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Reactive nitrogen species dominance is key in the fight against antimicrobial resistance

Reactive nitrogen species dominance is key in the fight against antimicrobial resistance
Cells of S. aureus and E. coli that cope with more RNS than ROS activate physiological mechanisms associated with anaerobic fermentation, cell wall & DNA repair and apoptosis. Credit: Microbiological Research (2024). DOI: 10.1016/j.micres.2024.127986

In a study in Microbiological Research, scientists from Surrey investigated how different RNS and ROS ratios affect harmful bacteria, including Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Using advanced imaging and transcriptional analysis, they identified how these bacteria respond differently depending on the balance of these molecules.

The researchers found that this balance works similarly to dealing with weeds in a garden. RNS is like pulling weeds out by the roots—it removes them completely, preventing regrowth. But when ROS dominates, it's like just cutting the weeds at the surface; the bacteria may look weaker at first, but they can recover, form protective layers (biofilms), and become even harder to eliminate.

This discovery is important because are a growing global health threat, making many antibiotics less effective. Understanding how RNS and ROS interact at a could help scientists develop new treatments that enhance the body's natural defenses and slow the spread of antimicrobial resistance (AMR).

"We used to think both reactive oxygen and nitrogen hurt bacteria in the same way, but our research found it's more complicated. While nitrogen-heavy environments kill bacteria, an oxygen-rich environment can actually make bacteria stronger and harder to kill, especially by helping them form protective layers that resist antibiotics," says Dr. Jorge Gutierrez.

Using a unique plasma device called ReCAP, designed by industrial manufacturer Fourth State, the research team exposed bacterial cultures to controlled mixtures of RNS and ROS. They grew the bacteria on liquid and solid media (a gel-like surface). Then, they used advanced imaging techniques, including scanning , to capture detailed changes in the bacteria's membranes.

In addition, they performed transcriptional analysis (a technique that reveals which genes are active or inactive in response to different conditions) to monitor how key genes responded to the different RNS/ROS ratios. This combined approach allowed the researchers to directly link specific molecular changes to the bacteria's survival strategies and provided clear evidence of how the balance between RNS and ROS dictates bacterial outcomes.

"The research highlights how treatments that boost reactive nitrogen species might be good for fighting , while treatments that mainly boost could make things worse. More research needs to be done to fully understand the relation between RONS and bacterial responses, which could lead to more effective antibacterial strategies in the future," says Gutierrez.

More information: Athanasios Nikolaou et al, The ratio of reactive oxygen and nitrogen species determines the type of cell death that bacteria undergo, Microbiological Research (2024).

Journal information: Research

Provided by University of Surrey

Citation: Reactive nitrogen species dominance is key in the fight against antimicrobial resistance (2025, February 27) retrieved 23 July 2025 from /news/2025-02-reactive-nitrogen-species-dominance-key.html
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