title: Engineered xylose utilization enhances bio-products productivity in the cyanobacterium Synechocystis sp. PCC 6803.
abstract: Hydrolysis of plant biomass generates a mixture of simple sugars that is particularly rich in glucose and xylose. Fermentation of the released sugars emits CO2 as byproduct due to metabolic inefficiencies. Therefore, the ability of a microbe to simultaneously convert biomass sugars and photosynthetically fix CO2 into target products is very desirable. In this work, the cyanobacterium, Synechocystis 6803, was engineered to grow on xylose in addition to glucose. Both the xylA (xylose isomerase) and xylB (xylulokinase) genes from Escherichia coli were required to confer xylose utilization, but a xylose-specific transporter was not required. Introduction of xylAB into an ethylene-producing strain increased the rate of ethylene production in the presence of xylose. Additionally, introduction of xylAB into a glycogen-synthesis mutant enhanced production of keto acids. Isotopic tracer studies found that nearly half of the carbon in the excreted keto acids was derived from the engineered xylose metabolism, while the remainder was derived from CO2 fixation.
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA.
authors.forename: Tai-Chi
authors.initials: TC
authors.lastname: Lee
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Xiong
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA.
authors.forename: Troy
authors.initials: T
authors.lastname: Paddock
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA.
authors.forename: Damian
authors.initials: D
authors.lastname: Carrieri
authors.affiliation: Institute of Plant Biology, National Taiwan University, Taipei, Taiwan.
authors.forename: Ing-Feng
authors.initials: IF
authors.lastname: Chang
authors.affiliation: Institute of Pharmacology, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hui-Fen
authors.initials: HF
authors.lastname: Chiu
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Ungerer
authors.affiliation: Department of Genome Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: hjuo@kmu.edu.tw.
authors.forename: Suh-Hang
authors.initials: SH
authors.lastname: Hank Juo
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA. Electronic address: Pinching.Maness@nrel.gov.
authors.forename: Pin-Ching
authors.initials: PC
authors.lastname: Maness
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA. Electronic address: Jianping.Yu@nrel.gov.
authors.forename: Jianping
authors.initials: J
authors.lastname: Yu
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000096:biosynthesis / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D060847:Metabolic Engineering / Q000379:methods*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000235:genetics; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism; D014994:Xylose / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D014994:Xylose; D017853:Phosphotransferases (Alcohol Group Acceptor); C032700:xylulokinase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase
keywords: Cyanobacteria; Isotopic tracing; Photomixotrophic growth; Xylose utilization