Abstract

Glycerol can be converted into more valuable compound dihydroxyacetone by the nicotinamide adenine dinucleotide (NAD⁺)-dependent glycerol dehydrogenase. However, it is economically prohibitive to produce dihydroxyacetone using purified glycerol dehydrogenase at the expense of a stoichiometric amount of the cofactor NAD⁺. In this study, Escherichia coli was engineered for dihydroxyacetone production by enhancing its glycerol dehydrogenase activity and introducing NADH oxidase activity. Under optimized conditions, dihydroxyacetone productivity reached 0.13 g/h/g wet cell mass by recombinant E. coli D4 (pET-24b-gldA+nox) cells co-expressinggldA gene from E. coli and nox gene from Enterococcus faecalis. It was interesting to note that exogenous NAD⁺ greatly improved dihydroxyacetone production for the whole-cell biotransformation process. These results should be useful for the development of advanced bioprocess in terms of glycerol utilization.

Key words: Dihydroxyacetone, Glycerol dehydrogenase, NAD⁺, whole-cell biotransformation, Escherichia coli.

Abbreviation

Abbreviations: DHA, Dihydroxyacetone; NAD⁺, nicotinamide adenine dinucleotide;GDH, glycerol dehydrogenase; NOX, NADH oxidase; IPTG, isopropyl-β-D-thiogalactoside; LB, Luria-Bertani; Kan, kanamycin; WCM, wet cell mass; SDS-PAGE, sodium dodecyl sulfate/polyacrylamide gel electrophoresis.