Researchers have gained new insights into how bacteria move in complex environments. Bacteria move using a system called "swim-and-tumble": they swim in a straight line for a bit, then tumble in a circle, which gives them a chance to correct their course. They can't see where they're going - they can't see at all - but they can sense and follow gradients of increasing concentration of food, like following a delicious smell into the kitchen. This type of movement is called chemotaxis, and it's been well studied in bacteria moving in a clear area. But in the real world, such as inside the human... Like this podcast? Please help us by supporting the Naked Scientists