title: D-2,3-butanediol production due to heterologous expression of an acetoin reductase in Clostridium acetobutylicum.
abstract: Acetoin reductase (ACR) catalyzes the conversion of acetoin to 2,3-butanediol. Under certain conditions, Clostridium acetobutylicum ATCC 824 (and strains derived from it) generates both d- and l-stereoisomers of acetoin, but because of the absence of an ACR enzyme, it does not produce 2,3-butanediol. A gene encoding ACR from Clostridium beijerinckii NCIMB 8052 was functionally expressed in C. acetobutylicum under the control of two strong promoters, the constitutive thl promoter and the late exponential adc promoter. Both ACR-overproducing strains were grown in batch cultures, during which 89 to 90% of the natively produced acetoin was converted to 20 to 22 mM d-2,3-butanediol. The addition of a racemic mixture of acetoin led to the production of both d-2,3-butanediol and meso-2,3-butanediol. A metabolic network that is in agreement with the experimental data is proposed. Native 2,3-butanediol production is a first step toward a potential homofermentative 2-butanol-producing strain of C. acetobutylicum.
authors.affiliation: Laboratory of Microbiology, Wageningen University and Research Centre, Dreijenplein 10, 6703 HB Wageningen, Netherlands.
authors.forename: Marco A J
authors.initials: MA
authors.lastname: Siemerink
authors.forename: Wouter
authors.initials: W
authors.lastname: Kuit
authors.forename: Ana M
authors.initials: AM
authors.lastname: López Contreras
authors.forename: Gerrit
authors.initials: G
authors.lastname: Eggink
authors.forename: John
authors.initials: J
authors.lastname: van der Oost
authors.forename: Servé W M
authors.initials: SW
authors.lastname: Kengen
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D056804:Biofuels / Q000382:microbiology; D002072:Butylene Glycols / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D046969:Clostridium acetobutylicum / Q000235:genetics / Q000378:metabolism*; D046970:Clostridium beijerinckii / Q000235:genetics*; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D015870:Gene Expression; D005818:Genetic Engineering; D011401:Promoter Regions, Genetic; D013237:Stereoisomerism
chemical_list: D056804:Biofuels; D002072:Butylene Glycols; C026978:2,3-butylene glycol; D000429:Alcohol Oxidoreductases; C019801:butanediol dehydrogenase