This chapter discusses the assessment of metabolic potential of biofilm-associated bacteria. In the study of the microbial ecology of bacteria involved in biofilm formation, two major questions concern the metabolic status and phylogenetic identity of community members. Identification of bacteria has been revolutionized by rRNA-based phylogeny, and the development of rRNA-targeted oligonucleotide probes for fluorescent hybridization (FISH) in natural microbial communities. If combined with spectroscopy or flow cytometry, some of them might also be useful tools at the population level. Most measurements of metabolic activities can be roughly grouped into methods detecting activities of specific enzymes, synthesis of macromolecules, or membrane potentials. Some of these methods, however, are not presented here, either because they have not yet been applied to environmental samples of biofilm populations or because they are not widely used in studies of bacterial metabolic activities. They include detection of (1) esterase activity by fluorescent substrates such as fluorescein diacetate or sulfofluorescein diacetate; (2) cell division by microcolony formation; (3) membrane potential by rhodamine or by propidium iodide; (4) membrane integrity by plasmolytic response to osmotic stress; or (5) DNA and RNA degradation by lysozyme treatment and 4', 6-diamidino-2-phenylindole (DAPI) staining. Thus, this chapter starts with the presentation of two of the most widely applied procedures for the detection of bacterial metabolic potentials: the cyanoditolyl tetrazolium chloride (CTC) method, and the direct viable count (DVC) method..
Anatomy & Physiology
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