A novel isolate, strain SA-276(T), was isolated from the water of Lake St. Ana, a
crater lake which is located in Romania. Phylogenetic analysis based on the 16S rRNA
gene revealed that the new strain is a member of the family Rhizobiaceae, showing
a high pairwise similarity value (97.65%) to Rhizobium tubonense CCBAU 85046(T) (=DSM
25379(T)), Rhizobium leguminosarum USDA 2370(T) (=LMG 14904(T)), Rhizobium anhuiense
CCBAU 23252(T) and Rhizobium laguerreae FB206(T). Cells of strain SA-276(T) were rod-shaped,
motile, oxidase negative and weakly catalase positive. The predominant fatty acids
were C(18:1)7c and cyclo C(19:0)8c, the major respiratory quinones were Q-10 and Q-9,
and the main polar lipids were phosphatidylmonomethylethanolamine, phosphatidylglycerol
and phosphatidylcholine. The G+C content of the genomic DNA of strain SA-276(T) was
60.8mol%. The novel isolate can be distinguished from the closest related type strain
R. tubonense DSM 25379(T) based on its broader substrate specificity and positive
trypsin enzyme activity. On the basis of the phenotypic, chemotaxonomic and molecular
data, strain SA-276(T) is considered to represent a new species, for which the name
Rhizobium aquaticum sp. nov. is proposed. The type strain is SA-276(T) (=DSM 29780(T)=JCM
31760(T)).