ENHANCING PROTEOLYTIC ACTIVITY OF LYSOBACTER ENZYMOGENES BY UV MUTAGENESIS

Background and Aim:Increasing the amount of protease enzymes from microbial sources is in the center of attention nowadays. Random mutagenesis is a cost effective procedure for reliable short-term strain improvement and is the method of choice. In this study, UV mutagenesis was done in order to achieve a mutant Lysobacter enzymogenes strain which shows higher production rate of protease enzyme.Methods:Random mutagenesis by UV radiation was performed at the distance of 20 cm from light source. The overnight cultures of Lysobacter enzymogenes were transferred to sterile Petri plates, which were exposed to UV light for 100, 150 and 200 seconds. Then the dilution of mutated bacteria was cultured in nutrient agar medium to obtain single colonies. The mutated isolates were randomly cultured from the nutrient agar medium to casein agar plate, as a selective media. Screening was performed by comparing the diameter of the halo zone in the skimmed milk agar plates of wild type with the mutated strains. Further, the protease activity of selected strains was quantitatively evaluated by Lowry method.Results:The results showed that UV radiation was not hampering the growth of the bacteria even in the 200 second exposure. After screening procedure we could find some mutated strains which showed a larger halo zone diameter and increased enzymatic activity compared to the wild-typed bacteria.Conclusion:Random mutagenesis by physical method (UV radiation) was a facile and effective way for increasing protease production in Lysobacter enzymogenes.

Keywords:

Lysobacter enzymogenes , proteolytic activity , random mutagenesis , ultraviolet radiation