Molecular assessment of intestinal microflora

The application of molecular methodologies to intestinal microflora analysi s should enable the development of a detailed knowledge of the microbial ec ology of the human colon. This knowledge is essential to derive scientifica lly valid probiotics. Molecular typing (genetic fingerprinting) methods, eg , ribotyping and pulsed field gel electrophoresis of DNA digests, provide a means of distinguishing bacterial strains inhabiting the intestinal tract. Analysis of lactobacillus, bifidobacterial, and enterobacterial population s with the use of these methods has shown that human and porcine subjects h arbor a characteristic collection of bacterial strains. Additionally, pertu rbations and transitions that occur in these populations and are caused by antibiotic administration or by autogenic or allogenic factors can be detec ted by molecular analysis of the intestinal microflora. In future studies, molecular typing methods could be used to analyze the composition of bacter ial populations before, during, and after the administration of the probiot ic product. This experimental approach would provide information on the eff ect of the probiotic on indigenous strains inhabiting the intestinal tract of humans and other animals.