Isolation And Identification Of A Strain Producing1,3-Dihydroxyacetone And Studies On Fermentation Process

As a pesticide synthesis intermediates and fine chemical raw materials and pharmaceutical precursors,1,3-dihydroxyacetone is an important and versatile, high volume fine chemical products.A spectrophotometry method was established for the determination of1,3-dihydroxyacetone of thefermentation broth using glycerol. Several factors influencing the determination were studied, such as theamount of color reagent, reaction temperature, reaction time, color stability time, broth composition andcell autolysis in the broth. The detection limits and recovery rate were0⁰.4g/L (R2=0.999) and theaverage recover was100.1%å'Œ102.4%, respectively. The results showed that glycerol and other impuritiesin the fermentation broth have no significant interferences to the determination of1,3-dihydroxyacetone,and this method proved to be fast and accurate.A strain, Gluconobacter frateurii CGMCC5397, producing DHA was isolated from rotted fruit. Aseries of morphological and biochemical characteristics and sequence analysis of16S rRNA reveal that itbelongs to Gluconobacter frateurii, which named Gluconobacter frateurii HD924and preserved by ChinaGeneral Microbiological Culture Collection Center. The preservation number is CGMCC5397. Apreliminary study of fermentation showed that when cultured in medium contaiing80g/L glycerol ascarbon source the strain produced63.04g/L of1,3-dihydroxyacetone.Flask fermentation conditions on the HD924growth and the production of1,3-dihydroxyacetone werestudied. Orthogonal methodology was used to optimizate the seed medium.Response surface methodologywas firstly used to optimizate the fermentation medium for1,3-dihydroxyacetone production using Gluconobacter frateurii HD924. It was found that the CaCO₃, corn steep liquid and glycerol significantlyimproved the production of1,3-diyhroxyacetone. The Response Surface Methodology (RSM) based on athree-factor Box-Behnken design of experiments was used to build an analytical model and finallyemployed as a constraint in an obvious optimization process. The optimized parameters were CaCO₃of15.22g/L, corn steep liquid of22.13g/L, and glycerol of103.33g/L. Under those optimization conditions,it was predicted that the the highest concentation of1,3-diyhroxyacetone recached81.54g/L. Afteroptimization, the1,3-diyhroxyacetone production increased by30.48%, and the experimental data basicallyin line with the predicted values.In7L fermentor,the effection of ventilation and glycerol concentration on the production of1,3-dihydroxyacetone was also studied. The optimium condition of aeration rate and glycerol concentrationwere2.0vvm aeration rate, and150g/L and the1,3-dihydroxyacetone production was123.70g/L, theresidual glycerol5.62g/L.