1,3-PROPANEDIOL: STATISTICAL OPTIMIZATION OF MEDIUM TO IMPROVE PRODUCTION BY Clostridium beijerinckii DSM 791

Abstract

Biodiesel is a promising alternative biofuel, and as its production increases, so does production of the principal co-product, glycerol. The present study is aimed at maximizing the glycerol consumption and 1,3-propanediol (1,3-PDO) production by C. beijerinckii DSM 791, using sequential experimental design methodology for optimization of nutrients concentration for the fermentation medium. Three sequential experimental designs were performed: Plackett-Burman, fractional factorial and central composite rotational. The following nutrients of the medium were evaluated: urea, yeast extract, C₂H₃NaO₂, KH₂PO₄, K₂HPO₄, MgSO₄.7H₂O, MnSO₄.H₂O, FeSO₄.7H₂O, glycerol, butyric acid, glucose and CaCO₃. Urea, KH₂PO₄, MgSO₄.7H₂O, MnSO₄.H₂O, FeSO₄.7H₂O, butyric acid, glucose and CaCO₃ were removed from the medium optimization since they had an insignificant statistical effect on 1,3-PDO production. The optimal concentrations of yeast extract, C₂H₃NaO₂, K₂HPO₄ and glycerol predicted by the optimization were as follows (g/l): 0.5, 0.005, 5 and 8, respectively, which were validated experimentally. Desirability function allows the maximization of the 1,3-PDO production and percentage glycerol consumption simultaneously, which resulted in yield of 0.58 mol/mol of 1,3-PDO and 100 % of glycerol consumption. The results showed that the use of sequential experimental design and the use of the desirability function led to the optimization of the 1,3-PDO fermentation by C. beijerinckii DSM 791.