Full text loading...
Abstract
Two bacterial strains (FA1 and FA2T) were isolated from the phyllosphere of a leguminous tree, Acacia caven, in central Argentina. The strains were Gram-negative, strictly aerobic, rod-shaped, motile and formed yellow-pigmented colonies on nutrient agar. The two-primer RAPD patterns of the two strains were identical, suggesting that they belong to the same species. The complete 16S rRNA gene sequences of the two strains were obtained and comparisons demonstrated that they cluster phylogenetically with the species of the genus Sphingomonas sensu stricto. Strain FA2T was most closely related (97·6 %) to Sphingomonas adhaesiva. 16S rRNA gene sequence similarities to all other established Sphingomonas species ranged from 94·4 % (to Sphingomonas echinoides) to 97·6 % (to S. adhaesiva). Strains FA1 and FA2T were catalase-positive and oxidase-negative. Aesculin was hydrolysed, gelatin and urea were not. β-Galactosidase was produced. From 51 compounds tested 21 were used as single sources of carbon. The major respiratory lipoquinone was ubiquinone-10. The predominant cellular fatty acids were 16 : 0, 18 : 1ω7c and 16 : 1ω7c (from summed feature 3). Hydroxy fatty acids 14 : 0 2-OH and 15 : 0 iso 2-OH were present as well (from summed feature 4). The polar lipids detected in strain FA2T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, sphingoglycolipid and two unidentified phospholipids. The DNA G+C content of strain FA2T was 61 mol%. DNA–DNA hybridization experiments showed 27·6 % relatedness between strain FA2T and S. adhaesiva DSM 7418T. Based upon phenotypic and molecular evidence, a novel species of the genus Sphingomonas is proposed, Sphingomonas phyllosphaerae sp. nov., with strain FA2T (=LMG 21958T=CECT 5832T) as the type strain.
- Published Online: