Proposal of Helicobacter higonensis sp. nov. isolated from a human clinical specimen, and emended description of Helicobacter valdiviensis collado, 2014.

We have previously isolated a gram-negative microaerophilic strain, PAGU 2000 T from a patient presenting with a fever in Kumamoto Prefecture, Japan. The present study aimed to comprehensively analyze the taxonomy of the isolated strain using a polyphasic approach. The 16S rRNA gene sequence analysis indicated that the strain was a member of enterohepatic Helicobacter. The strain PAGU2000 T shared a 97.5 % 16S rRNA gene nucleotide identity with Helicobacter valdiviensis, and this taxonomic position was confirmed by phylogenetic analysis of the GyrA amino acid sequences. The proposed strain PAGU2000 T has a 1.482 Mbp chromosome with a DNA G+C content of 31.3 mol% and encodes 1520 predicted coding sequences. The average nucleotide identity between the strain PAGU 2000 T and type strain of H. valdiviensis was 70.3%, which was lower than the recommended threshold of 95% for species delineation. The strain PAGU2000 T was a motile, non-spore-forming, and spiral-shaped bacterium, exhibiting catalase and oxidase activities but not urease and nitrate reduction. This study demonstrates that the isolate represents a novel species within enterohepatic Helicobacter, for which the name Helicobacter higonensis is proposed (type strain: PAGU 2000 T =GTC 16811 T=LMG 33095 T). In this study, we describe the phenotypic and morphological features of this strain and propose an emended description of some biochemical traits of H. valdiviensis.