Methods for Whole Cell Detection of Microorganisms
Food Science and Human Nutrition
Microbes are ubiquitous, and can be found occupying nearly every imaginable niche on Earth. These include organic and inorganic surfaces, interfacial boundaries and within macroscopically solid matrices, such as the pore space of rocks. Because phylogenetically divergent microbes may be visually indistinguishable, understanding the species distribution and ecological significance of environmental microbes requires diagnostic tools that extend beyond simple phenotypic description. Methods for microbial diagnostics can be divided into two broad categories: cellular and acellular. Acellular techniques, such as the polymerase chain reaction or certain immunoassay formats may be effective at detecting molecular, structural or biochemical targets associated with specific cell types, but this information is provided out of its "natural", and arguably most meaningful context — that of the individual microbial cell. In contrast, cellular methods have the potential to preserve an abundance of valuable information. Apart from molecular identity, this includes information regarding cell morphology and other physiological characteristics, cell number and distribution within a sample, and physical or spatial associations with other cell types. The aim of this chapter is to provide an overview of whole cell methods for microbial detection, including both existing approaches and those still in development. The tools described here are expected to find wide application for the detection of microbes on surfaces or within complex matrices across a number of parallel or allied fields, including environmental, food and clinical microbiologies.