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Acholeplasma equirhinis sp. nov. isolated from respiratory tract of horse (Equus caballus) and Mycoplasma procyoni sp. nov. isolated from oral cavity of raccoon (Procyon lotor)


We describe two novel species of Acholeplasma sp. strain N93 and Mycoplasma sp. strain LR5794 which were isolated from the nasopharynx of a horse from the United Kingdom and from the oral cavity of a North American raccoon from Canada, respectively. These strains were phenotypically and genetically characterized and compared to other established Mycoplasma and Acholeplasma species. Both strains are facultative anaerobes, resistant to penicillin, and produce acid from glucose but do not hydrolyze arginine and urea. Both strains grew well in microaerophilic and anaerobic atmospheric conditions at 35–37 °C using PPLO (pleuropneumonia-like organisms) medium. Acholeplasma sp. N93 does not require serum for growth. Colonies of both strains showed a typical fried-egg appearance and transmission electron microscopy of bacterial cells revealed a typical mycoplasma cellular morphology. Molecular characterization included assessment of several genetic loci. The genetic analysis indicated that Acholeplasma sp. N93 and Mycoplasma sp. LR5794 were most closely related to A. hippikon and A. equifetale, and M. molare and M. lagogenitalium, respectively. However, both novel strains were genetically unique in comparison to other well-known Mycoplasma and Acholeplasma species. Based on the isolation source history, phenotypic, genotypic, and phylogenetic characteristics of these novel strains, we propose the name Acholeplasma equirhinis sp. nov. for Acholeplasma sp. isolated from the nasopharynx of a horse [the type strain is N93T (= DSM 106692T = ATCC TSD-139T = NCTC 14351T)], and the name Mycoplasma procyoni sp. nov. for the Mycoplasma sp. isolated from the oral cavity of a North American raccoon [the type strain is LR5794T (= DSM 106703T = ATCC TSD-141T = NCTC 14309T)].

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We dedicate this study in memory of Drs. Ruth M. Lemcke and H. Louise Ruhnke for their outstanding scientific contributions to Mycoplasmology research focused on studying animal mycoplasmas, and for the primary isolation of Acholeplasma equirhinis sp. nov. and Mycoplasma procyoni sp. nov., respectively, which were deposited by them to the International Organization for Mycoplasmology Mollicutes Collection and thus saved these unique microorganisms for future characterization and scientific studies.


The authors received no specific funds from any funding agency.

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Correspondence to Dmitriy V. Volokhov.

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Maureen K. Davidson and Vladimir E. Chizhikov currently retired from the US FDA.

The GenBank accession number for the 16S rRNA gene sequences of the type strains N93T and LR5794T are EU925159 and FJ226566, respectively, and the GenBank accession numbers for other housekeeping genes used for the genetic characterization of each novel species described in this study are provided in the manuscript.

Communicated by Erko Stackebrandt.

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Volokhov, D.V., Gao, Y., Davidson, M.K. et al. Acholeplasma equirhinis sp. nov. isolated from respiratory tract of horse (Equus caballus) and Mycoplasma procyoni sp. nov. isolated from oral cavity of raccoon (Procyon lotor). Arch Microbiol 202, 411–420 (2020).

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  • Acholeplasma
  • Mycoplasma
  • Horse
  • Raccoon
  • Phylogeny