Confirmatory assays of selected BPS-sensitive deletion strains identified by functional profiling. The wild type strain and known mutants defective in iron metabolism, aft1Δ and fet4Δ (not identified in the functional studies), were included for comparison. A Growth assays in YPD agar plates. Cultures of individual deletion strains were pre-treated by growing overnight on BPS or ferrozine-containing plates, followed by serial dilution and spotting onto YPD plates ± 100 μM BPS. The strain hoΔ was included as a deletion control. B Growth assays in liquid SD media with 0, 50 or 100 μM BPS. Cultures were pre-treated and diluted in fresh media as before for the assay. Curves show the optical density at 595 nm (OD595) of the culture monitored for a period of 24 hours. Mutants exhibited different degrees of sensitivity to BPS, which is indicative of the relative importance of the missing gene in iron deficiency. Among these genes, AFT1, FET3 and FTR1 were the most essential for growth. The severity of the iron-deficient phenotype did not always correlate between liquid and solid media for the same strain (see results and discussion).