Optimization of culture medium for improve glycerol consumption and 1,3-propanediol production by Clostridium beijerinckii DSM 791

Biodiesel is a promising alternative biofuel, as its production increases, so does production of the principle co-product, glycerol. The present study aimed at maximizing the glycerol consumption and 1,3-propanediol production by Clostridium beijerinckii DSM 791, using sequential experimental design methodology for optimizing the concentrations of nutrients for fermentation medium. Three sequential experimental designs were performed: Planckett & Burman, fractional factorial (2^6-2) and central composite rotational. That last one was used for better visualizing the optimum conditions. The following nutrients of the medium composition were evaluated: urea, yeast extract, sodium acetate, KH₂PO₄, K₂HPO₄, MgSO₄, MnSO₄, FeSO₄, glycerol, butyric acid, glucose and CaCO₃. Urea, KH₂PO₄, MgSO₄, MnSO₄, FeSO₄, butyric acid, glucose and CaCO₃ were removed from the medium optimization since they did not present significant statistical effect on 1,3-propanediol production. The optimal concentrations of yeast extract, sodium acetate, K₂HPO₄ and glycerol predicted by the optimization were as follows: 0.5g/L, 0.005g/L, 5g/L and 8g/L, respectively, which were validated experimentally. By the use of the desirability function, it was possible to maximize the percentage glycerol consumption and 1,3-propanediol production simultaneously, which resulted in values for percentage glycerol consumption of 100% and for 1,3-propanodiol production of 3.9g/L. These values corresponded to 1,3-propanediol yield of 0.48g/g and productivity of 0.32g/L.h in 12 hours of fermentation. The results showed that the use of sequential experimental design and the use of the desirability function can be used satisfactorily to optimize the 1,3-propanediol fermentation by Clostridium beijerinckii DSM 791.