Campylobacter sputorum subsp. bovis subsp. nov., isolated from cattle, and an emended description of Campylobacter sputorum

Six urease-negative <i>Campylobacter</i> strains were isolated from cattle faeces over a 19-month period from 2009 to 2010. These strains were initially identified as <i>Campylobacter sputorum</i> by 16S rRNA gene and <i>atpA</i> typing. Initial studies characterizing these strains by multilocus sequence typing and genome sequencing further supported their classification as <i>C. sputorum</i> but indicated that these strains form a divergent clade within the species. A polyphasic study was undertaken here to clarify their taxonomic position. Phylogenetic analyses were performed based on 16S rRNA gene sequences and the concatenated sequences of 330 core genes, with the latter analysis also placing the six strains into a clade distinct from the three <i>C. sputorum</i> biovars. Pairwise digital DNA-DNA hybridization values identified these strains as <i>C. sputorum</i>, and the pairwise average nucleotide identity values were consistent with those observed between current <i>Campylobacter</i> subspecies pairs. Standard phenotypic testing was also performed. All strains are microaerobic, anaerobic, motile, Gram-negative and oxidase- and catalase-positive; cells are curved rods or spirals. Strains can be distinguished from the <i>C. sputorum</i> biovars by the presence of alkaline phosphatase activity and triphenyltetrazolium chloride reduction and absence of nitrate reduction. The data presented here show that these strains represent a novel subspecies within <i>C. sputorum</i>, for which the name <i>C. sputorum</i> subsp. <i>bovis</i> subsp. nov. (type strain RM8705^T=LMG 32300^T=CCUG 75470^T) is proposed.