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Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Species/Subspecies: Mesomycoplasma hyorhinis
Etymology: Genus name: between other mycoplasmas (fungus shaped).
Species epithet: from the pig nose.
Significance:Worldwide distribution.
Alternative Species Name(s):Mycoplasma hyorhinis
Type Strain: BTS7 = ATCC 17981 = NCTC 10130.
Macromorphology (smell):
Forms small and atypical colonies, which lack a clearly defined nipple (no "fried egg appearance") and should be observed in a microscope.
Micromorphology: Very small and pleomorphic.
Gram +/Gram -:G-, but is normally not gram stained since the cells are fragile and fragmented by this staining method.
Fermentation of carbohydrates: Glucose +
Spec. Char.: Optimal growth temperature: 37°C.
HostsDiseaseClinical picture
PigArthritis and polyserositis in pigs from 3 up to 10 weeks of age.Fever, difficulty in breathing, paralysis and swollen joints.
Genome Sequence:
Acc-noStrainSize (bp)Genome
CP002669 MCLD 0 829 709 1c + 0 
Three strains have been sequenced, plasmids have not been found.

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
AF412982 BTS7T 1468 

About 15 species have been described within the genus Mesomycoplasma. Mesomycoplasma hyorhinis is closely related to M. dispar, M. ovipneumoniae, M. hyopneumoniae as well as M. flocculare.

Note that the letter M in the phylogenetic tree (Fig. 37:2) can mean Mycoplasma, Mesomycoplasma, Metamycoplasma, Mycoplasmoides or Mycoplasmopsis.

Comment:Based on whole genome sequencing, the taxonomy of mycoplasmas has recently undergone a comprehensive revision. The new taxonomy has now been introduced in VetBact, but it will still be possible to search for the alternative species names. Read more about the revised taxonomy of the mollicutes under the Term list of VetBact and see reference 164 below..

M. hyorhinis is often found as a contaminant of cell cultures.

Reference(s): No. 164, 170


New names of taxa within the classification category phylum

During October 2021, an article was published by A. Oren och G.M. Garrity, in which new names are proposed for a number of taxa within the classification category phylum. This has resulted in many discussions in social media about whether it was really necessary to make these changes, which have created confusion among microbiologists and other professionals who come into contact with bacteriology.

Published 2022-09-28. Read more...

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