Beneficial Bacteria (image) University of Delaware Caption Disease symptoms are reduced in plants treated at the roots with Bacillus subtilis. The bacterium hijacks the plants' immune system for a period. Credit University of Delaware Usage Restrictions Image must include credit to University of Delaware. 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.