Characterization of a new keratinolytic Trichoderma atroviride strain F6 that completely degrades native chicken feather

Abstract

To isolate novel nonpathogenic fungus that completely degrades native chicken feather and characterize its keratinases. Feather-degrading fungi were isolated from decaying feathers using a novel method based on simulating decaying process in the environment. The isolate F6 with high keratinolytic activity was identified as Trichoderma atroviride based on morphological traits and ITS1-5.8S-ITS2 sequence analysis. The purified dominant component of keratinase had a molecular mass of 21 kDa. The purified keratinase belonged to serine protease. Its isoelectric point, molecular weight, optimum pH, optimum temperature, and substrate specificity are different from those of other serine proteases of Trichoderma species. The optimum pH and temperature values of purified keratinase were consistent with those of crude keratinase. However, the differences between crude and purified enzymes such as thermostability, resistance to Ba(2+), Mn(2+), Hg(2+), Zn(2+), Cu(2+), 1,10-phenanthroline, 2,2'-bipyridyl, and PMSF (phenylmethylsulfonyl fluoride) were observed. The results suggested the purified keratinase is predominantly extracellular proteins when strain F6 was grown on keratinous substrates. The protease, in combination with other components, is effective in feather degradation. The strain F6 is more suitable for feather degradation than its purified keratinase. The novel nonpathogenic T. atroviride F6 with high feather-degrading activity showed potentials in biotechnological process of converting feathers into economically useful feather meal.