The inner and outer body surfaces, such as the skin, the airways, the gastrointestinal and urogenital tract of all mammals are colonized with a great number of microbes, including bacteria, viruses, fungi and even parasites. The entity of these microbes are known as the commensal microbiota and importantly contribute to the well-being of the host through for example digestion of fibers, production of vitamins and maturation of the immune system.


The home for the germ-free and gnotobiotic mice. Isolators are plastic film bubbles that are pressurized and obtain HEPA-filtered air in order to maintain the sterile environment. Each isolator is endued with a double-port that allows to import material via a sterile way. The isolator is regularly restocked with sterilized water, bedding and food imported via a sterilized connecting sleeve. Depending on the size of the isolator, 4-50 cages have space in one isolator. All manipulations are performed via sleeves and gloves giving access to the inside of the isolator.

Germ-free mice

Germ-free or axenic mice are born and raised in a completely sterile milieu. This is achieved by housing them in pressurized HEPA-filtered plastic film isolators. These mice have no (commensal) microbiota at all and are completely sterile.

Gnotobiotic mice

Gnotobiotic (from Greek: roots gnostos "known" and bios "life") mice are colonized with a defined microbiota chosen by the researcher. They usually derive from germ-free mice that are colonized through co-housing with another gnotobiotic mouse or through gavaging the microbes of interest into a germ-free mouse. Gnotobiotic mice can be de novo generated from germ-free mice at any age or mouse colonies can be bred under gnotobiotic conditions to obtain so called “born and raised” colonized mice.

Peracetic acid

Peracetic acid (CH3CO3H) is an antimicrobial reagent used to sterilize the ports or connecting sleeves of isolators before opening the inner port of the isolator. Sterilization time is 45 minutes.