Streptomyces and Bacillus Keratinases: Properties and Uses

Introduction. Feather waste is a promising source of feed protein. Its chemical composition is a valuable source of nutrients and can become an important component of feed additives. The research objective was to screen bacteria with a high keratinolytic activity and develop a bio-product based on a bacterial consortium in order to recycle complex organic poultry waste, thus reducing the anthropogenic load on the ecosystem. Study objects and methods. The research featured lyophilized strains of microorganisms provided by State Research Institute «Gosniigenetika» and feather waste provided by Kuzbass Broiler LLC (Russia, Novokuznetsk district). The study involved such advanced bioinformatic methods of data processing as phylogenetic identification of enzymes and InParanoid 8 algorithm for searching orthologous genes. The standard biotechnological methods included an electrophoretic analysis in polyacrylamide gel, an analysis of amino acid composition, a microscopy, and a high-performance liquid chromatography. Results and discussion. Keratinolytic strains were screened using protein sequence databases. The homologous keratinase strains with homology of more than 98% appeared to belong to the genera Streptomyces and Bacillus. The research helped to identify groups of enzymes that are potentially involved in keratin degradation. The selected enzymes were subjected to a phylogenetic identification based on InParanoid 8, a specialized algorithm of orthologous genes search. Conclusion. The experiment made it possible to select four strains of microorganisms with maximum enzymatic activity in relation to keratin. These strains included bacteria of the genus Bacillus, namely Bacillus licheniformis B-740, Bacillus pumilus B-508 and Bacillus subtilis ATCC 6051, and the bacterium Streptomyces albidoflavus ATCC 25422. These strains were used to create a biocompatible consortium for processing feather waste into a feed additive. The research confirmed the presence of biologically valuable substances in the obtained hydrolysates, as well as the possibility of their use as a high-protein component of feed additives for farm animals.