B. fragilis T1RM specificity sequence after phage introduction

In a previous study, we demonstrated that phase variation of specificity proteins for a Type I restriction-modification system (R-M) of B. fragilis results in altered transcription of some capsular polysaccharides with potential altered immunomodulatory functionality of these bacteria. Since the Type I R-M systems are known to provide protection against bacteriophage, we used long-reads sequencing to quantify the orientations of the genes encoding the Type I R-M specificity proteins upon exposure to Barc2635. Our results demonstrate different patterns of specificity gene combination in the expression locus in B. fragilis isolated from mice inoculated with the phage compared to those not exposed to phage.