Rhizobium lacunae sp. nov., Isolated From a Freshwater Pond
Abstract Bacterial strain designated CSW-27T was isolated from a freshwater pond in Taiwan. Cells were Gram-stain-negative, aerobic, oxidase-positive, catalase-negative, rod-shaped and motile by flagella. Strain CSW-27T grew at 20-40 oC (optimum, 30-37 oC), at pH 5-9 (optimum, pH 6-7) and in the presence of 0-4% NaCl (optimum, 0%). Phylogenetic analyses based on 16S rRNA gene sequences and an up-to-date bacterial core gene set revealed that strain CSW-27T was affiliated with species in the genus Rhizobium. Analysis of 16S rRNA gene sequences showed that strain CSW-27T had the highest similarity to Rhizobium straminoryzae CC-LY845T (98.5%) followed by Rhizobium capsici CC-SKC2T (96.9%). The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between strain CSW-27T and the closely related Rhizobium species were 73.4-86.5, 66.0-88.8 and 13.3-22.1%, respectively. The principal fatty acid was summed feature 8 (C18:1ω7c and/or C18:1ω6c). The main polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, phosphatidylcholine, one uncharacterized aminophospholipid, three uncharacterized aminolipids and two uncharacterized lipids. The predominant polyamine was spermidine. The major isoprenoid quinone was Q-10. Genomic DNA G+C content of strain CSW-27T was 63.3%. These polyphasic taxonomic data indicited that strain CSW-27T should be considered as representing a novel species in the genus Rhizobium, for which the name Rhizobium lacunae sp. nov. is proposed with strain CSW-27T (=BCRC 81244T =LMG 31684T) as the type strain.