BACKGROUND Fermentation of xylose to ethanol has been achieved in S. cerevisiae by genetic engineering. Xylose utilization is however slow compared to glucose, and during anaerobic conditions addition of glucose has been necessary for cellular growth. In the current study, the xylose-utilizing strain TMB 3415 was employed to investigate differences between anaerobic utilization of glucose and x...

Production of several yeast products occur in presence of mixtures of monosaccharides. To study effect of xylose and glucose mixtures with system aeration and nitrogen source as the other two operative variables on xylitol production by Pichia guilliermondii, the present work was defined. Artificial Neural Network (ANN) strategy was used to athematically show interplay between these three c...

Fermentation of cellulosic and hemicellulosic sugars from biomass could resolve food-versus-fuel conflicts inherent in the bioconversion of grains. However, the inability to coferment glucose and xylose is a major challenge to the economical use of lignocellulose as a feedstock. Simultaneous cofermentation of glucose, xylose, and cellobiose is problematic for most microbes because glucose repre...

BACKGROUND Current methods of ethanol production from lignocelluloses generate a mixture of sugars, primarily glucose and xylose; the fermentation cells are always exposed to stresses like high temperature and low nutritional conditions that affect their growth and productivity. Stress-tolerant strains capable of using both glucose and xylose to produce ethanol with high yield are highly desira...

Lignocellulosic biomass, which contains large amounts of glucose and xylose, is the new ideal feedstock for ethanol production used as renewable liquid fuel for transportation. The naturally occurring Saccharomyces yeasts traditionally used for industrial ethanol production are unable to ferment xylose. We have successfully developed genetically engineered Saccharomyces yeasts that can effectiv...

The phosphoenolpyruvate-dependent glucose-specific phosphotransferase system (PTS(Glc)) is the main glucose uptake pathway in Escherichia coli that affects both substrate assimilation and metabolism leading to the product formation. In this study, the effect of single PTS(Glc) mutation on cell growth and substrate consumption was investigated by knocking out the genes involved in the phosphotra...

BACKGROUND In spite of the substantial metabolic engineering effort previously devoted to the development of Saccharomyces cerevisiae strains capable of fermenting both the hexose and pentose sugars present in lignocellulose hydrolysates, the productivity of reported strains for conversion of the naturally most abundant pentose, xylose, is still a major issue of process efficiency. Protein engi...

BACKGROUND The yeast Saccharomyces cerevisiae is unable to ferment pentose sugars like d-xylose. Through the introduction of the respective metabolic pathway, S. cerevisiae is able to ferment xylose but first utilizes d-glucose before the d-xylose can be transported and metabolized. Low affinity d-xylose uptake occurs through the endogenous hexose (Hxt) transporters. For a more robust sugar fer...

BACKGROUND Considerable interest in the bioconversion of lignocellulosic biomass into ethanol has led to metabolic engineering of Saccharomyces cerevisiae for fermentation of xylose. In the present study, the transcriptome and proteome of recombinant, xylose-utilising S. cerevisiae grown in aerobic batch cultures on xylose were compared with those of glucose-grown cells both in glucose represse...

Global transcription machinery engineering (gTME) was employed to engineer xylose metabolism. Mutation of the transcription factor gene Sptl5 was introduced by error-prone PCR, followed by screening on media using xylose as the sole carbon source. One recombinant strain growing well on such media was chosen for further research. This strain showed modest growth rates in the media containing 50 ...