Harnessing Bacillus keratinases for sustainable keratin waste valorization: a current appraisal

The global accumulation of keratin-rich waste, primarily from poultry and livestock industries, presents significant environmental and economic challenges. This review explores the potential of Bacillus-derived keratinases as a sustainable solution for keratin waste valorization and prospects of value-addition. Keratinases, the keratin hydrolyzing proteases produced predominantly by various Bacillus species, exhibit exceptional capability in degrading keratin, a highly stable and recalcitrant protein. This degradation process not only mitigates the environmental impact of keratin waste, but also converts it into valuable by-products with potential industrial applications. We systematically review various aspects, including: the production, properties and the mechanism of keratin degradation by Bacillus keratinases, highlighting their enzymatic properties, substrate specificity, and efficiency in valorizing keratin into peptides and amino acids. Biomolecular aspects and catalytic behavior relevant to the activity and stability of Bacillus keratinases are visited via in silico modeling. The economic and environmental benefits of utilizing keratinases for waste valorization are assessed, including reductions in waste disposal costs, greenhouse gas emissions, and the potential for creating new economic opportunities through the utilization of keratin-derived products. The recent advancements in keratin waste enzyme treatment and their utilization in developing circular bioeconomy are highlighted in the present article.