ABSTRACT
This chapter describes two main driving forces from a historical perspective. They are an awareness of its importance in human disease, development, nutrition, behavior, and well-being and the development of technologies. Antonie van Leeuwenhoek was the first person to use light microscopy to investigate the indigenous microbiota of humans when he observed the presence of animalcules in dental plaque and in feces. Recognition of the involvement of members of the indigenous microbiota in a wide range of diseases has become an important stimulus to research into the characterization of the microbial communities associated with humans. The microbes present in a sample can be identified by transmission electron microscope or scanning electron microscope using antibodies or oligonucleotide probes. In order to render these probes visible by electron microscopy they must be linked to electron-dense markers such as nanogold or ferritin.
