1,3-Dihydroxyacetone can be produced by biotransformation of glycerol with glycerol dehydrogenase from Cluconobacter oxydans cells. Firstly, improvement the activity of glycerol dehydrogenase was carried out by medium optimization. The optimal medium for cell cultivation was composed of 5.6 g/l yeast extract, 4.7 g/l glycerol, 42.1 g/l mannitol, 0.5 g/l K(2)HPO(4), 0.5 g/l KH(2)PO(4), 0.1 g/l MgSO(4)center dot 7H(2)O, and 2.0 g/l CaCO(3) with the initial pH of 4.9. Secondly, an internal loop airlift bioreactor was applied for DNA production from glycerol by resting cells of G. oxydans ZJB09113. Furthermore, the effects of pH, aeration rate and cell content on DHA production and glycerol feeding strategy were investigated. 156.3 +/- 7.8 g/l of maximal DNA concentration with 89.8 +/- 2.4% of conversion rate of glycerol to DHA was achieved after 72 h of biotransformation using 10 g/l resting cells at 30 degrees C, pH 5.0 and 1.5 vvm of aeration rate. (C) 2011 Elsevier Ltd. All rights reserved.