Effect of Culture Conditions on the Production of an Extracellular Protease by Bacillus sp. Isolated from Soil Sample of Lavizan Jungle Park

Abstract

Soil samples of Tehran jungle parks were screened for proteolytic Bacilli. Among eighteen protease producers one of the isolates obtained from Lavizan park, in north east of Tehran, was selected for further experimental studies. This isolate was identified as Bacillus sp. strain CR-179 based on partial sequencing of 16S rRNA. Various nutritional and environmental parameters affected protease production by Bacillus sp. strain CR-179. Protease production by this Bacillus cultivated in liquid cultures reached a maximum at 24 h, with levels of 340.908 U/mL. Starch and maltose were the best substrates for enzyme production while some pure sugars such as fructose, glucose, and sucrose could not influence production of protease. Among various organic nitrogen sources corn steep liquor, which is commercial, was found as the best substrate followed by yeast extract, whey protein, and beef extract. The optimal pH and optimal temperature of enzyme production were 8.0 and 45°C, respectively. Studies on enzymatic characterization revealed that crude protease showed maximum activity at pH 9.0 and 60°C, which is indicating the enzyme to be thermoalkaline protease.