The effects of energy availability on the conjugative-transfer kinetics of plasmid RP4

Batch kinetic experiments were carried out to measure conjugative-transfer kinetics for plasmid RP4, which encodes resistance to kanamycin, tetracycline and ampicillin. The donor species was Rhodobacter capsulatus, while the recipient was a Pseudomonas strain obtained in our laboratory. Evaluated was a mass-action kinetic model that had a donor-to-recipient rate coefficient k₁₁ and a transconjugant-to-recipient rate coefficient k₂. Experimental results demonstrated that k₁₁ and k₁₂ were of similar magnitudes and could be reasonably large: e.g. up to 0.03 l g_T/g_D g_R day for k₁₁. However, the rate coefficients were not constants. Instead, they increased dramatically as the energy availability increased. Energy was made available in kinetic experiments from the energy substrates and from internal storage materials, carried over from prior batch growth cultures.