title: Recent advances to improve fermentative butanol production: genetic engineering and fermentation technology.
abstract: Butanol has recently attracted attention as an alternative biofuel because of its various advantages over other biofuels. Many researchers have focused on butanol fermentation with renewable and sustainable resources, especially lignocellulosic materials, which has provided significant progress in butanol fermentation. However, there are still some drawbacks in butanol fermentation in terms of low butanol concentration and productivity, high cost of feedstock and product inhibition, which makes butanol fermentation less competitive than the production of other biofuels. These hurdles are being resolved in several ways. Genetic engineering is now available for improving butanol yield and butanol ratio through overexpression, knock out/down, and insertion of genes encoding key enzymes in the metabolic pathway of butanol fermentation. In addition, there are also many strategies to improve fermentation technology, such as multi-stage continuous fermentation, continuous fermentation integrated with immobilization and cell recycling, and the inclusion of additional organic acids or electron carriers to change metabolic flux. This review focuses on the most recent advances in butanol fermentation especially from the perspectives of genetic engineering and fermentation technology.
authors.affiliation: Laboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Jin
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Institute of Advanced Study, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; Laboratory of Soil Microbiology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, 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 Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, 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: D056804:Biofuels / Q000600:supply & distribution; D000440:Butanols / Q000378:metabolism*; D003013:Clostridium / Q000235:genetics / Q000378:metabolism; D004579:Electron Transport; D005285:Fermentation / Q000235:genetics; D005818:Genetic Engineering; D008031:Lignin / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics
chemical_list: D056804:Biofuels; D000440:Butanols; C036909:lignocellulose; D008031:Lignin
keywords: Butanol fermentation; Butanol-producing microorganisms; Fermentation technology; Genetic engineering; Lignocellulosic material