Investigation of the Mesoscale Structure and Volumetric Features of Biofilms Using Optical Coherence Tomography

Optical coherence tomography (OCT) was successfully applied to visualize the mesoscale structure of three different heterotrophic biofilms For this purpose, biofilm volumes of 4 x 4 x 1 6 mm(3) were scanned with spatial resolutions lower than 20 mu m within an acquisition time of 2 mm A heterogeneous structure was detected for biofilms cultivated in laminar as well as transient flow conditions The structure was found to be more homogeneous for the biofilm grown in turbulent flow This biofilm structure was characterized by a volumetric porosity of 0 36, whereas the porosity calculated for biofilms grown in laminar and transient conditions was 0 65 These results were directly generated from the distribution of porosity calculated from the OCT images acquired and can be linked to structural properties Up to now, the mesoscale biofilm structure was only observable with time-consuming and expensive studies, for example, magnetic resonance microscopy OCT will most certainly be helpful for unproved understanding and prediction of biofilm physics with respect to macroscale processes, for example, mass transfer and detachment as the inform anon about mesoscale is easily accessible using this method In the context of this study, we show that CLSM images do not necessarily provide an accurate representation of the biofilm structure at the mesoscale Additionally, the typical characteristic parameters obtained from CLSM image stacks differ largely from those calculated from OCT images Nevertheless, to deter mine the local distribution of biofilm constituents, microscopic methods such as confocal laser scanning microscopy are required Biotechnol Bioeng 2010,107 844-853 (C) 2010 Wiley Periodicals, Inc