Expression of clostridium thermocellum exo-β-1, 4-glucanase gen in bacillus subtilis

Abstract

The exo-$\beta$-1, 4-glucanase gene (exoglucanase gene) previously cloned from Clostridium thermocellum in our laboratory was tried to transfer from the Escherichia coli host cell to Bacillus subtilis cell to produce the enzyme extracellularly. The unnecessary parts of both N-terminal and C-terminal regions of the exoglucanase gene contained in pCE64 were removed to increase expression efficiency. The constructed plasmid was designated as pCX33 in which a 3.3 kilobase fragment containing the exoglucanase gene fused to the lacZ gene is contained. After confirming expression of the exoglucanase gene in E. coli, the exoglucanase gene in pCX33 was retransferred to a Bacillus expression vector pJH31 to make a new plasmid pJX33. Bacillus subtilis transformed with pJX33 was grown in LB medium. The Bacillus subtilis transformant produced 719 mU/ml of exoglucanase which was completely secreted into the culture medium.