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Experimental evidence for the selection of salinity-tolerant ecotypes of the Microcystis aeruginosa complex.

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Title: Experimental evidence for the selection of salinity-tolerant ecotypes of the Microcystis aeruginosa complex.
Authors: Martínez de la Escalera G; Departamento de Microbiología, Centro de Investigación en Ciencias Ambientales, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Avenida Italia 3318, 11600 Montevideo, Uruguay., Segura AM; Departamento de Modelización Estadística de Datos e Inteligencia Artificial (MEDIA), CURE-Rocha, Universidad de la República, Uruguay., Kruk C; Departamento de Modelización Estadística de Datos e Inteligencia Artificial (MEDIA), CURE-Rocha, Universidad de la República, Uruguay; Limnología, IECA, Facultad de Ciencias, Universidad de la República, Uruguay., González C; Laboratorio de Limnología, DEGE, Facultad Ciencias Exactas y Naturales, UBA, Buenos Aires, Argentina., Piccini C; Departamento de Microbiología, Centro de Investigación en Ciencias Ambientales, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Avenida Italia 3318, 11600 Montevideo, Uruguay. Electronic address: cpiccini@iibce.edu.uy.
Source: Harmful algae [Harmful Algae] 2025 Nov; Vol. 149, pp. 102936. Date of Electronic Publication: 2025 Aug 07.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Elsevier Country of Publication: Netherlands NLM ID: 101128968 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1878-1470 (Electronic) Linking ISSN: 15689883 NLM ISO Abbreviation: Harmful Algae Subsets: MEDLINE
Imprint Name(s): Original Publication: Amsterdam ; New York : Elsevier, c2002-
MeSH Terms: Microcystis*/physiology , Microcystis*/genetics , Ecotype* , Salinity* , Salt Tolerance*, Microcystins/metabolism
Abstract: Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Microcystis aeruginosa complex (MAC) generate harmful blooms in multiple aquatic ecosystems, from freshwater to estuaries. The intra-complex genetic diversity and its phenotypic plasticity emerge as the main hypothesis of ecological success of the group in eutrophic ecosystems. This intra-complex diversity is composed of ecotypes, phylogenetically closely related organisms differing in their ecological preferences that could be considered species. Under the hypothesis of a rapid selection of ecotypes caused by salinity, here, we experimentally evaluated the role of salinity (0, 5, 10 and 25 ppt) in the ecotype community configuration and toxicity of MAC. We assessed the response to different salinities by analyzing ecotype composition (mcyJ based genotyping) combined with mcyJ amplicon sequencing for ecotypes identification, MC-producing cells abundance and their toxin-production activity (mcy gene copies and transcripts abundance, and MC variants concentration), and machine learning methods for data analysis. We found that, although the abundance of MC-producing cells, the mcyE transcription and MC concentration were negatively affected by increasing salinity, the treatments at 10 and 25 ppt selected MAC ecotypes showing different profiles of MC variants. The results indicate that when freshwater MAC species are transported to brackish waters, the salt-induced stress (salinities between 5 and 10 ppt) selects salt-tolerant ecotypes, generating a shift in the MC variants produced. At higher salinities (25 ppt), the selected ecotypes maintain their abundance but MC production decreases. The existence of MC-producing ecotypes adapted to different salinity conditions is relevant in determining the success of MAC organisms in a wide range of ecosystems and poses a risk to estuarine health, justifying further research.
(Copyright © 2025. Published by Elsevier B.V.)
Contributed Indexing: Keywords: Ecotypes; Environmental gradient; Microcystin; Microcystis aeruginosa complex; Salinity
Substance Nomenclature: 0 (Microcystins)
Entry Date(s): Date Created: 20250911 Date Completed: 20250915 Latest Revision: 20250915
Update Code: 20250916
DOI: 10.1016/j.hal.2025.102936
PMID: 40935515
Database: MEDLINE
Description
Abstract:Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.<br />Microcystis aeruginosa complex (MAC) generate harmful blooms in multiple aquatic ecosystems, from freshwater to estuaries. The intra-complex genetic diversity and its phenotypic plasticity emerge as the main hypothesis of ecological success of the group in eutrophic ecosystems. This intra-complex diversity is composed of ecotypes, phylogenetically closely related organisms differing in their ecological preferences that could be considered species. Under the hypothesis of a rapid selection of ecotypes caused by salinity, here, we experimentally evaluated the role of salinity (0, 5, 10 and 25 ppt) in the ecotype community configuration and toxicity of MAC. We assessed the response to different salinities by analyzing ecotype composition (mcyJ based genotyping) combined with mcyJ amplicon sequencing for ecotypes identification, MC-producing cells abundance and their toxin-production activity (mcy gene copies and transcripts abundance, and MC variants concentration), and machine learning methods for data analysis. We found that, although the abundance of MC-producing cells, the mcyE transcription and MC concentration were negatively affected by increasing salinity, the treatments at 10 and 25 ppt selected MAC ecotypes showing different profiles of MC variants. The results indicate that when freshwater MAC species are transported to brackish waters, the salt-induced stress (salinities between 5 and 10 ppt) selects salt-tolerant ecotypes, generating a shift in the MC variants produced. At higher salinities (25 ppt), the selected ecotypes maintain their abundance but MC production decreases. The existence of MC-producing ecotypes adapted to different salinity conditions is relevant in determining the success of MAC organisms in a wide range of ecosystems and poses a risk to estuarine health, justifying further research.<br /> (Copyright © 2025. Published by Elsevier B.V.)
ISSN:1878-1470
DOI:10.1016/j.hal.2025.102936