Efficient keratinase expression via promoter engineering strategies for degradation of feather wastes

Jin Song Gong, Jin Peng Ye, Li Yan Tao, Chang Su, Jiufu Qin, Yan Yan Zhang, Heng Li, Hui Li, Zheng Hong Xu, Jin Song Shi*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Keratinases are promising alternatives over ordinary proteases in several industrial applications due to their unique properties compared with their counterparts in the protease categories. However, their large-scale industrial application is limited by the low expression and poor fermentation efficiency of keratinase. Here, we demonstrate that the expression level of keratinase can be improved by constructing a more efficient enzyme expression system hereby enables the highest production titer as regarding recombinant keratinase production to date. Specially, ten promoters were evaluated and the aprE promoter exhibits a significant promotion of keratinase (kerBv) titer from 165 U/mL to 2605 U/mL in Bacillus subtilis. The batch fermentation mode resulted in a maximum keratinase activity of 7176 U/mL at 36 h in a 5-L fermenter. Furthermore, the extracellular keratinase activity attained up to 16,860 U/mL via fed-batch fermentation within 30 h. The combination of keratinase with L-cysteine brings about 66.4 % degree of degradation of feather. Our work provides a new insight into the development of efficient keratinase fermentation processes with B. subtilis cell factory.

Original languageEnglish
Article number109550
JournalEnzyme and Microbial Technology
Number of pages8
Publication statusPublished - 2020


  • Biodegradation
  • Expression
  • Fermentation
  • Keratinase
  • Promoter screening


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