Production of diacetyl by metabolically engineered Enterobacter cloacae.

ABSTRACT: Diacetyl, a high value product that can be extensively used as a food ingredient, could be produced from the non-enzymatic oxidative decarboxylation of ?-acetolactate during 2,3-butanediol fermentation. In this study, the 2,3-butanediol biosynthetic pathway in Enterobacter cloacae subsp. dissolvens strain SDM, a good candidate for microbial 2,3-butanediol production, was reconstructed for diacetyl production. To enhance the accumulation of the precursor of diacetyl, the ?-acetolactate decarboxylase encoding gene (budA) was knocked out in strain SDM. Subsequently, the two diacetyl reductases DR-I (gdh) and DR-II (budC) encoding genes were inactivated in strain SDM individually or in combination to decrease the reduction of diacetyl. Although the engineered strain E. cloacae SDM (?budA?budC) was found to have a good ability for diacetyl production, more ?-acetolactate than diacetyl was produced simultaneously. In order to enhance the nonenzymatic oxidative decarboxylation of ?-acetolactate to diacetyl, 20?mM Fe(3+) was added to the fermentation broth at the optimal time. In the end, by using the metabolically engineered strain E. cloacae SDM (?budA?budC), diacetyl at a concentration of 1.45?g/L was obtained with a high productivity (0.13?g/(L·h)). The method developed here may be a promising process for biotechnological production of diacetyl.

SUBMITTER: Zhang L 

PROVIDER: S-EPMC4357014 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature