Helicobacter labacensis sp. nov., Helicobacter mehlei sp. nov., and Helicobacter vulpis sp. nov., isolated from gastric mucosa of red foxes (Vulpes vulpes)

Six Helicobacter - like isolates were recovered from 15 gastric mucosa samples of red foxes (Vulpes vulpes) shot by hunters in the surroundings of Ljubljana, Slovenia. Gram-negative, tightly coiled, intensely motile, 7-15 mu m long and <= 1 mu m wide bacteria grew on the biphasic blood agar plates. By using a genus-specific polymerase chain reaction (PCR), all isolates were confirmed as Helicobacter sp. and subsequently subjected to whole-genome sequencing (WGS). Five isolates showed a genome-wide average nucleotide identity (ANI) value of <95% to the previously described Helicobacter species and one isolate was classified as Helicobacter fells. In the five unidentified isolates, the 16S rRNA gene sequence similarity to the type strains of all Helicobacter species ranged from 98.6 to 98.9%. Their taxonomic status was established using a polyphasic taxonomic approach comprising the core genome-based phylogeny, morphological and phenotypic characteristics, including an analysis of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectra. Phylogeny revealed the existence of three novel and well-supported clusters, with Helicobacter bizzozeronii and Helicobacter baculiformis being the most closely related species. The isolates also differed from the previously described species in their MALDI-TOF profiles and some biochemical characteristics. In conclusion, the data presented herein indicate that the obtained isolates, excluding H. fells isolate, represent three novel Helicobacter species, for which the names Helicobacter labacensis sp. nov., Helicobacter mehlei sp. nov., and Helicobacter vulpis sp. nov. are proposed, with isolates L9(T) (=DSM 108823(T)=CRBIP 111719(T)), L15(T) (=DSM 108730(T)=CCUG 72910(T)) and L2(T) (=DSM 108727(T)=CCUG 72909(T)) as type strains, respectively.