Bacterial Degradation of Microcystin

Abstract

Cyanobacteria exist under a variety of climatic, nutrient and physical conditions, and are likely to form blooms. This distinct group of bacteria is photosynthetic and produce several metabolites that include a number of endotoxins, of which are commonly found in mass occurrences of cyanobacteria, especially under eutrophic conditions. Microcystins (MCs) are well-studied cyanobacterial cyclic hepatopeptide heapatotoxins predominantly produced by freshwater cyanobacteria, including species of Microcystis, Anabaena, Nostoc and Planktothrix. Potential chronic toxicity from MC led the WHO to establish a guideline value of 1 μg l–1 as a maximum concentration of MC-LR in drinking water. Additional concern regarding the importance of cyanotoxins, is reflected by their inclusion in the US Environmental Protection Agency (USEPA) drinking water contaminant list and in major reviews along with chemical warfare agents. Furthermore, MC-LR was classified as a possible human carcinogen (group 2B). However, only very less data on the occurrence of microbial degradation of MC are available in the world.