Fig. 4: Bacteroides-specific beta-lactamases CfiA and CblA are functional in E. coli.

A AR genes TEM, cfiA, cepA, cblA, and cfxA were cloned onto plasmids either with no promoter (TEM only), their native Bacteroides promoter, or a synthetic E. coli promoter, transformed into E. coli and tested on ampicillin to determine their minimum inhibitory concentrations (MIC). B MICs to various antibiotics were determined using antibiotic strips on agar for E. coli carrying cfiA and cblA, placed under its native Bacteroides promoter (yellow) and an E. coli-specific promoter (purple). E. coli without plasmid were used as a control. C E. coli tested for growth on agar plates treated with cefotaxime strips. E. coli harboring no plasmid, or a plasmid harboring cfiA under control of its native B. fragilis promoter, the synthetic E. coli promoter, or a mutant library of B. fragilis cfiA promoters (Mutated). D Histogram of mutations within the B. fragilis native promoter identified in the mutated cfiA promoter library after 18 h of growth in 0.5 ug/ml of cefotaxime. The native B. fragilis promoter sequence is shown, as are the predicted B. fragilis and E. coli promoters in the native sequence, the mutated consensus sequence and a depiction of the canonical E. coli promoter.