Solid-supported microorganism of Burkholderia cenocepacia cultured via solid state fermentation for biodiesel production: Optimization and kinetics

The objectives of this work were to investigate the optimization and kinetics of ethanolysis for biodiesel production by solid-supported microorganism of Burkholderia cenocepacia cultured via solid state fermentation (SSF). Operational parameters affecting the biodiesel yield were successively optimized by Plackett–Burman design followed with Box–Behnken method. The biodiesel yield of ca. 91.3% was verified under the optimized conditions of 4.3:1 of alcohol/oil molar ratio, 1.63g/mL of solid-supported microorganism mass, 4.6% (wt/wt) of water and 44.2°C of temperature. Furthermore, the kinetic model was developed on the basis of Ping Pong Bi Bi mechanism with competitive alcohol inhibition. The proposed model had a satisfactory correlation coefficient of R2=97.60%, and kinetic parameters of vmax=3.88mmol/(Lmin), KmTG=0.27mmol/L, KmC2H5OH=4.03mmol/L, and Ki=0.34mmol/L were obtained. In addition, the calculated activation energy (Ea) of the biocatalyst was estimated to be 37.95kJ/mol. The rate-limiting reaction step for the ethanolysis by solid-supported microorganism in tert-butanol was demonstrated to be the conversion of di-glyceride to mono-glyceride. Finally, the reusability of the solid-supported microorganism was evaluated in successive batch reactions and presented 66.9% of original activity after 288h repeated usage.