SCREENING AND ISOLATION OF AN ORGANIC-SOLVENT TOLERANT ALKALOPHILIC PROTEASE PRODUCER BACILLUS SP.

Background and Aim:Among the microbial enzymes, Bacillus proteases have attracted much attention due to their potential uses in various fields, including the pharmaceutical, food, leather, textile and so on.Methods:In this study, Bacillus sp. was isolated from the Dehloran hot springs in Ilam, Iran. It was grown in Luria–Bertani (LB) medium enriched with cyclohexane and toluene. After autoclaving, toluene and cyclohexane were added to this medium at a final concentration of 10% and 30%(v/v), respectively. Covered flasks were incubated for 48 hours at 37 °C and shaked at 120 rpm. Repeated cultures were carried out several times in the mentioned environment with the same organic solvents concentration. The desired protease activity was determined from clear zone diameter around the colonies grown onto Skim milk agar-plates (SMA) medium. Then, a strain with high protease activity was selected and inoculated to the liquid medium of the protease production at 10% (v/v) concentration from pre-culture medium and it was incubated for 48 hours at 37 °C and 120 rpm. The isolated strain was identified as Bacillus strain based on the phenotypic characteristics and phylogenetic analysis of the 16S rDNA sequence. For bacterial growth optimization, isolate was incubated at different temperatures, pH and times, and protease activity was assayed.Results:Result showed that optimal condition for bacterial growth to produce the highest amount of protease was at temperature 37 ° C, pH 9 and 72 hours incubation.Conclusion:Considering these properties, this Bacillus sp. is a promising protease producer strain that has the potential to be used in laundry detergents and biotechnology applications.

کلیدواژه ها:

Screening ، Microorganisms ، Organic solvent ، Protease ، Bacillus sp