Characterization and overexpression of a novel keratinase from Bacillus polyfermenticus B4 in recombinant Bacillus subtilis

Abstract

Background

Keratins, insoluble proteins with a robust structure, are a major component of epidermal tissue and appendages such as hair, feathers, nails, and walls. Keratinous waste mainly emanates from poultry and leather industries, thereby severely contaminating the environment. Keratinase can lyse proteins with robust cross-linked structures, such as keratin, and can hence be used in animal feed, fertilizer, detergent, leather, pharmaceutical, and cosmetic industries. Bacillus polyfermenticus B4, isolated from feather compost, secretes keratinase to metabolize feathers. Hence, this study aimed to investigate the enzymatic characteristics and recombinant production of keratinase from B. polyfermenticus B4.

Methods

A novel keratinase KerP was isolated from B. polyfermenticus B4 and overexpressed in B. subtilis PT5, via the T7 promoter.

Results

The highest keratinolytic activity of recombinant KerP was observed at pH 9.0 and 60 °C. Enzyme activity was enhanced with Fe²⁺, Mn²⁺, and SDS, and inhibited by Zn²⁺, Ni²⁺, EDTA, PMSF, and β-mercaptoethanol. KerP production was the highest at 473 ± 20 U/mL with B. subtilis aprE signal peptide using LB broth.

Conclusions

The novel keratinase KerP has potential industrial applications, particularly in the treatment of keratinous waste.

Keywords

Keratinase / Bacillus polyfermenticus / Keratinous waste / Characterization / Overexpression / Bacillus subtilis

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