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High- and low-acetylated galactoglucomannooligosaccharides (GGMOS_Ac and GGMOS, respectively) were assayed as substrates in the TIM-2 in vitrocolon model using, as inoculum, fecal microbiota from the elderly. The effects on the microbiota and their activity were also compared to a standard ileal efflux medium (SIEM). GGMOS resulted in higher organic acid productions and higher short-chain fatty acids/total organic acid molar ratios. Although comparable Actinobacteria abundances were observed with both substrates, GGMOS fermentation led to higher Firmicutes/Bacteroidetes ratios and lower Proteobacteria percentages than GGMOS_Ac. No differences were found concerning the percentages of beneficial genus such as Blautia, Faecalibacterium, Coprococcus, or Bifidobacterium. However, higher bacterial diversities and numbers of genera such as Oscillospiraand Lachnospirawere found with GGMOS_Ac. This suggests that GGMOS would be more suitable substrates for the elderly, even though GGMOS_Ac promoted positive effects that support the interest of further research using these oligosaccharides as “carriers” of desired substituents.

The aqueous fractionation of native lignocellulosic materials with hot, compressed water (also known as hydrothermal processing or autohydrolysis) has been proposed as a fractionation method for biorefineries, as it enables the simultaneous removal of water‐soluble extractives and the solubilization of hemicelluloses, yielding a solid phase enriched in lignin and cellulose. When the operation is carried out under favorable conditions, the liquid phase from autohydrolysis contains valuable products derived from hemicelluloses, including oligosaccharides that keep the major structural features of the polymer (including substitution by acetyl groups). Post‐hydrolysis of oligosaccharides in media catalyzed by acids or enzymes yields fermentable media containing hemicellulosic sugars; whereas harsh acid hydrolysis conditions result in the production of levulinic acid. Subsequent delignification of autohydrolyzed solids enables the separation of the three major lignocellulose components (hemicelluloses, cellulose, and lignin). As an alternative way for using autohydrolyzed solids, they can be used as substrates for the enzymatic hydrolysis of cellulose, leaving lignin as a solid by‐product. The sustainable manufacture of materials, fuels and chemicals from the biorefinery schemes cited above is discussed. Particular attention is paid to hemicellulose‐derived products. © 2011 Society of Chemical Industry and John Wiley & Sons Ltd

Eucalyptuswood hydrolysates were extracted with organic solvents (ethyl acetate and diethyl ether) to remove part of the phenolics derived from lignin. In order to obtain increased phenolic removal, the effects of the major experimental variables affecting extraction (type of solvent, hydrolysate to solvent volume ratio, temperature, pH and coupling of extraction stages) were explored. Under the best operational conditions, up to 84% of the initial lignin-derived compounds were extracted. The phenolic compounds extracted by solvents showed antioxidant activity. Under the best conditions, the antioxidant activity coefficient was 64% of the value found with a synthetic antioxidant (BHT). Extracted hydrolysates led to xylose solutions, allowing an enhanced fermentative production of xylitol with the yeast Debaryomyces hansenii.

Phaffia rhodozyma NRRL Y-17268 cells were proliferated in xylose-containing media made from Eucalyptus wood. Wood samples were subjected to acid hydrolysis under mild operational conditions, and hydrolysates were neutralized with lime. Neutralized hydrolysates were treated with charcoal for removing inhibitors and then supplemented with nutrients to obtain culture media useful for proliferation of the red yeast P. rhodozyma. A set of experiments carried out in orbital shakers proved that hydrolysates containing 16.6 g xylose/L supplemented only with 3 g peptone/L performed well as fermentation media. At the end of experiments, xylose was depleted and 10.5 g cells/L were obtained. Biomass was highly pigmented and volumetric carotenoid concentrations up to 5.8 mg carotenoids/L (with 4.6 mg astaxanthin/L) were reached. Further experiments in batch fermentors using concentrated hydrolysates (initial xylose concentrations within 16.6 and 40.8 g/L) led to good biomass concentrations (up to 23.2 g cells/L) with increased pigment concentration (up to 12.9 mg total carotenoids/L, with 10.4 mg astaxanthin/L) and high volumetric rates of carotenoid production (up to 0.079 mg/L·h). © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59: 501–506, 1998.