Isolation and characterization of highly active keratinolytic microorganisms with promising potential for waste sheep wool processing

The huge amounts of keratin-rich waste generated daily by various industries, slaughterhouses, and processing plants need to be properly managed. Most keratin degradation-related research focuses on keratin from bird feathers, but a vast minority focuses on keratin from sheep wool, which also presents a serious environmental problem. In this article, we describe the isolation, identification, and characterization of new keratinolytic microorganisms capable of sheep wool degradation from sheep wool and soil enriched with wool keratin. We isolated four bacterial species from the genus Bacillus (B. subtilis, B. altitudinis, B. mycoides, and B. wiedmannii), one streptomycete species Streptomyces coelicoflavus identified by whole genome sequencing, and a fungal species Aphanoascus reticulisporus. In some of the isolated microorganisms, we detected keratinolytic activity for the first time, and for most of them, the ability to degrade sheep wool has not been previously demonstrated. The keratinases of the new isolates are active in a wide range of temperatures (25-85 degrees C) and pH (6.0-10.0), so all isolates show great potential for further biotechnological use in industry and in various environmental and agricultural applications to reduce and recycle keratin-rich wastes such as sheep wool and waste woollen textiles.