Sphingobacterium populi sp. nov., isolated from bark of Populus × euramericana.

A Gram-stain-negative, aerobic, non-motile bacterial strain, 7Y-4T, was isolated from bark tissue of Populus × euramericana. The isolate was able to grow between 10 and 37 °C, with optimal growth occurring at 28-30 °C. Strain 7Y-4T was positive for oxidase and catalase activities, but did not reduce nitrite from nitrate. Positive reactions were observed for the activities of β-galactosidase, urease and β-glucosidase, but negative reactions for the activities of gelatinase and the production of indole, acetoin and H2S. Citrate was not utilized. The major fatty acids of strain 7Y-4T are iso-C15 : 0 (28.6 %), C16 : 1ω7c/C16 : 1ω6c (31.8 %) and iso-C17 : 0 3-OH (23.3 %).The major polar lipids of the novel isolate include phosphatidylethanolamine, three unknown phospholipids (PL1-3) and six unknown lipids (L1-6), and the predominant menaquinone is MK-7. The DNA G+C content is 41.7 mol%. Analysis of 16S rRNA gene sequences revealed that the novel isolate shared the greatest sequence similarity with Sphingobacterium hotanense XH4T (93.50 %). On the basis of phenotypic and genotypic characteristics, strain 7Y-4T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium populi is proposed. The type strain is 7Y-4T (=CFCC 11742T=KCTC 42247T).