Sphingomonas aeria sp. nov. from indoor air of a pharmaceutical environment

A proteobacterial strain designated R1-3(T) was isolated from indoor air of a pharmaceutical environment. Cells were Gram-stain-negative, oxidase- and catalase-positive, aerobic, motile and rod-shaped. Strain R1-3(T) grew optimally at pH 7, 30 °C and in 0-2 % NaCl on R2A agar. The 16S rRNA gene sequence analysis indicated that strain R1-3(T) belongs to the genus Sphingomonas, and is closely related to Sphingomonas paucimobilis ATCC 29837(T) (98.4 % sequence similarity). However, the DNA-DNA relatedness between the two strains was 43 ± 5 % (reciprocal = 37 ± 3 %), which was well below the suggested level for species distinction. Sphingomonas yabuuchiae GTC868(T) (97.7 % 16S rRNA gene sequence similarity) and Sphingomonas pseudosanguinis G1-2(T) (97.6 %) were also found as distantly related taxa. Strain R1-3(T) was sensitive to most of the tested antibiotics except for erythromycin and streptomycin. The major fatty acid was a summed feature consisting of C18:1 ω7c and/or C18:1 ω6c, and minor proportions of C14:0 2-OH, C16:0 and a summed feature consisting of C16:1 ω7c and/or C16:1 ω6c were also present. The DNA G + C content was 67.2 ± 1.0 mol%. The major polyamines were sym-homospermidine and spermidine. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, and minor amounts of a sphingoglycolipid, a phospholipid, an aminoglycolipid and an unidentified lipid were also present. The phenotypic, phylogenetic and chemotaxonomic data not only supported the affiliation of strain R1-3(T) to the genus Sphingomonas, but also distinguished R1-3(T) from related species. On the basis of physiological, chemotaxonomic and phylogenetic evidences, strain R1-3(T) clearly merits recognition as a novel species of Sphingomonas, for which the name Sphingomonas aeria sp. nov. is proposed. The type strain is R1-3(T) (= KCTC 42061(T) = JCM 19859(T)).