title: Enhanced production of dihydroxyacetone from glycerol by overexpression of glycerol dehydrogenase in an alcohol dehydrogenase-deficient mutant of Gluconobacter oxydans.
abstract: Gluconobacter oxydans can rapidly and incompletely oxidize glycerol to dihydroxyacetone (DHA), a versatile product extensively used in cosmetic, chemical and pharmaceutical industries. To improve DHA production, the glycerol dehydrogenase (GDH) responsible for DHA formation was overexpressed in G. oxydans M5AM, in which the gene coding for the membrane-bound alcohol dehydrogenase (ADH) was interrupted. Real-time PCR and enzyme activity assay revealed that the absence of ADH together with the overexpression of GDH gene resulted in an increased GDH activity in the resulting strain M5AM/GDH, which led to a substantially enhanced production of DHA in a resting cell system. In a batch biotransformation process, M5AM/GDH exhibited a 2.4-fold increased DHA productivity of 2.4g/g CDW/h from 1.0g/g CDW/h, yielding 96g/L DHA from 100g/L glycerol. When 140g/L glycerol was supplied, a final DHA concentration of 134g/L was accumulated within 14h. In four repeated batch runs, 385g DHA over a time period of 34h was achieved from 400g glycerol with an average productivity of 2.2g/g CDW/h. These results indicated that this newly developed strain G. oxydans M5AM/GDH with high productivity and increased tolerance against product inhibition has potential for DHA production in an industrial bioconversion process.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, Institute of Newworld Biotechnology, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Ming-hua
authors.initials: MH
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Xu
authors.initials: X
authors.lastname: Liu
authors.forename: Jin-ping
authors.initials: JP
authors.lastname: Lin
authors.forename: Dong-zhi
authors.initials: DZ
authors.lastname: Wei
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
mesh_terms: D000426:Alcohol Dehydrogenase / Q000172:deficiency* / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D001711:Biotransformation / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology; D004098:Dihydroxyacetone / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial / Q000235:genetics; D020600:Gluconobacter oxydans / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D005990:Glycerol / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013401:Sugar Alcohol Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D013401:Sugar Alcohol Dehydrogenases; D000426:Alcohol Dehydrogenase; C020672:glycerol dehydrogenase; D004098:Dihydroxyacetone; D005990:Glycerol