FIGURE 2.

The number of transconjugants and transfer frequencies (TFs) obtained from conjugation experiments in LB media supplemented with ZnSO₄ and CuSO₄ at 0.5 and 1 mM. Conjugation experiments used waterborne bacterial donor communities from two La Paz River basin sites and E. coli CV601 as the recipient strain. The bars represent mean values of the number of SMX-TMP resistant transconjugants (A,B) and transfer events per recipient (C,D) in the presence of ZnSO₄ and CuSO₄. Data were obtained from three independent conjugation experiments. The error bars represent the standard deviation of the mean. For both sampling sites, the number of SMX-TMP-resistant transconjugants and TFs did not differ significantly between the experiments performed in LB media and LB media supplemented with metals.