Temperate hyper-saline ecosystems induce spatial distribution and halo-thermotolerance potential in indigenous cultivable bacterial community

Extreme environmental conditions like high salinity and temperature are continuously affecting fertile lands and trigger an ecological imbalance, thereby inducing indigenous microbial communities for adaptation to such extreme environments. Present study relates with the isolation and characterization of halo-thermotolerant bacteria (HTTB) from hyper-saline areas of districts Kashmore and Khairpur, Sindh, Pakistan. The isolated bacteria were initially screened for their tolerance to elevated salt concentrations and extreme temperature ranges. Out of twenty-six bacterial isolates, six bacteria from district Kashmore (60%) and thirteen bacterial isolates from district Khairpur (81.25%) tolerated NaCl concentration up to 15-17% (w/v), and grown efficiently when incubated in the temperature ranges 55-65 degrees C. The principle component and multivariate cluster analyses revealed three different clusters of HTTB bacteria based on their tolerance and spatial distribution. In general, the hyper-saline environments of district Kashmore harbored more HTTB than Khairpur, but individually there was extreme halotolerance and thermotolerance among Khairpur isolates. Finally, the PCR-based molecular typing of 16S rRNA genes revealed, majority of the isolates were identified to be various strains of genus Bacillus, i.e., Bacillus subtilis, B. licheniformis, B. aerius, B. vallismortis, B. aquimaris and B. flexus. Only one bacterial strain, i.e., KJ1WB, was identified as Pseudomonas pseudoalcaligenes. These HTTB bacterial strains may extend significant potential for future applications like environmental, biotechnological and enormous industrial due to their valuable enzymatic profiles and metabolite repositories.

Automated summary

In this study, halo-thermotolerant bacteria (HTTB) were isolated and characterized from hyper-saline areas of Kashmore and Khairpur districts in Sindh, Pakistan. The isolated bacteria were screened for their tolerance to elevated salt concentrations and extreme temperatures, and multiple clusters of HTTB were identified based on their tolerance and spatial distribution. Majority of the isolates were identified as various strains of the genus Bacillus, with only one strain identified as Pseudomonas pseudoalcaligenes. These HTTB bacterial strains have potential applications in environmental, biotechnological, and industrial fields due to their valuable enzymatic profiles and metabolite repositories.