Abstract
The global tomato plants are seriously threatened by soilborne bacterial wilt, which is caused by Ralstonia solanacearum. Biological control agents (BCAs) are considered as a promising strategy. In this study, strain NEAU-383, which exhibited significant inhibitory activity against R. solanacearum, was isolated from the rhizosphere soil of a healthy tomato plant in a serious soilborne diseased field. Based on phylogenetic analysis, ANI values, and digital DNA-DNA relatedness, strain NEAU-383 was included in the genus Streptomyces and may be a potential new species. In pot experiments, both pre-inoculation with the spore suspension and fermentation extracts of strain NEAU-383 could effectively prevent tomato bacterial wilt, and the biological control efficiency was 85.2% and 95.1%, respectively. The fermentation extracts of strain NEAU-383 showed the MIC value against R. solanacearum with 0.8 mg/L, and also exhibited broad-spectrum antifungal activity against 5 phytopathogenic fungi. AntiSMASH analysis of the whole genome sequence of strain NEAU-383 revealed a number of key function gene clusters that contribute to the biosynthesis of active secondary metabolites. Moreover, 10 compounds were detected via gas chromatography-mass spectrometry (GC-MS). The maltol and myristic acid were the dominant active metabolites in the crude extract of strain NEAU-383. Moreover, strain NEAU-383 could produce protease and siderophore at a lower level, which also contributed to its antibacterial activity against R. solanacearum. Hence, Streptomyces sp. NEAU-383 may be a potential biocontrol agent used in the management of tomato bacterial wilt and the exploitation of biofertilizer.