The survival of bacteria is associated with the ability to respond to changing environmental conditions. For example, during situations of environmental pressure (e.g. UV, heat, or drug exposure) ROS levels can increase, leading to damage of DNA, lipids and an initiation of signaling events that can lead to cell death. Fortunately, bacterial possess enzymes such as superoxide dismutase (SOD) and catalase enzymes, as well as other antioxidant agents that can reduce ROS. However, when the balance between the production and elimination of ROS is upset, it can have unwanted effects. Thus, the ability of bacteria to increase their tolerance to ROS would be beneficial to the cell’s survival.