Expression, Characterization and Fermentation Optimization of Keratinase from Bacillus licheniformis in Escherichia coli

Abstract

In order to enhance the production of keratinase in Escherichia coli and study the enzymatic properties, the ker gene(1 140 bp) was cloned from a feather-degrading bacterium of Bacillus licheniformis BBE11-1. After the 1 053 bp fragment of signal peptide-truncated ker gene was inserted into the expression vector pET-22b(+), the recombinant plasmid was transformed into E. coli BL21(DE3). The recombinant keratinase purif ied by hydrophobic interaction chromatography using HiTrap Phenyl-sepharose Fast Flow was a serine protease most active at 50 ℃ and pH 10. The activity of keratinase was enhanced by Mg2+ and K+, and inhibited by Mn2+. The highest keratinase activity was 460.2 U/mL in growth medium containing inducer(0.05 mmol/L IPTG, 150 mmol/L glycine and 60 g/L yeast extract) at 20 ℃. This report focused on the expression and characterization of recombinant keratinase in E. coli. We found that optimizing culture conditions could preferably enhance production of keratinase in E. coli. The results would be helpful in producing keratinase by gene engineering strain. Fig 4, Tab 1, Ref 22