Diversity analysis and metagenomic insights into the Antibiotic Resistance and Metal Resistances among Hot Spring Bacteriobiome- insinuating inherent environmental baseline levels of Antibiotic and Metal tolerance

Abstract

Mechanisms of occurrence and expressions of antibiotic resistance genes (ARGs) in thermophilic bacteria are still unknown owing to limited research and data. The evolution and proliferation of ARGs in the thermophilic bacteria is unclear and needs a comprehensive study. In this research, comparative profiling of antibiotic resistance genes and metal tolerance genes among the thermophilic bacteria has been done by culture-independent functional metagenomic methods. Metagenomic analysis showed the dominance of Proteobacteria, Actinobacteria. Firmicutes and Bacteroidetes in these hot springs. ARG analysis through shotgun gene sequencing was found to be negative in case of thermophilic bacteria. However, few of genes were detected but they were showing maximum similarity with mesophilic bacteria. Concurrently, metal resistance genes were also detected in the metagenome sequence of hot springs. Detection of metal resistance gene and absence of ARGs investigated by whole genome sequencing, in the reference genome sequence of thermophilic Geobacillus also conveyed the same message. This evolutionary selection of metal resistance over antibiotic genes may have been necessary to survive in the geological craters which are full of different metals from earth sediments rather than antibiotics. Furthermore, the selection could be environment driven depending on the susceptibility of ARGs in thermophilic environment as it reduces the chances of horizontal gene transfer. With these findings this article highlights many theories and culminates different scopes to study these aspects in thermophiles.