Bactericidal Effect of sp. nov., a Novel Species Against Reduces Disease Severity of Bacterial Leaf Streak of Rice.

is a diverse genus of Gammaproteobacteria with increasing novel species exhibiting versatile trains including antimicrobial and insecticidal activity, as well as plant growth-promoting, which make them well suited as biocontrol agents of some pathogens. Here we isolated strain 1257 that exhibited strong antagonistic activity against two pathovars of , especially . pv. () responsible for the bacterial leaf streak (BLS) in rice. The phylogenetic, genomic, physiological, and biochemical characteristics support that strain 1257 is a representative of a novel species that is most closely related to the entomopathogenic bacterium We propose to name it sp. nov. Comparative genomics analyses showed that 1257 possesses most of the central metabolic genes of two closely related strains L48 and CFML 90-83, as well as a set of genes encoding the type IV pilus system, suggesting its versatile metabolism and motility properties. Some features, such as insecticidal toxins, phosphate solubilization, indole-3-acetic acid, and phenylacetic acid degradation, were disclosed. Genome-wide random mutagenesis revealed that the non-ribosomal peptide catalyzed by LgrD may be a major active compound of 1257 against RS105, as well as the critical role of the carbamoyl phosphate and the pentose phosphate pathway that control the biosynthesis of this target compound. Our findings demonstrate that 1257 could effectively inhibit the growth and migration of in rice tissue to prevent the BLS disease. To our knowledge, this is the first report of a novel species that displays a strong antibacterial activity against . The results suggest that the strain could be a promising biological control agent for BLS.