Thanks for your quesiton! Changes in media color often come from exposure to air, but media color changes can also come from contamination. This happens with bacterial contamination, which causes the pH to decline and begin changing the media to an orange or yellow color. The media often also has an increase in turbidity with bacterial and fungal contamination. Some fungal contaminations can cause the pH to increase and become more pink rather than the neutral pH red color, but this is less common. Please let us know if you have any other questions!
