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S. J. ROBINSON, Beckman Institute for Advanced Science & Technology, Univ. of Illinois, Urbana-Champaign, Imaging Technology Group, 405 N. Mathews Ave., Urbana, IL 61801 Microscopy is essential to developing a detailed understanding of the structure and function of biofilms. This talk will present some of the basics of light, scanned probe, and electron microscopy, giving specific examples in certain cases and demonstrating the advantages of some techniques over others in this pursuit. Light and fluorescent microscopy are helpful in elucidating the basic shapes of bacteria, as well as aiding in the determination of species and highlighting characteristics that may be imaged using fluorescent markers. An advanced light-related methodology, laser scanning confocal microscopy, can provide much better imaging, in part due to its ability to optically section samples with excellent resolution. Of the scanned probe microscopies, atomic force microscopy (AFM) is best adapted to biological samples, and tapping mode is likely the best of the specific AFM techniques available for imaging biofilms. Transmission electron microscopy (TEM) is most easily performed on whole mount samples of bacteria, but there is a limit to what may be determined using whole mounts. Embedding and sectioning bacteria for TEM is much more difficult and time-consuming, but it provides by far the best means of imaging the microstructure inside bacterial cells. Conventional high vacuum scanning electron microscopy produces what are perhaps the most pleasing images of bacteria, but the processing involved can be destructive to something as fragile as a biofilm. Although imaging biofilms using environmental scanning electron microscopy (ESEM; in which the specimen chamber is held at a reduced vacuum), can be difficult, it may provide some of the best images of specimens unaltered by processing.
Session 51, Biofilms in the food environment: Current approaches and findings
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