Proteomic analysis reveals the mechanism of different environmental stress-induced tolerance of Pseudomonas aeruginosa to monochloramine disinfection

Although drinking water disinfection proved to be an effective strategy to eliminate many pathogens, bacteria can still show disinfection tolerance in drinking water distribution systems. To date, the molecular mechanisms on how environmental stress affects the tolerance of Pseudomonas aeruginosa to monochloramine are not well understood. Here, we investigated how three stress conditions, namely starvation, low temperature, and starvation combined with low temperature, affected the monochloramine tolerance of Pseudomonas aeruginosa, an opportunistic pathogen commonly found in drinking water distribution systems. All stress conditions significantly promoted monochloramine tolerance, among which starvation had the most drastic effects. Proteomic analyses suggested that the three conditions not only triggered a positive antioxidant defense against oxidative damages but also prepared the bacteria to employ a passive defense mechanism against disinfectants via dormancy. Moreover, the expression of antioxidant enzymes reached the maximum under the starvation condition and further low temperature treatment had little effect on bacterial response to oxidative stress. Instead, we found further treatment of the starved cells with low temperature decreased the osmotic stress response and the stringent response, which generally play pivotal roles in disinfection tolerance. Taken together, these findings shed light on how abiotic factors influence the bacterial disinfection tolerance and will aid design of efficient strategies to eliminate Pseudomonas aeruginosa from drinking water.