E. coli cells (IMAGE) Washington University in St. Louis Caption E. coli cells shifted from nutrient-rich conditions (left) to nutrient-free conditions (right). These cells contain fluorescent protein fusions that make the cytoplasm green and the periplasm, the space between the cell membrane and the outer membrane, red. Credit Kerwyn Casey Huang laboratory, Stanford University Usage Restrictions For editorial purposes 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.