Cellobiose was once regarded as a byproduct that should be removed from biomass hydrolysates because of its inhibitory activity to cellulases. It was revealed, however, that cellobiose could serve as a co-substrate for xylose fermentation by engineered Saccharomyces cerevisiae. Despite its advantages, to date, little is known about cellodextrin transporters that endow S. cerevisiae with cellobiose transporting ability. In this study, engineered S. cerevisiae strains capable of fermenting cellobiose were constructed by expressing various fungal cellobiose transporters and intracellular β-glucosidases. Among them, the strain expressing a putative sugar transporter from Penicillium chrysogenum (Pc_ST) and β-glucosidase from Thielavia terrestris (Tt_BG) showed an improved cellobiose fermentation performance compared to the strain expressing a cellodextrin transporter from Neurospora crassa (Nc_CDT-1) and β-glucosidase from N. crassa (Nc_GH1-1). Cellobiose fermentation by S. cerevisiae Pc_ST/Tt_BG under microaerobic conditions resulted in 14.5±0.5g/L of final ethanol concentration with a yield of 0.37±0.01g ethanol/g cellobiose, which are 22% and 26% higher than the corresponding values of S. cerevisiae Nc_CDT-1/Nc_GH1-1. These results suggest that the yield and rate of cellobiose fermentation can be improved by adopting optimal pairs of cellobiose transporters and β-glucosidase.
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http://dx.doi.org/10.1016/j.jbiotec.2013.10.030 | DOI Listing |
FEBS J
January 2025
Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, India.
Cellulases are an ensemble of enzymes that hydrolyze cellulose chains into fermentable glucose and hence are widely used in bioethanol production. The last enzyme of the cellulose degradation pathway, β-glucosidase, is inhibited by its product, glucose. The product inhibition by glucose hinders cellulose hydrolysis limiting the saccharification during bioethanol production.
View Article and Find Full Text PDFFront Microbiol
December 2024
Winogradsky Institute of Microbiology, Federal Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
Soda lakes are unique double-extreme habitats characterized by high salinity and soluble carbonate alkalinity, yet harboring rich prokaryotic life. Despite intensive microbiology studies, little is known about the identity of the soda lake hydrolytic bacteria responsible for the primary degradation of the biomass organic matter, in particular cellulose. In this study, aerobic and anaerobic enrichment cultures with three forms of native insoluble cellulose inoculated with sediments from five soda lakes in south-western Siberia resulted in the isolation of four cellulotrophic haloalkaliphilic bacteria and their four saccharolytic satellites.
View Article and Find Full Text PDFBraz J Microbiol
December 2024
Laboratory of Yeast Biochemistry (LabBioLev), Federal University of Fronteira Sul, Campus Chapecó, Chapecó, SC, Brazil.
This study aimed to compare the effects of cellobiose hydrolysis, whether occurring inside or outside the cell, on the ability of Saccharomyces cerevisiae strains to ferment this sugar and then apply the most effective strategy to industrial S. cerevisiae strains. Firstly, two recombinant laboratory S.
View Article and Find Full Text PDFMicrob Cell Fact
November 2024
Laboratory of Enzymology and Molecular Biology of Microorganisms (LEBIMO), Department of Biochemistry and Tissue Biology, Institute of Biology, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-862, Brazil.
Background: Fermentation of sugars derived from plant biomass feedstock is crucial for sustainability. Hence, utilizing customized enzymatic cocktails to obtain oligosaccharides instead of monomers is an alternative fermentation strategy to produce prebiotics, cosmetics, and biofuels. This study developed an engineered strain of Aspergillus niger producing a tailored cellulolytic cocktail capable of partially degrading sugarcane straw to yield cellooligosaccharides.
View Article and Find Full Text PDFFolia Microbiol (Praha)
October 2024
University of Brasilia (UnB), Institute of Biological Sciences, Department of Phytopathology, Brasília, DF, 70910-900, Brazil.
Yeasts are unicellular fungi that occur in a wide range of ecological niches, where they perform numerous functions. Furthermore, these microorganisms are used in industrial processes, food production, and bioremediation. Understanding the physiological and adaptive characteristics of yeasts is of great importance from ecological, biotechnological, and industrial perspectives.
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