Detection of Cyanotoxin-Producing Genes in a Eutrophic Reservoir (Billings Reservoir, São Paulo, Brazil)

Abstract

CyanoHABs (cyanobacterial harmful algal blooms) are blooms of cyanobacteria capable of producing cyanotoxins, a large group of secondary metabolites that are toxic to most eukaryotes. In this work, the main aim was to evaluate the presence of multiple genes from each of the clusters responsible for biosynthesis of cyanotoxins (cylindrospermopsin, microcystin and saxitoxin) in total DNA obtained from sixteen environmental water samples by PCR. Microcystin gene mcyE was amplified in all analyzed samples. Among the cylindrospermopsin genes analyzed, only the cyrC gene was amplified from DNA obtained from three of sixteen samples. Of the three different saxitoxin genes analyzed, sxtB and sxtI were present in four and three of the sixteen samples studied, respectively, and sxtA did not show any positive result. Based on our results, we suggest caution when using only one gene from the full clusters responsible for biosynthesis of cyanotoxins, given that it may not be sufficient to confirm or exclude the toxigenic potential of a sample.

Ganga river water quality assessment using combined approaches: physico-chemical parameters and cyanobacterial toxicity detection with special reference to microcystins and molecular characterization of microcystin synthetase (mcy) genes carrying cyanobacteria

“…These ndings of PCR ampli cation were same for both the years of study. Previous studies have also shown the identi cation and detection of toxic cyanobacteria in environmental samples based on mcy genes using a PCR technique (Baker et al 2002, Ribeiro et al 2020) with universal primers targeting conserved sequences (Hisbergues et al 2003) and species-speci c primers designed based on differences within the mcy gene clusters (Rantala et al 2006), respectively. The mcy genes preferably targeted are mcyA, B, C, D and E however, in several studies a combination of the mcy genes were used (Ouellette et al 2006).…”

“…Number of analytical techniques such as protein phosphatase inhibition assay (PPIA), enzyme-linked immunosorbent assay (ELISA), highperformance liquid chromatography (HPLC), mass spectrometry (MS) has been employed for the monitoring of different MCs in the contaminated water samples (Kumar et al 2020a; Massey et al 2020). Molecular technique such as polymerase chain reaction (PCR) based detection of mcy genes (mcyA, mcyB, mcyD, mcyE and mcyG) is rapid, cost-effective as well as facilitated the culture independent identi cation of toxic cyanobacteria in environmental samples (Genuario et al 2010; Ribeiro et al 2020). Numbers of studies were available on the assessment of river Ganga water quality based on physico-chemical parameters, bacterial and fungal diversity and metal toxicity (Behera et al 2020;Matta et al 2020;Prasad et al 2020;Dimri et al 2020).…”

Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil

“…The identification and quantification of cyanobacteria by traditional microscopy is not adequate for the identification of toxic populations, since toxic and nontoxic strains are morphologically identical [11]. For the detection of toxin-producing strains, PCR-targeting genes that encode specific toxins may be a fast and useful approach [12]. If the number of potentially toxin-producing cyanobacteria is needed, e.g., in environmental studies, quantitative PCR (qPCR) can be applied and serve as a powerful and sensitive tool [13][14][15][16][17].…”

“…In Brazil, relatively few studies have focused on molecular approaches for the detection of toxic genes for early warning of cyanotoxin episodes, despite the frequent occurrence of cyanobacterial blooms [12,[18][19][20][21]. In most cases, traditional PCR was used to detect the presence of potentially cyanotoxin-producing strains, but the application of qPCR-targeting genes in the MC synthesis was performed by Lorenzi [19], Pimentel and Giani [11] and Guedes et al [22] to quantify the mcyA gene in Salto Grande reservoir, the mcyD gene in Furnas reservoir and the mcyB in Funil reservoir, respectively.…”

Hydrochemical Parameters and Biometric Data of Fish Species From the Bororé, Billings Reservoir, São Paulo, Brazil

“…Several freshwater ecosystems in tropical regions are subjected to anthropic disruptions, which promote the degradation of the water quality and the ecological patterns of resident species (Heath, 1990;Ogashawara et al, 2014;Ribeiro et al, 2020). The Billings Reservoir is in the Upper Tietê River Basin, on the Billings-Tamanduateí sub-basin and is the main reservoir for water supply in the Metropolitan Region of São Paulo (MRSP) (approximately 15% of the MRSP population) (SIGRH, 2009;Risso et al, 2018).…”