Arabinoxylan oligosaccharides (AXOS) are a promising class of prebiotics that have the potential to stimulate the growth of bifidobacteria and the production of butyrate in the human colon, known as the bifidogenic and butyrogenic effects, respectively. Although these dual effects of AXOS are considered beneficial for human health, their underlying mechanisms are still far from being understood. Therefore, this study investigated the metabolic interactions between Bifidobacterium longum subsp. longum NCC2705 (B. longum NCC2705), an acetate producer and arabinose substituent degrader of AXOS, and Eubacterium rectale ATCC 33656, an acetate-converting butyrate producer. Both strains belong to prevalent species of the human colon microbiota. The strains were grown on AXOS during mono-and coculture fermentations, and their growth, AXOS consumption, metabolite production, and expression of key genes were monitored. The results showed that the growth of both strains and gene expression in both strains were affected by cocultivation and that these effects could be linked to changes in carbohydrate consumption and concomitant metabolite production. The consumption of the arabinose substituents of AXOS by B. longum NCC2705 with the concomitant production of acetate allowed E. rectale ATCC 33656 to produce butyrate (by means of a butyryl coenzyme A [CoA]:acetate CoA-transferase), explaining the butyrogenic effect of AXOS. Eubacterium rectale ATCC 33656 released xylose from the AXOS substrate, which favored the B. longum NCC2705 production of acetate, explaining the bifidogenic effect of AXOS. Hence, those interactions represent mutual cross-feeding mechanisms that favor the coexistence of bifidobacterial strains and butyrate producers in the same ecological niche. In conclusion, this study provides new insights into the bifidogenic and butyrogenic effects of AXOS. F ermentation in the human colon is carried out by trillions of bacteria that contribute not only to health and well-being but also to disease (1-4). For instance, a decrease in the relative abundance of bifidobacteria in the human colon has been associated with antibiotic-associated diarrhea, irritable bowel syndrome, inflammatory bowel disease, allergies, and regressive autism (5, 6). Although it is currently not yet clear whether changes in microbial composition are a cause or a consequence of these disorders, there are indications that metabolites, in particular, the short-chain fatty acids (SCFAs), such as acetate, butyrate, and propionate, that are produced during fermentation in the colon play an important role in intestinal homeostasis (3, 7). Among the SCFAs produced in the human colon, butyrate has drawn the most attention, as it is an essential energy source for the colon epithelial cells and has a protective effect against inflammatory bowel disease and colon cancer (3,8,9). Most butyrate producers belong to the Firmicutes phylum and use a butyryl coenzyme A (CoA):acetate CoA-transferase in the final step of butyrate biosynthesis, which involves the n...

Bifidobacterium longum subsp. longum is among the dominant species of the human gastrointestinal microbiota and could thus have potential as probiotics. New targets such as antioxidant properties have interest for beneficial effects on health. The objective of this study was to evaluate the bioaccessibility of antioxidants in milk fermented by selected B. longum subsp. longum strains during in vitro dynamic digestion. The antioxidant capacity of cell extracts from 38 strains, of which 32 belong to B. longum subsp. longum, was evaluated with the ORAC (oxygen radical absorbance capacity) method. On the basis of screening and gene sequence typing by multilocus locus sequence analysis (MLSA), five strains were chosen for fermenting reconstituted skim milk. Antioxidant capacity varied among the strains tested (P = 0.0009). Two strains of B. longum subsp. longum (CUETM 172 and 171) showed significantly higher ORAC values than the other bifidobacteria strains. However, there does not appear to be a relationship between gene sequence types and antioxidant capacity. The milk fermented by each of the five strains selected (CUETM 268, 172, 245, 247, or PRO 16-10) did not have higher initial ORAC values compared to the nonfermented milk samples. However, higher bioaccessibility of antioxidants in fermented milk (175–358%) was observed during digestion.

Lactic acid bacteria (LAB) found in milk can be responsible for organoleptic defects in cheese. To identify sources of LAB that could potentially develop during cheese making, we evaluated their prevalence and abundance in milk according to the type of forage used in dairy cow feeding. Forages and bulk tank milk were sampled 3 times on 24 farms using either hay alone (control), or grass or legume silage supplemented with corn silage or not. Both types of silage were either non-inoculated or inoculated with commercial preparations containing at least a Lactobacillus buchneri strain along with Lactobacillus casei, Lactobacillus plantarum, Enterococcus faecium, or Pediococcus pentosaceus. Our results indicate that LAB viable counts in milk samples (2.56 log cfu/mL) did not differ according to the type of forage used. A total of 1,239 LAB were isolated and identified by partial 16S rRNA gene sequencing. Although inoculation increased lactobacilli abundance in grass silage by 35%, we did not observe an effect on the LAB profile of milk. Indeed, we found no significant difference in milk LAB prevalence and abundance according to the type of forage (P > 0.05). Moreover, isolates belonging to the L. buchneri group were rarely found in bulk tank milk (3 out of 481 isolates). Random amplified polymorphic DNA typing of 406 LAB isolates revealed the plausible transfer of some strains from silage to milk (~6%). Thus, forage is only a minor contributor to LAB contamination of milk.

The dairy farm environment influences the raw milk microbiota and consequently affects milk processing. Therefore, it is crucial to investigate farm management practices such as the bedding materials. The aim of this study was to evaluate the effect of recycled manure solids (RMS) as bedding material on bulk tank milk and microbiological implications for cheese quality. Bulk tank samples were collected from 84 dairy farms using RMS or straw bedding. The use of RMS did not influence thermophilic and mesophilic aerobic viable counts from spores. However, straw-milk samples gave higher values for mesophilic anaerobic spore-forming bacteria (0.44 log cfu/mL) than RMS-milk samples (0.17 log cfu/mL). The presence of thermoresistant lactic acid bacteria was not increased in milk from farms using RMS. Nevertheless, taxonomic profiles of thermoresistant bacteria isolated were different between the 2 types of milk. More Enterococcus faecalis and Streptococcus spp. were identified in RMS-milk samples. Thermoresistant enterococci and streptococci could easily end up in cheese. Therefore, milk proteolytic activities of these isolates were tested. Neither Streptococcus spp. nor Enterococcus faecium isolates exhibited proteolytic activities, whereas 53% of E. faecalis showed some. Also, only 1 vancomycin-resistant enterococcus was detected. Survival of selected RMS-milk samples isolates (3 E. faecalis and 1 Streptococcus thermophilus) was evaluated during a model Cheddar cheese manufacture. Although those strains survived well, they did not modify the acidification curve of milk. However, they might cause organoleptic defects during cheese maturing.

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Erythropoietin (Epo) represents for some athletes the ultimate tool to gain an edge over their peer competitors. Underground information indicates that its usage is spreading at an epidemic pace since no analytical technique is yet available to detect its utilization. We hereby report observations obtained from analysis of urine specimens collected from top-level athletes after international-calibre competitions. Possible Epo misuse was evaluted by the measurement of urine total degradation products (TDPs), excretory fragments attributed by Sakakibara et al. to the fibrinolytic action of Epo. Markedly elevated urine TDP levels were measured in more than 13% of the 76 top-level athletes evaluated in this study. Analyses of urine specimens from a control hockey player group and from out-of-competition resting subjects indicate that the urine TDP content is not significantly influenced by exercise per se. Solid confirmation of TDP measurement as a sound probe to detect illicit Epo users should come from controlled studies with concomitant administration of Epo.

The expression International Sensitivity Index (ISD was proposed first by Loeliger and Lewis in 1982 (1), based on a multicenter calibration study of reference materials for thromboplastins undertaken by the European Community Bureau of Reference (B.C.R.). The calibration model that emerged from the BCR study was adopted by the World Health Organization Expert Committee on Biological Standardization in 1982 (2). Subsequently, a workshop on thromboplastin calibration was held in 1983 and a joint ICT}V ICSH policy statement was proposed with respect to reporting the prothrombin time in oral anticoagulant control (3). A slightly modified version of this policy statement was then accepted at the 1983 meeting of the ICTH subcommittee for standardization of the prothrombin time in Stockholm. The ICTH/ICSH recommendations were published in 1985 (4). Already during the 1983 workshop, the expression "sensitivity index" was cnticized for various reasons (3). At that time, it was decided not to modify this expression because it had already been adopted by WHO. We agree with Exner and Dybkaer that the expression ISI was not an ideal choice but it is recognized by international usage and a change of terminology would have to be adopted not only by ICSH and the Scientific and Standardization Committee of ISTH, but also would require acceptance by the wHo. Kirkwood explained clearly why the logarithm of prothrombin times obtained with a candidate reagent system should be expressed on the horizontal axis and the corresponding results with the reference procedure on the vertical axis (5). This choice of axes leads to a simple formula for the calculation of INR: INR-(t'T-ratio)srone where the PT-ratio obtained with the candidate reagent is raised to the power of the slope of the orthogonal regression line.

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