Polymerase chain reaction (PCR) detection of the predominant microcystin-producing genotype of cyanobacteria in Mozambican lakes

Abstract

Mozambique is a developing country with a wide range of aquatic ecosystems. Given the limited resources of the country, problems of aquatic pollution have not received the required consideration. The aim of the present study was to assess the presence of microcystins (MCs) and identify the genotypes of MC-producing cyanobacteria in Mozambique. Polymerase chain reaction (PCR) based detection methods were used to analyze samples from three study freshwater bodies which are used as sources of drinking water. The occurrence of cyanobacterial toxic genes in Nhambavale lake and Chòkwé irrigation channels is reported based on general and genus-specific PCR amplification of the cpcB-cpcA, mcyA and mcyB genes. The genera of MC-producing cyanobacteria were differentiated by restriction fragment length polymorphism (RFLPs) analysis. Microcystis was identified as the predominant potential MC-producing genera. Analysis for MCs in passive sampling devices (PSDs) by liquid chromatography-mass spectroscopy (LC-MS) revealed 3 MC variants (MC-LR, -YR and -RR) at concentrations of 2.1 to 159.4 ng/g of PSD. MC-LR was the dominant variant which was detected in all study sites. This study has established that Microcystis was the predominant genotype and it may be the genus responsible for the production of the MCs detected in water. Results from this study showed that the RFLPs method was able to differentiate MC-producing from the non-MC-producing cyanobacteria in Mozambique.

Development of a chitosan-multi-walled carbon nanotubes composite for application in solid-phase adsorption toxin tracking of microcystins

“…To determine the potential of the composite to adsorb and desorb different congeners of MCs (MC-LR, RR and YR), we exposed SPATT samplers loaded with 0.2 g of the composite to 1 L of raw dam water with pH of 7.29 ± 0.71, EC of 878.67 ± 42.44 μS/cm and MCs with the following mean concentrations: MC-LR 25.14 ± 2.34; MC-YR 10.21 ± 0.41 and MC-RR 7.92 ± 0.10 µg/L. Similar congeners were (MC-LR, −YR and −RR), were reported by Pedro et al 23 when using passive sampling devices (PSDs) followed by LC-MS when monitoring the toxins in Southern Mozambique. Levels of MCs in the range 2.1-159.4 ng/g of PSDs reported by (23) were consistent to the levels reported here (Figure 7).…”

“…Similar congeners were (MC-LR, −YR and −RR), were reported by Pedro et al 23 when using passive sampling devices (PSDs) followed by LC-MS when monitoring the toxins in Southern Mozambique. Levels of MCs in the range 2.1-159.4 ng/g of PSDs reported by (23) were consistent to the levels reported here (Figure 7).…”