Fig. 6

Inactivation of the pefCD transporter leads to cellular accumulation of heme in cells grown in the presence of heme. a UV-visible spectra across wavelengths (250–700 nm) were recorded for organic fractions recovered after acidified chloroform extraction performed on a range of hemin chloride standards. b The observed absorbance at 388, 450, and 330 nms from UV scans (of organic fractions) were plugged into A _c = 2A ₃₈₈ − (A ₄₅₀ + A ₃₃₀) equation. The A_c values for standards extracted using chloroform for a range of hemin concentrations (0–4 μM, with 0.5 μM increments) were plotted against its hemin concentrations to generate a standard plot. The line equation of a standard plot was used to extrapolate hemin concentrations in the experimental samples. Cultures of NZ131 (WT), ZE4951 (Mutant), ZE4951/pANKITA5b (Complement), and ZE4951/pKSM201 (Empty vector) strains were treated with 3 μM heme during the mid logarithmic phase of growth (60–70 Klett units). Cells were harvested, washed, and were subjected to chloroform extraction. c UV-visible spectra across different wavelengths (250–700 nm) of the collected organic phases from tests samples were recorded. d Heme concentration in the test samples. The concentrations of heme in the test samples were calculated using the standard curve shown in B. The data are derived from two independent experiments each done in triplicates. The asterisk (*) denotes that the observed P value is statistically significant (P < 0.05) calculated using student t-test (equal variance) at 0.05 levels of significance