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XenorhabdusRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Gammaproteobacteria -> Enterobacteriales -> Enterobacteriaceae -> Xenorhabdus OVERVIEW: Asporogenous, rod-shaped cells 0.3–2 × 2–10 μm and occasionally with filaments 15–50 μm in length. Spheroplasts, averaging 2.6 µm in diameter, appear in the last third of exponential growth. Proteinaceous crystalline inclusions develop in a large proportion of cells in stationary phase cultures. Gram negative. Motile by means of peritrichous flagella. Swarming may occur on 0.6–1.2% agar. Facultatively anaerobic, with both respiratory and fermentative types of metabolism. Optimum temperature usually ∼28°C or less; a few strains grow at 40°C. Acid (no gas) production from glucose; ferment some other carbohydrates but poorly. No catalase activity; nitrate is not reduced to nitrite. Negative for most tests used to differentiate Enterobacteriaceae. Lipase detected with Tween 20 and egg yolk agar; most strains lipolytic on Tween 40, 60, 80, and/or 85. Positive for deoxyribonuclease and protease. Phase shift occurs to varying degrees in stationary phase cultures, giving rise to phase II, which lacks dye adsorption, antibiotic production, protein inclusions, and some other characteristics of the phase I isolated from the natural environment. Only known from the intestinal lumen of entomopathogenic nematodes of the family Steinernematidae and insects infected by these nematodes. The mol% G + C of the DNA is: 43–50 (Bd). Type species: Xenorhabdus nematophila |