FIG 6 .

Interspecies transfer of pESI during S. Infantis infection. Female C57BL/6 mice were infected with 1.5 × 10⁸ CFU of S. Infantis strain 119944 (harboring pESI) and screened for non-Salmonella microbiota that have acquired pESI following the infection. (A) The donor (S. Infantis 119944) and three mouse-isolate microbiota E. coli transconjugants were plated on XLD plates supplemented with tetracycline. (B) To confirm the presence of pESI in the above E. coli transconjugants, PCR amplification of pESI-specific genes (hp pESI and faeAB) and Salmonella-specific (invA) and E. coli-specific (lacZ) genes was conducted. S. Infantis 119944 and S. Infantis 335-3 lacking pESI were used as positive and negative controls, respectively. (C) Five representative microbiota isolates, including E. coli (isolate 481-49), L. reuteri (isolates 480-44 and 482-46), Ruminococcaceae (isolate 482-50), and an unknown bacterium (isolate 481-27) were subjected to PCR using primers from the pESI-specific gene irp2. S. Infantis 119944 and a pESI-negative S. Infantis isolate (335-3) were used as positive and negative controls, respectively. (D) Total DNA (100 ng) that was extracted from the above microbiota isolates was subjected to a dot blot hybridization using a DIG-labeled incP pESI backbone probe. A DIG-labeled rpoD probe was used as a hybridization control, and the identity (in percentage) between the rpoD sequence of S. Infantis (used to synthesize the rpoD probe) and its homolog in the tested genome is shown at the bottom of the panel.