Plant sweet and yeast MSF transporter capable of transporting different sugars simultaneously

Inventors

Jin, Yong-Su • KUANYSHEV, Nurzhan • LIU, Jing-Jing • DEEWAN, Anshu • RAO, Christopher V. • PANNEERSELVAM, Balaji • Shukla, Diwakar • JAGTAP, Sujit

Assignees

University of Illinois System

Abstract

The present disclosure provides genetically engineered microorganisms for the simultaneous fermentation of pentose and hexose sugars, for example, glucose and xylose. The microorganisms can be modified to express AtSWEET polypeptides, LST1 polypeptides, mutants thereof, homologs thereof or combinations thereof. Also provided are methods of co-fermenting hexose and pentose sugars, methods of increasing the conversion of lignocellulosic biomass via microbial fermentation, and methods of generating biofuel.

Core Innovation

Genetically engineered yeasts are provided for simultaneous fermentation or co-fermentation or co-utilization of glucose and xylose by expressing heterologous plant SWEET transporters, including Arabidopsis thaliana SWEET7 (AtSWEET7) and/or other SWEET transporters, and optionally an oleaginous yeast transporter LST1_205437. The invention addresses glucose repression and inhibition of native xylose uptake, which reduce simultaneous utilization and promote sequential fermentation behavior.

The invention uses recombinant yeast comprising one or more heterologous polynucleotides encoding SWEET transporter polypeptides with high sequence identity to SEQ ID NO: 3, together with specific transporter amino-acid substitutions. For AtSWEET7, the Asn145Ser substitution, the Ala175Phe substitution, or both substitutions are used to address glucose inhibition behavior and support improved co-transport.

The approach also includes heterologous transporter expression in yeast lines while excluding expression of selected endogenous or heterologous hexose and galactose transporters to reduce competing sugar transport routes. Experimental narratives in the document describe mixed-sugar fermentation profiles showing co-consumption versus sequential behavior, uptake-kinetics differences among ScGal2, LST1_205437, and AtSWEET7, and mutation effects associated with improved co-consumption and reduced glucose inhibition.

Claims Coverage

The claims include one independent claim directed to a recombinant yeast comprising heterologous polynucleotides encoding an AtSWEET7 transporter polypeptide with constrained sequence identity and specific Asn145 and/or Ala175 substitutions. The claim set further adds transporter-expression exclusions, optional putative glucose/xylose transporters, and co-utilization fermentation contexts including ethanol production and continuous bioreactor conversion of lignocellulosic biomass, totaling multiple inventive features.

Overall, the claim coverage centers on recombinant yeast expressing an AtSWEET7 transporter with at least 90% sequence identity to SEQ ID NO: 3 and specific Asn145 and/or Ala175 substitutions, with exclusions for certain hexose and galactose transporters, optional putative glucose/xylose transporters, and co-utilization fermentation contexts including ethanol production from lignocellulosic biomass and continuous conversion in a bioreactor.

Stated Advantages

Documented Applications