Optimized Of Production Of Dihydroxyacetone From Glycerol By Gluconobacter Frateurii

Dihydroxyacetone(abbreviated as DHA) is a commercially important chemical, manly used as a self-tanning agent in cosmetic industry, also as fine chemical raw materials and pharmaceutical precursors and a pesticide synthesis intermediates. Glycerol, as the main substrate of DHA production by microbial, played an important role in the DHA industrial production. Crude glycerol, is abundantly available because it is the main by-product of the conversion of vegetable oils into biodiesel. The progressive increase of biodiesel production has in turn caused a sudden increase of crude glycerol. Make full use of crude glycerol can reduce the production cost of biodiesel, effectively alleviate the energy crisis.In this work, condition optimized of DHA production by Gluconobacter frateurii was developed, which use crude glycerol(the byproduct of palm oil biodiesel) as substrate. Flask fermentation conditions were studied, the optimum temperature is 30℃, the optimum pH is 6.0, the optimum shaker speed is 200 rpm. It was found that the CaCO3 and beef extract significantly improved the production of 1,3-diyhroxyacetone. The Response Surface Methodology(RSM) was used to build an analytical model and finally employed as a constraint in an obvious optimization process. The optimized parameters were crude glycerol of 117.18 g/L, beef extract of 15.05 g/L, and CaCO3 of 3.27 g/L. Under those optimization conditions, it was predicted that the highest concentation of 1,3-diyhroxyacetone recached 80.13 g/L. After optimization, the1,3-diyhroxyacetone production increased by 24%. In 5 L fermentor, the effection of glycerol concentration on the production of 1,3-dihydroxyacetone was also studied. When the initial concentration of glycerol was 140 g/L, after 48 h of fermentation, DHA production reached 112.38 g/L, the conversion rate was 80.27%.Effect of oxygen volumetric mass transfer coefficients(kLa) on DHA fermentation was studied. By the contrast of unbaffled flask cultures and baffled flask cultures, we found that baffled flask culture was better for DHA fermentation. The yield of fermentation increased from 80.13 g/L to 131.16 g/L, whichincreased by 63.68%. When compared with the original yield, it increased by 102.97%. The result of fermentation tank filling material batch fermentation indicated that high kLa values more conductive to the synthesis of DHA. The yield of fermentation increased from 112.38 g/L to 175.44 g/L, whichincreased by 56.11%. From evaluate the kinetics of DHA fermentation, we found that the oxygen are the main factors of DHA fermentation.Resting cell technology was used to product DHA was studied, experiments the effect of oxygen supply, pH, glycerol concentration, inoculated cell age and yield, determining the optimal experimental conditions was 220 rpm, pH was 5.0~6.0, glycerol concentration was 60~80 g/L, inoculated cell age was 24~28 h, inoculated cell yield was 1.5 g/L. Studied the stability of resting cell cultured batch reuse. When the initial glycerol concentration was 60 g/L, the DHA productivity and yield was higher, during the cycling culture of 4 times, the total DHA yield was 205.11 g/L, volumetric productivity was 4.28 g/(L·h), the average conversion rate was 85.46%.