To evaluate the prebiotic potential and intestinal fermentation products of wheat bran-derived arabinoxylooligosaccharides (AXOS) in relation to their structure, 5 preparations with structurally different AXOS were included ( approximately 4% wt:wt) in rat diets that mimicked the average Western human diet composition. Xylooligosaccharides (XOS), fructooligosaccharides (FOS), and inulin were used as references. The observed effects mainly depended on the average degree of polymerization (avDP) of the AXOS preparations. The AXOS and XOS preparations with a low avDP (

The tolerance and prebiotic effect following oral intake by healthy human subjects of arabinoxylan-oligosaccharides (AXOS), produced by partial enzymic hydrolysis of the wheat fibre arabinoxlyan, were studied. A total of twenty healthy subjects participated in the present randomised, placebo-controlled cross-over study. They consumed 10 g AXOS or placebo per d each for 3 weeks with a 4-week wash-out period in between. Before and immediately after each intake period, blood samples were taken to measure haematological and clinical chemistry parameters and the subjects completed a questionnaire about gastrointestinal symptoms. Additionally, urine was collected over 48 h for analysis of p-cresol and phenol content by GC -MS, and faeces were collected over 72 h for analysis of microbiota using real-time PCR. Of the subjects, ten also performed a urine and faeces collection 2 weeks after the start of intake (during intervention). A limited number of tested blood parameters were influenced in a statistically significantly way by either AXOS or placebo intake, but these changes remained within the normal range. Blood lipids remained unchanged. AXOS had no statistically significant effect on the range of gastrointestinal symptoms, except for a mild increase in flatulence. Urinary p-cresol excretion, an indicator of protein fermentation, was significantly decreased after 2 weeks of AXOS intake. The levels of bifidobacteria were significantly increased after 2 and 3 weeks of AXOS intake as well as after 3 weeks of placebo. However, the effect of AXOS on bifidobacteria was more pronounced than that of placebo. In conclusion, AXOS are a well-tolerated prebiotic at the dose of 10 g/d. AXOS intake increases faecal bifidobacteria and reduces urinary p-cresol excretion. Arabinoxylan-oligosaccharides: Prebiotics: Protein fermentation: ToleranceArabinoxylan-oligosaccharides (AXOS) are produced by partial enzymic hydrolysis of the cereal fibre arabinoxylan (AX) and have recently been proposed as a new prebiotic substrate (1) . To classify a food component as a prebiotic, it needs to fulfil three criteria (2) . The first criterion is resistance to gastric acid, gastrointestinal enzymes and absorption in the small bowel. In vitro studies have shown that AXOS resist a pH value of 2·0 and are less acid-sensitive than xylo-oligosaccharides and fructo-oligosaccharides (FOS) (3,4) . It has also been reported that xylobiose (xylosyl-b-1,4-xylose) is not degraded to xylose upon addition of either saliva, pepsin-containing artificial gastric juice, a preparation of pancreatic enzymes or intestinal mucosal homogenate (5) and similar data have been obtained for AXOS (6) . Furthermore, studies with ileostomy patients demonstrated that AX from cereals is not or only poorly digested in the ileum (7 -9) . The second criterion is the fermentability of the candidate prebiotic by intestinal bacteria. An in vitro study with human faecal slurries demonstrated that AXOS are metabolised within 24 h, with production of acetic acid and lactic acid, and ...

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In aquatic environments, Legionella pneumophila survives, in association with other bacteria, within biofilms by multiplying in free-living amoebae. The precise mechanisms underlying several aspects of the uptake and intracellular replication of L. pneumophila in amoebae, especially in the presence of other bacteria, remain unknown. In the present study, we examined the competitive effect of selected non-Legionella bacteria (Escherichia coli, Aeromonas hydrophila, Flavobacterium breve, and Pseudomonas aeruginosa) on the uptake of L. pneumophila serogroup 1 by the amoebae Acanthamoeba castellanii and Naegleria lovaniensis. We also investigated their possible influence on the intracellular replication of L. pneumophila in both amoeba species. Our results showed that the non-Legionella bacteria did not compete with L. pneumophila for uptake, suggesting that the amoeba hosts took in L. pneumophila through a specific and presumably highly efficient uptake mechanism. Living and heat-inactivated P. aeruginosa best supported the replication of L. pneumophila in N. lovaniensis and A. castellanii, respectively, whereas for both amoeba species, E. coli yielded the lowest number of replicated L. pneumophila. Furthermore, microscopic examination showed that 100% of the A. castellanii and only 2% of the N. lovaniensis population were infected with L. pneumophila at the end of the experiment. This study clearly shows the influence of some non-Legionella bacteria on the intracellular replication of L. pneumophila in A. castellanii and N. lovaniensis. It also demonstrates the different abilities of the two tested amoeba species to serve as a proper host for the replication and distribution of the human pathogen in man-made aquatic environments such as cooling towers, shower heads, and air conditioning systems with potential serious consequences for human health.

In this study, several process parameters that may contribute to the efficiency of ultrasound disinfection are examined on a pilot scale water disinfection system that mimics realistic circumstances as encountered in an industrial environment. The main parameters of sonication are: (i) power; (ii) duration of treatment; (iii) volume of the treated sample. The specific energy (E(s)) is an indicator of the intensity of the ultrasound treatment because it incorporates the transferred power, the duration of sonication and the treated volume. In this study, the importance of this parameter for the disinfection efficiency was assessed through changes in volume of treated water, water flow rate and electrical power of the ultrasonic reactor. In addition, the influences of the initial bacterial concentration on the disinfection efficiency were examined. The disinfection efficiency of the ultrasonic technique was scored on a homogenous and on a mixed bacterial culture suspended in water with two different types of ultrasonic reactors (Telsonic and Bandelin). This study demonstrates that specific energy, treatment time of water with ultrasound and number of passages through the ultrasonic reactor are crucial influential parameters of ultrasonic disinfection of contaminated water in a pilot scale water disinfection system. The promising results obtained in this study on a pilot scale water disinfection system indicate the possible application of ultrasound technology to reduce bacterial contamination in recirculating process water to an acceptable low level. However, the energy demand of the ultrasound equipment is rather high and therefore it may be advantageous to apply ultrasound in combination with another treatment.