Living with microbes

Abstract This chapter introduces the concept of microbes. It notes how all healthy animals and plants are inhabited by communities called microbiomes, which are generally regarded as an indication of health. In many animals, the most abundant microbial populations are housed in the gut, while the roots of plants are associated with large and diverse microbial communities. Although microbiomes generally promote the host of the animal or plant host, they can occasionally be deleterious. Strategies to study microbiomes include the use of laboratory animals, especially mice and fruit flies, that are deprived of their resident microorganisms and colonized with specific microorganisms.