05 compared with the control media and L. rhamnosus HN001) (Fig. 1b). Lactobacillus
plantarum DSM 2648 also had a similar effect on TEER when tested using differentiated Caco-2 monolayers (18 days old) (Fig. 1c). This study demonstrates the strain-dependent effects of lactobacilli on intestinal barrier function and that all strains of the same species should not be assumed to have similar health-promoting properties. selleck chemical Lactobacillus plantarum are effective in enhancing TEER, with three out of the five L. plantarum isolates tested having a positive effect on TEER compared with the control media. A number of human oral isolates were also effective in enhancing TEER compared with the control media. Three out of four L. rhamnosus isolates, the L. paracasei isolate and the L. oris isolate had a positive effect on TEER.
However, several of the human oral isolates had a negative effect on TEER; three out of five L. fermentum isolates and the L. jensenii isolate induced a decrease in TEER compared with the control media. In contrast, one isolate of L. fermentum induced an increase in TEER compared with the control media. Lactobacillus plantarum DSM 2648 was chosen for further investigation because it had a greater positive effect on TEER compared with the benchmark, L. rhamnosus HN001, over the 12-h test period. Acid and bile tolerance (2 and 4 h) of L. plantarum DSM 2648 was compared with that of L. rhamnosus HN001 (Fig. 2). Both bacterial U0126 price strains were able to tolerate acidic conditions (pH 4 for 4 h) without the loss of cell viability; however, both strains had a reduced viability of 6–7 log units under conditions of pH 2 for 4 h. The viability of L. rhamnosus HN001 decreased by 2 log units in the presence of 0.5% bile and by 5 log units in the presence of
Idoxuridine 1% bile, whereas the viability of L. plantarum DSM 2648 only reduced by 2 log units by 1% bile. The ability of L. plantarum DSM 2648 to adhere to intestinal cells (3 and 6 h) was also compared with that of the benchmark strain, L. rhamnosus HN001 (Fig. 3). Lactobacillus plantarum DSM 2648 adhered in higher numbers (10 times more) to both confluent undifferentiated and differentiated Caco-2 cells compared with L. rhamnosus HN001 (P<0.05 at 3 and 6 h). Lactobacillus plantarum DSM 2648 displayed better in vitro tolerance to gastrointestinal conditions compared with L. rhamnosus HN001, which has been detected in human faeces after ingestion (Tannock et al., 2000); thus, it is possible that L. plantarum DSM 2648 may also survive passage through the human gastrointestinal tract. Lactobacillus plantarum DSM 2648 was also able to prevent the deleterious EPEC-induced TEER changes observed when the EPEC strain was incubated alone (Fig. 1d); however, the action of L. plantarum DSM 2648 was transient, lasting for at most 8 h. The action of L. plantarum DSM 2648 on EPEC interactions with Caco-2 cells was further explored using coculture adherence experiments.