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Abstract
Two strains (JA492T and JA590) of spiral-shaped, anaerobic, Gram-stain-negative, motile, purple non-sulfur bacteria were isolated from aquatic sediments from a bird sanctuary and a stream, respectively, and were characterized by a polyphasic taxonomic approach. Bacteriochlorophyll a and carotenoids (rhodopin, lycopene, hydroxylycopene glucoside and dihydroxylycopene diglucoside) were present as photosynthetic pigments. Intracellular photosynthetic membranes were of the stacked type. The major fatty acids were C18 : 1ω7c, C16 : 0 and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) in both strains. Ubiquinones and menaquinones were present as major quinone components. The genomic DNA G+C contents of strains JA492T and JA590 were 63.8 and 61.5 mol%, respectively. Both strains were closely related (mean DNA–DNA hybridization >70 %). Phylogenetic analysis showed that the strains clustered with species of the genus Phaeospirillum of the family Rhodospirillaceae , class Alphaproteobacteria . Based on 16S rRNA gene sequence analysis, both strains showed highest sequence similarity with Phaeospirillum oryzae JA317T (97.2–97.4 %), Phaeospirillum molischianum DSM 120T (96.5–96.7 %), Phaeospirillum fulvum DSM 113T (96.7–96.9 %) and Phaeospirillum chandramohanii JA145T (96.5–96.7 %). DNA–DNA relatedness between strain JA492T and its closest relative in the genus Phaeospirillum was less than 42 %. It is evident from phenotypic, chemotaxonomic and molecular genetic data that strain JA492T represents a novel species of the genus Phaeospirillum , for which the name Phaeospirillum tilakii sp. nov. is proposed; the type strain is JA492T ( = NBRC 107650T = KCTC 15012T).
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Funding
- Department of Biotechnology, Government of India