title: Molecular cloning and expression of fungal cellobiose transporters and β-glucosidases conferring efficient cellobiose fermentation in Saccharomyces cerevisiae.
abstract: Cellobiose was once regarded as a byproduct that should be removed from biomass hydrolysates because of its inhibitory activity to cellulases. It was revealed, however, that cellobiose could serve as a co-substrate for xylose fermentation by engineered Saccharomyces cerevisiae. Despite its advantages, to date, little is known about cellodextrin transporters that endow S. cerevisiae with cellobiose transporting ability. In this study, engineered S. cerevisiae strains capable of fermenting cellobiose were constructed by expressing various fungal cellobiose transporters and intracellular β-glucosidases. Among them, the strain expressing a putative sugar transporter from Penicillium chrysogenum (Pc_ST) and β-glucosidase from Thielavia terrestris (Tt_BG) showed an improved cellobiose fermentation performance compared to the strain expressing a cellodextrin transporter from Neurospora crassa (Nc_CDT-1) and β-glucosidase from N. crassa (Nc_GH1-1). Cellobiose fermentation by S. cerevisiae Pc_ST/Tt_BG under microaerobic conditions resulted in 14.5±0.5g/L of final ethanol concentration with a yield of 0.37±0.01g ethanol/g cellobiose, which are 22% and 26% higher than the corresponding values of S. cerevisiae Nc_CDT-1/Nc_GH1-1. These results suggest that the yield and rate of cellobiose fermentation can be improved by adopting optimal pairs of cellobiose transporters and β-glucosidase.
authors.affiliation: Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 151-742, Republic of Korea; Interdisciplinary Program for Bioengineering, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Yi-Hyun
authors.initials: YH
authors.lastname: Bae
authors.affiliation: Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Kyeong-Hyeon
authors.initials: KH
authors.lastname: Kang
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 1206 West Gregory Dr., Urbana, IL 61801, USA.
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Jin
authors.affiliation: Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 151-742, Republic of Korea; Interdisciplinary Program for Bioengineering, Seoul National University, Seoul 151-742, Republic of Korea. Electronic address: jhseo94@snu.ac.kr.
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Seo
mesh_terms: D002475:Cellobiose / Q000378:metabolism*; D003001:Cloning, Molecular; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D001617:beta-Glucosidase / Q000235:genetics* / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D002475:Cellobiose; D001617:beta-Glucosidase
keywords: Cellobiose fermentation; Cellodextrin transporter; Ethanol; Saccharomyces cerevisiae; β-glucosidase