P29: Optimization of Culture Conditions for Trehalose Production from Crude Glycerol by Recombinant Escherichia coli using Response Surface Method

Crude glycerol, the principal by-product of biodiesel industry, is expensive to purify for use in food, cosmetic, and pharmaceutical industries and therefore, alternative methods for utilizing this raw glycerol without purification are required. This work explored the potential of using this crude glycerol to produce trehalose by E. coli expressing trehalose biosynthetic genes (otsBA). Emerging areas of applications of trehalose are in pharmaceuticals as stabilizer of vaccines during storage, in cosmetics as a liposome stabilizer and in food industry as stable sweetener. Crude glycerol was acidified and then precipitated fatty acids were removed by centrifugation. Recombinant Escherichia coli cells were cultured in M9 medium supplemented with 20 g/L of fatty-acid free crude glycerol as a sole carbon source. IPTG induction was essential and 37^oC was better than 27^oC for the production. The concentrations of validamycin A, IPTG, and NaCl in medium were optimized using Box-Behnken Design. The highest amount of trehalose, 304 mg/L was obtained at 0.1 mM IPTG, 10 μM validamycin A, and 298 mM NaCl.