FIG. 2.

Mutation frequency. L. plantarum strain NZ1807 was used as a G-stretch reporter strain. The mutation frequency is the number of revertants per 10⁸ CFU. The background mutation frequency is the mutation frequency at 30°C with the empty vector pNZ8154. The effect of incubation with 300 μg/ml NTG for 1 h at 30°C on the mutation frequency was also determined with the empty vector pNZ8154. Plasmids pNZ1813 and pNZ1814 were used to determine the effects of HexA and tr-HexA, respectively, on the mutation frequency.