Biological Control and Growth-Promoting Activities of Burkholderia vietnamiensis FBCC-B8049 Isolated from Freshwater.

Colletotrichum and Fusarium are globally important plant-pathogenic fungi that cause serious diseases in chili pepper and other crops, leading to substantial yield losses due to their broad host range, environmental persistence, and the limited effectiveness of chemical control, thereby highlighting the need for sustainable alternatives such as biological control. We investigate the biological control and plant growth-promoting potential of Burkholderia vietnamiensis FBCC-B8049, isolated from freshwater environments. The strain exhibited significant antifungal activity against Colletotrichum gloeosporioides, Colletotrichum acutatum, and Fusarium oxysporum in dual-culture assays, with stronger effects against Colletotrichum species. The inhibition was likely due to direct antagonism and volatile organic compounds (VOCs) produced by FBCC-B8049, which were particularly effective against Colletotrichum species. Additionally, FBCC-B8049 demonstrated plant growth-promoting activities including siderophore production for iron acqusition, phosphate solubilization for enhanced nutrient availability, and indole-3-acetic acid synthesis to promote root development. These combined activities enhance nutrient availability and promote seed germination and seedling growth in chili pepper. Ex vivo assays further revealed the effectiveness of FBCC-B8049 in suppressing anthracnose disease on pepper fruits through both direct application and bacterial VOCs emission. Phylogenetic analysis of 16S rRNA and recA gene sequences positioned FBCC-B8049 closely to Burkholderia vietnamiensis, a known plant growth-promoting rhizobacterium. These findings highlight FBCC-B8049 as a promising candidate for sustainable agricultural applications.