Thermostable alkaline proteases of Bacillus licheniformis MIR 29: isolation,production and characterization |
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Authors: | M A Ferrero G R Castro C M Abate M D Baigorí F Siñeriz |
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Institution: | (1) Planta Piloto de Procesos Industriales Microbiológicos (PROIMI) MIRCEN-CONICET. Av. Belgrano y Pje. Caseros, 4000, S.M. de Tucumán, Argentina, Fax: 54 81 330087 E-mail: RNPROIMI@ACRIDE.EDU.AR, AR |
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Abstract: | Bacillus licheniformis MIR 29 has been isolated and produces extracellular proteases. It is able to grow at temperatures up to 60 °C and at pH values
up to 9.0. Casein was the best carbon source for production of a thermostable protease activity which, in some conditions,
is 90% extracellular. The synthesis of alkaline protease is not constitutive; different levels of production were found with
different carbon and nitrogen sources. Casein was thought to be an inducer of enzyme synthesis. The optimal pH and temperature
of the enzyme activity were 12 °C and 60 °C, respectively. The enzyme was stable up to 60 °C in the absence of stabilizers.
The protease activity was inhibited with phenylmethylsulphonyl fluoride, indicating a serine-protease activity. The proteolytic
activity was lowered by molecules present in the culture supernatant, which include amino acids and peptides, indicating end-product
inhibition. Electrophoresis assay on denaturating gels showed two bands with alkaline protease activity, in the 25 to 40-kDa
molecular mass range.
Received: 7 June 1995/Received revision: 14 September 1995/Accepted: 20 September 1995 |
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