Purification and characterization of four key enzymes from a feather-degrading Bacillus subtilis from the gut of tarantula Chilobrachys guangxiensis

•We isolated a probiotics from the gut of tarantula Chilobrachys guangxiensis.•The biodegradation time of 2.0 g l−1 intact feather was reduced from 36 h to 24 h.•Four enzymes were purified and identified as having principal roles in degradation.•Relationship between keratinolytic and reduction reaction were explored.

A feather-degrading bacterium was isolated from the gut of the tarantula Chilobrachys guangxiensis, and was classified as Bacillus subtilis (named Bacillus subtilis CH-1) according to both the phenotypic characteristics and 16S rRNA profile. The improved culture conditions for feather-degrading were 10.0 g l−1 mannitol, 10.0 g l−1 tryptone, 0.1 g l−1 MgCl2, 0.4 g l−1 KH2PO4, 0.3 g l−1 K2HPO4, 0.5 g l−1 NaCl, and 2.0 g l−1 intact feather, with pH 8.5 and 37 °C. In the optimized medium, the intact black feather was completely degraded by Bacillus subtilis CH-1 in 24 h. Furthermore, four kinds of enzymes which include extracellular protease Vpr, peptidase T, γ-glutamyl transpeptidase and glyoxalmethylglyoxal reductase were identified as having principal roles. Simultaneously, the relationship between the disulfide bond reducing activity (DRT) and the keratinase activity (KT) in B. subtilis CH-1 fermentation system was discussed. This is the first report for a feather-degrading enteric bacterium from tarantula. The identification of the enzymes shines a light on further understanding the molecular mechanism of feather-degrading by microbes.