Sphingomonas zeicaulis sp nov., an endophytic bacterium isolated from maize root

A novel Gram-staining-negative, aerobic and rod-shaped strain designated 541(T) was isolated from surface-sterilized root tissue of maize, collected from the Fangshan District of Beijing, People's Republic of China, and was subjected to a taxonomic study using a polyphasic approach. According to a phylogenetic tree based on 16S rRNA gene sequences, strain 541(T) represented a member of the genus Sphingomonas and clustered with Sphingomonas sanxanigenens DSM 19645(T), with which it shared the highest 16S rRNA gene sequence similarity (98.8 %). The predominant respiratory quinone was ubiquinone-10 (Q-10), the major polyamine was sym-homospermidine and the major cellular fatty acids were C-18 : 1 omega 7c (50.9 %), C-16 : 0 (22.0 %) and C-14 : 0 2-OH (11.4 %). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and sphingoglycolipid. The DNA G+C content was 64.7 mol%. DNA-DNA relatedness between strain 541(T) and its closest phylogenetic relative Sphingomonas sanxanigenens DSM 19645(T) was 50.8 %. The results of physiological and biochemical tests and the differences in the fatty acid profiles allowed a clear phenotypic differentiation of strain 541(T) from closely related species of the genus Sphingomonas. Strain 541(T) represents a novel species within the genus Sphingomonas, for which the name Sphingomonas zeicaulis sp. nov. is proposed, with the type strain 541(T) (=CGMCC 1.15008(T)=DSM 100587(T)).