Planktotalea frisia gen. nov., sp. nov., isolated from the southern North Sea.

A heterotrophic, aerobic bacterium, designated strain SH6-1(T), was obtained from a seawater sample collected from the open North Sea during a phytoplankton bloom. Strain SH6-1(T) was isolated from a 10(-6) dilution culture, which indicated a high abundance of this organism in the environmental sample. 16S rRNA gene sequence comparison revealed that strain SH6-1(T) belonged to the marine Roseobacter clade (order Rhodobacterales) within the class Alphaproteobacteria. Pelagicola litoralis CL-ES2(T) was the closest phylogenetic neighbour (96.4% 16S rRNA gene sequence similarity). Cells of strain SH6-1(T) were small or elongated irregular rods. Optimal growth occurred between 20 and 25 °C and between pH 7.5 and 9.0 with peptone and yeast extract. On marine agar, the isolate formed non-pigmented, small, circular, convex colonies. For growth, cells required sodium ions and the vitamins pantothenic acid and nicotinic acid amide. The DNA G+C content was 53.8 mol%. The fatty acids (>1%) were C(10:0) 3-OH, C(16:0), C(12:1), C(12:1) 3-OH, C(18:0), C(18:1)ω7c, C(18:2) and 11-methyl C(18:1)ω7c. The polar lipid pattern indicated the presence of phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid and one unidentified phospholipid. The major respiratory lipoquinone was ubiquinone Q-10. Strain SH6-1(T) contained the genes pufLM, which code for the bacterial photosynthesis reaction centre; however, no bacteriochlorophyll a could be detected. Physiological, genotypic and phenotypic differences from P. litoralis support the description of a novel genus and species, for which we suggest the name Planktotalea frisia gen. nov., sp. nov; the type strain of the type species is SH6-1(T) (=DSM 23709(T)=LMG 25294(T)).