The simplest way to prevent bacteria from decomposing a dead body is by eliminating water from their environment. All life forms require liquid water to live, so dehydrating bacteria prevents them from feeding and multiplying. This process of dehydration is called desiccation, which is actually the first step of creating many types of fossils. It's also the reason Otzi was naturally mummified — frozen in a flash and suspended in solid ice for well over 5,000 years, his bacteria was killed along with him. King Tutankhamun was desiccated as well, but without sub-zero temperatures to work in, his royal embalmers had a much bigger project on their hands.