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.

Key words: Cyanobacteria, microcystins, Mozambique, PCR, RFLP.