Killing Zone (IMAGE) Arizona State University Caption When bacteria contain the DNA plasmid pAPEC-1, they produce a powerful toxin that kills other bacteria. The top spot and bottom spot both contain pAPEC-1, creating a lysis zone where no other bacteria can grow within the area. The spot in the middle of the plate contains no pAPEC-1, allowing bacteria to grow and surround the spot. Credit The Biodesign Institute, Arizona State University 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.