Comparison of bacterial communities from the surface and adjacent bottom layers water of Billings reservoir

Here, we describe the microbial diversity and physicochemical properties in freshwater samples from the surface and bottom layer of Billings reservoir in Sao Paulo state, Brazil. Twenty-two matched samples were characterized using the 16S rRNA gene Illumina MiSeq platform. Taxonomical composition revealed an abundance of Cyanobacteria phyla, followed by Proteobacteria, with 1903 and 2689 known bacterial genera in the surface and deep-water layers, respectively. Shannon diversity index ranging from 2.3 - 5.39 and 4.04 - 6.86 in the surface and bottom layer, respectively. Among the 120 pathogenic genera identified, Flavobacterium was the most predominant genus. Temperature and phosphorus concentration were the most influential factors in shaping the microbial communities of both layers. Predictive functional analysis suggests that the reservoir is enriched in motility genes involved in the flagellar assembly. The overall results present new information on the significantly altered diversity composition of the bacterial community detected in Billings freshwater reservoir. IMPORTANCEIn this study, we investigated the bacterial distribution, community composition, potential metabolic activity, potentially pathogenic bacteria, and toxin genes of Cyanobacteria in the bottom layers and surface along Billings reservoir in the southeast of Brazi. Our results provide essential information about the pattern of bacterioplankton communities variation inhabiting the Billings reservoir and the combination of environmental that shaped their structure. These results may help pave the way for future studies devoted to control and improve the water quality in the Billings reservoir, which is facing rapid urban development and urbanization.