Optimization of Fermentation Conditions for Production of 1, 3-Dihydroxyacetone from Glycerol Obtained as a Byproduct during Biodiesel Production

Abstract

Aims: Present study was carried out using the glycerol obtained during biodiesel production for the conversion of 1,3-Dihydroxyacetone (DHA) by fermentation using bacterial strains G. oxydans, B. licheniformis and Acetobacter sp. Study Design: Experiments were carried out to optimize fermentation conditions like media optimization by the addition of metal ions, physical parameters such as pH (3.5 to 7), temperature (20ºC to 45ºC), glycerol concentration (2% to 20%) and fermentation time (24 h to 144 h) were considered for optimization studies. Methodology: Fermentation was carried in 2000 ml Erlenmeyer flask with agitation speed 120 rpm in shaker incubator (Scigenics Biotech Pvt. Ltd.), starter cultures was adjusted to approximately 5x105 CFU/ml with sterile saline solution. Experiments were carried out in triplicate and standard deviation was calculated. Amount of DHA produced in the final fermentation broth was estimated by 3, 5-Dinitrosalicylic acid (DNS) and HPLC method. Coagulation, filtration, lyophilization and vacuum evaporation were carried out to extract DHA from the fermentation broth in a pure form. Results: The optimum fermentation conditions for conversion of crude glycerol to DHA by G. oxydans were found to be fermentation period of 72 h with 10% glycerol concentration using modified MRS media at pH of 5.5 and 30ºC of temperature. The yield of DHA was 92.61 g/l. Conclusion: The present study can be potentially useful for the efficient DHA production on industrial scale. In 1000 ml of fermentation media that contain 100 g of crude glycerol, and metal ions, were obtained 92.61 g of DHA (92% conversion rate of glycerol to DHA) after 72 h of fermentation with G. oxydans.