43]  David P. Hamilton,et al.  Summer flow event induces a cyanobacterial bloom in a seasonal Western Australian estuary , 2003 .

[44]  J. Kromkamp,et al.  The use of variable fluorescence measurements in aquatic ecosystems: differences between multiple and single turnover measuring protocols and suggested terminology , 2003 .

[45]  J. Stefels.  Physiological aspects of the production and conversion of DMSP in marine algae and higher plants , 2000 .

[46]  大塚 泰介.  宍道湖産Microcystis sp.の形態観察 , 2000 .

[47]  S. Suda,et al.  Characterization of morphospecies and strains of the genus Microcystis (Cyanobacteria) for a reconsideration of species classification , 1999 .

[48]  I. Suzuki,et al.  Genetic engineering of the unsaturation of fatty acids in membrane lipids alters the tolerance of Synechocystis to salt stress. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[49]  P. Orr,et al.  Relationship between microcystin production and cell division rates in nitrogen‐limited Microcystis aeruginosa cultures , 1998 .

[50]  M. Hagemann,et al.  Synthesis of glucosylglycerol in salt-stressed cells of the cyanobacterium Microcystis firma , 1987, Archives of Microbiology.

[51]  A. Walsby,et al.  Changes in turgor pressure in response to increases in external NaCl concentration in the gas-vacuolate cyanobacterium Microcystis sp. , 1985, Archives of Microbiology.

[52]  J. Waterbury,et al.  Generic assignments, strain histories, and properties of pure cultures of cyanobacteria , 1979 .

[53]  A. D. Brown,et al.  Microbial water stress. , 1976, Bacteriological reviews.

[54]  I. Smet.  Plant Organogenesis , 2013, Methods in Molecular Biology.

[55]  M. Hagemann.  Molecular biology of cyanobacterial salt acclimation. , 2011, FEMS microbiology reviews.

[56]  J. Huisman,et al.  Production of cyanopeptolins, anabaenopeptins, and microcystins by the harmful cyanobacteria Anabaena 90 and Microcystis PCC 7806 , 2009 .

[57]  Hugh L. MacIntyre,et al.  Using Cultures to Investigate the Physiological Ecology of Microalgae , 2005 .

[58]  UvA-DARE Effects of rising CO₂ on the harmful cyanobacterium Microcystis , 2022 .