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Liquors from rice husk autohydrolysis, containing xylooligosaccharides (XOS), other saccharides, and nonsaccharide compounds, were refined by membrane processing to increase the proportion of substituted XOS in refined liquors. XOS were assayed for composition and degree of polymerization (DP) distribution and hydrolyzed with commercial enzymes for obtaining XOS with DP in the range of 2-6. Nanofiltered, hydrolyzed liquors were subjected to ion exchange processing to yield a final product containing monosaccharides, XOS (accounting for 55.6% of the nonvolatile solutes), and other nonvolatile compounds. The solution obtained after enzymatic hydrolysis with commercial xylanases (in which 82.8% of XOS were in the DP range of 2-6) was examined as a medium for promoting the growth of Bifidobacterium adolescentis CECT 5781, B. longum CECT 4503, B. infantis CECT 4551, and B. breve CECT 4839. The growth rate of B. adolescentis (0.58 h(-1)) was higher than the ones determined for B. longum, B. infantis, and B. breve (0.37, 0.30, and 0.40 h(-1), respectively). The percentage of total XOS consumption by B. adolescentis was 77% after 24 h, the highest percentage of utilization corresponding to xylotriose (90%), followed by xylobiose (84%), xylotetraose (83%), and xylopentaose (71%).

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The objective of this study was to compare the in vitro fermentability of xylo-oligosaccharides (XOS) with different degrees of polymerisation (DP) by the intestinal digesta collected in three distinct intestinal sections of the porcine intestinal tract: ileum, caecum, and distal colon. The studied oligosaccharides included commercial short-chain XOS (DP 2e5), and medium-chain (DP 2e14) and long-chain (DP 2e25) XOS obtained by autohydrolysis of brewery's spent grain (BSG), corn cobs (CC) and Eucalyptus globulus wood (EUC). The oligosaccharide and monosaccharide consumption, lactate and short-chain fatty acids concentrations were correlated with shifts on PCR titres of Bacteroides/ Prevotella, Bifidobacterium and Lactobacillus/Pediococcus populations, by using group-and genus-specific primers.All tested XOS were extensively fermented by the piglet ileal, caecal and colonic microbiota. The rate of consumption of medium-and longchain XOS was notably reduced in the fermentations by the ileal inoculum as compared to commercial XOS. EUC XOS, CC XOS and commercial XOS supported an enhancement of bifidobacteria and lactobacilli replication in a first stage of the fermentations. Apparently this stimulation was not selective, because Bacteroides/Prevotella replication increased in a second stage of the fermentations, coincident in time with the highest consumption rates of some XOS mixtures tested. Mostly due to the slow fermentability by the ileal microbiota, medium-chain and long-chain XOS mixtures can be regarded as promising functional candidates suitable to act as distally fermentable substrates.

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a b s t r a c tThis paper discusses the overall energy consumption and greenhouse gas emissions when extracting pigments and producing hydrogen from Spirogyra sp. microalga biomass. The energy evaluation from the biomass leftovers was also included in this work. The influence of the functional unit and different allocation criteria on the biorefinery assessments is also shown. The study consists of laboratory tests showing Spirogyra sp. growth, harvesting, drying, pigment extraction and fermentation by Clostridium butyricum. Electrocoagulation and solar drying were tested and compared to conventional centrifugation and electrical dewatering in terms of their energy consumption for harvesting and dewatering, respectively. To discuss the biorefinery viability, the pigments and biohydrogen (bioH 2 ) retail costs are considered against operational costs according to electricity needs. The low yield of biochemical hydrogen and the high energy requirements for the pigment extraction were identified as main topics for further research. This research hopefully contributes to highlight the importance of energy and emission balances in order to decide on feasibility of the biorefinery.