Production and Properies of Protease Produced by Thermotolerant Bacteria Isolated from the Thai Fish Sauce Fermentation Process(Thai)

Abstract

Proteolytic bacteria were isolated from a fermented broth of Thai fish sauce. The highest protease production was found in mM73 liquid medium cultured with the isolate S2-1 (identified as Bacillus megaterium) at 45 o C, pH 9 for 24 h. The study of protease characterization and activity indicated that B. megaterium produced alkaline protease under optimum pH and temperature of pH 9 and 55 o C, respectively. This protease was stable in the pH and temperature ranges of 7 to 10 and 30 to 50 o C, respectively, resulting in relative activity of higher than 80%. A strong inhibitor was diisopropyl fluorophosphate which protease activity was decreased 95% (relative activity of 5%). Metal ions inhibiting protease activity were Cd2+, Cu2+, Cu3+, Hg2+ and Zn2+, while Mn2+and Ca2+ enhanced protease activity.