Fig. 1

Identifying pathogen vulnerability using redox perturbation with different ROS. Compared to singlet oxygen and hydroxyl radicals, superoxide and peroxide have much longer diffusion lengths and half-lives in the cellular environment (red circles, not to scale) [24, 82]. Singlet oxygen and hydroxyl radicals are also more nonselective – they react rapidly with an abundance of endogenous biomolecules. Superoxide is more selective, partly due to its negative charge, and it reacts with very particular consequential cellular targets such as iron-sulfur clusters [25]. The endogenous bacterial defense against superoxide is less abundant than the defense against nonselective ROS. This leads to a drastically lower observed toxicity threshold when compared to other species [24]. Unlike other ROS, superoxide offers a large window of dosage that yields toxicity in pathogens and nontoxicity in hosts [19, 24]