Myxococcus xanthus R31 Suppresses Tomato Bacterial Wilt by Inhibiting the Pathogen Ralstonia solanacearum With Secreted Proteins

Abstract

The pathogenic bacterium Ralstonia solanacearum caused tomato bacterial wilt (TBW), a destructive soil-borne disease worldwide. There is an urgent need to develop effective control methods. Myxobacteria are microbial predators and are widely distributed in the soil. Compared with other biocontrol bacteria that produce antibacterial substances, the myxobacteria have great potential for biocontrol. This study reports a strain of Myxococcus xanthus R31 that exhibits high antagonistic activity to R. solanacearum. Plate test indicated that the strain R31 efficiently predated R. solanacearum. Pot experiments showed that the biocontrol efficacy of strain R31 against TBW was 81.9%. Further study found that the secreted protein precipitated by ammonium sulfate had significant lytic activity against R. solanacearum cells, whereas the ethyl acetate extract of strain R31 had no inhibitory activity against R. solanacearum. Substrate spectroscopy assay and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of secreted proteins showed that some peptidases, lipases, and glycoside hydrolases might play important roles and could be potential biocontrol factors involved in predation. The present study reveals for the first time that the use of strain M. xanthus R31 as a potential biocontrol agent could efficiently control TBW by predation and secreting extracellular lyase proteins.

Diseased-induced multifaceted variations in community assembly and functions of plant-associated microbiomes

“…A higher relative abundance of K05998 (pseudomonalisin [EC:3.4.21.100], peptidases, and inhibitors) was found in RH. Peptidases have been reported to be potential biocontrol factors participating in the predation of Myxococcus xanthus on R. solanacearum (Dong et al, 2022 ; Figure 6B ). An important differential pathway worth noting is “Quorum sensing,” which was found to be significantly enriched in the diseased rhizosphere ( Figure 6C ).…”

A Disturbed Siderophore Transport Inhibits Myxobacterial Predation

“…A predation assay was performed on TPM plates (10 mM Tris-HCl (pH 7.6), 1 mM KPO 4 pH 7.6, 8 mM MgSO 4 , 1.5% agar) using the colony-induced predation method as described [ 36 , 37 ]. Overnight cultures of P. aeruginosa PAO1 were resuspended in an LB medium and cultured to the mid-exponential phase.…”

Isolation identification and application of myxobacteria

“…It was later found that myxobacteria could also be used in the control of plant bacterial diseases with remarkable results. Myxococcus xanthus R31 showed a good biological control effect on tomato bacterial wilt [9]. Moreover, the secondary metabolites of myxobacteria cannot be ignored to inhibit plant diseases, which play an important role in agricultural applications.…”