Question: Is there bacteria everywhere?

Katie Fala answered on 20 Nov 2019:

Pretty much! Even places that you would think are incompatible with life, such as deep sea vents where there is no light and extremely high pressure, we find microbes that have evolved and adapted to be able to survive in those conditions. Another example, while raw building materials might often have low levels of microbes, when we build homes and hospitals and roads we gradually see different species colonise and establish communities on them (some people study this as the microbiology of the built environment). And of course, many living things including humans have evolved alongside bacteria to the point that we could not live without them e.g. in our skin and gut microbiomes. There are some exceptions, for example some body organs are designed to stop bacteria entering and would be sterile in healthy people, for example the liver, heart, kidney. Another example would be foods that have been processed with heat/pressure to make them free from living organisms, such as UHT milk.