title: Increased ethanol production by deletion of HAP4 in recombinant xylose-assimilating Saccharomyces cerevisiae.
abstract: The Saccharomyces cerevisiae HAP4 gene encodes a transcription activator that plays a key role in controlling the expression of genes involved in mitochondrial respiration and reductive pathways. This work examines the effect of knockout of the HAP4 gene on aerobic ethanol production in a xylose-utilizing S. cerevisiae strain. A hap4-deleted recombinant yeast strain (B42-DHAP4) showed increased maximum concentration, production rate, and yield of ethanol compared with the reference strain MA-B42, irrespective of cultivation medium (glucose, xylose, or glucose/xylose mixtures). Notably, B42-DHAP4 was capable of producing ethanol from xylose as the sole carbon source under aerobic conditions, whereas no ethanol was produced by MA-B42. Moreover, the rate of ethanol production and ethanol yield (0.44 g/g) from the detoxified hydrolysate of wood chips was markedly improved in B42-DHAP4 compared to MA-B42. Thus, the results of this study support the view that deleting HAP4 in xylose-utilizing S. cerevisiae strains represents a useful strategy in ethanol production processes.
authors.affiliation: Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-0046, Japan. a-matsushika@aist.go.jp.
authors.forename: Akinori
authors.initials: A
authors.lastname: Matsushika
authors.affiliation: Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-0046, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Hoshino
mesh_terms: D000693:Anaerobiosis; D023081:CCAAT-Binding Factor / Q000172:deficiency* / Q000235:genetics; D000431:Ethanol / Q000378:metabolism* / Q000600:supply & distribution*; D005947:Glucose / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D014934:Wood / Q000737:chemistry / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*
chemical_list: D023081:CCAAT-Binding Factor; C061437:HAP4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D014994:Xylose; D005947:Glucose
keywords: Ethanol production; HAP4 gene; Lignocellulosic hydrolysate; Saccharomyces cerevisiae; Xylose