FIG. 4.

Attachment of ¹⁴C-labeled E. coli O55 cells to trophozoites. E. coli (Ec) O55 (10⁹) (300 cpm/10⁶ bacteria) was added to freshly harvested and washed trophozoites of E. histolytica (HK-9 and HM-1:IMSS) (10⁶) grown in axenic conditions and monoxenically cultivated with E. coli O55 or 346 for 1 month. The reaction was carried out in suspension for 30 min at 4°C. Nonadherent bacteria were separated by a Percoll gradient centrifugation as described in the text. Attachment of ¹⁴C-labeled E. coli O55 to axenic trophozoites was taken as 100%.