Rhodococcus parequisp. nov., a new species isolated from equine farm soil closely related to the pathogenRhodococcus equi

Abstract

We present the description of the new species,Rhodococcus(Prescottella)parequi, found during phylogenomic investigations of a global collection of strains identified asRhodococcus(Prescottella)equi. Strain PAM 2766 was isolated from horse-breeding farm soil in Normandy, France, and was indistinguishable fromR. equibased on the usual identification tests. Whole-genome phylogenetic analyses located PAM 2766 in the sameRhodococcussublineage asR. equi, together withRhodococcus agglutinans,Rhodococcus defluvii,Rhodococcus soli,Rhodococcus subtropicus,Rhodococcus spongiicolaandRhodococcus xishaensis. PAM 2766 is most closely related to, but sufficiently distinct fromR. equiDSM 20307Tto be considered as a separate species. Average Nucleotide Identity (ANI) and Average Amino Acid Identity (AAI) values are 88.60% and 92.35, respectively, well below the species cutoff. The PAM 2766 draft genome is ~5.3 Mb in size with 68.98% G+C mol content. PAM 2766 is aerobic, non-motile, and produces smooth creamy to buff-coloured colonies very similar to those ofR. equi. It phenotypically differs from the latter by the ability to grow at 5°C, a strongly positive urease test at 24 h, and specificities in the carbon and nitrogen source utilization profile as determined by phenotype microarray screens. Our data indicate that PAM 2766 belongs to a novel species, for which the nameRhodococcus parequisp. nov. is proposed.R. parequiwas avirulent in macrophage infection assays and is assumed to be non-pathogenic. The type strain is PAM 2766T(=CETC 30995T= NCTC 14987T).