Molecular characterization and growth optimization of halo-tolerant protease producing Bacillus Subtilis Strain BLK-1.5 isolated from salt mines of Karak, Pakistan

Abstract

Microbial proteolytic enzyme is one of the most important industrial enzymes that hydrolyze proteins. The applications of proteases under harsh industrial conditions like alkalinity, salinity, and temperature make them inactive and unstable. This suggests need for search for novel microbial sources for protease production having diverse properties. For this purpose, 54 bacterial strains were isolated from different salt mines of Karak, Pakistan and were investigated for their proteolytic activity on skim milk agar plates. The strain which showed maximum protease activity was characterized by 16S rRNA gene sequence analysis. Furthermore, growth and protease production was optimized for the characterized bacteria under different physical factors, i.e., pH, temperature and salinity. The isolate BLK-1.5 exhibited strong protease production and was identified as Bacillus subtilis based on biochemical characteristics and 16S rRNA gene sequence analysis. Maximum production of protease was recorded at pH 10, 37 °C and 7 % (w/v) NaCl. Molecular weight of proteases was estimated 38 kDa and its optimum activity was observed at pH 10, 50 °C and 2 % (w/v) NaCl. In conclusion, the protease produced by halo-tolerant Bacillus subtilis strain BLK-1.5 has diverse characteristics and could be useful in various industrial applications.

Detergent‐Compatible Robust Alkaline Protease from Newly Isolated Halotolerant Salinicoccus sp. UN‐12

“…The optimum temperature of the studied protease was higher than those previously reported for proteases from halophilic/halotolerant bacteria [15,18,[22][23][24]. The outcomes related to the enhancement of protease activity in the presence of calcium ions are in agreement with former reports on the thermal stability of temperature-sensitive proteases by the addition of Ca 2?…”

“…[15], Bacillus sp. NPST-AK15 [17], Bacillus subtilis BLK-1.5 [18], and Bacillus iranensis (X5B) [19]. On the contrary, the protease obtained from moderately halophilic Virgibacillus sp.…”

Molecular characterization and growth optimization of halo-tolerant amylase producing bacteria isolated from salt mines of Karak, Pakistan

“…These results showed that the most favorable temperature for growth of the isolate JIK-1.10 and SBA-5 was 37 0 C. The isolate BKH-A showed maximum growth (0.663OD) as well as maximum amylase production (43.81 µg/ml) at 37 0 C ( Figure 5C). Further raise in temperature reduced the enzyme production as well as growth of the isolate BKH-A, so it was found that the optimum temperature for the growth and amylase production of the different strains of Bacillus Subtilis is 37 0 C. This temperature is also reported the optimum temperature for the growth of Bacillus Subtilis [8,14]. In this study, the effect of pH and temperature on the amylase production is varied with that of bacterial growth.…”

“…There are different reports from Pakistan about the importance of extremophiles. The author has also reported the protease producing bacteria and its commercial importance [8].…”

Kinetics of Halophilic Enzymes

“…This interest is due to their capacity to efficiently catalyze a process and show optimal activities at different salt concentrations. Halophiles are the most probable source of extremozymes, since they are also capable of tolerating alkaline pH and high temperatures, as reported by several authors [68][69][70][71][72][73][74][75][76][77][78][79].…”