Two Gram-negative, rod-shaped, non-spore-forming bacterial strains designated C42T and C52T were isolated in the Medical Clinic for Small Animals and Ungulates at the University for Veterinary Medicine Vienna, Austria. On the basis of 16S rRNA gene sequence similarity, both strains were shown to belong to the genus Sphingomonas. Strain C42T showed the greatest levels of sequence similarity with Sphingomonas melonis DSM 14444T and Sphingomonas aquatilis KCTC 2881T (both 97.7 %). Strain C52T showed the greatest levels of sequence similarity with Sphingomonas koreensis KCTC 2882T (97.2 %), Sphingomonas aquatilis KCTC 2881T (97.1 %) and S. melonis DSM 14444T (97.0 %). The presence of Q-10 as the main ubiquinone, the predominance of the compound sym-homospermidine in the polyamine patterns, the presence of a Sphingomonadaceae-specific sphingoglycolipid in the polar lipid patterns, the presence of the fatty acid 2-OH C(14 : 0) and the lack of 3-hydroxy fatty acids supported the identification of the two novel strains as members of the genus Sphingomonas sensu stricto. Unique physiological characteristics, protein patterns, quantitative differences in their fatty acid profiles and the results of genomic fingerprinting and DNA-DNA hybridizations differentiated strains C42T and C52T from closely related Sphingomonas species. Hence, the two strains are described as novel species of the genus Sphingomonas sensu stricto. The names Sphingomonas abaci sp. nov. (type strain C42T=LMG 21978T=DSM 15867T) and Sphingomonas panni sp. nov. (type strain C52T=LMG 21979(T)=DSM 15761T) are proposed.
