Microbial diversity analysis and culturable antibiotic susceptibility profile of polyextremophilic bacteria from Tso Kar Hypersaline Lake, Ladakh, India

Polyextremophilic microorganisms can thrive in multiple extreme environments and are model microorganism in Astrobiology. Mars analogues site on Earth includes super-arid regions, sand dunes, hot springs, hypersaline lake and permafrost. In our study, we collected sample from sediment of Tso kar hypersaline lake (TKHSL) situated in high-altitude region of Ladakh, India and 16S rRNA gene based bacterial diversity analysis of lake showed the distinct diversity in terms of phylum, class, order, family and genus. We isolated bacteria from TKHSL and screened them by incubating under different lab-simulated extreme conditions [high salt concentration (10% NaCl), temperature (7 ℃ and 37 ℃), pH (5.5 and 7.2) and in combination]. Out of the 22 isolates, 3 isolates (TKHSL 4, TKHSL 5 and TKHSL 17) showed best growth response in polyextreme condition (polyextremophiles) and are identified with 16S rRNA gene sequencing. The 22 bacterial isolates are subjected for antibiotics susceptibility test against ampicillin, cefpodoxime, streptomycin and erythromycin. The study determined that Halomonas alkaliphila (TKHSL 4), Halomonas bluephagenesis (TKHSL 5) and Halomonas SSL3 (TKHSL 17) are resistant to ampicillin and streptomycin. Halomonas alkaliphila (TKHSL 4) is sensitive to erythromycin while Halomonas bluephagenesis (TKHSL 5) and Halomonas SSL3 (TKHSL 17) are resistant. All the polyextremophilic isolates were sensitive to cefpodoxime.