First Polyphasic Study of Cheffia Reservoir (Algeria) Cyanobacteria Isolates Reveals Toxic Picocyanobacteria Genotype
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Date
2023-10-30
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microorganisms
Abstract
Abstract: Monitoring water supply requires, among other quality indicators, the identification of the
cyanobacteria community and taking into account their potential impact in terms of water quality.
In this work, cyanobacteria strains were isolated from the Cheffia Reservoir and identified based
on morphological features, the 16S rRNA gene, phylogenetic analysis, and toxin production by
polymerase chain reaction PCR screening of the genes involved in the biosynthesis of cyanotoxins
(mcyA, mcyE, sxtA, sxtG, sxtI, cyrJ, and anaC). Thirteen strains representing six different genera:
Aphanothece, Microcystis, Geitlerinema, Lyngbya, Microcoleus, and Pseudanabaena were obtained. The
results demonstrated the importance of morphological features in determining the genus or the
species when incongruence between the morphological and phylogenetic analysis occurs and only
the utility of the 16S rRNA gene in determining higher taxonomic levels. The phylogenetic analysis
confirmed the polyphyly of cyanobacteria for the Microcystis and Oscillatoriales genera. Unexpectedly,
Aphanothece sp. CR 11 had the genetic potential to produce microcystins. Our study gives new insight
into species with picoplanktonic (or small) cell size and potentially toxic genotypes in this ecosystem.
Thus, conventional water treatment methods in this ecosystem have to be adapted, indicating
the requirement for pre-treatment methods that can effectively eliminate picocyanobacteria while
preserving cell integrity to prevent toxin release.