Use of glycerol for producing 1,3-dihydroxyacetone by Gluconobacter oxydans in an airlift bioreactor

Abstract

1,3-Dihydroxyacetone can be produced by biotransformation of glycerol with glycerol dehydrogenase from Gluconobacter oxydans cells. Firstly, improvement the activity of glycerol dehydrogenase was carried out by medium optimization. The optimal medium for cell cultivation was composed of 5.6g/l yeast extract, 4.7g/l glycerol, 42.1g/l mannitol, 0.5g/l K2HPO4, 0.5g/l KH2PO4, 0.1g/l MgSO4·7H2O, and 2.0g/l CaCO3 with the initial pH of 4.9. Secondly, an internal loop airlift bioreactor was applied for DHA 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±7.8g/l of maximal DHA concentration with 89.8±2.4% of conversion rate of glycerol to DHA was achieved after 72h of biotransformation using 10g/l resting cells at 30°C, pH 5.0 and 1.5vvm of aeration rate.