THERMOSTABLE ALKALINE PROTEASES OF BACILLUS-LICHENIFORMIS MIR-29 - ISOLATION, PRODUCTION AND CHARACTERIZATION

Bacillus licheniformis MIR 29 has been isolated and produces extracell ular proteases. It is able to grow at temperatures up to 60 degrees C and at pH values up to 9.0, Casein was the best carbon source for prod uction of a thermostable protease activity which, in some conditions, is 90% extracellular. The synthesis of alkaline protease is not consti tutive; different levels of production were found with different carbo n and nitrogen sources, Casein was thought to be an inducer of enzyme synthesis, The optimal pH and temperature of the enzyme activity were 12 degrees C and 60 degrees C, respectively, The enzyme was stable up to 60 degrees C in the absence of stabilizers. The protease activity w as inhibited with phenylmethylsulphonyl fluoride, indicating a serine- protease activity, The proteolytic activity was lowered by molecules p resent in the culture supernatant, which include amino acids and pepti des, indicating end-product inhibition, Electrophoresis assay on denat urating gels showed two bands with alkaline protease activity, in the 25 to 40-kDa molecular mass range.