A wild-type Lactobacillus crispatus, showing a cell aggregation phenotype and its spontaneous nonaggregating mutant were compared for their in vitro adhesion properties to human ileal mucus and to a cultured human colonic cell line (Caco2) and for their in vivo colonization and adhesion potential with colonoscopy patients as volunteers in feeding trials. The wild-type strain adhered better to mucus or to Caco2 cells than did the mutant. Altogether, three human trials with the wild type and two with the mutant strain were performed. In two of the trials, the wild type could be recovered from either fecal samples or biopsies taken from the colon, while the mutant strain could not be demonstrated in either of the trials where it was used. The L. crispatus colonies recovered from the trials were often mixed, and several enterococci and lactobacillus strains coaggregating with L. crispatus wild type could be isolated. The results indicate that the surface-mediated properties, such as aggregation, of lactobacilli can have a role in adhesion and colonization.

Three commercially available assays, designed to specifically detect the presence of Mycobacterium avium subsp. paratuberculosis (MAP) in fecal samples by IS900-PCR, were compared with a conventional culture method. Fecal samples from 100 dairy cows were tested. Fifty-four (67.5%) of 80 culture-positive samples were positive for an assay that detects MAP DNA by dot spot hybridization of polymerase chain reaction products (kit A), 48 (60%) were positive by an assay using ethidium bromide staining for agar gel visualization of amplification products (kit B), and 49 (61.3%) were positive by an assay in which amplified products are detected by a colorimetric detection system (kit C). Relative sensitivity of all tests increased in proportion to the presence of MAP in fecal samples. Specificity was 100% based on results from 20 culture-negative samples from an MAP-free herd.

Aims: Characterization of the aggregation-promoting factor (APF) of the human intestinal isolate Lactobacillus crispatus M247 and its homologous nonaggregating mutant Mu5. Methods and Results: Western blot analysis revealed that the supernatant of both M247 and Mu5 contains a 28-kDa protein which cross reacts with the antiserum produced against the APF of Lact. gasseri 4B2. The apf genes of M247 and Mu5 strains were identical and were shown to be 672 nucleotides in length and encoding a protein of 223 amino acids with a predicted molecular weight of 24AE0 kDa. Conclusion: Our results shows that the lost of aggregation in Mu5 is not related to a defect in secretion of the APF protein or a mutation in the apf gene. Significance and Impact of the Study: These results suggest that the mutation in Mu5 may be contained in another molecule involved in aggregation such as a possible receptor for APF.

Three different molecular techniques were used to characterize bacterial strains isolated from dairy products and phenotypically classified as Lactobacillus casei. Some strains were taxonomically identified as Lb. casei and Lb. paracasei using 23S rRNA‐targeted probes specific for Lb. casei and Lb. paracasei. Chromosomal DNA was analyzed by pulsed‐field gel electrophoresis. Lb. paracasei strains had a variable number of SfiI fragments harboring rRNA genes, while Lb. casei strains showed more homogeneous patterns. The chromosome size of Lb. paracasei ATCC 334 was evaluated to be 2.17 Mb.

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