Sphingomonaszeicaulis sp. nov., an endophytic bacterium isolated from maize root.

A novel Gram-staining-negative, aerobic and rod-shaped strain designated 541T 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 541T represented a member of the genus Sphingomonas and clustered with Sphingomonas sanxanigenens DSM 19645T, 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 C18 : 1ω7c (50.9 %), C16 : 0 (22.0 %) and C14 : 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 541T and its closest phylogenetic relative Sphingomonas sanxanigenens DSM 19645T 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 541T from closely related species of the genus Sphingomonas. Strain 541T represents a novel species within the genus Sphingomonas, for which the nameSphingomonas zeicaulis sp. nov. is proposed, with the type strain 541T (=CGMCC 1.15008T=DSM 100587T).