Non-aqueous phase liquids (NAPLs) can become entrapped in subsurface rock fractures and become a long-term groundwater contaminant source. While remediation technologies exist, they can be expensive. Subsurface microorganisms can also degrade NAPLs trapped in the subsurface; however, this is a slow process. The possibility of enhancing microbial degradation of NAPLs via a plasmid transfer mechanism in a model rock fracture aquifer was explored. There was no indication that introduction of donor strain Pseudomonas putida SM1443::gfp2x-pWW0::dsRed into the model system led to transfer of the degradative TOL plasmid pWWO, or led to increased degradation of model NPL toluene. Plate matings with the donor strain and a groundwater-derived microbial consortium indicated that few potential recipients existed in the community. Nutrient concentration was ruled out as a limiting factor of plasmid transfer.