Characterization of a new keratinolytic bacterium that completely degrades native feather keratin

Abstract

A novel feather-degrading microorganism was isolated from poultry waste, producing a high keratinolytic activity when cultured on broth containing native feather. Complete feather degradation was achieved during cultivation. The bacterium presents potential use for biotechnological processes involving keratin hydrolysis. Chryseobacterium sp. strain kr6 was identified based on morphological and biochemical tests and 16S rRNA sequencing. The bacterium presented optimum growth at pH 8.0 and 30 degrees C; under these conditions, maximum feather-degrading activity was also achieved. Maximum keratinase production was reached at 25 degrees C, while concentration of soluble protein was similar at both 25 and 30 degrees C. Reduction of disulfide bridges was also observed, increasing with cultivation time. The keratinase of strain kr6 was active on azokeratin and azocasein as substrates, and presented optimum pH and temperature of 7.5 and 55 degrees C, respectively. The keratinase activity was inhibited by 1,10-phenanthroline, EDTA, Hg(2+), and Cu(2+) and stimulated by Ca(2+).