l-Arabinose triggers its own uptake via induction of the arabinose-specific Gal2p transporter in an industrial Saccharomyces cerevisiae strain

• Published in: Biotechnology for biofuels Vol. 11; no. 1; p. 231
• Main Authors: Oehling, Verena, Klaassen, Paul, Frick, Oliver, Dusny, Christian, Schmid, Andreas
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 23.08.2018; BioMed Central; BMC
• Subjects: adenosine triphosphate; Arabinose; Biodiesel fuels; Biofuels; Biomass; Biorefineries; biorefining; Carbon; Catabolite repression; Conversion; D-Galactose; Deactivation; Dehydrogenases; energy; Energy metabolism; Energy sources; Ethanol; ethanol production; feedstocks; Fermentation; Gal2p; Galactose; Gene expression; Genetic aspects; Genomes; Glucose; Glucose transport; Hexose; Hydrolysates; Inactivation; Kinases; l-Arabinose fermentation; l-Arabinose uptake; Lignocellulose; Lignocellulosic ethanol; Metabolism; Methods; Pentose; pentoses; Physiological aspects; Physiology; Production processes; quantitative polymerase chain reaction; R&D; Regeneration; Research & development; reverse transcriptase polymerase chain reaction; Ribonucleic acid; RNA; Saccharomyces cerevisiae; sequence analysis; Substrates; Sugar; transcriptome; Yeast; Germany; Catabolite repression; RNA-seq; l-Arabinose fermentation; Gal2p; Lignocellulosic ethanol; l-Arabinose uptake; Next generation sequencing; Saccharomyces cerevisiae
• ISSN: 1754-6834; 1754-6834; 2731-3654
• DOI: 10.1186/s13068-018-1231-8

Bioethanol production processes with using lignocellulosic biomass as feedstock are challenged by the simultaneous utilization of pentose and hexose sugars from biomass hydrolysates. The pentose uptake into the cell represents a crucial role for the efficiency of the process. The focus of the here presented study was to understand the uptake and conversion of the pentose l-arabinose in and reveal its regulation by d-glucose and d-galactose. Gal2p-the most prominent transporter enabling l-arabinose uptake in wild-type strains-has an affinity for the transport of l-arabinose, d-glucose, and d-galactose. d-Galactose was reported for being mandatory for inducing expression. expression is also known to be regulated by d-glucose-mediated carbon catabolite repression, as well as catabolite inactivation. The results of the present study demonstrate that l-arabinose can be used as sole carbon and energy source by the recombinant industrial strain DS61180. RT-qPCR and RNA-Seq experiments confirmed that l-arabinose can trigger its own uptake via the induction of expression. Expression levels of during growth on l-arabinose reached up to 21% of those obtained with d-galactose as sole carbon and energy source. l-Arabinose-induced expression was also subject to catabolite repression by d-glucose. Kinetic investigations of substrate uptake, biomass, and product formation during growth on a mixture of d-glucose/l-arabinose revealed impairment of growth and ethanol production from l-arabinose upon d-glucose depletion. The presence of d-glucose is thus preventing the fermentation of l-arabinose in DS61180. Comparative transcriptome studies including the wild-type and a precursor strain delivered hints for an increased demand in ATP production and cofactor regeneration during growth of DS61180 on l-arabinose. Our results thus emphasize that cofactor and energy metabolism demand attention if the combined conversion of hexose and pentose sugars is intended, for example in biorefineries using lignocellulosics.