Abstract
Abstract:
Background: Halophilic bacteria are studied extensively to explore molecular basis of adaptation, enzymatic potential, drug resistance and their other biotechnological implications. Their ability to survive in hypersaline condition is often linked to the potential of biosynthesizing a well-known compatible solute, namely ectoine.
Aim: In this study, four bacterial strains, which were previously identified from hypersaline environment were studied for their growth pattern and ectoine biosynthesis proteins expression under varying NaCl concentration. In addition, antibiotic susceptibility of the strains was also investigated.
Methods: The growth pattern of the bacterial strains were studied in LB broth supplemented with different NaCl concentration. Bradford method was employed for protein estimation, and optical densities of the samples were quantified through UV-Vis spectrophotometer. Moreover, expression of the ectoine proteins were detected through SDS-PAGE, and disc diffusion method was used for profiling the antibiotic resistance of the strains.
Results: The results indicated distinct growth patterns, with each strain demonstrating preferences for specific salinity levels. Notably, Staphylococcus cohnii strain F exhibited optimal growth at 10% NaCl, while Jeotgalicoccus huakuii strain 3.7 thrived at 15% NaCl. Total protein analysis revealed a consistent trend of decreasing protein content with rising NaCl concentrations, elucidating a potential adaptive strategy. Staphylococcus cohnii strain F stood out, maintaining higher protein levels at 20% NaCl, indicative of unique adaptive mechanisms. Antibiotic susceptibility testing uncovered diverse resistance profiles, emphasizing the strain-specific nature of responses. The expression of ectoine biosynthesis genes in Staphylococcus cohnii strain F underlines its adaptive advantage in high salinity.
Conclusion: The findings contribute not only to basic microbial physiology knowledge but also hold implications for biotechnological applications and clinical practices, emphasizing the importance of tailored approaches in antibiotic therapy and highlighting the strain-specific nature of bacterial adaptations.

Key words: Halophilic bacteria, Salinity, Protein expression, Antibiotic susceptibility