Isolation of keratinase-producing Bacillus strains and enhanced enzyme production using in vitro mutagenesis

Millions of tons of feathers produced annually by the poultry industry cause environmental pollution and waste a significant source of protein. In the present study, three keratinolytic Bacillus strains, Bacillus sp. MK1, MK2, and MK3 were isolated. Some of the enzymatic properties of these keratinases were determined. The effects of some chemicals on enzyme activities were investigated. The specific activities of MK1, MK2, and MK3 were 2.76, 0.77, and 5.48 U/mg protein at 40°C, respectively, and mutant varieties were overexpressed after EtBr treatment. A comparison of keratinase activity between native and improved isolates showed that mutant variants exhibited higher activity ranging from 116 to 214%. According to BLAST analysis, the Bacillus sp. MK1 rDNA sequence was 96.83% similar to that of B. subtilis subsp. stercoris strain 153, B. subtilis strain FR10, B. tequilensis strain P12, and B. subtilis strain SRR21, and Bacillus sp. MK2 and MK3 16S rDNA sequences were 99.54% similar to those of B. subtilis strain 21M and B. subtilis strain NX17 sequences. The results of the enzymatic analysis of the enzymes and overexpressed mutant varieties are promising for application in the industrial production and application of the enzymes decomposition of feathers in poultry sector.