title: CaCO3supplementation alleviates the inhibition of formic acid on acetone/butanol/ethanol fermentation by Clostridium acetobutylicum.
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 CaCO3supplementation condition.
  
  
  RESULTS
  From the medium containing 50 g sugars l-1and 0.5 g formic acid l-1, only 0.75 g ABE l-1was 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-1was produced when pH was adjusted by 4 g CaCO3l-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.
  
  
  CONCLUSIONS
  The inhibiting effect of formic acid on ABE fermentation can be alleviated by CaCO3supplementation due to its buffering capacity.
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Gaoxiang
authors.initials: G
authors.lastname: Qi
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China.
authors.forename: Lian
authors.initials: L
authors.lastname: Xiong
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Lin
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Huang
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China.
authors.forename: Xuefang
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, China. cxd_cxd@hotmail.com.|Guangdong Key Laboratory of New and Renewable Energy Research and Development, Chinese Academy of Sciences, Guangzhou, 510640, China. cxd_cxd@hotmail.com.|Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China. cxd_cxd@hotmail.com.|Xuyi Center of Attapulgite Applied Technology Research Development & Industrialization, Chinese Academy of Sciences, Xuyi, 211700, China. cxd_cxd@hotmail.com.|, No. 2 Energy Road, Tianhe District, Guangzhou, 510640, China. cxd_cxd@hotmail.com.
authors.forename: Xinde
authors.initials: X
authors.lastname: Chen
mesh_terms: D000096:Acetone / Q000378:metabolism*; D000440:Butanols / Q000378:metabolism*; D002119:Calcium Carbonate / Q000378:metabolism*; D046969:Clostridium acetobutylicum / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005561:Formates / Q000378:metabolism*
chemical_list: D000440:Butanols; D005561:Formates; C030544:formic acid; D000096:Acetone; D000431:Ethanol; D002119:Calcium Carbonate
keywords: Acetone/butanol/ethanol fermentation; Acid crash; Calcium carbonate; Clostridium acetobutylicum; Formic acid; Lignocellulosic hydrolysate; PH adjustment methods