A gene encoding the Carboxymethyl cellulase (CMCase) of a psychrophilic marine bacterium, Psychrobacter aquimaris LBH-10 was cloned in Escherichia coli JMB109. The optimal conditions of rice bran, ammonium chloride, and initial pH of the medium for cell growth of E. coli JM109/LBH-10 were 73.4 g/L, 5.8 g/L, and 6.5, respectively, whereas those for production of CMCase were 57.1 g/L, 6.4 g/L, and 6.7. The optimal temperatures for cell growth and the production of CMCase by E. coli JM109/LBH-10 were found to be and 40 and 35°C, respectively. The optimal agitation speeds and aeration rates of a 7 L bioreactor for cell growth and production of CMCase were 480 rpm and 1.0 vvm. In this study, the optimal conditions for cell growth and the production of CMCase by E. coli JM109/ LBH-10 were found to be different from those for its wild type, P. aquimaris LBH-10. The maximal production of CMCase by E. coli JM109/LBH-10 was 576.8 U/mL, which was 1.80 times higher than that by P. aquimaris LBH-10.