[An ATP bioluminescence assay for the analysis of bacterial biofilms]

To analyze the bio-activity of the bacterial biofilm, the ATP content of the biofilm was assayed using the ATP bioluminescence assay. A linear relationship between the ATP content and the number of the planktonic Pseudomonas aeruginosa cells was observed. An in vitro experiment was set up using a modified Robbins device (MRD). A biofilm of P. aeruginosa was developed on the silicon discs of this device by recirculating artificial urine medium through the MRD. The activity of the biofilm, assayed by ATP luminescence, increased rapidly during the first 4 hrs of circulation, and essentially remained unchanged for 32 hrs during medium circulation. After the biofilm developed, the medium was exchanged to the new artificial urine with piperacillin or clarythromycin or ofloxacin and circulated for 8 hrs. The biofilm changed its bio-activity by the antibiotics, and the change could be detected by measuring the ATP content. These changes of ATP content studied were correlated well with the findings detected by scanning electron microscopy. Finally, ATP measurement of the bacterial biofilm was useful in analyzing the bio-activity of bacterial biofilm.