The role and regulation of reactive oxygen species for microbial disease control

Reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radicals, and superoxide anions are continuously produced by most cells undergoing aerobic metabolism. The term "ROS" encompasses nonradical oxidants such as hydrogen peroxide and singlet oxygen and oxygen free radicals such as superoxide anion and hydroxyl radicals. Higher doses of ROS may induce lethal oxidative lesions in the DNA, proteins, lipids, and related metabolites. As antibiotics kill bacteria in part by inducing ROS, targeting microbial ROS production might potentiate antibiotic activity. However, they also function as secondary messengers in signal transduction pathways. Thus, depletion of ROS can affect many signaling pathways related to redox equilibrium and eventually lead to cell death. Therefore, it is necessary to study ROS balance in microorganisms in order to control microbial infections. This chapter is focused on the role of ROS in oxidative injury, as well as on the effects of depletion of ROS.