(624c) Supplementation of Growth Medium with Biochar Enhances Production of Acetone-Butanol-Ethanol from Switchgrass By Clostridium Beijerinckii

ABE fermentation medium typically contains expensive P2 buffer and mineral stock solutions as both solutions account for approximately 75% of the total medium cost. Biochar could serve as an inexpensive pH buffer and source of mineral and trace metal nutrients for ABE fermentations. In this study, Clostridium beijerinckii was used for the production of acetone, butanol and ethanol (ABE) using lignocellulose-derived sugars, switchgrass hydrolysates, as substrates. Buffer and mineral stock solutions were replaced with biochar from four different sources (switchgrass, SGBC; forage sorghum, FSBC; redcedar, RCBC; and poultry litter, PLBC). Medium containing non-detoxified switchgrass hydrolysates, P2 buffer and minerals without biochar (Ctrl) was used as a control. Fermentations were performed at 35 ÌŠC in 250 mL bottles with a 50 mL working volume under anaerobic condition without shaking for 72 h. Liquid samples were withdrawn at 12 h intervals for organic acid and ABE analysis. Supplementation of non-detoxified switchgrass hydrolysate medium with biochar resulted in higher ABE concentration (SGBC, 17.0 g/L; RCBC, 17.3 g/L; PLBC, 16.4 g/L) than the Ctrl medium without biochar (10.1 g/L). It is inferred that biochar provided minerals and buffer to C. beijerinckii and possibly played a role in reducing the toxicity of microbial inhibitors typically present in the lignocellulosic biomass hydrolysates (LBH). This study demonstrates that biochar can serve as a cost-effective substitute for mineral and buffer solutions component of ABE fermentation medium and additive for effective fermentation of (LBH) to ABE.