Biotechnology Bulletin ›› 2021, Vol. 37 ›› Issue (10): 100-109.doi: 10.13560/j.cnki.biotech.bull.1985.2021-0106

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Directed Mutagenesis of β-mannanase Gene from Bacillus licheniformis KD-1 for Improving Enzyme Activity and Stability

TIAN Geng(), GAO Wei-qiang, CHEN Xiao-bo, ZHANG Chun-xiao()   

  1. Department of Bioscience and Bioengineering,Hebei University of Science and Technology,Shijiazhuang 050018
  • Received:2021-01-27 Online:2021-10-26 Published:2021-11-12
  • Contact: ZHANG Chun-xiao E-mail:741033155@qq.com;cxzhang2009@163.com

Abstract:

The β-mannanase gene from Bacillus licheniformis strain KD-1 was directed mutated for improving its activity and stability. The β-mannanase gene manBl from B. licheniformis strain KD-1 was cloned and directed mutated by PCR. The gene and its mutants were expressed in B. subtilis DB104. The activities of the enzymes were measured by dinitrosalicylic acid,and DNS method. The β-mannanase ManBl and its 6 variants had the same optimal pH 6.0 and optimal temperature 60℃. All the variants had higher specific activity and pH stability between pH 6.0-10.0 than wild-type ManBl. The specific activity of the mutant ManBlT112R/K291E)was(9 742±370.0)U/mg,which was 2.6 times of wild-type ManBl. The Km value of ManBlT112R/K291E)was 2.67 mg/mL. The half-life of ManBl(T112R/K291E)was 80 min at 70℃. The two enzymes with 6×His-tagged at the C terminal had lower specific activity and thermostability than the corresponding enzyme without His-tag. The β-mannanase mutant ManBlT112R/K291E)shows potential application in feed,food and laundry industrial fields with its high specific activity,pH stability and thermostability.

Key words: β-mannanase, Bacillus licheniformis, directed mutation, enzyme activity, stability