How long would a person live without bacteria was recently closed as primarily opinion based. This is puzzling to me.
It can be argued that this (eliminating all microorganisms) has never been tested in humans, but much of out knowledge about human physiology has not been derived from experiments on humans; indeed the vast majority of what we know about human physiology and medical conditions has been derived from animal studies.
The dog genome has been mapped out not only for it's importance to veterinarians, but also because dog-models have been so vital (and suitable) to research of human disease. The role of mouse models has been invaluable. As stated in Mouse Models of Developmental Genetic Disease:
It is the recognition that humans and mice share the same organ systems, similar reproductive cycles, skeletons, biochemistry, physiology, and most importantly pathologies that have enabled us to progress in our understanding of the basis of human disease and this shows no sign of abating in the foreseeable future.
The use of gnotobiotic mice has recently been important to the better understanding of microbiomes and obesity, cholesterol metabolism, inflammatory bowel disease and infection-mediated diseases, type 1 diabetes, allergies, Antibiotic-Associted Diarrhea (C. difficile) and cancer, to mention only a few diseases.
In defending the use of gnotobiotics as a crucial element in studying human diseases, Rolf Freder points out
…[I]f one chooses to be rigorous in the definition of what constitutes the reproduction of a human disease, one may well state that no such model has ever been discovered.
Why, then, is a question that absolutely can be answered by studies in the murine model judged to be POB?
I would appreciate any insights, as well as what would need to be done to make this question on topic, as I believe an interest in the human (and therefore animal model) microbiomes and disease (or lack thereof) will prove an illuminating subject of study in the coming decades.
Leading the way: canine models of genomics and disease (Disease Models & Mechanisms)
Animal models of human disease: zebrafish swim into view
Mouse models of human disease
Mouse Models of Developmental Genetic Disease
From Structure to Function: the Ecology of Host-Associated Microbial Communities
Methods and Special Applications in Bacterial Ecology