PRODUCTION AND CHARACTERIZATION OF AN EXTRACELLULAR HA-LO-ALKALINE PROTEASE PRODUCED BY Bacillus ISOLATES FROM FESEEKH (Mujil auratus) PRODUCTS

Document Type : Original Article

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Department of Agricultural Microbiology, Faculty of Agriculture, Ain Shams Univ., Shobra El-Kheima Cairo, Egypt

Abstract

Ninety five isolates were collected from com-mercially and laboratory manufactured feseekh products and tested for protease production on standard skim milk agar and gelatin media sup-plemented with 15% NaCl salt. They were identi-fied to be Bacillus isolates. Out of the 95 isolates, three Bacillus isolates (11pb, 14pb, 13pb) were selected based on their highest protease produc-tion. Five media were tested for select the most suitable medium for production by the three above isolates. Fish by-product medium gave the highest protease production by the three isolates, reaching 126.5, 136.5, 147.5 u/ml by 11pb, 14pb, 13pb, respectively. These levels were obtained between late logarithmic growth phase and beginning of stationary phase for the isolates. The highest Pro-tease production was obtained at pH 8, tempera-ture 30C and NaCl concentration 5%, the enzyme was stable at temperature ranged between 60 and 65C during the period tested (1h) and the prote-ase was optimally active at pH 10 and 60C. The enzyme was stable for 10 days at 30 C during the period tested (1 month) where it lost 10 % of its activity after 20 days while lost 85% of its activity after 30 days of storage at 30C. These properties make the enzyme suitable for detergent industry.

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