A study on the characterization of extracellular amylases producing from a Bacillus cereus isolate

Starch is a polymer of glucose linked to another one through the glycosidic bond. Starch hydrolysis is carried out by an enzyme in a moderate and specific condition .Amylases have potential application in a number of industrial processes such as food, fermentation and detergent industries. For commercial applications, amylase is mainly derived from the genus Bacillus. The aim of this study was to determinate the characterization of extracellular amylases producing Bacillus cereus. Soil samples were collected from agricultural and gardening area, in Borujen city. Bacterial isolates were screened for amylolytic properties by starch hydrolysis test on a starch agar plate. The isolate with a maximum zone of hydrolysis was identified by various staining and biochemical tests and molecular experiments. Times courses of cell growth, amylase production, was studied by Bacillus strain. Effect of pH on enzyme production was studied by adjusting the incubation at pH 6,7, 8, 9 and 10 and Similarly, effect of aeration speed and glucose concentration was studied by adjusting aeration speed 75, 100, 150, 200 rpm and glucose concentration0/5, 1, 2 (w/v) in the production medium. Enzyme production was studied in various media including NB, molasses and milk media. A bacterial strain identified as Bacillus cereus was isolated from the Borujen soil. Maximum enzyme production was achieved 7/04 U/ml after 72h cultivation in amylase production medium containing 1%starch as an inducer. In this study maximum enzyme production was 7/412 U/ml in pH=8 and aeration speed 200 rpm after 72h. Bacillus cereus showed the highest enzyme activity in beet molasses the amount 4/89 U/ml. Due to the characterization, this isolate and amylase enzyme production by Bacillus cereus can be introduced as a candidate to produce the favorite amount of the enzyme.

کلیدواژه ها:

Amylase enzyme ، Bacillus cereus ، Culture medium