Enhancement of alkaline protease production by <i>Bacillus clausii</i> using Taguchi experimental design

Abstract

The effect of culture conditions on protease production and bacterial growth of Bacillus clausii was investigated using Taguchi design of experiment. Five factors viz., carbon source, organic and
inorganic nitrogen sources, agitation and metal ion, each at four levels were selected and an orthogonal array layout of L16 (45) were performed. The proposed medium for alkaline protease production
consisted of (g/l): sucrose, 10; yeast extract, 10; KNO3, 5; trace element without Mn2+. Under these optimal conditions, 4 fold enhancement in protease production (from 250 to 1000 U/ml) was obtained. At the optimum culture for bacterial growth, which contained (g/l): starch, 10; yeast extract, 10; ammonium ions, 5; trace element without Zn2+, 1.88 fold increase in growth production (from OD600 nm of about 8.5 in basal medium to OD600 nm of 16 in optimized medium) were observed. The inorganic nitrogen source was the most significant factor on protease production with 57.75% contribution. The organic nitrogen and carbon sources by 35.28 and 34.93% contributions were prominent factors in bacterial growth.