Pseudoneobacillus rhizolycopersici sp. nov., a novel multifunctional rhizobacterium for the biocontrol of tomato bacterial wilt.

Abstract

A novel Gram-stain-positive, rod-shaped bacterium with peritrichous flagella, designated C159T, was isolated from tomato rhizosphere soil. Growth of strain C159T occurred at 4-45 °C, pH 6.0-10.0 and in the presence of 0-5% NaCl. Based on 16S rRNA gene sequence analysis, strain C159T belongs to the genus Pseudoneobacillus and has a sequence similarity of 98.70% with Pseudoneobacillus rhizosphaerae JJ-79T. The whole genome of strain C159T was 4.65 Mb, with a DNA G+C content of 38.65 mol%. The average nucleotide identity between strain C159T and P. rhizosphaerae JJ-79T was 75.31%, and the digital DNA-DNA hybridization value was 19.6%, supporting its designation as a novel species of the genus Pseudoneobacillus. The major respiratory quinone of strain C159T was menaquinone 7; the major fatty acids were iso-C14:0, iso-C15:0 and anteiso-C15:0; and the major polar lipids are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Based on its phenotypic, chemotaxonomic, phylogenetic and genomic characteristics, strain C159T represents a novel species in the genus Pseudoneobacillus, for which the name Pseudoneobacillus rhizolycopersici sp. nov. is proposed. The type strain is C159T (=GDMCC 1.5552T=KCTC 43820T). In addition, strain C159T possesses the ability to produce indole-3-acetic acid (33.72 mg·l-1) and to mineralize insoluble organic phosphorus. In a pot experiment, this strain demonstrated a plant growth-promoting effect of 22.68-44.49% and a disease suppression efficacy of 89.29% against bacterial wilt of tomato caused by Ralstonia solanacearum. The above results confirm that strain C159T is a novel multifunctional rhizobacterium for the biocontrol of tomato bacterial wilt.