title: Candida utilis assimilates oligomeric sugars in rice straw hydrolysate via the Calcium-Capturing-by-Carbonation (CaCCO) process for glutathione- and cell-biomass production.
abstract: Rice-straw hydrolysate (RSH) prepared via the CaCCO (Calcium Capturing by Carbonation) process contains not only monosaccharides but also significant amounts of oligosaccharides. In this study, a glutathione-producing yeast, Candida utilis NBRC 0626, was found to assimilate those oligosaccharides. The yields of reduced glutathione (GSH) and dry cell weight (DCW) per consumed sugars in a medium with RSH after 72h incubation were 10.1mg/g-sugars and 0.49g/g-sugars, respectively. The yields were comparative to those in a medium containing a model monosaccharide mix, suggesting that the assimilated oligosaccharides contribute to additional GSH and DCW production. Glycosyl linkage analysis indicated that the yeast could cleave xylose-, galactose-, and arabinose residues as well as glucose residues at the non-reducing ends. After 72h incubation, 99.1% of the total glucose residues and 84.2% of the total xylose residues in RSH were depleted. Thus the yeast could be applied for efficient utilization of lignocellulosic hydrolysates.
authors.affiliation: National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Koyama
authors.affiliation: National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
authors.affiliation: National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Ike
authors.affiliation: National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan. Electronic address: tokuyasu@affrc.go.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Tokuyasu
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002175:Candida / Q000145:classification / Q000166:cytology / Q000502:physiology*; D049109:Cell Proliferation / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D005978:Glutathione / Q000096:biosynthesis* / Q000302:isolation & purification; D006868:Hydrolysis; D012275:Oryza / Q000737:chemistry / Q000382:microbiology*; D035261:Plant Components, Aerial / Q000737:chemistry / Q000382:microbiology*; D013045:Species Specificity; D014994:Xylose / Q000378:metabolism*
chemical_list: D014994:Xylose; D005978:Glutathione; D005947:Glucose; D002118:Calcium
keywords: Candida utilis; Cell biomass; Glutathione; Oligosaccharides; Rice straw