Description of Sphingosinicella xenopeptidilytica sp. nov., a beta-peptide-degrading species, and emended descriptions of the genus Sphingosinicella and the species Sphingosinicella microcystinivorans.

A Gram-negative, rod-shaped bacterium, strain 3-2W4(T), was isolated from the aeration tank of a wastewater treatment plant in Zurich and was found to have the exceptional capacity to degrade synthetic beta-peptides. 16S rRNA gene sequence analysis showed that strain 3-2W4(T) is closely related to Sphingosinicella microcystinivorans Y2(T), but DNA-DNA hybridization experiments between these two strains revealed that they belong to two different species. The two strains displayed different fingerprints after PCR analysis using the repetitive primers BOX, ERIC and REP. Strain 3-2W4(T) did not degrade microcystin, which is a characteristic trait of Sphingosinicella microcystinivorans Y2(T). Like Sphingosinicella microcystinivorans Y2(T), strain 3-2W4(T) had the following characteristics: fatty acids comprising mainly C(18 : 1)omega7c, summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH) and C(16 : 0), the presence of ubiquinone Q-10 and sym-homospermidine as the predominant polyamine compound. The polar lipid profiles of the two strains were almost identical, consisting of phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol and sphingoglycolipid. Strain 3-2W4(T) and Sphingosinicella microcystinivorans Y2(T) utilized the beta-peptides H-betahVal-betahAla-betahLeu-OH and H-betahAla-betahLeu-OH as sole carbon and energy sources and shared beta-peptidyl aminopeptidase activity in common, which distinguishes them from Sphingomonas and Sphingopyxis type strains. On the basis of these results, strain 3-2W4(T) represents a novel species of the genus Sphingosinicella, for which the name Sphingosinicella xenopeptidilytica sp. nov. is proposed. The type strain is 3-2W4(T) (=DSM 17130(T)=CCUG 52537(T)). The descriptions of the genus Sphingosinicella and the species Sphingosinicella microcystinivorans are emended.