FIG 4.
Postirradiation time course for transiently undetectable (by culture) cells. Triplicate (A) and quadruplicate (B) E. coli suspensions in PBS at 1 × 108 CFU/ml were separately irradiated with UV light for 45 to 50 s. Cell suspensions were incubated at room temperature in PBS after UV exposure. Aliquots were taken for MVT (white bars) and plating (triangles) before (No UV) and at time points (0, 1, 4, 24, and 120 h) following irradiation. MVT (RT-qPCR) data are expressed as ΔCq values (left axes). For MVT, ΔCq (unstimulated minus stimulated) values of >1 (dashed lines) indicate viable cells. Black triangles indicate no detected colonies (below the limit of detection).