Wild strain of Bacillus cereus and Bacillus polymixa in alkaline protease synthesis, isolated from the soils of Isfahan (Iran)

Abstract

fter amylases, proteases are the most useful industrial enzymes that are produced 500 tones annually.
In industry, proteases are produced from bacteria and fungi. The alkaline proteases, with an optimum
activity in pH: 9 - 11, have numerous applications in daily life of peoples such as food complementary of
beast and poultry, confectionary, bakery, fermentation industries, leathering, detergent industry,
biotransformation and so on. In this research a wild strain of Bacillus cereus and Bacillus polymixa,
isolated from the soils of Isfahan (Iran), showed the best alkaline protease activity in industrial mediums
such as sweet sorghum extract and molasses. The maximum alkaline protease activity in productive
culture mediums after 72 h in 30°C and with100 R.P.M. were measured. The results with B. polymixa
were 46.7 (u/ml) in T.S.B, 57 (u/ml) in N.B, 60.22 (u/ml) in peptone solution, 67 (u/ml) in sweet sorghum
solution, 216 (u/ml) in yeast extract solution, 358 (u/ml) in glucose solution, 413 (u/ml) in casamino acid
solution, 418 (u/ml) in whey, 470.5 (u/ml) in casein solution, 490.5 (u/ml) in molasses, 525 (u/ml) in sweet
sorghum extract and 580.5 (u/ml) in milk and with B. cereus were 34.72 (u/ml) in T.S.B, 39.85 (u/ml) in
N.B, 39.1 (u/ml) in peptone solution, 58 (u/ml) in sweet sorghum solution, 200.65 (u/ml) in yeast extract
solution, 363 (u/ml) in glucose solution, 191.5 (u/ml) in casamino acid solution, 302.5 (u/ml) in whey,
455.5 (u/ml) in casein solution, 485.5 (u/ml) in molasses, 510.5 (u/ml) in sweet sorghum extract and 535.5
(u/ml) in milk. The fixation experiments with alkaline protease from B. polymixa showed that this enzyme
after 3 month in sawdust, perlit and silica has protected its stability and has 50, 100 and 100% of its
primary activity respectively. In the case of immobilization with the same enzyme and the same
bacterium, the examinations showed that the alkaline protease activity on perlit after one, two and three
washing treatment were 52, 30 and 20% of its primary activity but in the case of silica were 93, 90 and
84% of its primary activity