Production of microbial keratinase using a newly isolated strain of Stenotrophomonas maltophilia and its characterization and applications.

Abstract

Biodegradation of keratin containing wastes viz. bird feathers, nails, hairs, animalwool is a low-cost, nutrient-rich biotechnological process that turns this plentiful waste into a low-cost, nutrient-rich substance. It is a sustainable green approach towards the solution of environmental threats created by these wastes. This study aimed to screen for potential keratinase-producing microorganisms and to optimize physicochemical parameters to produce keratinase and its characterization. Samples were collected from various poultry farms of Surat (India). Screening for keratinase-production was carried using a feather basal medium. Among these samples, 16 isolates showed keratinolytic activity in primary screening using skim milk agar medium among which, nine isolates showed keratinolytic activity using keratin agar medium. Isolate KA1a gave the highest yield of keratinase and was identified as a strain of Stenotrophomonas maltophilia (NCBI Accession number MT478451), based on 16S rRNA sequencing. It delivered highest enzyme production (108 U/ml) in the medium with feathers (2.2%), NaCl (0.5%), K2HPO4(0.3%), KH2PO4(0.4%), pH7, with 10% inoculum of young cell mass, at 37°C for 24 h under shaking conditions. Optimum temperature for keratinase activity was 40°C and pH 7.0. Enzyme showed stability over different temperature and pH for up to 90 min. It showed potential applications as a detergent additive, animal feed, and organic fertilizer.