Expression and Antagonistic Activity Against Plant Pathogens of the Phage Tail-like Protein from Burkholderia multivorans WS-FJ9

Microorganisms exert antagonistic effects on pathogens through different mechanisms, thereby achieving biological control of plant diseases. Many <i>Burkholderia</i> strains can produce complex secondary metabolites and substances that have toxic effects on host cells. The phage tail-like bacteriocins (tailocins) is a compound with antibacterial activity. However, its function in <i>B. multivorans</i> has not yet been reported. This article explores the ability of <i>B. multivorans</i> WS-FJ9 to antagonise plant pathogenic fungi and oomycetes, screening the potential tailocins in the strain WS-FJ9 and verifying their function, to reveal its novel antimicrobial mechanisms. We found that WS-FJ9 had strong antagonistic effects on the plant pathogenic fungi <i>Phomopsis macrospore</i> and <i>Sphaeropsis sapinea</i>, and the pathogenic oomycete <i>Phytophthora cinnamomi</i>. The phage tail-like protein Bm_67459 was predicted from the WS-FJ9 strain genome. The Bm_67459 cDNA encoded 111 amino acid sequence, and the relative molecular weight was approximately 11.69 kDa, the theoretical isoelectric point (pI) was 5.49, and it was a hydrophilic protein. Bm_67459 had no transmembrane helix region or signal peptide, and it belonged to the Phage_TAC_7 super family. qRT-PCR results showed that <i>Bm_67459</i> gene expression was significantly upregulated during contact between WS-FJ9 and <i>P. cinnamomi</i>. The purified Bm_67459 protein significantly inhibited <i>P. cinnamomi</i> mycelial growth at 10 μg·mL^-1. In summary, the WS-FJ9 strain had broad-spectrum anti-phytopathogenic activity, and the tailocin Bm_67459 was an important effector against the plant pathogen <i>P. cinnamomi</i>, which helps to reveal the antagonistic mechanism of this strain at the molecular level and provides excellent strain resources for the biological control of plant diseases.