Gracilibacillus suaedae sp. nov., an indole acetic acid-producing endophyte isolated from a root of Suaeda salsa.

Abstract

A Gram-stain-positive, facultatively anaerobic, spore-forming, motile with unipolar biflagella, rod-shaped, indole acetic acid-producing bacterium, named LD4P30T, was isolated from a root of Suaeda salsa collected in Inner Mongolia, northern China. Strain LD4P30T grew at pH 6.0-11.0 (optimum, pH 7.0), 10-40 °C (35 °C) and in the presence of 1-15% (w/v) NaCl (5%). The strain was positive for oxidase and negative for catalase. The major cellular fatty acids of strain LD4P30T were iso-C15:0, C15:1 ω5c and anteiso-C15:0; the major polar lipids were diphosphatidylglycerol and phosphatidylglycerol; and menaquinone-7 was the only respiratory quinone. The genomic DNA G+C content was 36.7 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain LD4P30T clustered with Gracilibacillus thailandensis TP2-8T, Gracilibacillus saliphilus YIM 91119T and Gracilibacillus lacisalsi BH312T, and showed 99.0, 98.9, 98.0 and <97.7% 16S rRNA gene similarity to G. thailandensis TP2-8T, G. saliphilus YIM 91119T, G. lacisalsi BH312T and all other current type strains, respectively. The digital DNA-DNA hybridization and average nucleotide identity based on blast values between strain LD4P30T and G. saliphilus YIM 91119T, G. thailandensis TP2-8T and G. lacisalsi BH312T were 44.9, 44.7 and 44.4%, and 91.1, 91.0 and 90.8%, respectively. Based on its phenotypic, physiological and phylogenetic characteristics, strain LD4P30T represents a novel species, for which the name Gracilibacillus suaedae is proposed. The type strain is LD4P30T (=CGMCC 1.17697T=KCTC 82375T).