Preliminary Isolation and Characterization of Halotolerant and Halophilic Bacteria from Salt Mines of Karak, Pakistan

Halophiles are extremophile organisms that thrive in environments with very high concentrations of salt. The salt mines of Karak region, is an extremely saline environment and its microbial communities have not yet been explored. In the present study, twenty one halotolerant and halophilic bacterial strains were isolated from salt mines of Karak region. These strains can grow in media with 5-40% NaCl concentrations. Morphological, physiological and biochemical characteristics of these strains were studied by optimizing their growth conditions such as pH, NaCl and temperature. A high microbial density was observed at low NaCl concentration. Halophilic bacterial strains were divided into three groups on the basis of NaCl concentration; first was slightly halotolerant / halophilic; second, moderately halophilic and third, extreme halophilic bacteria. The phylogenetic analyses inferred from 16S rRNA gene sequence of these strains demonstrated that these are closely related to species belonging to different genera: Thalassobacillus, Halomonas, Brevibacterium, Oceanobacillus, Terribacillus, Pseudomonas, Bacillus, Enterobacter, Halobacillus, Staphylococcus and Virgibacillus. This preliminary study showed that the salt mine of Karak are rich in halotolerant / halophilic bacterial population with diverse bacterial communities, which may be utilized in various industrial applications.