Assessing the Reason Why Heterotrophic Bacteria Present in Aquatic Environments Are Not Affected by Microcystins and Unraveling Alternative Genes for Microcystin Degradation †
by
and
Joana Andrade
1, 
Catarina Silva
2,
Luis Vieira
2,
Miguel Pinto
3,
João Paulo Gomes
3 and
Elisabete Valério
1,4,*,‡ 1
Departamento de Saúde Ambiental, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal
2
Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal
3
Departamento de Doenças Infecciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal
4
Blue Biotechnology and Ecotoxicology (BBE), CIIMAR—Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208 Porto, Portugal
*
Author to whom correspondence should be addressed.
†
Presented at the 7th Iberian Congress on Cyanotoxins/3rd Iberoamerican Congress on Cyanotoxins, Ponta Delgada, Portugal, 18–20 July 2022.
‡
Presenting author (oral communication).
Biol. Life Sci. Forum 2022, 14(1), 33; https://doi.org/10.3390/blsf2022014033
Published: 25 July 2022
(This article belongs to the Proceedings of The 7th Iberian Congress on Cyanotoxins/3rd Iberoamerican Congress on Cyanotoxins)
Abstract
:Cyanobacteria are a ubiquitous and diverse group of phototrophic prokaryotes, which mainly inhabit aquatic ecosystems. In certain optimal environmental conditions, there may be a rapid increase in cyanobacteria populations, leading to the formation of blooms, which are frequently associated with the presence of cyanotoxins. Microcystins (MCs) are the most frequent hepatotoxin produced by cyanobacteria. Scarce previous studies have shown that the growth of aquatic heterotrophic bacteria, which co-occur with cyanobacteria, may not be affected by the presence of MCs, or may present a reduction, never being totally inhibited by their presence. In this study, we examined the effects of three microcystin variants (MCLR, MCRR and MCYR) on a set of heterotrophic aquatic bacteria living in the same ecosystem as cyanobacteria. In particular, the impact of microcystins on the growth of heterotrophic bacteria was tested, and a PCR screening for the presence of microcystin-degrading genes (mlr) was performed. The growth assays supported the hypothesis from previous studies, where most heterotrophic bacteria were only slightly or not at all affected by exposure to MCs. Moreover, it seems that the behavior of the isolates when exposed to these cyanotoxins was strain specific. A new bacteria, mlr+, was identified, belonging to Flectobacillus sp. Furthermore, we decided to perform a genomic study of 14 isolates from a set of potentially interesting bacteria, including Flavobacterium spp. and Aeromonas spp., to search for xenobiotic-related genes that could be involved in MC degradation. The whole-genome sequencing analysis of these 14 isolates revealed that no COG genes (COG0625; COG0841; COG1566) were present; however, genes similar to CAAX genes were present in the Aeromonas spp. isolates analyzed. These results shed new light into alternative molecular mechanisms for microcystin degradation.
Author Contributions
Conceptualization, E.V. and J.A.; methodology, J.A.; DNA sequencing, C.S. and L.V.; bioinformatics, M.P. and J.P.G.; formal analysis, J.A. and E.V.; writing, all authors. All authors have read and agreed to the published version of the manuscript.
Funding
This work is a result of the GenomePT project (POCI-01-0145-FEDER-022184), supported by COMPETE 2020—the Operational Programme for Competitiveness and Internationalisation (POCI); the Lisboa Portugal Regional Operational Programme (Lisboa2020), the Algarve Portugal Regional Operational Programme (CRESC Algarve2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and by Fundação para a Ciência e a Tecnologia (FCT). This research was also supported by the strategic funding UIDB/04423/2020 and UIDP/04423/2020 through national funds provided by FCT.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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MDPI and ACS Style
Andrade, J.; Silva, C.; Vieira, L.; Pinto, M.; Gomes, J.P.; Valério, E. Assessing the Reason Why Heterotrophic Bacteria Present in Aquatic Environments Are Not Affected by Microcystins and Unraveling Alternative Genes for Microcystin Degradation. Biol. Life Sci. Forum 2022, 14, 33. https://doi.org/10.3390/blsf2022014033
AMA Style
Andrade J, Silva C, Vieira L, Pinto M, Gomes JP, Valério E. Assessing the Reason Why Heterotrophic Bacteria Present in Aquatic Environments Are Not Affected by Microcystins and Unraveling Alternative Genes for Microcystin Degradation. Biology and Life Sciences Forum. 2022; 14(1):33. https://doi.org/10.3390/blsf2022014033
Chicago/Turabian StyleAndrade, Joana, Catarina Silva, Luis Vieira, Miguel Pinto, João Paulo Gomes, and Elisabete Valério. 2022. "Assessing the Reason Why Heterotrophic Bacteria Present in Aquatic Environments Are Not Affected by Microcystins and Unraveling Alternative Genes for Microcystin Degradation" Biology and Life Sciences Forum 14, no. 1: 33. https://doi.org/10.3390/blsf2022014033
