Aquabacterium limnoticum sp. nov., isolated from a freshwater spring.

A Gram-negative, facultatively anaerobic, short-rod-shaped, non-motile and non-spore-forming bacterial strain, designated ABP-4(T), was isolated from a freshwater spring in Taiwan and was characterized using the polyphasic taxonomy approach. Growth occurred at 20-40 °C (optimum, 30-37 °C), at pH 7.0-10.0 (optimum, pH 7.0-9.0) and with 0-3% NaCl (optimum, 0%). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain ABP-4(T), together with Aquabacterium fontiphilum CS-6(T) (96.4% sequence similarity), Aquabacterium commune B8(T) (96.1%), Aquabacterium citratiphilum B4(T) (95.5%) and Aquabacterium parvum B6(T) (94.7%), formed a deep line within the order Burkholderiales. Strain ABP-4(T) contained summed feature 3 (comprising C(16:1) ω7c and/or C(16:1) ω6c), C(18:1) ω7c and C(16:0) as predominant fatty acids. The major cellular hydroxy fatty acid was C(10:0) 3-OH. The major isoprenoid quinone was Q-8 and the DNA G+C content was 68.6 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, diphosphatidylglycerol and several uncharacterized phospholipids. The DNA-DNA relatedness of strain ABP-4(T) with respect to recognized species of the genus Aquabacterium was less than 70%. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain ABP-4(T) represents a novel species in the genus Aquabacterium, for which the name Aquabacterium limnoticum sp. nov. is proposed. The type strain is ABP-4(T) (=BCRC 80167(T)=KCTC 23306(T)).