Effects of Some Cultural Conditions on Keratinase Production by Bacillus licheniformis Strain NBRC 14206

Abstract

Effects of Some Cultural Conditions on Keratinase Production by Bacillus licheniformis Strain NBRC 14206 Aims: Microbial keratinase is an extracellular enzyme capable of degrading keratin present in feathers, hair, and wool. They are widely used in chemical, medical industries as well as in animal feed industry and basic biological science. This study investigated the isolation and effects of some cultural conditions on keratinase production by Bacillus licheniformis strain NBRC 14206 using raw feather. Study Design: One-factor-at-a-time strategy was adopted to evaluate the effects of some fermentation conditions on keratinase production. Place and Duration of Study: Department of Microbiology, Faculty of Science, University of Port Harcourt, Nigeria, between September 2015 and June 2016. Methodology: A total of twenty (20) bacterial isolates were isolated from three (3) feather dumping sites. Out of the 20 isolates screened, only one isolate with the highest zone of inhibition was selected. The isolate was morphologically and biochemically characterized based on Bergey’s manual of determinative bacteriology flowchart as well as molecular analysis. In order to improve keratinase production by the selected isolate, culture medium and the effect of environmental parameters were individually screened and optimized using one-factor-at-a-time methodology. The following cultural parameters: pH, temperature, nitrogen sources, local carbon sources, carbon sources, substrate concentration and incubation time were evaluated for the production of keratinase by the bacterium. Results: The highest keratinase producing bacteria, isolate KDB1 was found to belong to the genus Bacillus. The highest enzyme production was obtained at 72 h after incubation. The optimum pH and temperature for the production of keratinase by the bacterium were pH 9.0 and 40°C, respectively. The best carbon, local carbon and nitrogen sources were lactose, corn stalk and yeast extract at concentration of 1%, respectively. The highest activity was observed at 1% feather concentration. Conclusion: Result obtained from this study showed that keratinase produced from isolate KDB1 could be useful in decomposition of keratin-waste (feather) and could find application in leather, pharmaceutical and cosmetics industries as well.