Purple Bacteria (image) University of Miami Caption Purple bacteria make a "gel" around the individual cells which binds them into a colony. That is why they appear as "clouds." The insert illustrates the general principle of the model used in the study. It depicts photons arriving, then being passed around the bacteria's membrane, where the light harvesting mechanism is located, then arriving at the various reaction center 'kitchens', being processed, and then being turned out as metabolic products for the bacteria to survive. Credit Dr. Wayne B. Lanier Usage Restrictions Must be properly credited to Dr. Wayne B. Lanier 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.