Sphingomonas starnbergensis sp. nov., isolated from a prealpine freshwater lake.

A novel type of freshwater bacterium was isolated from the prealpine mesotrophic Starnberger See (Bavaria, southern Germany). Cells of strain 382(T) were Gram-negative and rod-shaped, motile and creamy-white. The isolate was strictly aerobic, catalase- and oxidase-positive, and grew at pH values of 6-9 (optimum, pH 7) and temperatures of 10-37 °C (optimum, 28 °C). The genomic G+C content of strain 382(T) was 64.1 mol%. Based on 16S rRNA gene sequence analyses, strain 382(T) belongs to the family Sphingomonadaceae and clusters within the genus Sphingomonas. Sphingomonas histidinilytica UM 2(T) and Sphingomonas wittichii DSM 6014(T) were the closest relatives, as indicated by the highest 16S rRNA gene sequence similarities (97.1 % and 96.8 %, respectively). Sphingomonas paucimobilis DSM 1098(T) (the type species of the genus Sphingomonas) exhibited 95.3 % sequence similarity. This affiliation of strain 382(T) to the genus Sphingomonas is confirmed by the presence of Q-10 as the major respiratory quinone, two sphingoglycolipids, C14 : 0 2-OH as the major 2-hydroxy fatty acid and sym-homospermidine as the major polyamine. The main cellular fatty acids of strain 382(T) were C18 : 1ω7c (39 %), C16 : 1ω7c (21 %), C16 : 0 (10 %) and C14 : 0 2-OH (10 %). Based on the phylogenetic distance from other species of the genus Sphingomonas and its unusually high C16 : 1ω7c content, strain 382(T) represents a novel species of the genus Sphingomonas, for which the name Sphingomonas starnbergensis is proposed. The type strain is 382(T) ( = DSM 25077(T) = LMG 26763(T))