Filomicrobium insigne sp. nov., isolated from an oil-polluted saline soil

Strain SLG5B-19(T), isolated from an oil-polluted saline soil in Gudao in the coastal Shengli Oilfield, eastern China, was Gram-negative with monoprosthecae or bipolar prosthecae and buds on the prosthecal tips. Growth occurred at NaCl concentrations between 0 and 7 % (w/v), at temperatures between 4 and 45 degrees C, and at pH 6.0-9.0. Strain SLG5B-19(T) had Q-9 as the major respiratory quinone and unsaturated C(18 : 1)omega7c as the predominant cellular fatty acid. The G+C content of the genomic DNA was 59.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SLG5B-19(T) belonged to a clade with the genera Filomicrobium and Hyphomicrobium in the class Alphaproteobacteria. However, 16S rRNA gene sequence similarities of strain SLG5B-19(T) to the phylogenetically most closely related strains, i.e. the type strains of Filomicrobium fusiforme and Hyphomicrobium zavarzinii, were 95.8 and 94.5 %, respectively. In addition, the 16S rRNA gene sequence of strain SLG5B-19(T) had 24 signature nucleotides that were identical to those of the type strain of F. fusiforme. Based on phylogenetic analysis of 16S rRNA gene sequences, strain SLG5B-19(T) could be allocated to the genus Filomicrobium. However, distinct phenotypic differences were observed between strain SLG5B-19(T) and the type strain of F. fusiforme. It is therefore proposed that strain SLG5B-19(T) represents a novel species in the genus Filomicrobium, Filomicrobium insigne sp. nov. The type strain is SLG5B-19(T) (=CGMCC 1.6497(T)=LMG 23927(T)).