Isolation of a novel feather-degrading Ectobacillus sp. JY-23 strain and characterization of a new keratinase in the M4 metalloprotease family

• Published in: Microbiological research 2023-09, Vol.274, p.127439-127439, Article 127439
• Main Authors: Peng, Shuaiying, Li, Hanguang, Zhang, Shuaiwen, Zhang, Rong, Cheng, Xin, Li, Kuntai
• Format: Article
• Language: English
• Subjects: Amino Acids - metabolism; Animals; Bacterial keratinase; Chickens; Feather degradation; Feathers - metabolism; Feathers - microbiology; Genome de novo sequencing; Heterologous expression; Hydrogen-Ion Concentration; Keratins - metabolism; Metalloproteases - metabolism; Peptide Hydrolases - metabolism
• ISSN: 0944-5013; 1618-0623
• DOI: 10.1016/j.micres.2023.127439

Microbial keratinases have prominent potential in biotransformation of recalcitrant keratin substrates to value-added products which has made keratinases a research focus in the past decades. In this study, an efficient feather-degrading bacterium was isolated and identified as a novel species in Ectobacillus genus and designated as Ectobacillus sp. JY-23. The degradation characteristics analysis revealed that Ectobacillus sp. JY-23 could utilize chicken feathers (0.4% w/v) as the sole nutrient source and degraded 92.95% of feathers in 72 h. A significant increase in sulfite and free sulfydryl group content detected in the feather hydrolysate (culture supernatant) indicated efficient reduction of disulfide bonds, which inferred that the degradation mechanism of isolated strain was a synergetic action of sulfitolysis and proteolysis. Moreover, abundant amino acids were also detected, among which proline and glycine were the predominant free amino acids. Then, the keratinase of Ectobacillus sp. JY-23 was mined and Y1_15990 was identified as the keratinase encoding gene of Ectobacillus sp. JY-23 and designated as kerJY-23. Escherichia coli strain overexpressing kerJY-23 degraded chicken feathers in 48 h. Finally, bioinformatics prediction of KerJY-23 demonstrated that it belonged to the M4 metalloprotease family, which was a third keratinase member in this family. KerJY-23 showed low sequence identity to the other two keratinase members, indicating the novelty of KerJY-23. Overall, this study presents a novel feather-degrading bacterium and a new keratinase in the M4 metalloprotease family with remarkable potential in feather keratin valorization. •The isolated strain was a novel species in Ectobacillus genus.•Ectobacillus sp. JY-23 is a promising candidate for keratin valorization.•Ectobacillus sp. JY-23 degrades feather by synergetic action of proteolysis and sulfitolysis.•kerJY-23 is the specific keratinase-encoding gene in Ectobacillus sp. JY-23.•KerJY-23 is a new keratinase protein in the M4 metalloprotease family.