Optimization of keratinase production by a native isolate, Bacillus sp FUM120, using one factor at a time methodology

Nowadays, demand for Keratinase enzyme with the industrial application is increasing due to the extensive use of this enzyme in various fields including, animal feed, leather industry, water treatment, medicine, and pharmacy. In the present study, Keratinase production was examined and optimized in FUM120 Keratinolytic strain isolated from a poultry farm in Mashhad. Using of Azokeratin substrate, it was determined that the isolate produces the most in the 72nd hours of its growth with the amount of 49.965 U/ml. Then, In order to increase the production of keratinase, the single-variable optimization of parameters, temperature, pH, substrate concentration, extra carbon and nitrogen sources, inoculum size and aeration rates were done and it was determined that pH:10.5 and 0.6% concentration of ammonium chloride, as an additional source of nitrogen, at 37 °C had a significant effect on keratinolytic activity and increased the enzyme production by more than 2 times. In addition, the isolate was able to produce the high level of enzyme in the presence of 50% aeration without the addition of carbon source. Finally, enzyme production reached to 117/45 U/ml and the enzyme unit showed an increase of 2.34 fold compared to the beginning of the optimization. The morphological studies and the gene sequence of 16SrRNA determined that FUM120 belongs to the genus Bacillus and shows 100 % similarity to Bacillus pumilus ATCC 7061.