Each of your cells uses hundreds of mitochondria to generate energy, so we have effectively tamed a part of our ancient microbiome into directly working for us.

Each of your cells uses hundreds of mitochondria to generate energy, so we have effectively tamed a part of our ancient microbiome into directly working for us. A similar type of taming seems to be occurring at intestinal surfaces covered in mucus, where the body secretes a complex mixture of protein and sugars that simultaneously keeps the bulk of microbes at bay while actually feeding desirable bacteria. You wouldn't die of lack of microbiome, you'd die of being unable to maintain your sterile environment and eventually being infected, unless you lived in a bubble (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3477854/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3477854/), and Mars is actually not too far from that. Much better to allow yourself to be colonized by harmless bacteria which will fill up all the ecological niches that the pathogens require to thrive.