Optimization of cultural conditions for enhanced keratinase production by Bacillus cereus N14 obtained from the poultry farm of Himachal Pradesh (India)

Abstract

To enhance the keratinolytic potential of bacterial strain Bacillus cereus N14, isolated from poultry farm of Sundernagar, District Mandi, Himachal Pradesh, different process parameters like temperature, pH, incubation time, inoculum size, inoculum age etc. were optimized using One Variable at a Time (OVAT) approach and Response Surface Methodology (RSM). Bacillus cereus N14 showed maximum enzyme activity (19.5 U/mL) after 3rd day of incubation at 35°C, pH 9.0, 12.5 (%) of inoculum size using 3 days old culture and 2.5 and 2.0 per cent of maltose and yeast extract as best carbon and nitrogen source, respectively in the presence of Mn2+ as divalent metal ion and EDTA as best media additive. Central composite design (CCD) of RSM was successfully applied to investigate the effect of 5 independent variables viz., incubation time (days), inoculums size (%), inoculum age (days), concentration of carbon and nitrogen source (%) on keratinase production. The maximum enzyme activity (74.86 U/mL) was attained by the B. cereus N14 at 22nd run. The main highlight of the present study is that a significant increase of 27.5 per cent in keratinase production after optimizing different process parameters, by Bacillus cereus N14 was observed.