Indigo Clean (IMAGE) University of Strathclyde Caption This is a microbial contamination on a contact agar plate with a 405nm light source in the background. Credit University of Strathclyde Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.