Microbes - can't live with them, can't live without them. Increasingly, we're finding out that our microbiota (the microbes that live on us) are essential for our wellbeing - they provide us with nutrients and vitamins and play a key role in developing our immune system. On the other hand, they are responsible for a great deal of misery, as they are major causes of death and debility around the world. As well as our own microbiota turning against...