Brewer's spent grain (BSG) samples were subjected to a two-step aqueous processing (starch extraction and autohydrolysis) in order to assess their potential as a raw material for obtaining a mixture of arabinoxylooligosaccharides (AXOS) suitable to be use as prebiotics for elderly. After hydrothermal treatment, the liquors were refined by a sequence of purification and conditioning steps including membrane filtration, enzymatic hydrolysis, and ion exchange. The presence of both substituted (degree of polimerization (DP) = 2-10) and unsubstituted (DP = 2-16) oligosaccharides made up of xylose and arabinose (AXOS) were confirmed in purified mixtures (in which total OS content = 84% w/w) by using chromatographic techniques and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Finally, AXOS were evaluated for their prebiotic activity by in vitro fermentation assays using fecal inocula from elderly people, demonstrating that AXOS were slightly better substrates than FOS, in terms of bacterial population shifts as in the production of SCFA.

Glucomannans (GM) are polymers that can be found in natural resources, such as tubers, bulbs, roots, and both hard- and softwoods. In fact, mannan-based polysaccharides represent the largest hemicellulose fraction in softwoods. In addition to their structural functions and their role as energy reserve, they have been assessed for their healthy applications, including their role as new source of prebiotics. This paper summarizes the scientific literature regarding the manufacture and functional properties of GM and their hydrolysis products with a special focus on their prebiotic activity.

Fructooligosaccharides (FOS) and xylooligosaccharides (XOS) were employed as substrates for in vitro fermentations to assess their capacity to counteract the effects caused by three antibiotics (ABs) at different doses on the elderly gut microbiota and its metabolic activity. The AB type and dose scarcely affected the total bacterial numbers and the microbiota composition after 24 h. However, in the presence of ABs, the relative percentages of Lactobacillus decreased (from 11.4% to 3.2% in the presence of XOS1), as well as the butyrate production, whereas the population of Bacteroides increased significantly in the presence of XOS1 (from 27.5% to 55.7%). FOS were able to counteract these effects by increasing the butyrate production and the number of Lactobacillus, while maintaining the number of Bacteroides almost constant and decreasing the clostridia. XOS2 (mainly DP = 2-4) also showed ability to increase the percentages of Bifidobacterium and the production of both butyrate and acetate.

The present study was undertaken to describe the epiflora of the eggs of an important fishing species collected in a coastal zone. Microflora associated with sardine (Sardina pilchardus) eggs collected in the Ría de Vigo was examined from January to June 2000. The count was carried out in three different ways: a total direct count by epifluorescence, a heterotrophic bacteria count on marine agar (MA) and a total vibrio count on thiosulfate citrate bile sucrose (TCBS). It was observed that the counts of total bacteria by epifluorescence were always higher by 2-3 logarithms than the bacterial counts on MA, and by 3-4 logarithms than the count of vibrios on TCBS. In both cases the differences were statistically significant. Throughout the sampling period only a slight variation was observed in the counts undertaken, and in the measured physicochemical parameters. For the qualitative study, 250 strains isolated from MA and 81 strains recovered on TCBS were identified. Members of the genera Vibrio, Pseudoalteromonas, Pseudomonas and Moraxella were found to dominate on the culturable adherent microflora of sardine eggs and Aeromonas, Tenacibaculum (Flexibacter), Flavobacterium and Cytophaga spp. were present in minor amounts. Vibrio anguillarum and Vibrio fischeri, pathogens of fish larvae, as well as Tenacibaculum ovolyticum, a pathogen of fish eggs, were detected.

The development of new prebiotics capable to modulate the gut microbiota in the elderly has become an area of great interest due to the particular vulnerability and frailty of this...