The recA gene and cadmium toxicity in Escherichia coli K12.

The influence of the recA gene on cadmium toxicity was studied in Escherichia coli K12 strains. Those strains mutant in the recA gene showed a 1,000-fold loss of viability upon exposure to cadmium, but recovered and started growing approximately 16-20 h following the initial exposure to cadmium. In contrast to previous studies with E. coli B strains, the E. coli K12 strains carrying a functional recA gene showed little or no loss of viability upon exposure to cadmium. The cells also exhibited a significant lag period in which no net growth occurred and then began growing 16-20 h after initial exposure to cadmium. These results indicate the importance of the recA gene to cell survival during exposure to metals, and also support the hypothesis that cadmium causes DNA damage.