Bacterial strains and culture conditions
The bacterial strains used in this study are listed in Table 1. Lactobacillus strains were cultivated anaerobically in MRS-broth (Difco, BD, Franklin Lakes, New Jersey) at +37°C. Enterotoxigenic Escherichia coli (ETEC) was cultured in Luria-Bertani (LB) broth (Difco, BD) with agitation at +37°C in the experiments assessing the effect of Lactobacillus strains on ETEC adherence. The E. coli strains used for the cloning and expression of Slp-encoding genes were cultivated with agitation in LB broth, or in the heterologous gene expression, in M9ZB medium [30] at +37°C, with kanamycin (30 μg/ml) being added when appropriate. In the pathogen inhibition assays, all the pathogens were cultivated in tryptic soy agar (TSA) plates (Difco) and subcultured in tryptic soy broth (TSB, Difco) at +37°C with agitation.
Table 1  Strains used in this study  amolecular weight of mature protein bnot tested for adherence cnot present dculture collection of the Department of Veterinary Biosciences/Veterinary Microbiology and Epidemiology, University of Helsinki, Finland.