Secretion of an alkaline protease from a salt- tolerant and alkaliphilic, Streptomyces clavuligerus strain Mit-1

Abstract

An alkaliphilic and salt- tolerant actinomycete, Streptomyces clavuligerus strain Mit-1, was isolated from Mithapur, the western coast of India. The organism was Gram-positive, having filamentous, long thread like structure. The sporulation started after two days of growth and the optimum level of alkaline protease (130 U/ml) was produced during the early stationary phase. The strain could grow and produce protease with 0-10% NaCl (w/v), the optimum being 5% NaCl (w/v). Growth and protease production was optimum at pH 9 with substantial decline at neutral pH. Sucrose and gelatin were the best carbon and nitrogen sources respectively, whereas gelatin broth was the preferred medium for protease production. Mit-1 produced substantial protease with various amino acids, when employed as the sole nitrogen sources. Crude substrates, such as molasses, whey and wheat flour had significant effect on enzyme production. The results are quite valuable, as only few actinomycetes, particularly salt-tolerant alkaliphilic ones, have so far been explored for their enzymatic potential and process optimization.