Scientists have come up with a creative way to turn a harmful microbe into a tiny cancer fighter. They redesigned Salmonella which normally causes stomach illness so it naturally moves into colorectal tumours where oxygen is low and immune activity is weak. Once the bacteria settle inside the tumour they are programmed to break apart on purpose and release a strong immune boosting protein called LIGHT which pushes the body to form organised immune hubs right inside the tumour tissue. These immun