A systematic review of antioxidant defense mechanisms in bacteria species

Abstract

Oxidative stress, driven by reactive oxygen and nitrogen species, poses a major challenge to bacterial survival and virulence. This review systematically evaluated antioxidant defense mechanisms across Gram-positive and Gram-negative bacterial species, highlighting enzymatic and molecular strategies that mitigate oxidative stress. A total of 27 studies were assessed, applying SYRCLE’s and OHAT risk of bias tools. The bacteria investigated included Gram-positive species such as Streptococcus thermophilus , Bacillus subtilis , Bacillus velezensis , Staphylococcus aureus , Streptomyces coelicolor , Lactobacillus casei Shirota , Mycobacterium tuberculosis , and Deinococcus radiodurans. Gram-negative bacteria comprised Escherichia coli , Francisella tularensis , Stenotrophomonas sp. , Agrobacterium tumefaciens , Cupriavidus pinatubonensis , Helicobacter pylori , Klebsiella variicola , Salmonella Typhimurium , Ehrlichia chaffeensis , and Brucella abortus . These organisms employed diverse antioxidant strategies, including enzymatic detoxification, metal ion homeostasis, and small-molecule scavengers to neutralize reactive species. Clinically relevant findings indicated that antioxidant mechanisms not only ensure bacterial survival under host immune attack and antibiotic exposure but also contribute to pathogenic persistence. Bacterial antioxidant defenses represent critical determinants of stress resistance and pathogenicity. Understanding these mechanisms provides insight into host–pathogen interactions and may inform novel antimicrobial strategies targeting redox balance.