Effect of cadmium on the infection of Lactobacillus lactis by bacteriophage LL-H

The infectivity of Lactobacillus lactis bacteriophage LL-H was shown to be calcium-dependent. Of 10 different divalent cations screened, cadmium specifically decreased the infectivity of LL-H in the presence of calcium. At 1 to 2 mM, CdCl2 resulted in a decrease of the burst size of about 2.5- to 4-fold. Cd2+ was shown to reduce specifically the level of total phage DNA synthesis, resulting in a reduced progeny phage yield. Moreover, Cd2+ had the most profound irreversible effect on progeny phage production between 20 and 60 min after LL-H infection. This paralleled the beginning of phage DNA synthesis. Possible modes of action of Cd2+ on phage DNA replication are discussed.