title: 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 α-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 α-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 (ΔbudAΔbudC) was found to have a good ability for diacetyl production, more α-acetolactate than diacetyl was produced simultaneously. In order to enhance the nonenzymatic oxidative decarboxylation of α-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 (ΔbudAΔbudC), 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.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Lijie
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Yingxin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Qiuyuan
authors.initials: Q
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Liying
authors.initials: L
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Mandong
authors.initials: M
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Lv
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China.
authors.forename: Cuiqing
authors.initials: C
authors.lastname: Ma
mesh_terms: D061249:Batch Cell Culture Techniques; D053898:Biosynthetic Pathways; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D003931:Diacetyl / Q000378:metabolism*; D016972:Enterobacter cloacae / Q000235:genetics* / Q000378:metabolism*; D004789:Enzyme Activation; D005285:Fermentation; D005290:Ferric Compounds / Q000378:metabolism; D060847:Metabolic Engineering; D009154:Mutation
chemical_list: D005290:Ferric Compounds; D002262:Carboxy-Lyases; C023746:acetolactate decarboxylase; D003931:Diacetyl