Cultural characteristics
Biochemical characters
Phylum Actinobacteria, Class Actinobacteria , Subclass Actibacteridae, Order Actynomycetales, Suborder Micrococcinae, Family
Microbacteriaceae, Genus Rathayibacter,
Rathayibacter toxicus (Riley and Ophel 1992) Sasaki, Chijimatsu and Suzuki 1998.

Historical synonyms:
Clavibacter toxicus Riley and Ophel 1992.
Gram positive coryneform rods,  0.6-0.75 / 1.5 µm, including a capsule that is 0.08 to 0.14 µm thick. Non-motile. Non-spore-forming.
Mycolic acids are not present.
Requires the addition of 0.1% yeast extract to the growth medium. Colonies on 523M
agar are convex, smooth, entire, mucoid, and glistening, with yellow pigmentation;
after 3 weeks form streaks or convex protrusions. From cultured inoculum, single
colonies take 5 to 6 days to appear, and from rehydrated anhydrobiotic material
obtained from colonized ryegrass colonies take 8 to 14 days to appear. Colonies are
often variable in size because the adhesive properties of the mucoid capsule make
dispersal to single cells difficult. Colonies on R agar are flat, smooth, pale yellow after
5 days culture at 30 ºC.
Obligately aerobic.
Grows at 26 ºC, optimum. No growth at 37
ºC. Can grow in maximum 1% NaCl
media. No growth in 0.030% potassium tellurite.
The type strain was isolated from ryegrass from a site in Murray Bridge, South Australia, where toxicity to grazing animals had been
observed. The site was infested with the vector nematode, Anguina funesta.
Colonizes seedheads and nematode galls in ryegrass and occasionally the seedheads of other grasses at the same sites
produces antibiotics that belong to the tunicamycin group (termed corynetoxins) in colonized plants;  production of corynetoxins
declines rapidly during isolation and subculture.
A bacteriophage which lysed all of the strains tested has been described.
All of the strains tested (1992) adhere to some populations of the seed gall-forming nematode Anguina funesta, the nematode with
which it is most commonly associated in infested ryegrass, and some other
Anguina spp., such as Anguina tritici, with which it is not
normally associated.
Produces antibiotics that belong to the tunicamycin group (termed corynetoxins) in colonized grasses and is responsible for often
fatal poisoning of livestock.
Colonizes seedheads and nematode galls in ryegrass and occasionally the seedheads of other grasses at the same sites.
Inoculation of host grasses has limited success without the nematode vector.
  1. Riley I.T. and Ophel K.M., 1992. Clavibacter toxicus sp. nov. the Bacterium Responsible for Annual Ryegrass Toxicity in Australia.
    Int. J. Syst. Bacteriol. Vol. 42, No.1, 64-68.
  2. Sasaki J., Chijimatsu M. and Suzuki K.I., 1998. Taxonomic significance of 2,4=diaminobutyric acid isomers in the cell wall
    peptidoglycan of actinomycetes and reclassification of Clavibacter toxicus as Rathayibacter toxicus comb. nov. Int. J. Syst.
    Bacteriol. 48, 403-410.
  3. Dorofeeva L.V., Evtushenko L.I., Krausova V.I., Karpov A.V., Subbotin S.A. and Tiedje J.M., 2002. Rathayibacter caricis sp. nov. and
    Rathayibacter festucae sp. nov., isolated from the phyllosphere of Carex sp. and the leaf gall induced by the nematode Anguina
    graminis on Festuca rubra L., respectively. Int. J. Syst. Evol. Microbiol. 52, 1917-1923.

Positive results for catalase, acid production from galactose & mannose.

Negative results for gelatinase, methyl red reduction, nitrate reduction, oxidase, starch hydrolysis, Tween 60, 80 hydrolysis, tyrosine
hydrolysis, urease, Voges-Proskauer test, acid production from: adonitol, dulcitol, erythritol, ethanol, inulin, mannitol & melezitose.

Variable results for H
2S production, acid production from xylose.
Rathayibacter toxicus
(c) Costin Stoica
Culture media
Biochemical tests
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