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

34Mechanisms of occurrence and expressions of antibiotic resistance genes (ARGs) in 35 thermophilic bacteria are still unknown owing to limited research and data. The evolution and 36 proliferation of ARGs in the thermophilic bacteria is unclear and needs a comprehensive study. 37 In this research, comparative profiling of antibiotic resistance genes and metal tolerance genes 38 among the thermophilic bacteria has been done by culture-independent functional metagenomic 39 methods. Metagenomic analysis showed the dominance of Proteobacteria, Actinobacteria. 40 Firmicutes and Bacteroidetes in these hot springs. ARG analysis through shotgun gene 41 sequencing was found to be negative in case of thermophilic bacteria. However, few of genes 42 were detected but they were showing maximum similarity with mesophilic bacteria. 43Concurrently, metal resistance genes were also detected in the metagenome sequence of hot 44 springs. Detection of metal resistance gene and absence of ARG's investigated by whole genome 45 sequencing, in the reference genome sequence of thermophilic Geobacillus also conveyed the 46 same message. This evolutionary selection of metal resistance over antibiotic genes may have 47 been necessary to survive in the geological craters which are full of different metals from earth 48 sediments rather than antibiotics. Furthermore, the selection could be environment driven 49 depending on the susceptibility of ARG's in thermophilic environment as it reduces the chances 50 of horizontal gene transfer. With these findings this article highlights many theories and 51 culminates different scopes to study these aspects in thermophiles. 52 53 54 55 56 58The generic term "antibiotic" is used to denote any class of chemotherapeutic agents that inhibits 59 or kills microbes (pathogens) by specific interactions with microbial targets [1]. However, the 60 increasing rate of antibiotic resistance in microorganisms is a critical challenge to public health 61 [2-4]. The spread of antibiotic-resistant superbug is posing a threat to morbidity and mortality 62 worldwide [5]. The potential clinical threat of antibiotic-resistant bacteria has abled to gain 63 attention with a focus on the identification and management of environmental reservoirs of 64 antibiotic resistance genes (ARGs). Though antibiotic resistance occurs naturally, human activity 65 including misuse or overuse of antibiotics has exacerbated the scenario. Pathogenic and non-66 pathogenic bacteria belonging to the mesophilic world has been extensively studied in terms of 67 antibiotic resistance. However, researchers have paid very less attention to antibiotic resistance 68 in thermophilic bacteria. The distribution of ARGs and their antibiotic resistance profile needs 69 attention to avert the possible emergence of an opportunistic pathogen of thermophilic origin. 70 Extensive application of thermophilic bacteria in biotechnological and industrial fields also 71 supports the possibility of future pathogenic emergence with high antibiotic resistan...

Metagenomics revealing molecular profiling of community structure and metabolic pathways in natural hot springs of the Sikkim Himalaya

“…The abundance of both the phyla is reported to be positively correlated in thermal springs [ 27 ]. However, in this study, the relatively reduced presence of cyanobacterial species was noted in Polok and Reshi, which was similar to the earlier studies on metagenomics of thermal aquatic habitats of this region [ 11 , 28 ]. This signifies that the growth of cyanobacteria could be influenced by some other geochemical factors in these sites, which need to be further investigated.…”

“…Thus, Polok habitat, with the higher side of the temperature (60 °C), is suitable for supporting the growth of thermophiles or hyperthermophiles from Aquificae and Thermotogae. A similar observation has been made in a previous metagenomic investigation on the hot water sites of this temperature range [ 11 , 28 , 29 ].…”