Bacterial Diversity in the Metal-Rich Terrestrial Deep Subsurface Sediments of Krishna Godavari Basin, India

Abstract

Krishna Godavari (KG) basin, located in the eastern continental margin of India, is a geological region well known for the abundance of economically important minerals. However, less is known about the microbial ecology of its subsurface sediments. The present study is the first report on the comprehensive culture-independent census of bacterial communities of deep subsurface of KG basin and their relationship with the geochemical environment. Elemental and mineralogical characterization of the sediments highlighted the presence of carbon and nitrogen deprived conditions along with the abundance of metalliferous minerals, especially rich in valuable elements like zirconium, vanadium, cesium, and rare earth elements. Diversity analysis based on Illumina MiSeq high-throughput sequencing platform revealed the predominance of Firmicutes (44.24%), Proteobacteria (34.17%), Bacteroidetes (15.18%), and Actinobacteria (3.81%) in the deep subsurface of this basin. ‘Abundant’ and ‘rare’ sub-communities analysis indicated that a large number of phyla like Acidobacteria, Armatimonadetes, Chloroflexi, and Deinococcus-Thermus were exclusively present as a rare community. Statistical analyses demonstrated that geochemical parameters, especially depth, pH, and metal content, showed significant influence on the microbial community structure. The present study should help future investigations for microbial mediated sustainable utilization of mineral-rich sediments of the region.