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Biological control of plant diseases has gained attraction for controlling various bacterial diseases at a field trial stage. An isolated endophytic bacterium, Bacillus velezensis 25 (Bv-25), from Citrus species had strong antagonistic activity against Xanthomonas citri subsp. citri (Xcc), which causes citrus canker disease. When Bv-25 was incubated in Landy broth or yeast nutrient broth (YNB), the ethyl acetate extract of Landy broth exhibited higher levels of antagonistic activity against Xcc compared to that of YNB. Therefore, the antimicrobial compounds in the two ethyl acetate extracts were detected by high performance liquid chromatography–mass spectrometry. This comparison revealed an increase in production of several antimicrobial compounds, including difficidin, surfactin, fengycin, and Iturin-A or bacillomycin-D by incubation in Landy broth. RNA sequencing for the Bv-25 grown in Landy broth were performed, and the differential expressions were detected for the genes encoding the enzymes for the synthesis of antimicrobial compounds, such as bacilysin, plipastatin or fengycin, surfactin, and mycosubtilin. Combination of metabolomics analysis and RNA sequencing strongly suggests that several antagonistic compounds, especially bacilysin produced by B. velezensis, exhibit an antagonistic effect against Xcc. [ABSTRACT FROM AUTHOR]

Microbial biocontrol agents are efficient and environment-friendly in eradicating plant pathogenic bacteria. In recent years, Bacillus velezensis has gained popularity as a potential biocontrol agent in many countries. Several B. velezensis-based biocontrol products, previously identified as B. amyloliquefaciens or B. amyloliquefaciens subsp. plantarum, have received commercial approval, particularly in China and Europe. In this study, we compiled recent research findings on B. velezensis related to the production of antimicrobials, volatile organic compounds, induction of disease resistance, and the effect of this bacterium on plant growth promotion and yield. However, some recent research indicates that this important resource is also linked to several diseases in crops, including peach, onion, and potato, and the negative aspects of this bacterium in terms of its virulence traits to infect crops have not been summarized before. In this review, we compile the recent reports of this bacterium in term of its beneficial properties in agriculture. In addition, we also discuss several reports about its harmful effect on several crops as well. Therefore, due to the inherent pathogenicity of this bacterium to several crops, care must be taken when using it in a novel crop cultivation technique. [ABSTRACT FROM AUTHOR]

Microbes produce a diverse range of secondary metabolites in response to various environmental factors and interspecies competition. This enables them to become superior in a particular environment. Bacilysin, a dipeptide antibiotic produced by Bacillus species, is active against a broad range of microorganisms. Because of its simple structure and excellent mode of action, i.e., through the inhibition of glucosamine 6-phosphate synthase, it has drawn the attention of researchers. In addition, it acts as a pleiotropic signaling molecule that affects different cellular activities. However, all Bacillus species are not capable of producing bacilysin. The biosynthesis of bacilysin by Bacillus species is not uniform throughout the population; specificity and heterogeneity at both the strain and species levels has been observed. This review discusses how bacilysin is biosynthesized by Bacillus species, the regulators of its biosynthesis, its importance in the host, and the abiotic factors affecting bacilysin production. [ABSTRACT FROM AUTHOR]