Recombinant expression and characterization of the family 5 cellulase from Bacillus velezensis in Escherichia coli BL21-CodonPlus (DE3)-RIPL

Abstract

B. velezensis RB. IBE29 is a chitinolytic bacterium originally isolated from agricultural soil of Vietnam. Previous studies demonstrated this bacterium was a promising chitinase producer, biocontrol agent, and biofertilizer for crop production. The complete genome sequence of the bacterium was reported and possesses the gene encoding family 5 cellulase; however, role of this enzyme has not been experimentally characterized. This work aimed to express and biologically characterize family 5 cellulase of strain RB. IBE29. The ORF (without signal peptide) of the celA of strain RB. IBE29 was expressed in E. coli BL21-CodonPlus (DE3)-RIPL using the vector pColdII, and the corresponding product (rBvCelA, 55.17 kDa) was successfully purified using the HisTrap FF column. The purified rBvCelA showed the highest cellulase activity against CMC, followed by sugarcane bagasse and rice straw, and had optimal temperature and pH at 60 °C and 6.0, respectively. Metal salts ZnCl₂, FeCl₂, MgCl₂, CuSO₄, and MnCl₂ enhanced the cellulase activity by 103.85, 124.24, 109.38, 105.64, and 115.12 %, respectively. In addition, the supplementation of the purified rBvCelA in the feed enhanced the growth and improved the feed intake of broiler chickens by 5.88 and 5.19 %, respectively. These results indicated that family 5 cellulase of B. velezensis has a promising role in crop production and poultry breeding. As far as we know, this is the first report describing the contribution of family 5 cellulase from B. velezensis in broiler breeding.