Step-by-step explanation:
Probiotics are a combination of live beneficial bacteria and/or yeasts that naturally live in your body. Bacteria is usually viewed in a negative light as something that makes you sick. However, you have two kinds of bacteria constantly in and on your body — good bacteria and bad bacteria.
Using a harmless strain of E. coli that colonizes the liver, the researchers programmed the bacteria to produce a luminescent signal that can be detected with a simple urine test.