Gottfriedia endophyticus sp. nov., a novel indole-acetic acid producing bacterium isolated from the roots of rice plant

Abstract

A Gram-stain-positive, aerobic, motile and rod-shaped bacterium, designated RG28T, was isolated from the roots of rice plant collected from paddy fields in Ilsan, South Korea. Cells of the strain were oxidase-negative but catalase-positive. Strain RG28T was found to grow at 10-50°C (optimum, 25-30°C), pH 5.0-10.0 (optimum, pH 7.0) and in 1.0-5.0% (w/v) NaCl (optimum, 0%). The cell-wall peptidoglycan contained meso-diaminopimelic acid and the predominant menaquinones were MK-7 and MK-6. The predominant cellular fatty acids were C16:0, iso-C15:0 and anteiso-C15:0. The major polar lipids included phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, four unidentified aminophosphoglycolipids, four unidentified aminophospholipids, two unidentified glycolipids, one unidentified aminoglycolipid and four unidentified lipids. The genomic DNA G + C content was 33.5mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain was closely related to Gottfriedia acidiceleris CBD 119T (98.6%), Gottfriedia solisilvae LMG 18422T (98.5%) and Gottfriedia luciferensis LMG 18422T (98.4%). The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strain RG28T and type strains of Gottfriedia species were lower than the cut-offs (≥ 95-96% for ANI and ≥ 70% for is DDH) required to define a bacterial species. Meanwhile, the strain has the ability to produce indole-acetic acid (40.5µg/mL). Phylogenetic, physiological and chemotaxonomic data suggested that strain RG28T represented a novel species of the genus Gottfriedia, for which the name Gottfriedia endophyticus sp. nov. is proposed, with the type strain RG28T (= KCTC 43327T = TBRC 15151T).