Dyadobacter endophyticus sp. nov., an endophytic bacterium isolated from maize root

A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain, designated 65T, was isolated from surface-sterilized root tissue of maize, collected from Fangshan District of Beijing, People's Republic of China, and was subjected to a taxonomic study by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 65T belonged to the genus Dyadobacter and had highest 16S rRNA gene sequence similarity to Dyadobacter jiangsuensis CGMCC 1.12969T (99.1 %), Dyadobacter beijingensis CGMCC 1.6375T (98.8 %), Dyadobacter fermentans DSM 18053T (98.6 %) and Dyadobacter soli KCTC 22481T (98.6 %). However, the new isolate exhibited relatively low levels of DNA-DNA relatedness with respect to D. jiangsuensis CGMCC 1.12969T (18.2±1.3 %), D. beijingensis CGMCC 1.6375T (14.2±2.0 %), D. fermentans DSM 18053T (14.1±2.0 %) and D. soli KCTC 22481T (13.8±0.6 %). The predominant respiratory quinone was menaquinone-7 (MK-7) and the major cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 1ω5c, iso-C15 : 0 3-OH, C16 : 0 3-OH and C16 : 0. The polar lipid profile of strain 65T revealed the presence of phosphatidylethanolamine, four aminolipids and two unidentified phospholipids. The DNA G+C content was 46.6 mol%. The results of physiological and biochemical tests and the differences in the fatty acid profiles allowed the clear phenotypic differentiation of strain 65T from closely related species of the genus Dyadobacter. Strain 65T thus represents a novel species within the genus Dyadobacter, for which the name Dyadobacterendophyticus sp. nov. is proposed. The type strain is 65T (=CGMCC 1.15288T=DSM 100786T).