title: Intracellular metabolic changes of Clostridium acetobutylicum and promotion to butanol tolerance during biobutanol fermentation.
abstract: During the fermentation process, Clostridium acetobutylicum cells are often inhibited by the accumulated butanol. However, the mechanism underlying response of C. acetobutylicum to butanol stress remains poorly understood. This study was performed to clarify such mechanism through investigating the butanol stress-associated intracellular biochemical changes at acidogenesis phase (i.e., middle exponential phase) and solventogenesis phase (i.e., early stationary phase) by a gas chromatography-mass spectrometry-based metabolomics strategy. With the aid of partial least-squares-discriminant analysis, a pairwise discrimination between control group and butanol-treated groups was revealed, and 27 metabolites with variable importance in the projection value greater than 1 were identified. Under butanol stress, the glycolysis might be inhibited while TCA cycle might be promoted. Moreover, changes of lipids and fatty acids compositions, amino acid metabolism and osmoregulator concentrations might be the key factors involved in C. acetobutylicum metabolic response to butanol stress. It was suggested that C. acetobutylicum cells might change the levels of long acyl chain saturated fatty acids and branched-chain amino acids to maintain the integrity of cell membrane through adjusting membrane fluidity under butanol stress. The increased level of glycerol was considered to be correlated with osmoregulation and regulating redox balance. In addition, increased levels of some amino acids (i.e., threonine, glycine, alanine, phenylalanine, tyrosine, tryptophan, aspartate and glutamate) might also confer butanol tolerance to C. acetobutylicum. These results highlighted our knowledge about the response or adaptation of C. acetobutylicum to butanol stress, and would contribute to the construction of feasible butanologenic strains with higher butanol tolerance.
authors.affiliation: Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Yan-Feng
authors.initials: YF
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Tian
authors.affiliation: Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Zhi-Hua
authors.initials: ZH
authors.lastname: Ji
authors.affiliation: Institute of Environment and Health, Jianghan University, Wuhan 430056, China.
authors.forename: Mao-Yong
authors.initials: MY
authors.lastname: Song
authors.affiliation: Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China. Electronic address: lihao@mail.buct.edu.cn.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
mesh_terms: D056804:Biofuels / Q000382:microbiology*; D000440:Butanols / Q000378:metabolism* / Q000494:pharmacology*; D046969:Clostridium acetobutylicum / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005285:Fermentation / Q000187:drug effects; D042541:Intracellular Space / Q000187:drug effects* / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D056804:Biofuels; D000440:Butanols
keywords: Biobutanol; Butanol stress; Clostridium acetobutylicum; Gas chromatography–mass spectrometry; Metabolomics