In addition to metabolic investigation, cookie acid washes were also analyzed for DNA, and PCR amplification procedures were attempted on these samples. Although nanomolar concentrations of DNA were detected in the acid washes, 16S eubacterial rRNA PCR amplification was unsuccessful (data not shown). These results suggest that the DNA, although present, was either damaged during acidification, or that it contained inhibitory compounds, and was not PCR-amplifiable. Other methods of biofilm recovery and preparation, which may better preserve both biofilm metabolites and DNA, are being explored.