Production of Extracellular Halo-alkaline Protease from a Newly Isolated Haloalkaliphilic Bacillus sp. Isolated from Seawater in Western India

摘要

Haloalkaliphilic, gram positive, aerobic, coccoid Bacillus sp. Po2 was isolated from a seawater sample in Gujarat, India. On the basis of 16s rRNA gene homology, Po2 was 95% related to Bacillus pseudofirmus. A substantial level of extracellular alkaline protease was produced by Po2, which corresponded with the growth and reached a maximum level (264 U/ml) during the stationary phase at 24 h. The production thereafter remained nearly static at optimal level till 36 h. Po2 could grow in the range of 0-20% NaCl (w/v) and pH 7-9, optimally at 10% NaCl (w/v) and pH 8. The protease production was salt-dependent and optimum production required 15% NaCl (w/v) and pH 8. Among the organic nitrogen sources, optimum growth and protease production (260 U/ml) were supported by the combination of peptone and yeast extract. However, growth and protease production were highly suppressed by the inorganic nitrogen sources used; with the exception of potassium nitrate, which supported both growth and protease production to limited extent (24 U/ml). Strong inhibition of enzyme production was observed at above 1% glucose (w/v). Wheat flour served as both carbon and nitrogen source supporting growth and protease production.