Germ-free animal
Such organisms are raised using various methods to control their exposure to viral, bacterial or parasitic agents.
[2] Due to lacking a microbiome, many germ-free organisms exhibit health deficits such as defects in the immune system and difficulties with energy acquisition.
[5] Germ-free organisms are generated by a variety of different means, but a common practice shared by many of them is some form of sterilization step followed by seclusion from the surrounding environment to prevent contamination.
After the cesarean birth, the pups must then be transferred to a sterile incubator with a germ-free mother for feeding and growth.
Typically for experiments, each mouse is housed separately in a sterile isolator to prevent cross-contamination between mice.
Germ-free offspring of the nematode C. elegans, which is used in research, can be produced by rupturing adult worms to release eggs.
This bleach solution ruptures the adult worms, breaking them down while simultaneously releasing and surface sterilizing any eggs.
C. elegans consumes bacteria, so before the eggs can be transferred to the plate, the food must be killed by either heat or irradiation.
This method for creating germ-free nematodes has the added benefit of age-synchronizing the worms, so that they are all of similar ages as they grow.
[14] Seeds are surface sterilized with chemicals, such as ethanol or an antibiotic solution, to produce a germ-free plant.
[18] Due to lacking a healthy microbiome, many germ-free organisms exhibit major health deficits.
[6] Germ-free mice have been shown to have defects in their immune system and energy uptake due to lacking a healthy microbiome.
[13][19][20] Germ-free plants exhibit severe growth defects due to lacking symbionts that provide necessary nutrients to them.
[25][26] Germ free animals have been used to demonstrate a causal role for the gut microbiome in varied settings such as neural development,[27] longevity,[28] cancer immunotherapy,[29] and numerous other health related contexts.
