Sphingomonas astaxanthinifaciens sp. nov., a novel astaxanthin-producing bacterium of the family Sphingomonadaceae isolated from Misasa, Tottori, Japan
2007
Asker, Dalal | Beppu, Teruhiko | Ueda, Kenji
A red-pigmented, Gram-negative, motile, strictly aerobic, mesophilic, oval- or short rod-shaped bacterium (TDMA-17T) was isolated from fresh water collected at Misasa, a radioactive site in Japan. TDMA-17T was slightly tolerant against gamma-ray irradiation, and effectively produced carotenoids (2.8 mg g⁻¹ dry cells) including, astaxanthin and astaxanthin isomers. Phylogenetic analysis based on 16S rRNA gene sequences placed TDMA-17T in a distinct lineage in the family Sphingomonadaceae, and the highest degree of sequence similarity determined were to Sphingomonas aerolata NW12T (94.5%), Sphingomonas aurantiaca MA101bT (94.0%), Sphingomonas melonis DAPP-PG 224T (94.0%), Sphingomonas asaccharolytica IFO 15499T (93.9%) and Sphingomonas abaci C42T (93.9%). The major fatty acids were C₁₇ : ₁ω6c (33.0%) and C₁₈ : ₁ω7c (20.8%). The DNA G+C content was 67.7 mol%. The presence of Q-10 as the main ubiquinone, the presence of Sphingomonadaceae-specific sphingoglycolipid in the polar lipid profiles, the presence of 2-hydroxy fatty acids and the absence of 3-hydroxy fatty acids supported the identification of this strain as a member of the genus Sphingomonas sensu stricto. Phylogenetic distinctiveness and unique phenotypic characteristics differentiated strain TDMA-17T from the closely related Sphingomonas species. The results of polyphasic taxonomic analyses suggested that TDMA-17T represents a novel Sphingomonas species, for which the name Sphingomonas astaxanthinifaciens sp. nov. is proposed. The type strain is TDMA-17T (=NBRC 102146=CCUG 53608).
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