Identification and characterization of a versatile keratinase, KerZJ, from Stenotrophomonas sp. LMY.

Keratinases have drawn increasing attention in recent decades owing to their catalytic versatility and broad applications from agriculture to medicine. In the present study, we isolated a highly keratinolytic and fibrinolytic bacterium from the campus soil and named it Stenotrophomonas sp. LMY based on genetic information. To identify the potential keratinase genes, the genome sequence of the strain was obtained and analyzed. Sequence alignment and comparison revealed that the protein 1_737 (KerZJ) had the highest sequence homology to a reported keratinase KerBL. We recombinantly expressed KerZJ in Escherichia coli Origami™ (DE) pLysS and purified it to homogeneity. KerZJ showed the highest activity at 40 °C and pH 9.0, and metal ions exhibited no significant effects on its activity. Although reducing agents would break the disulfide bonds in KerZJ and reduce its activity, KerZJ still exhibited the ability to hydrolyze feather keratin in the presence of ß-ME. KerZJ could efficiently digest human prion proteins. In addition, KerZJ showed fibrinolytic activity on fibrin plates and effectively eliminated blood clots in a thrombosis mouse model without side effects. Our results suggest that KerZJ is a versatile keratinase with significant potential for keratin treatment, decontamination of prions, and fibrinolytic therapy.

Effects of Feather Hydrolysates Generated by Probiotic Bacillus licheniformis WHU on Gut Microbiota of Broiler and Common carp.

Due to the ever-increasing demand for meat, it has become necessary to identify cheap and sustainable sources of protein for animal feed. Feathers are the major byproduct of poultry industry, which are rich in hard-to-degrade keratin protein. Previously we found that intact feathers can be digested into free amino acids, short peptides, and nano-/micro-keratin particles by the strain Bacillus licheniformis WHU in water, and the resulting feather hydrolysates exhibit prebiotic effects on mice. To explore the potential utilization of feather hydrolysate in the feed industry, we investigated its effects on the gut microbiota of broilers and fish. Our results suggest that feather hydrolysates significantly decrease and increase the diversity of gut microbial communities in broilers and fish, respectively. The composition of the gut microbiota was markedly altered in both of the animals. The abundance of bacteria with potentially pathogenic phenotypes in the gut microbial community of the fish significantly decreased. Staphylococcus spp., Pseudomonas spp., Neisseria spp., Achromobacter spp. were significantly inhibited by the feather hydrolysates. In addition, feather hydrolysates significantly improved proteolytic activity in the guts of broilers and fish. In fish, the expression levels of ZO-1 and TGF-α significantly improved after administration of feather hydrolysates. The results presented here suggest that feather hydrolysates generated by B. licheniformis WHU could be an alternative protein source in aquaculture and could exert beneficial effects on fish.