Fe-MoS ₂ Nanozymes Combined with Antagonistic Bacteria for the Inhibition of <i>Agrobacterium tumefaciens</i> Growth and Biofilm Formation

Agrobacterium tumefaciens (A. tumefaciens) underlies the pathogenesis of crown gall disease and is characterized by tumor-like gall formation on the stems and roots of a wide variety of economically important plant species. It is necessary to explore anti-A. tumefaciens agents due to the limited availability of current treatments. In this study, Fe,S-decorated polyoxometalate-based molybdenum disulfide nanosheet (Fe-MoS2 NS) nanozymes were designed and synthesized to efficiently act against A. tumefaciens. Based on antagonistic bacteria (AT-11) from soil with a high infection rate of A. tumefaciens , the isolated strain presents anti-A. tumefaciens property, and Fe-MoS2-bound AT-11 exhibited excellent peroxidase (POD)-like activity for specifically inhibiting the growth and biofilm formation of A. tumefaciens. In addition, electron transfer between Fe2+/Fe3+ and Mo4+/Mo6+ provided more active sites, further increasing the POD-like catalytic activity based on Fenton-like mechanisms, amplifying the chemodynamic therapy potential. Compared to MoS2, Fe-MoS2 exhibited a 37.1-fold increase in the POD-like catalytic activity. Fe-MoS2 combined with AT-11 demonstrated a remarkable synergistic effect against A. tumefaciens with a minimum fungicidal concentration value of 15 μg/mL and significantly reduced the biofilm formation with 15 μg/mL concentration while preserving AT-11 species. The research results indicated that A. tumefaciens inactivation began with membrane rupture, followed by the oxidation and leakage of intracellular substances. Moreover, Fe-MoS2 inhibits tumor formation on the tomato stem when treatments were applied after A. tumefaciens infection to wounded tissues. This study demonstrated that Fe-MoS2 can serve as an effective and economical bactericide for an efficient biocontrol of crown gall disease with good biocompatibility and low cost.