HeLa cells pre-conditioned by the adhesion of EACF 205 were treated with antibiotics and washed in order to remove the adherent bacteria. Afterwards, pre-conditioned HeLa cells were used to test the adhesion of the EAEC strains (Figure 3, frame A). No increment in bacterial adherence was observed showing that the enhanced adhesion was not primed by host cells. However, the same assay Ro 61-8048 datasheet carried out in the absence of washing step showed an increased adherence similar to that observed with live bacteria. Thus, the EACF 205 population adhered to HeLa cells and inactivated by antibiotics still
held the capability to boost the adhesion of the EAEC strain 340-1 (Figure 3, frame B). These results showed that the increase in the bacterial adherence developed by EACF 205-EAEC CX-5461 purchase combinations were supported by physical interactions, which were triggered by EAEC strains, independently of chemical signals or the influence of host cells. Figure 3 Adhesion of EAEC strain selleckchem 340-1 to pre-conditioned HeLa cells. Frame A describes the adhesion assay employing host cells pre-conditioned by the adherence of EACF strain 205.
Frame B shows the parallel assay that was carried out in the absence of washing step. Bacterial cells of EACF 205 adhered to HeLa cells and inactivated by antibiotics still held the capability to boost EAEC adherence. EACF 205 and traA-positive EAEC strains form bacterial aggregates Aggregation assays showed that the EAEC strain 042 was capable of intense autoaggregation (aggregation rate of 0.999 ± 0.007). As a consequence, this strain was not
used in the aggregation assays which intended to address inter-specific interactions. Standing overnight cocultures of EACF 205 and EAEC 340-1 aggregated at levels (0.70 ± 0.04) higher than C. freundii 047-EAEC 340-1 cocultures (0.52 ± 0.05) and monocultures of EACF 205 (0.34 ± 0.11), C. freundii 047 (0.12 ± 0.02) or EAEC 340-1 (0.53 ± 0.05). These assays indicated the occurrence of inter-specific interactions between EACF 205 and EAEC 340-1. Settling profile assays showed that the bacterial aggregates formed by EACF 205 and EAEC 340-1 were not restored if the overnight coculture was homogenized. Moreover, the assays showed that bacterial aggregates were not formed when overnight monocultures of EACF 205 and EAEC 340-1 were mixed (data not shown). Carnitine palmitoyltransferase II These results indicated that the aggregation involving EACF 205 and EAEC 340-1 strains occurred at a specific time during the bacterial growth and involved inter-specific recognition. In order to verify these events, settling profile assays were performed employing bacterial cultures in mid-log phase. The assays showed that EAEC strains 340-1 and 205-1 aggregated, and consequently settled, only in the presence of EACF 205 (Figure 4A). When mixed with EACF 205, the EAEC strains 340-1 or 205-1 induced a steady drop in the settling curve at the 15-min time point.