Belisa B de Sales1, Bruna Scheid1, Davi L Gonçalves1, Marilia M Knychala1, Akinori Matsushika2, Elba P S Bon3, Boris U Stambuk4. 1. Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, 88040-900, Brazil. 2. Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-0046, Japan. 3. Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, 21941-909, Brazil. 4. Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, 88040-900, Brazil. boris.stambuk@ufsc.br.
Abstract
OBJECTIVES: Since uptake of xylose limits its fermentation, we aimed to identify novel sugar transporters from Scheffersomyces stipitis that allow xylose uptake and fermentation by engineered Saccharomyces cerevisiae. RESULTS: An hxt-null S. cerevisiae strain, lacking the major hexose transporters (hxt1Δ-hxt7Δ and gal2Δ) but having high xylose reductase, xylitol dehydrogenase and xylulokinase activities, was transformed with a genomic DNA library from S. stipitis. Four plasmids allowing growth on xylose contained three genes encoding sugar transporters: the previously characterized XUT1 permease, and two new genes (HXT2.6 and QUP2) not previously identified as xylose transporters. High cell density fermentations with the recombinant strains showed that the XUT1 gene allowed ethanol production from xylose or xylose plus glucose as carbon sources, while the HXT2.6 permease produced both ethanol and xylitol, and the strain expressing the QUP2 gene produced mainly xylitol during xylose consumption. CONCLUSIONS: Cloning novel sugar transporters not previously identified in the S. stipitis genome using an hxt-null S. cerevisiae strain with a high xylose-utilizing pathway provides novel promising target genes for improved lignocellulosic ethanol production by yeasts.
OBJECTIVES: Since uptake of xylose limits its fermentation, we aimed to identify novel sugar transporters from Scheffersomyces stipitis that allow xylose uptake and fermentation by engineered Saccharomyces cerevisiae. RESULTS: An hxt-null S. cerevisiae strain, lacking the major hexose transporters (hxt1Δ-hxt7Δ and gal2Δ) but having high xylose reductase, xylitol dehydrogenase and xylulokinase activities, was transformed with a genomic DNA library from S. stipitis. Four plasmids allowing growth on xylose contained three genes encoding sugar transporters: the previously characterized XUT1 permease, and two new genes (HXT2.6 and QUP2) not previously identified as xylose transporters. High cell density fermentations with the recombinant strains showed that the XUT1 gene allowed ethanol production from xylose or xylose plus glucose as carbon sources, while the HXT2.6 permease produced both ethanol and xylitol, and the strain expressing the QUP2 gene produced mainly xylitol during xylose consumption. CONCLUSIONS: Cloning novel sugar transporters not previously identified in the S. stipitis genome using an hxt-null S. cerevisiae strain with a high xylose-utilizing pathway provides novel promising target genes for improved lignocellulosic ethanol production by yeasts.
Authors: Shalley Sharma; Eldho Varghese; Anju Arora; K N Singh; Surender Singh; Lata Nain; Debarati Paul Journal: Front Bioeng Biotechnol Date: 2018-09-24
Authors: Marilia M Knychala; Angela A Dos Santos; Leonardo G Kretzer; Fernanda Gelsleichter; Maria José Leandro; César Fonseca; Boris U Stambuk Journal: J Fungi (Basel) Date: 2022-01-15