title: High acetone-butanol-ethanol production in pH-stat co-feeding of acetate and glucose.
abstract: We previously reported the metabolic analysis of butanol and acetone production from exogenous acetate by (13)C tracer experiments (Gao et al., RSC Adv., 5, 8486-8495, 2015). To clarify the influence of acetate on acetone-butanol-ethanol (ABE) production, we first performed an enzyme assay in Clostridium saccharoperbutylacetonicum N1-4. Acetate addition was found to drastically increase the activities of key enzymes involved in the acetate uptake (phosphate acetyltransferase and CoA transferase), acetone formation (acetoacetate decarboxylase), and butanol formation (butanol dehydrogenase) pathways. Subsequently, supplementation of acetate during acidogenesis and early solventogenesis resulted in a significant increase in ABE production. To establish an efficient ABE production system using acetate as a co-substrate, several shot strategies were investigated in batch culture. Batch cultures with two substrate shots without pH control produced 14.20 g/L butanol and 23.27 g/L ABE with a maximum specific butanol production rate of 0.26 g/(g h). Furthermore, pH-controlled (at pH 5.5) batch cultures with two substrate shots resulted in not only improved acetate consumption but also a further increase in ABE production. Finally, we obtained 15.13 g/L butanol and 24.37 g/L ABE at the high specific butanol production rate of 0.34 g/(g h) using pH-stat co-feeding method. Thus, in this study, we established a high ABE production system using glucose and acetate as co-substrates in a pH-stat co-feeding system with C. saccharoperbutylacetonicum N1-4.
authors.affiliation: Laboratory of Microbial Technology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Ming
authors.initials: M
authors.lastname: Gao
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; Laboratory of Microbial Environmental Protection, Tropical Microbiology Unit, Center for International Education and Research of Agriculture, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Tashiro
authors.affiliation: Department of Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Qunhui
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; Laboratory of Microbial Environmental Protection, Tropical Microbiology Unit, Center for International Education and Research of Agriculture, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakai
authors.affiliation: Laboratory of Microbial Technology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; Laboratory of Functional Food Design, Department of Functional Metabolic Design, Bio-Architecture Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. Electronic address: sonomoto@agr.kyushu-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sonomoto
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D000085:Acetates / Q000378:metabolism* / Q000494:pharmacology; D000096:Acetone / Q000378:metabolism* / Q000494:pharmacology; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D019149:Bioreactors; D002262:Carboxy-Lyases / Q000378:metabolism; D003013:Clostridium / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D015256:Coenzyme A-Transferases / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D010709:Phosphate Acetyltransferase / Q000378:metabolism
chemical_list: D000085:Acetates; D000096:Acetone; D000431:Ethanol; D020001:1-Butanol; D000429:Alcohol Oxidoreductases; C060833:butanol dehydrogenase; D010709:Phosphate Acetyltransferase; D015256:Coenzyme A-Transferases; D002262:Carboxy-Lyases; C023743:acetoacetate decarboxylase; D005947:Glucose
keywords: Acetate; Acetone–butanol–ethanol production; Clostridium saccharoperbutylacetonicum; Enzymatic analysis; pH-stat