The effect of nickel and cadmium on the diversity of the trfA2 gene in the IncP plasmid origin of replication region

Sequences of the trfA2 gene were compared to determine if exposure to cadmium or nickel increased IncP plasmid diversity. Community DNA was extracted from Savannah River sediments spiked with Cd, Ni, or unspiked controls, and the trfA2 gene was amplified using established replicon-specific primers, cloned and sequenced. The majority of sequences were identified as trfA2 genes from IncP plasmids, a few were identified as IncP or IncP genes, but no IncP sequences were detected. However, research results also indicated the need for more selective primers for IncP and IncP subgroups. Considerable variability within the IncP trfA2 sequences was observed, but AMOVA analysis did not indicate significant differences among treatments. Whittakers Index of Association indicated that Cd and Ni plasmid communities were more similar to control communities than to each other.