Quantification of local water and biomass in wild type PA01 biofilms by Confocal Raman Microspectroscopy

Confocal Raman Microspectroscopy (CRM) can be used as a tool for the in situ evaluation of the chemical composition of living, fully submerged, unstained biofilms. In this study the estimation of the local water content in Pseudomonas aeruginosa PA01 biofilms is given as an example.The ratio of the area of the O–H stretching vibration band at 3450 cm− 1, (water), to that of the C–H stretching bands at 2950 cm− 1 (biomass), was used to estimate the relative biofilm water content. The quantification of biofilm water and biomass was based on calibration curves generated from protein solutions. Water/biomass ratios (W:BR) equivalent to that of a 30% (w/v) protein solution were observed within some biofilm colonies.