Fig 1. Growth phenotype of ∆yfcJ, ∆yhjE, and ∆ydiM mutants.

The strains were grown on plates under either aerobic (top row) or anaerobic (bottow row) conditions. The parental strain is the E. coli K-12 (BW25113) used to generate the Keo library (Materials and Methods). In the bo₃⁺ strain bo₃-Qox is the only functional quinol oxidase, whereas all quinol oxidases are absent in ∆bo₃ strain, which does not grow under aerobic conditions. The MFS-type transporters mutants ∆yfcJ, ∆yhjE, and ∆ydiM lack bd-Qox1 and bd-Qox2 quinol oxidases, and unlike the bo₃⁺ strain show poor aerobic growth phenotype like the ∆bo₃ mutant bo₃-Qox.