Strategies for improved isopropanol–butanol production by a Clostridium strain from glucose and hemicellulose through consolidated bioprocessing

• Published in: Biotechnology for biofuels Vol. 10; no. 1; p. 118
• Main Authors: Xin, Fengxue, Chen, Tianpeng, Jiang, Yujiang, Dong, Weiliang, Zhang, Wenming, Zhang, Min, Wu, Hao, Ma, Jiangfeng, Jiang, Min
• Format: Journal Article
• Language: English
• Published: England BioMed Central 08.05.2017; BMC
• Subjects: Acetone; Acids; Alcohol; Alcohol dehydrogenase; Alcohols; Automobile engines; Bacteria; Batch culture; biodiesel; Biodiesel fuels; Biofuels; Biomass; Bioprocessing; buffering capacity; Buffers; Butanol; byproducts; Cellulase; Cellulose; Clostridium; Clostridium sp; Consolidation; Conversion; Cost engineering; Dehydrogenases; Diesel; economic feasibility; Economics; Enzymes; Ethanol; Extraction; Feasibility; Fermentation; fuel production; Fuels; Genomes; Glucose; Hemicellulose; In situ extraction; Integrated software; Isopropanol; isopropyl alcohol; Laboratories; Lignocellulose; lignocellulosic wastes; Metabolism; Metabolites; Monosaccharides; Phylogenetics; Polysaccharides; Productivity; Saccharides; saccharification; Secretion; Solvents; Substrates; Temperature effects; Temperature shift; thermal stability; value-added products; Wastes; xylanases; Clostridium sp; Polysaccharides; Xylanase; Butanol; In situ extraction; Temperature shift; Consolidated bioprocessing; Isopropanol
• DOI: 10.1186/s13068-017-0805-1
• ISSN: 1754-6834

High cost of traditional substrates and formation of by-products (such as acetone and ethanol) in acetone-butanol-ethanol (ABE) fermentation hindered the large-scale production of biobutanol. Here, we comprehensively characterized a newly isolated solventogenic and xylanolytic species, which could produce butanol at a high ratio with elimination of ethanol and conversion of acetone to more value-added product, isopropanol. Ultimately, direct butanol production from hemicellulose was achieved with efficient expression of indigenous xylanase by the novel strain via consolidated bioprocessing. A novel wild-type sp. strain NJP7 was isolated and characterized in this study, which was capable of fermenting monosaccharides, e.g., glucose into butanol via a fermentative acetone-isopropanol-butanol pathway. With enhancement of buffering capacity and alcohol dehydrogenase activities, butanol and isopropanol titer by sp. strain NJP7 was improved to 12.21 and 1.92 g/L, respectively, and solvent productivity could be enhanced to 0.44 g/L/h. Furthermore, with in situ extraction with biodiesel, the amount of butanol and isopropanol was finally improved to 25.58 and 5.25 g/L in the fed-batch mode. Meanwhile, sp. strain NJP7 shows capability of direct isopropanol-butanol production from hemicelluloses with expression of indigenous xylanase. 2.06 g/L of butanol and 0.54 g/L of isopropanol were finally achieved through the temperature-shift simultaneous saccharification and fermentation, representing the highest butanol production directly from hemicellulose. The co-production of isopropanol with butanol by the newly isolated sp. strain NJP7 would add on the economical values for butanol fermentation. Furthermore, the high isopropanol-butanol production with in situ extraction would also greatly enhance the economic feasibility for fermentative production of butanol-isopropanol in large scale. Meanwhile, its direct production of butanol-isopropanol from polysaccharides, hemicellulose through secretion of indigenous thermostable xylanase, shows great potential using lignocellulosic wastes for biofuel production.