An exploration of microbial and associated functional diversity in the OMZ and non-OMZ areas in the Bay of Bengal

Abstract

Depletion of oxygen in certain marine areas creates oxygen minimum zones (OMZs), which can alter the species composition and abundance. We have carried out high-throughput 16S rRNA gene amplicon profiling from the Bay of Bengal (BOB) OMZ and non-OMZ areas. Typically, a total of 35 families of micro-organisms were identified as biomarkers for OMZ and non-OMZ regions in the BOB. Our analysis has identified families Pseudoalteromonadaceae, OM60 and Synechococcaceae to be abundant in oxygenated water, whereas organisms belonging to families Pelagibacteraceae and Caulobacteraceae, which are involved in sulphur and nitrogen metabolism, were prominent in the OMZ areas. Predictive functional analysis for these identified bacteria clearly that suggested an abundance of microbes with assimilatory sulphurreducing genes (cysl and csH) in the non-OMZ, while bacteria involved in dissimilatory sulphate reduction (known to carry aprA and aprB genes) were enriched in the OMZ areas. Comparative analysis with OMZ areas from Peru and Chile revealed that OMZ areas in the BOB are characterized by specific and distinctive bacterial diversity. Overall, the current analysis provides valuable documentation about the bacterial populations and their characteristics, which can generate pointers for their functional significance in the BOB.