Impact of cyanobacterial bloom on microbiomes of freshwater lakes

Cyanobacterial blooms are harmful because of their cyanotoxins production. It occurs due to the eutrophication of freshwater reserves. Nagpur city has three lakes which serves as public water resource and are affected by algal bloom events. Metagenomic approach was used for the exploration of taxonomic, catabolic, and resistome profile of these lakes. Taxonomic profiling indicated prevalence of cyanobacterial species like Microcystis, Anabaena, Trichodesmium, Microcoleus, and Nodularia. These bacteria are well known for their association with algal bloom and microcystin production. High Performance Liquid Chromatography (HPLC) detected the presence of microcystin toxin and concentration was relatively higher in Ambazari lakewater. In addition, the presence of several antibiotic resistance genes like vancomycin, beta-lactamase, methicillin, and fluoroquinolones were observed. Genes conferring metal resistance such as copper, cadmium, zinc were also mined indicating presence of metal resistant microorganisms. The study suggests that lake water contaminated with Microcystis (algal bloom) harbors complex microbial community having diverse catabolic and resistome profiles, which negatively affect the ecosystems services.