Capturing air-water interface biofilms for microscopy and molecular analysis

Described here is a simple and versatile technique for capturing small samples of the thin biofilm that is located at the meniscus of almost every air-water interface (AWI), an electrostatically distinct aquatic domain/habitat. The method uses a microscope slide (and other supporting surfaces) coated in the lab with a collodion membrane, which has a strong affinity for the upper surface of the AWI biofilm. The structural integrity of the biofilm is maintained during the capture process, and components of the biofilm are effectively separated from the subtending liquid. The captured thin biofilm can be analyzed in many ways including almost any form of light, electron, and atomic force optics; and spatially significant molecular analyses may be performed on the captured biofilm or its components.