Question: Dear James, Approximately how many microbes in the human body couldn't we live with out. Thanks twright1

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  1. Hi twright1, awesome question!
    A lot of research is actually looking at this to try and work out if there is such a thing as a healthy human microbiome (a set of bacteria that live on/in healthy people that are not found in unhealthy people).
    There isn’t really a number but instead a series of jobs that need to be done by bacteria that when are not done will result in an increased chance of death. These jobs can be described as active or passive jobs.
    A passive job is one where the bacteria simply has to exist to to its job and nothing more. This includes hundreds and possibly thousands of species with live on your skin, and in your gut. These bacteria occupy space and eat skin or bits of you food from the gut but by doing this they prevent other bacteria doing the same thing. These other bacteria include all the nasty ones that make us sick. The good bacteria keep the bad ones away simply by living in and on you.
    An active job is when the bacteria do something that benefits us that we can’t do ourselves. Lactobacilli species species in our guts break down lactose (the sugar from milk) into various products but one is glucose, which we can use for energy which is important because we cannot break down lactose ourselves, and another is lactic acid. By making lactic acid the bacteria is protecting itself from other bacteria but in the process generates enough acid to fight away bad bacteria generally.