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Lactic acid, traditionally obtained through fermentation process, presents numerous applications in different industrial segments, including production of biodegradable polylactic acid (PLA). Development of low cost substrate fermentations could improve economic viability of lactic acid production, through the use of agricultural residues as lignocellulosic biomass. Studies regarding the use of sugarcane bagasse hydrolysates for lactic acid production by Lactobacillus spp. are reported. First, five strains of Lactobacillus spp. were investigated for one that had the ability to consume xylose efficiently. Subsequently, biomass fractionation was performed by dilute acid and alkaline pretreatments, and the hemicellulose hydrolysate (HH) fermentability by the selected strain was carried out in bioreactor. Maximum lactic acid concentration and productivity achieved in HH batch were 42.5 g/L and 1.02 g/L h, respectively. Hydrolyses of partially delignified cellulignin (PDCL) by two different enzymatic cocktails were compared. Finally, fermentation of HH and PDCL hydrolysate together was carried out in bioreactor in a hybrid process: saccharification and co‐fermentation with an initial enzymatic hydrolysis. The high fermentability of these process herein developed was demonstrated by the total consumption of xylose and glucose by Lactobacillus pentosus, reaching at 65.0 g/L of lactic acid, 0.93 g/g of yield, and 1.01 g/L h of productivity. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2718, 2019

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.

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