Inside our gut lives an entire ecosystem of bacteria and microbes, called the microbiome. In fact, the human body contains trillions of microorganisms, which outnumber our cells by ten to one. This means that technically we are more microbe than human. But not only do these microbes rely on us to survive, we also rely on them for some vital bodily functions. So what impact do these trillions of microbes have on our health? That’s the question that’s been bothering CrowdScience listener Russell, from Canada. Presenter Caroline Steel investigates. She visits the only museum in the world dedicated to microbes to ask exactly what they are, what they do and why we have so many of them inside our bodies. And she visits a microbiology lab filled with model guts to find out what impact the microbiome has on our physical health and if there is anything we can do to help our microbes function better. Caroline finds out what impacts our microbiome, what we can do to improve our inner ecosystem, and how our microbes can take a disturbing turn on us after we die. Produced by Hannah Fisher and presented by Caroline Steel for the BBC World Service. Editor: Richard Collings Production Coordinator: Jonathan Harris Contributors: Professor Glenn Gibson – Professor of Microbiology, University of Reading Jasper Buikx – Microbiologist and Head of ARTIS Micropia David Good – Doctoral Candidate at the University of Guelph Image Credit: Microbiota of the human intestine/CHRISTOPH BURGSTEDT/SCIENCE PHOTO LIBRARY