The Role of Pyoluteorin from Pseudomonas protegens Pf-5 in Suppressing the Growth and Pathogenicity of Pantoea ananatis on Maize

Abstract

The rhizospheric bacterium Pseudomonas protegens Pf-5 can colonize the seed and root surfaces of plants, and can protect them from pathogen infection. Secondary metabolites, including lipopeptides and polyketides produced by Pf-5, are involved in its biocontrol activity. We isolated a crude extract from Pf-5. It exhibited significant surface activity and strong antibacterial activity against Pantoea ananatis DZ-12, which causes maize brown rot on leaves. HPLC analysis combined with activity tests showed that the polyketide pyoluteorin in the crude extract participated in the suppression of DZ-12 growth, and that the lipopeptide orfamide A was the major biosurfactant in the crude extract. Further studies indicated that the pyoluteorin in the crude extract significantly suppressed the biofilm formation of DZ-12, and it induced the accumulation of reactive oxygen species in DZ-12 cells. Scanning electron microscopy and transmission electron microscopy observation revealed that the crude extract severely damaged the pathogen cells and caused cytoplasmic extravasations and hollowing of the cells. The pathogenicity of DZ-12 on maize leaves was significantly reduced by the crude extract from Pf-5 in a dose-dependent manner. The polyketide pyoluteorin had strong antibacterial activity against DZ-12, and it has the potential for development as an antimicrobial agent.

Toxicity of Bacillus thuringiensis Strains Derived from the Novel Crystal Protein Cry31Aa with High Nematicidal Activity against Rice Parasitic Nematode Aphelenchoides besseyi

“…Rhizobacteria have been widely reported as biological control agents for plant parasitic nematodes. Numerous Bacillus species have been studied for their role in reducing nematodes and insect pests [ 7 , 8 ]. Bacillus subtilis and Bacillus thuringiensis (Bt) are two of the Bacillus species that have been investigated against various pathogens, including nematodes [ 9 , 10 ].…”

Antagonistic Strain Bacillus halotolerans Jk-25 Mediates the Biocontrol of Wheat Common Root Rot Caused by Bipolaris sorokiniana

“…The methanol extract was filtered and evaporated to one-tenth of the original volume under vacuum. The crude extract was obtained by suspending samples in methanol and performing filtration (0.22 µm, Nylon) [ 49 , 50 ].…”

Evaluation of the Biocontrol Efficiency of Bacillus subtilis Wettable Powder on Pepper Root Rot Caused by Fusarium solani

“…Some studies have proven that the successful colonization of PGPR in the plant rhizosphere is the first prerequisite step [ 7 , 8 ]. During colonization, PGPR strains produce a wide spectrum of bioactive metabolites such as antibiotics, siderophores, volatile organic compounds (VOCs), and quorum-sensing signals to compete with other micro-organisms and survive in the rhizosphere [ 9 , 10 ]. Among these PGPR strains, the Bacillus species has received extensive attention and has become an important potential resource for biofertilizers or biopesticides, which are frequently used to control soil-borne plant diseases in the field and greenhouse [ 4 , 7 ].…”