Membrane Bioreactor (IMAGE) Max-Planck-Gesellschaft Caption An anammox culture is in a membrane bioreactor. The red color is due to the heme c group of the protein cytochrome c that plays an important role in the anammox metabolism. Credit B. Kartal 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.