Root Nodule Cut Open (IMAGE) American Society of Agronomy Caption Bacteria inside root nodules need oxygen to survive. A pink or red color inside a nodule indicates the oxygen supply is robust and the bacteria are thriving. Credit Mariangela Hungria. Usage Restrictions Please use with story only. 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.