Scientists identify enzyme that makes urine yellow

Scientists have identified the enzyme responsible for urine's yellow colour. It's called bilirubin reductase, and it's a result of degradation of red blood cells. Once they break down, a bright orange pigment called bilirubin is produced. Gut microbes encode the enzyme bilirubin reductase that converts bilirubin into urobilinogen, which degrades into urobilin that's responsible for the colour.