title: Repeated fermentation from raw starch using Saccharomyces cerevisiae displaying both glucoamylase and α-amylase.
abstract: A diploid yeast strain displaying both α-amylase and glucoamylase was developed for repeated fermentation from raw starch. First, the construct of α-amylase was optimized for cell surface display, as there have been no reports of α-amylase-displaying yeast. The modified yeast displaying both glucoamylase and α-amylase produced 46.5 g/l of ethanol from 200 g/l of raw corn starch after 120 h of fermentation, and this was 1.5-fold higher when compared to native α-amylase-displaying yeast. Using the glucoamylase and modified α-amylase co-displaying diploid strain, we repeated fermentation from 100g/l of raw starch for 23 cycles without the loss of α-amylase or glucoamylase activity. The average ethanol productivity and yield during repeated fermentation were 1.61 g/l/h and 76.6% of the theoretical yield, respectively. This novel yeast may be useful for reducing the cost of bio-ethanol production and may be suitable for industrial-scale bio-ethanol production.
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
authors.forename: Syun-ichi
authors.initials: S
authors.lastname: Yamakawa
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Yamada
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tanaka
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ogino
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D001709:Biotechnology / Q000379:methods*; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000431:Ethanol; D013213:Starch; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase