Pangenome Analysis Reveals Novel Contact-Dependent Growth Inhibition System and Phenazine Biosynthesis Operons in BL95 That Are Located in An Integrative and Conjugative Element.

is a leading cause of urinary tract infections and a common commensal of the gastrointestinal tract. Our recent study (JB) showed that strain BL95 employs a novel contact-dependent killing system against enteric bacteria in the mouse gut and in vitro. To uncover the genetic determinants of this system, we performed whole-genome sequencing of BL95 and compared it with 98 complete genomes of . BL95 carries 56 coding sequences (CDSs) not found in other . Over half of these unique genes are located on a novel integrative conjugative element (ICE) named ICE, inserted in tRNA-Phe and exclusive to BL95. ICE has integration, conjugation, and DNA replication modules nearly identical to ICE (common in ), but ICE of BL95 carries two unique operons for -a phenazine biosynthesis and a contact-dependent growth inhibition (CDI) system. ICE is absent in the (AR_0156) closest to BL95 and it is present in the genomes of several from mouse intestines, indicating its recent horizontal mobilization. BL95 shares over 100 genes of five different secretion systems with other , mostly poorly studied, making a large pool of candidate genes for the contact-dependent growth inhibition.