Genus Xenorhabdus
Tween 80
X. beddingii
X. bovienii
X. japonica
X. nematophila
X. poinarii
Photorhabdus luminescens
Cultural characteristics
Biochemical characters
Phylum Proteobacteria, Class Gammaproteobacteria, Order Enterobacteriales, Family Enterobacteriaceae, Genus Xenorhabdus,
- Xenorhabdus beddingii Akhurst 1986, basonym: X. nematophila subsp. beddingii corrig. Akhurst 1986,
- Xenorhabdus bovienii Akhurst 1983, basonym: X. nematophila subsp. bovienii  corrig. Akhurst 1986,
- Xenorhabdus budapestensis Lengyel et al. 2005 *,
- Xenorhabdus cabanillasii Tailliez et al. 2006,
- Xenorhabdus doucetiae Tailliez et al. 2006,
- Xenorhabdus ehlersii Lengyel et al. 2005 *,
- Xenorhabdus griffiniae Tailliez et al. 2006,
- Xenorhabdus hominickii Tailliez et al. 2006,
- Xenorhabdus indica Somvanshi et al. 2009,
- Xenorhabdus innexi Lengyel et al. 2005 *
- Xenorhabdus japonica Nishimura et al. 1995 ** (name japonicus has been corrected by Euzeby and Boemare 2000),
- Xenorhabdus koppenhoeferi Tailliez et al. 2006,
- Xenorhabdus kozodoii Tailliez et al. 2006,
- Xenorhabdus luminescens Thomas and Poinar 1979, transferred to Photorhabdus luminescens by Boemare 1993 **,
- Xenorhabdus magdalenensis Tailliez et al. 2012,
- Xenorhabdus mauleonii Tailliez et al. 2006,
- Xenorhabdus miraniensis Tailliez et al. 2006,
- Xenorhabdus nematophila Poinar and Thomas 1965, (name 'nematophilus'  has been corrected by Euzeby and Boemare 2000),
Achromobacter nematophilus) - type species of the genus,
- Xenorhabdus poinarii (Akhurst 1983) Akhurst and Boemare 1993,
- Xenorhabdus romanii Tailliez et al. 2006,
- Xenorhabdus stockiae Tailliez et al. 2006,
- Xenorhabdus szentirmaii Lengyel et al. 2005*,
- Xenorhabdus vietnamensis Tailliez et al. 2010.

* Note: X. budapestensis, X. ehlersii, X. innexi and X. szentirmaii appear on VALIDATION LIST N° 104 but  <<The inclusion of a name on this list is not to be construed as
taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to
another genus, thus necessitating the creation of a  new combination.>> VALIDATION LIST N° 104 cited. (Validation of publication of new names and new combinations
previously effectively  published outside the IJSEM. Int. J. Syst. Evol. Microbiol., 2005, 55, 1395-1397)
** Although the genus Photorhabdus has been proposed, many of the details concerning the phylogeny and taxonomy of the genera  Xenorhabdus and Photorhabdus have not
yet been settled.
Gram-negative rods 0.3–2 x 2–10 μm, occasionally presenting filaments of 15–50 μm
in length. May produce crystalline inclusions. Motile by means of peritrichous flagella.
Swarming may occur.
A particularity of genus Xenorhabdus is the phase variation: in nature can be found only
phase 1 but under in vitro conditions some strains can swich to phase 2, suffering
changes of colony and cell morphologies, motility, enzymes production and others.
Phase 1 colonies are granular, circular with slightly irregular margins and 1.5-2 mm in
diameter (4days incubation at 28 ºC), sometimes yellow to brown-pigmented. Phase 2
colonies are no-pigmented, circular, flatter and larger (2.5-3.5 mm in 4days at 28 ºC).
Facultatively anaerobic, optimum growth temperature 28 ºC. Grow on media: Nutrient
Agar or Nutrient Broth, Trypticase Soy Agar ± 5% sheep blood.
Isolated from nematodes in the genera Heterorhabditis and Steinernema. Xenorhabdus lives in these nematodes stomachs during
their non-feeding infective stage.
Symbiotic bacteria of entomopathogenic nematodes. Together, Xenorhabdus and their nematode host infect and kill insects that are
used during their reproductive cycles.
Toxicity for insects is caused by a series of antimicrobial end products that are excreted by the symbiont during the multiplication of
the nematodes in the insects hosts.
Some strains may have antibacterial or antifungal activity.
  1. J. G. Holt et al., 1994. Facultatively Anaerobic Gram-Negative Rods. Subgroup 1. Family Enterobacteriaceae. In: Begey’s Manual of
    Determinative Bacteriology, 9th-edition, Williams & Wilkins, pp 175-189.
  2. Akhurst R.J. &  Boemare N.E.: A numerical taxonomic study of the genus Xenorhabdus (Enterobacteriaceae) and proposed
    elevation of the subspecies of X. nematophilus to species. J. Gen. Microbiol., 1988, 134, 1835-1845.
  3. Lengyel K., Lang E., Fodor A., Szallas E., Schumann P. & Stackebrandt E.: Description of four novel species of Xenorhabdus,
    family Enterobacteriaceae: Xenorhabdus budapestensis sp. nov., Xenorhabdus ehlersii sp. nov., Xenorhabdus innexi sp. nov.,
    and Xenorhabdus szentirmaii sp. nov. Syst. Appl. Microbiol., 2005, 28, 115-122.
  4. Nishimura Y., Hagiwara A., Suzuki T. & Yamanaka S.: Xenorhabdus japonicus sp. nov. associated with the nematode
    Steinernema kushidai. World J. Microbiol. Biotechnol., 1994, 10, 207-210.
  5. Thomas G.M. & Poinar Jr. G.O.: Xenorhabdus gen. nov., a genus of entomopathogenic nematophilic bacteria of the family
    Enterobacteriaceae. International Journal of Systematic Bacteriology, 1979, 29, 352-360.
  6. Poinar Jr. G.O. and Thomas G.M.: A new bacterium, Achromobacter nematophilus sp. nov. (Achromobacteriaceae: Eubacteriales)
    associated with a nematode. International Bulletin of Bacteriological Nomenclature and Taxonomy, 1965, 15, 249-252.
  7. Boemare N.E., Akhurst R.J., Mourant R.G.: DNA relatedness between Xenorhabdus spp. (Enterobacteriaceae), symbiotic bacteria
    of entomopathogenic nematodes, and a proposal to transfer Xenorhabdus luminescens to a new genus, Photorhabdus gen. nov,  
    1993, International Journal of Systematic Bacteriology. 43:(2) 249-255.
  8. Don J. Brenner and J.J. Farmer III, 2001. Family I. Enterobacteriaceae. In: Bergey’s Manual of Systematic Bacteriology, Second
    edition, Vol two, part B, George M. Garrity (Editor-in-Chief), pp 587-897.
  9. Euzeby J.P., List of  Prokaryotic names with Standing in Nomenclature - Genus Xenorhabdus, https://www.bacterio.cict.
Positive results for methyl red, gelatin hydrolysis (most of strains), acid production from: glucose (without gas production), glycerol,
maltose, D-mannose and trehalose.

Negative results for catalase, oxidase, beta-galactosidase, arginine dihydrolase, lysine decarboxylase, ornithine decarboxylase,
indole production, H
2S production, urea hydrolysis, Voges-Proskauer reaction, growth on KCN media, nitrate reduction, acid
production from: L-arabinose, adonitol, cellobiose, dulcitol, lactose, D-mannitol, melibiose, alpha-methyl-D-glucoside, D-sorbitol,
raffinose, rhamnose, sucrose and xylose.
(c) Costin Stoica
Culture media
Biochemical tests
Legend:  + positive 90-100%, - negative 90-100%, [+] positive 75-89%, [-] negative 75-89%, d positive 25-74% of strains,
Differential characters of the species:
Previous page