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Fractionation of eucalyptus globulus wood by glycerol-water pretreatment : opti...

A glycerol-organosolv process can be a good alternative for Eucalyptus wood fractionation into its main compounds, improving the enzymatic saccharification of the cellulose. A study of process variables - glycerol−water percent content, temperature, and process time - was carried out using a Box-Behnken experimental design. The cellulose obtained from pretreated solids was recovered almost quantitatively, leadi...

Engineering yeast tolerance to inhibitory lignocellulosic biomass

In recent years the necessity for biotechnological manufacturing based on lignocellulosic feedstocks has become evident. However, the pre-treatment step in the production of lignocellulosic bioethanol leads to the accumulation of inhibitory byproducts. Robust second generation bioethanol processes require microorganisms able to ferment these inhibitory lignocellulosic hydrolysates. Significant progress has been...

Cell recycling during repeated very high gravity bio-ethanol fermentations usin...

A very high gravity (VHG) repeatedbatch fermentation system using an industrial strain of Saccharomyces cerevisiae PE-2 (isolated from sugarcane-to-ethanol distillery in Brazil) and mimicking industrially relevant conditions (high inoculation rates and low O2 availability) was successfully operated during fifteen consecutive fermentation cycles, attaining ethanol at 17.1 ± 0.2% (v/v) with a batch productivity o...

Plasmid-mediate transfer of FLO-1 into industrial Saccharomyces cerevisiae PE-2...

The flocculation gene FLO1 was transferred into the robust industrial strain Saccharomyces cerevisiae PE-2 by the lithium acetate method. The recombinant strain showed a fermentation performance similar to that of the parental strain. In 10 repeat-batch cultivations in VHG medium with 345 g glucose/L and cell recycling by flocculation–sedimentation, an average final ethanol concentration of 142 g/L and an ethan...

Effect of hemicellulose liquid phase on the enzymatic hydrolysis of autohydroly...

In this work, Eucalyptus globulus wood (EGW) was pretreated under autohydrolysis process at 210 and 220 ºC, obtaining a pretreated solid with high cellulose content. Moreover, the effect of the hemicellulosic liquid phase (HLP) addition on the enzymatic hydrolysis was studied. When the enzymatic hydrolysis was performed without addition of HLP, 87.38 and 107.46 g/L of glucose was obtained for 210 ºC and 220 ºC,...

Identification of Saccharomyces cerevisiae genes involved in the resistance to ...

Most of the current processes for bioethanol production are based on the use of Very-High-Gravity (VHG) technology and the processing of lignocellulosic biomass, limited by the high osmotic pressure and ethanol concentration in the fermentation medium, and by inhibitors resulting from biomass pre-treatments, respectively. Aiming the optimization of strains for industrial bioethanol production an integrated appr...

Robust industrial Saccharomyces cerevisiae strains for very high gravity bio-et...

The application and physiological background of two industrial Saccharomyces cerevisiae strains, isolated from harsh industrial environments, were studied in Very High Gravity (VHG) bio-ethanol fermentations. VHG laboratory fermentations, mimicking industrially relevant conditions, were performed with PE-2 and CA1185 industrial strains and the CEN.PK113-7D laboratory strain. The industrial isolates produced rem...

Identification of candidate genes for yeast engineering to improve bioethanol p...

Background: The optimization of industrial bioethanol production will depend on the rational design and manipulation of industrial strains to improve their robustness against the many stress factors affecting their performance during very high gravity (VHG) or lignocellulosic fermentations. In this study, a set of Saccharomyces cerevisiae genes found, through genome-wide screenings, to confer resistance to the ...

Identification of Saccharomyces cerevisiae genes involved in the resistance to ...

Optimization of low-cost medium for very high gravity ethanol fermentations by ...

Statistical experimental designs were used to develop a medium based on corn steep liquor (CSL) and other low-cost nutrient sources for high-performance very high gravity (VHG) ethanol fermentations by Saccharomyces cerevisiae. The critical nutrients were initially selected according to a Plackett–Burman design and the optimized medium composition (44.3 g/L CSL; 2.3 g/L urea; 3.8 g/L MgSO4·7H2O; 0.03 g/L CuSO4·...