Applying the mutation of Bacillus subtilis and the optimization of feather fermentation medium to improve Keratinase activity

Abstract

Energetic Bacillus subtilis was preliminarily isolated from feather meal selection medium experiment, which could be used to produce Keratinase. Through using the ultraviolet ray produced by ultraviolet light and the compound mutation of sodium nitrite solution, a mutated strain was produced which can yield Kerati-nase with a high activity. The activity of Keratinase was 75.9% higher than that before the compound mutation. This was achieved by optimizing the fermentation medium of mutated strain. The optimum fermentation medium had the parameters as feather meal 5.5%, maize silage 0.8%, K+ 0.018 mol/L, Mg2+ 0.065 mol/L, Ca2+ 0.072 mol/L, Fe2+ 0.010 mol/L, and Na+ 0.088 mol/L. Based on the optimized fermentation medium, the highest yielding rate for producing enzyme was 1.117 U/mL, 25.22% higher than that before the optimization. The amino acid in the fermentation medium fluid reached 22.66 mg/mL. This paper presents a simple, and low cost way to produce high quality bio-fermentation feather meal.