Improved n-butanol production from lignocellulosic hydrolysate by Closthdium strain screening and culture-medium optimization

摘要

AbstractThe use of lignocellulosic hydrolysate is a promising strategy to make fuel and chemical production feasible through biological processes. The major challenges facing this process are the presence of inhibitors in hydrolysate, as furan derivatives and phenolic compounds, and the inefficient consumption of the xylose found in hydrolysate. Therefore, this study aimed to select ideal Clostridium strains and an optimal medium for microbiological production ofn-butanol from sugarcane straw hydrolysate with high yield and productivity. From a screening of twelve Clostridium strains, two strains stood out: Clostridium saccharoperbutylacetonicum DSM 14923, by its potential to produce high titer ofn-butanol (4.95 g/L from 11.6 g/L glucose and 3.6 g/L xylose), and Clostridium saccharobutylicum DSM 13864, by its capacity to concomitantly consume similar quantities of glucose and xylose. Optimization of culture medium and inoculum preparation allowed an improvement inn-butanol production from 0.65 g/L for 5.39 g/L. Moreover, with optimized medium, a higher tolerance to lignocellulosic hydrolysate was obtained, avoiding a premature end to fermentation at hydrolysate and enabling the cultivation of these strains in 79% pure lignocellulosic hydrolysate. Among all the strains tested for lignocellulosic hydrolysate fermentation, C. saccharobutylicum DSM 13864 has the best performance. This strain, in a culture medium composed by 79% of pure lignocellulosic hydrolysate, showed a consumption of 95% of all sugar available (34 g/L of glucose and 22 g/L of xylose) and a total acetone,n-butanol, and ethanol (ABE) production of 10.33 g/L, being the most suitable strain forn-butanol production using this substrate.Highlights•Sugarcane straw hydrolysate was studied as feedstock for ABE fermentation.•ABE fermentation with hydrolysed medium were compared in twelveClostridiumstrains.•Optimization of cultivation parameters improved butanol and hydrolysate tolerance.•11 g/L of solvents were produced from 79% of pure lignocellulosic hydrolysate medium.