title: Development and physiological characterization of cellobiose-consuming Yarrowia lipolytica.
abstract: Yarrowia lipolytica is a promising production host for a wide range of molecules, but limited sugar consumption abilities prevent utilization of an abundant source of renewable feedstocks. In this study we created a Y. lipolytica strain capable of utilizing cellobiose as a sole carbon source by using endogenous promoters to express the cellodextrin transporter cdt-1 and intracellular β-glucosidase gh1-1 from Neurospora crassa. The engineered strain was also capable of simultaneous co-consumption of glucose and cellobiose. Although cellobiose was consumed slower than glucose when engineered strains were cultured with excess nitrogen, culturing with limited nitrogen led to cellobiose consumption rates comparable to those of glucose. Under limited nitrogen conditions, the engineered strain produced citric acid as a major product and we observed greater citric acid yields from cellobiose (0.37 g/g) than glucose (0.28 g/g). Culturing with a sole carbon source of either glucose or cellobiose induced additional differences on cell physiology and metabolism and a link is suggested to evasion of glucose-sensing mechanisms through intracellular creation and consumption of glucose. We ultimately applied this cellobiose-utilization system to produce citric acid from bioconversion of crystalline cellulose through simultaneous saccharification and fermentation (SSF).
authors.affiliation: Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801; Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinios, 61801; Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.
authors.forename: Stephan
authors.initials: S
authors.lastname: Lane
authors.forename: Shuyan
authors.initials: S
authors.lastname: Zhang
authors.forename: Na
authors.initials: N
authors.lastname: Wei
authors.forename: Christopher
authors.initials: C
authors.lastname: Rao
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Jin
mesh_terms: D056804:Biofuels / Q000382:microbiology; D002475:Cellobiose / Q000378:metabolism*; D002482:Cellulose / Q000031:analogs & derivatives / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism; D003912:Dextrins / Q000378:metabolism; D005285:Fermentation; D015870:Gene Expression; D008031:Lignin / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D009492:Neurospora crassa / Q000201:enzymology / Q000235:genetics; D025062:Yarrowia / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D056804:Biofuels; D003912:Dextrins; C036909:lignocellulose; D002475:Cellobiose; D019343:Citric Acid; D002482:Cellulose; D008031:Lignin; C068994:cellodextrin; D001617:beta-Glucosidase
keywords: biofuels; biotransformation; cellodextrin; citric acid; lignocellulose; lipid