Gaoxiang Qi1,2,3,4,5, Lian Xiong1,2,3,4, Xiaoqing Lin1,2,3,4, Chao Huang1,2,3,4, Hailong Li1,2,3,4, Xuefang Chen1,2,3,4, Xinde Chen6,7,8,9,10. 1. Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China. 2. Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China. 3. Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China. 4. Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China. 5. University of Chinese Academy of Sciences, Beijing, 100049, China. 6. Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China. cxd_cxd@hotmail.com. 7. Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China. cxd_cxd@hotmail.com. 8. Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China. cxd_cxd@hotmail.com. 9. Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China. cxd_cxd@hotmail.com. 10. , No. 2 Energy Road, Tianhe District, Guangzhou, 510640, China. cxd_cxd@hotmail.com.
Abstract
OBJECTIVE: To investigate the inhibiting effect of formic acid on acetone/butanol/ethanol (ABE) fermentation and explain the mechanism of the alleviation in the inhibiting effect under CaCO3 supplementation condition. RESULTS: From the medium containing 50 g sugars l-1 and 0.5 g formic acid l-1, only 0.75 g ABE l-1 was produced when pH was adjusted by KOH and fermentation ended prematurely before the transformation from acidogenesis to solventogenesis. In contrast, 11.4 g ABE l-1 was produced when pH was adjusted by 4 g CaCO3 l-1. The beneficial effect can be ascribed to the buffering capacity of CaCO3. Comparative analysis results showed that the undissociated formic acid concentration and acid production coupled with ATP and NADH was affected by the pH buffering capacity of CaCO3. Four millimole undissociated formic acid was the threshold at which the transformation to solventogenesis occurred. CONCLUSION: The inhibiting effect of formic acid on ABE fermentation can be alleviated by CaCO3 supplementation due to its buffering capacity.
OBJECTIVE: To investigate the inhibiting effect of formic acid on acetone/butanol/ethanol (ABE) fermentation and explain the mechanism of the alleviation in the inhibiting effect under CaCO3 supplementation condition. RESULTS: From the medium containing 50 g sugars l-1 and 0.5 g formic acid l-1, only 0.75 g ABE l-1 was produced when pH was adjusted by KOH and fermentation ended prematurely before the transformation from acidogenesis to solventogenesis. In contrast, 11.4 g ABE l-1 was produced when pH was adjusted by 4 g CaCO3 l-1. The beneficial effect can be ascribed to the buffering capacity of CaCO3. Comparative analysis results showed that the undissociated formic acid concentration and acid production coupled with ATP and NADH was affected by the pH buffering capacity of CaCO3. Four millimole undissociated formic acid was the threshold at which the transformation to solventogenesis occurred. CONCLUSION: The inhibiting effect of formic acid on ABE fermentation can be alleviated by CaCO3 supplementation due to its buffering capacity.