Biotype and ribotype diversity among lactobacillus isolates from the mouse ileum

The present study evaluated the relative diversity of lactobacilli in the mouse ileum as defined by conventional phenotypic characteristics versus ribotype patterns. Forty-one Lactobacillus isolates were first presumptively identified using data from carbohydrate fermentation and biochemical tests. Numerical analysis of the biotype data placed a total of four Lactobacillus species into three major clusters and six small clusters. Most of the isolates were typed as L. gasseri or L. fermentum. To further distinguish these isolates, restriction fragment length polymorphism (RFLP) analysis was performed using a 23S rRNA gene probe to develop ribotypes and allow clustering to genotypic groups. Numerical analysis of the ribotype data also revealed three main clusters, with identical grouping to those generated by the biotype data, with only one exception. Thus, for both the ribotype and biotype data the isolates were generally conserved within clusters. A direct microscopic-Gram-stain procedure was used to determine the relative adhesion capacity of the mouse ileum isolates. The Lactobacillus isolates varied widely in their ability to colonize a colonic epithelial cell line with no apparent relationship between adhesion phenotype and ribotype or biotype characteristics.