Optimization of Culture Conditions for Protease Production using Three Strains of Bacillus

Abstract

The aim of this work was to determine the effect of a few external factors on bacterial growth and the production of enzymes with a proteolytic effect in three strains of Bacillus: CMS5 (Bacillus subtilis), CMS4 (Bacillus sp.) and SPo5 14′ (Bacillus velenzensis) isolated from squashes packed in traditionally prepared cassava leaves, but also to determine the best source of carbon and nitrogen. All three strains have the ability to actively degrade milk casein. The strains were grown in Luria Bertani medium and the suspension from the cell culture was used to measure optical density and demonstrate enzyme activity on a petri dish containing skim milk. Several parameters were verified including the influence of temperature, pH, and carbon and nitrogen source on growth and enzyme production. Growth was possible from 25 to 60°C with an optimal temperature of 30°C after 24 hours. Enzyme production was observed from 25 to 55°C with an optimum at 37°C. For pH, growth and enzyme production was possible from pH 5.7 and 9 with an optimum of 7 in all three strains. Among the sources of carbons used, galactose is the best source for growth after 24 h in all three strains, and starch for production. Among nitrogen sources, Bacto-peptone is best for growth as well as production.

Keywords

• optimization
• production
• protease
• strain
• bacillus