Construction of a recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis> JM109/A-68 for production of carboxymethylcellulase and comparison of its production with its wild type, <Emphasis Type="Italic">Bacillus velezensis</Emphasis> A-68 in a pilot-scale bioreactor

A gene encoding carboxymethylcellulase (CMCase) of Bacillus velezensis A-68 had been cloned in Escherichia coli JM109. Based on productivity and economic aspect, rice bran and ammonium chloride were chosen to be optimal carbon and nitrogen sources for production of CMCase by E. coli JM109/A-68. The optimal conditions for rice bran, ammonium chloride, and initial pH of medium for production of CMCase were established by the response surface methodology (RSM). The concentrations of four salts in the medium, K₂HPO₄, NaCl, MgSO₄·7H₂O, and (NH₄)₂SO₄, for production of CMCase also were optimized. The optimal temperatures for cell growth and production of CMCase were 37°C. The maximal production of CMCase by E. coli JM109/A-68 was 880.2 U/mL, which was 10.5 time higher than its wild type, B. velezensis A-68. The production of CMCase by E. coli JM109/A-68 was compared with that by B. velezensis A-68 in a 100 L pilot-scale bioreactor under the optimized conditions. The production of CMCase by E. coli JM109/A-68 was found to be the mixed-growth associated unlike the growthassociated production of CMCase by B. velezensis A-68.