The biotechnological potential of subtilisin‐like fibrinolytic enzyme from a newly isolated Lactobacillus plantarum KSK‐II in blood destaining and antimicrobials

An antimicrobial oxidative‐ and SDS‐stable fibrinolytic alkaline protease designated as KSK‐II was produced by Lactobacillus plantarum KSK‐II isolated from kishk , a traditional Egyptian food. Maximum enzyme productivity was obtained in medium containing 1% lactose and 0.5% soybean flour as carbon and nitrogen sources, respectively. Purification of enzyme increased its specific activity to 1,140‐fold with a recovery of 33% and molecular weight of 43.6 kDa. Enzyme activity was totally lost in the presence of ethylenediaminetetraacetic acid and was restored after addition of Fe 2+ suggesting that KSK‐II is a metalloprotease and Fe 2+ acts as cofactor. Enzyme hydrolyzed not only the natural proteins but also synthetic substrates, particularly Suc‐Ala‐Ala‐Pro‐Phe‐pNA. KSK‐II can hydrolyze the Lys‐X easier than Arg‐X; thus, it was considered as a subtilisin‐family protease. Its apparent K m , V max , and K cat were 0.41 mM, 6.4 µmol mg −1 min −1 , and 28.0 s −1 , respectively. KSK‐II is industrially important from the perspectives of its maximal activity at 50°C (stable up to 70°C), ability to function at alkaline pH (10.0), stability at broad pH ranges (7.5–12.0) in addition to its stability toward SDS, H 2 O 2 , organic solvents, and detergents. We emphasize for the first time the potential of fibrinolytic activity for alkaline proteases used in detergents especially in blood destaining. © 2014 American Institute of Chemical Engineers Biotechnol. Prog. , 31:316–324, 2015