Metabarcoding of Bacterial Communities Impacting the Dynamics of Cyanobacterial Blooms in Freshwater Reservoirs, South India

Cyanobacterial harmful algal blooms (CyanoHABs) represent a significant threat to freshwater ecosystems globally. To investigate the bacterial communities associated with these blooms, we conducted a metabarcoding analysis of water samples collected during the blooming events in various freshwater reservoirs, including Veeranam, Wellington, Perumal lake at Cuddalore and Trichy Kottapattu Pond, Tamil Nadu, India. Utilizing Metabarcoding of 16S rRNA amplicon sequencing, we characterized the taxonomic composition of bacterial communities in freshwater reservoirs. Our study revealed the dominance of key phyla such as Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria across all four freshwater reservoirs. Predominantly, the abundance of cyanobacterial genera, notably toxin-producing Microcystis sp. and Nostoc sp., were identified, which played a crucial role in driving cyanobacterial bloom formation. Multifaceted interactions between bacteria and cyanobacteria, including core microbiomes and beta diversity patterns, shed light on the microbial dynamics underlying CyanoHABs. This provides a comprehensive understanding of freshwater reservoir Cyanobacterial dynamics, highlighting the bacterial communities involved in bloom events. These findings are crucial for protecting freshwater ecosystems and public health from the harmful effects of cyanobacterial blooms.