Biodegradation of keratin by Trichosporum loubieri RC-S6 isolated from tannery/leather waste

Keratin proteins are a major constituent of skin and its appendages including nails, hair, feathers, and wool. Keratinases are peptidases that degrade keratin. Keratinases are produced by a number of different bacterial genera as well as dermatophyte fungi. The aim of this research was to isolate and identify keratinolytic yeasts that produce enzymes that might replace some of the chemicals used during tanning in leather production. Bioprospecting/sampling targeted discarded leather scraps from chromium-polluted soil adjacent to a tannery. Isolated yeasts were selected for identification and further characterization based on their ability to hydrolyze keratin and based on zymography analyses. Yeast strain RC-S6 was putatively identified as a Trichosporon loubieri strain based on biochemical and ribosomal DNA analyses. This strain produced its highest keratinase activity on nail keratin (193.3 U ml−1). Sulfide production was observed for all keratin media types but the best substrate was human hair. T. loubieri RC-S6 secretes keratinases that degrade nails, hair, feathers and wool and degradation was faster with nail and hair keratin. The keratinases from this strain have biotechnological potential for dehairing in leather production.