Biobutanol production by batch and fed-batch fermentations from the green coconut husk hydrolysate using C. beijerinckii ATCC 10132

The present study evaluates the potential of green coconut fiber in the production of cellulosic butanol by ABE (acetone-butanol-ethanol) fermentation, using Clostridium beijerinckii ATCC 10132. Batch fermentation tests were carried out to investigate the influence of some nutrients (sources of nitrogen and mineral medium) in the supplementation of the enzymatic hydrolyzate of pretreated green coconut husks, as well as the effects of the initial concentration of sugars and the initial concentration of inoculum on the production of butanol among other fermentation products. The mode of conducting the process in a fed-batch was carried out to improve the yield and productivity of butanol. Using the enzymatic hydrolyzate obtained with 9 g/L of sugars (glucose + xylose), the ABE fermentation reached a yield of 0.53 g/g after 96 h, in which 3.4 g/L of butanol was obtained. The absence or insufficiency of some nutrients (minerals and phosphate buffer) resulted in low yields of ABE products, indicating the importance of adapting supplements to the chosen fermentation medium and the type of microorganism used. Fed-batch increased productivity in ABE fermentation (0.08 g/L.h for butanol). The results indicate that green coconut residues have energy potential and are low-cost raw materials for the biotechnological production of butanol, as an alternative and renewable product.