Interface variants in the BACTH assay.A, examination of interface variants in the BACTH β-galactosidase assay. Interface variants were examined in the BACTH β-galactosidase assay after 24 h incubation at 30 °C. Assay was performed in triplicate. Statistical significance was determined by a two-tailed, nonpaired Student's t test. ∗p < 0.01, ∗∗p < 0.001, ∗∗∗p < 0.0001. B, examination of interface variants in the BACTH MacConkey agar assay. Interface variants were examined in the BACTH MacConkey agar assay after 24 h incubation at 32 °C. Assay was performed in triplicate.