Shih, 1993. Poult. Sci., 72 (9): 1617-1620

The intensive and large-scale production of food animals and animal products has generated an enormous waste disposal problem for the animal industry. These wastes, which include animal excreta, mortalities, hair, feathers, and processing wastes, are largely organic materials and are convertible to useful resources. Making the conversion processes efficient and economical presents a great challenge to modern biotechnology. An efficient thermophilic anaerobic digester system has been developed that converts animal manure to methane for an energy source, solid residues for feed supplements, and liquid nutrients for aquaculture. This digester system also destroys pathogens and thus protects environmental health. During the development of this system, a feather-degrading bacterium was discovered and identified as a thermophilic Bacillus licheniformis, Strain PWD-1. The bacterium can ferment and convert feathers to feather-lysate, a digestible protein source for feed use. An enzyme, keratinase, secreted by this bacterium was purified and characterized. This keratinase is a potent protease that hydrolyzes all proteins tested, including collagen, elastin, and feather keratin. When the enzyme was mixed as an additive in feed, it significantly enhanced the digestibility of feather meal in chickens. In addition to feed technology, the bacterium and the enzyme are believed to have many other industrial and environmental applications.