The use of a combination of several antibacterial agents for therapy holds great promise in reducing the dosage and side effects of these agents, improving their efficiency, and inducing potential synergistic therapeutic effects. Herein, this study provides an innovative antibacterial treatment strategy by synergistically combining R12-AgNPs with H 2 O 2 therapy. R12-AgNPs were simply produced with the supernatant of an ionizing radiation-tolerant bacterium Deinococcus wulumuqiensis R12 by one-step under room temperature. In comparison with chemically synthesized AgNPs, the biosynthesized AgNPs presented fascinating antibacterial activity and peroxidase-like properties, which endowed it with the capability to catalyze the decomposition of H 2 O 2 to generate hydroxyl radical. After the combination of R12-AgNPs and H 2 O 2 , an excellent synergistic bacteriostatic activity was observed for both Escherichia coli and Staphylococcus aureus , especially at low concentrations. In addition, in vitro cytotoxicity tests showed R12-AgNPs had good biocompatibility. Thus, this work presents a novel antibacterial agent that exhibits favorable synergistic antibacterial activity and low toxicity, without the use of antibiotics or a complicated synthesis process.
Malachite green (MG) is a toxic triphenylmethane dye widely used in industry, as well as a controversial antimicrobial in aquaculture, leading to environmental concerns. In this study, the conditions for the decolorization of MG by Deinococcus wulumuqiensis R12 were optimized. Under the optimized conditions, a degradation efficiency of 99.30% was achieved for 200 mg/L MG within 30 min, with an initial biomass concentration of 5.5 g/L at 32 °C and pH 5.0. When the initial concentration of MG was increased to 1 g/L, the degradation efficiency surpassed 97% after 2.5 h. Analytical techniques, including UV–VIS, FTIR, GC–MS, and LC–MS analyses revealed that the degradation products included desmethyl-malachite green, di-desmethyl-malachite green, 4-(dimethylamino)benzophenone, and 4-(methylamino)benzophenone, indicating that the MG degradation mechanism of R12 was based on oxidation and demethylation processes. Furthermore, microbial assays confirmed that the byproducts of MG degradation by R12 are much less toxic than the parent compound, indicating the potential of Deinococcus wulumuqiensis R12 as an effective bioremediation agent for MG-contaminated environments.
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