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Investigation of In Vitro Endocrine Activities of Microcystis and Planktothrix Cyanobacterial Strains.

ABSTRACT: Cyanobacteria are cosmopolitan photosynthetic prokaryotes that can form dense accumulations in aquatic environments. They are able to produce many bioactive metabolites, some of which are potentially endocrine disrupting compounds, i.e., compounds that interfere with the hormonal systems of animals and humans. Endocrine disruptors represent potential risks to both environmental and human health, making them a global challenge. The aim of this study was to investigate the potential endocrine disrupting activities with emphasis on estrogenic effects of extracts from cultures of Microcystis or Planktothrix species. We also assessed the possible role of microcystins, some of the most studied cyanobacterial toxins, and thus included both microcystin-producing and non-producing strains. Extracts from 26 cyanobacterial cultures were initially screened in estrogen-, androgen-, and glucocorticoid-responsive reporter-gene assays (RGAs) in order to identify endocrine disruption at the level of nuclear receptor transcriptional activity. Extracts from selected strains were tested repeatedly in the estrogen-responsive RGAs, but the observed estrogen agonist and antagonist activity was minor and similar to that of the cyanobacteria growth medium control. We thus focused on another, non-receptor mediated mechanism of action, and studied the 17?-estradiol (natural estrogen hormone) biotransformation in human liver microsomes in the presence or absence of microcystin-LR (MC-LR), or an extract from the MC-LR producing M. aeruginosa PCC7806 strain. Our results show a modulating effect on the estradiol biotransformation. Thus, while 2-hydroxylation was significantly decreased following co-incubation of 17?-estradiol with MC-LR or M. aeruginosa PCC7806 extract, the relative concentration of estrone was increased.

SUBMITTER: Mallia V

PROVIDER: S-EPMC7232361 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Investigation of In Vitro Endocrine Activities of <i>Microcystis</i> and <i>Planktothrix</i> Cyanobacterial Strains.

Mallia Vittoria V Ivanova Lada L Eriksen Gunnar S GS Harper Emma E Connolly Lisa L Uhlig Silvio S

Toxins 20200404 4

Cyanobacteria are cosmopolitan photosynthetic prokaryotes that can form dense accumulations in aquatic environments. They are able to produce many bioactive metabolites, some of which are potentially endocrine disrupting compounds, i.e., compounds that interfere with the hormonal systems of animals and humans. Endocrine disruptors represent potential risks to both environmental and human health, making them a global challenge. The aim of this study was to investigate the potential endocrine disr ...[more]

PMID: 32260386

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Project description:BackgroundPhosphonates are the main components in the global phosphorus redox cycle. Little is known about phosphonate metabolism in freshwater ecosystems, although rapid consumption of phosphonates has been observed frequently. Cyanobacteria are often the dominant primary producers in freshwaters; yet, only a few strains of cyanobacteria encode phosphonate-degrading (C-P lyase) gene clusters. The phycosphere is defined as the microenvironment in which extensive phytoplankton and heterotrophic bacteria interactions occur. It has been demonstrated that phytoplankton may recruit phycospheric bacteria based on their own needs. Therefore, the establishment of a phycospheric community rich in phosphonate-degrading-bacteria likely facilitates cyanobacterial proliferation, especially in waters with scarce phosphorus. We characterized the distribution of heterotrophic phosphonate-degrading bacteria in field Microcystis bloom samples and in laboratory cyanobacteria "phycospheres" by qPCR and metagenomic analyses. The role of phosphonate-degrading phycospheric bacteria in cyanobacterial proliferation was determined through coculturing of heterotrophic bacteria with an axenic Microcystis aeruginosa strain and by metatranscriptomic analysis using field Microcystis aggregate samples.ResultsAbundant bacteria that carry C-P lyase clusters were identified in plankton samples from freshwater Lakes Dianchi and Taihu during Microcystis bloom periods. Metagenomic analysis of 162 non-axenic laboratory strains of cyanobacteria (consortia cultures containing heterotrophic bacteria) showed that 20% (128/647) of high-quality bins from eighty of these consortia encode intact C-P lyase clusters, with an abundance ranging up to nearly 13%. Phycospheric bacterial phosphonate catabolism genes were expressed continually across bloom seasons, as demonstrated through metatranscriptomic analysis using sixteen field Microcystis aggregate samples. Coculturing experiments revealed that although Microcystis cultures did not catabolize methylphosphonate when axenic, they demonstrated sustained growth when cocultured with phosphonate-utilizing phycospheric bacteria in medium containing methylphosphonate as the sole source of phosphorus.ConclusionsThe recruitment of heterotrophic phosphonate-degrading phycospheric bacteria by cyanobacteria is a hedge against phosphorus scarcity by facilitating phosphonate availability. Cyanobacterial consortia are likely primary contributors to aquatic phosphonate mineralization, thereby facilitating sustained cyanobacterial growth, and even bloom maintenance, in phosphate-deficient waters. Video Abstract.

Dataset Information

Investigation of In Vitro Endocrine Activities of Microcystis and Planktothrix Cyanobacterial Strains.

Publications

Investigation of In Vitro Endocrine Activities of <i>Microcystis</i> and <i>Planktothrix</i> Cyanobacterial Strains.

Similar Datasets

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