Location: Bioenergy ResearchTitle: Reprogrammed pathways of genetically engineered industrial yeast for xylose utilization
Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/26/2018
Publication Date: 4/27/2018
Citation: Liu, Z.L. 2018. Reprogrammed pathways of genetically engineered industrial yeast for xylose utilization [abstract]. Biotechnology for Fuels and Chemicals Symposium Proceedings. M27.
Technical Abstract: Conventional industrial yeast Saccharomyces cerevisiae is superb in glucose consumption but limited in uptake and utilization of xylose. Introduction of heterologous genes is commonly used to enable xylose metabolism. In this study, we report reprogrammed pathways for a genetically engineered industrial yeast derivative stain NRRL Y-50463 that enabled its utilization of xylose using pathway-based qRT-PCR array analyses. Strain Y-50463 has a genetic background with a synthesized yeast xylose isomerase gene YXI in its chromosome XV and a set of plasmid-carried heterologous genes from Scheffersomyces stipitis, including xylitol dehydrogenase, xylulokinase, and two xylose transporter genes XUT4 and XUT6. The extremely high levels of constitutive expression of YXI served as a necessary initiating step for xylose metabolism facilitated by the heterologous xylose transporter and utilization genes. The highly activated transketolase and transaldolase genes TKL1, TKL2, TAL1 and NQM1 as well as their complex interactions in the non-oxidative pentose phosphate pathway were critically important for the serial steps of sugar transformation to drive the metabolic flow of sugar into glycolysis. The introduced YXI-led heterologous gene set changed gene expression profiles of the yeast. Consequently, the altered gene interactions favored the non-oxidative pentose phosphate pathway in Y-50463, which enabled xylose to be transformed into glycolysis for increased ethanol production. Our results also suggest the industrial yeast, with many desirable characteristics, can be further improved to serve as a better delivery vehicle for new strain development in efficient lignocellulose-to-advanced biofuels production.