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Over the last years, there has been increasing interest in the intestinal microbiota internationally and in New Zealand. As an illustration of this, more than 26,000 items were selected on a curren...

The human colon contains a complex microbial community (the microbiota), composed mostly of bacteria, that degrades and ferments indigestible polysaccharides known collectively as dietary fibre. Ac...

The consumption of phytoestrogens has been related to a reduced risk of hormone-dependent cancer types as well as coronary heart diseases. Plant lignans that represent one class of phytoestrogens are found in relatively high concentrations in rye bran. When consumed, they are metabolized into mammalian lignans (enterodiol and enterolactone) by gut bacteria. In order to investigate whether an increased intake of plant lignans had an impact on the composition of the predominant bacterial community of the human gut a 2x6-week intervention study, with a crossover design, was conducted. Eighteen healthy postmenopausal women (age 55-71 years) were recruited and randomly assigned to two groups. The intervention comprised bread products with either rye bran or an inert wheat cellulose (Vitacel† ). Faecal samples were collected before and at the end of each intervention period and analysed for their predominant bacterial species composition by a cultivationindependent approach - polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The rye bran diet had no impact on the composition of gut microflora. However, the DGGE profiles demonstrated unique bacterial communities for each individual, which implied a differing efficiency among individuals to metabolize lignans.Key words: rye bran, lignans, human gut microflora, PCR-DGGE

The total concentration of cholesterol was measured in sera collected from groups of mice whose gastrointestinal microbiota differed only in the presence or absence of lactobacilli. Female mice had lower cholesterol concentrations than male animals. The presence of lactobacilli in the gastrointestinal tract did not influence the serum cholesterol concentration. Keywords - Lactobacilli, Digestive tract, Mice, Cholesterol.

Alkaline phosphatase and phosphodiesterase I activities of duodenal enterocytes harvested from mice with or without lactobacilli as intestinal inhabitants were determined. The presence of lactobacilli as members of the digestive tract microbiota did not influence the two enzyme activities. Keywords - Lactobacilli, Duodenum, Enterocytes, Enzymes, Alkaline phosphatase, Phosphodiesterase.

Twenty-eight strains of gastrointestinal lactobacilli, comprising isolates classified as Lactobacillus reuteri , L. acidophilus , L. delbrueckii , L. fermentum , L. gasseri and L. salivarius , were examined for the presence of cell-surface polypeptides. Whole cells were radioactively labelled with 125 I using lactoperoxidase or chloramine T as catalyst, proteins were extracted with sodium dodecyl sulphate (SDS) and separated by SDS-polyacrylamide gel electrophoresis. All lactobacilli tested had between 5 and 20 proteins that were accessible to the labelling agents on the surface of whole cells. Strains of L. reuteri had similar surface polypeptide profiles and were characterised by the presence of a high molecular mass band of approximately 185 kDa. Strains of L. acidophilus could be grouped on the basis of their surface protein patterns. In one group (five strains) the surface protein profile was dominated by a surface array protein of molecular mass 45 kDa. In the other groups approximately 15 polypeptides were identified as being surface exposed and these ranged in molecular mass from c . 15 to 100 kDa. Strains of L. fermentum had either a characteristic surface protein profile (with bands at 135 kDa) or were poorly surface labelled. Fowl or rodent strains of different species possessed high molecular mass surface proteins (> 130 kDa). There was no correlation however between the presence of a specific polypeptide and the ability of a strain to adhere to stratified, squamous epithelial surfaces either in vitro or in vivo . Surface protein profiles may provide an aid to classification of lactobacillus strains of some species. Keywords: Gastrointestinal lactobacilli; Surface proteins; Lactobacillus proteins; Cell-surface labelling.

The fate of the broad-host-range, conjugative plasmid pAMβ1 in the digestive tract of mice was monitored by DNA-DNA hybridisations using a probe containing the ermAM determinant (macrolide-lincosamide-streptogramin type B resistance). Transfer of pAMβ1 from Lactobacillus reuteri to Enterococcus faecium occurred in the digestive tract of infant mice and from E. faecium to E. faecalis and to L. fermentum in the adult intestinal tract. Long-term administration of lincomycin to the animals resulted in a modified form of pAMβ1 in the L. reuteri host. The modified plasmid was present in caecal isolates of the lactobacillus at higher concentration than in the stock culture used to inoculate the mice at the start of the experiment, and was maintained stably by the lactobacilli in vivo . In contrast, pAMβ1 was not stably maintained in the stock strain in the absence of antibiotic administration. The modified plasmid was no longer self-transmissible. Long-term administration of antibiotic to the animals resulted in erythromycin-resistant strains of Escherichia coli and eubacteria. Keywords: Digestive tract; Microflora; Antibiotic; Lactobacillus; Enterococcus; pAMβ1.