Introduction
Multicellular organisms are colonized by symbiotic, parasitic or infectious microorganisms. The extent of this colonization is best illustrated by the fact that 90% of human cells are actually microbial cells. In the oral cavity as well as in the intestine, one can identify up to 500 different species of microbes. Fortunately, very few microorganisms are pathogenic, and most microbes are either beneficial for the host or have no apparent effect on the host.
The most effective strategy for establishing what microbes do for the host is to generate germ-free animals that are raised under sterile (axenic) conditions. To such axenic mice one can re-introduce specific microbes - these animals are referred to as gnotobiotic animals - and study the impact of particular microbial strains on a given biological phenomenon. In addition, analysis of animals raised under germ-free conditions has permitted the proper attribution of a phenotype to a gene or biological pathway, independently of the microbial flora. Moreover, gnotobiotic studies allow the establishment of the ecologic rules that govern bacterial flora diversity. Numerous differences between germ-free and conventionally raised animals have been reported, and these include a decrease in specific tissue and organ size, altered metabolism and deficiencies for vitamins, as well as variation in a large array of immunologic characteristics.
EMMA offers as a service the generation of germ-free (axenic) mice.