Fig. 6

Analysis of T6SS loci transfer between co-resident strains. a Ethidium bromide-stained agarose gels showing the results of PCR amplification of regions specific to the B. fragilis CL05T12C13 GA2 T6SS locus (left) or the B. finegoldii CL09T03C10 GA1 T6SS locus (right) from co-resident strains. Bfra - B. fragilis, Bvul – B. vulgatus, Bcel – B. cellulosilyticus, Bova – B. ovatus, Bthe – B. thetaiotaomicron, Buni – B. uniformis, Pmer – P. merdae, Pdis – P. distasonis, Bfin – B. finegoldii, Bste – B. stercoris. The entire strain designation consists of three parts: a subject ID (e.g. CL09), an indicator of the isolation time in months (e.g. T03), and a colony ID (e.g. C10). b Comparison of T6SS-containing ICE DNA contained within four co-resident species. The three Bacteroides isolates sequenced for this work (B. cellulosilyticus, B. ovatus, and B. stercoris) contain DNA nearly identical to a previously sequenced isolate (B. finegoldii) from the same individual, strongly suggesting transfer of this ICE among co-resident strains. The small ORFs in the center of the B. finegoldii map are surrounded by Ns; this DNA is present in the three newly sequenced strains as well, but as separate small contigs, as the assembler used took a less aggressive scaffolding approach. The ICE containing this GA1 T6SS locus is greater than 110,000 bp in size. The ORF maps are colored according to the key provided in Fig. 1, except that tra genes are additionally colored dark green