Fig 4.

L. lactis HP expressing the genes spiFEGRR′K under the control of their native promoter in the vector pCI372 was assessed to discover if immunity could be induced in the presence of nisin. L. lactis HP was incubated in the presence of approximately 10 ng of either nisin A (A, B) or nisin U (C, D) prior to being challenged by agarose well diffusion assay with both nisin A (A, C) and nisin U (B, D). L. lactis HP/pCI372 alone was included as a control. The data show that the action of the spiFEG genes has not been induced and thus they are not active under these conditions.