Sphingomonas aurantiaca sp. nov., Sphingomonas aerolata sp. nov. and Sphingomonas faeni sp. nov., air- and dustborne and Antarctic, orangepigmented, psychrotolerant bacteria, and emended description of the genus Sphingomonas

Seven psychrotolerant, Gram-negative bacterial strains, five dust- and airborne isolates (MA101bT, MA306a, MA405/90, MA-olkiT and NW12T) and two from the Antarctic (Ant 20 and M3C203B-B), were subjected to a polyphasic characterization to determine their taxonomic position. High 16S rDNA sequences similarities (99?3–100?0%) demonstrated that they were closely related to each other. Phylogenetic evaluation of their 16S rDNA sequences revealed that they are members of the genus Sphingomonas sensu stricto, encompassing a separate branch
within this genus. They shared 94?4–96?6% 16S rDNA sequence similarity with species of this genus. All Sphingomonas-specific signature nucleotides were also detected. The presence of the major ubiquinone Q-10, sym-homospermidine as the predominant polyamine,
Sphingomonadaceae-specific sphingoglycolipid in the polar lipid patterns and a fatty acid profile containing C14 : 0 2-OH and lacking 3-OH fatty acids were in agreement with identification of these strains as members of the genus Sphingomonas sensu stricto. Results from DNA–DNA
hybridizations and comparison of protein patterns indicated that the seven strains are members of three distinct species. One species is represented by strains MA101bT, MA306a and MA405/90, the second by strains NW12T, Ant 20 and M3C203B-B and the third by one strain,
MA-olkiT. Their distinction at the species level was also supported by results of biochemical characterization and partly supported by riboprints and genomic fingerprints. On the basis of these results, three novel species of the genus Sphingomonas are proposed: Sphingomonas
aurantiaca sp. nov., consisting of strains MA101bT (=DSM 14748T=LMG 21377T), MA306a and MA405/90 (=DSM 14749=LMG 21378), Sphingomonas faeni sp. nov. MA-olkiT (=DSM 14747T=LMG 21379T) and Sphingomonas aerolata sp. nov., represented by strains NW12T (=DSM 14746T=LMG 21376T), Ant 20 (=ICMP 13599) and M3C203B-B (=SMCC M3C203B-B).