Xenorhabdus Thomas and Poinar 1979 (Approved Lists 1980)
General information
Description and emendation
Gram-negative, asporogenous, peritrichous rods measuring approximately 0.8 to 2.0 by 4.0 to 10.0 μm. Motile. In older cultures, crystalline inclusions (which are not poly-β-hydroxybutyrate) are formed within cells; spherical cells, resulting from the disintegration of the cell wall, average 2.6 μm in diameter. Facultatively anaerobic. Nutrition is chemoorganotrophic; good growth occurs on meat extract and on simple peptone agar. Metabolism is respiratory and fermentative. Acid, usually without gas, is produced from the fermentation of glucose and other carbohydrates (all carbohydrates tested gave positive to weakly positive results). Starch is not hydrolyzed. Colonies on nutrient agar are about 1 mm in diameter in 24 to 48 h at 24°C; they may be smooth, moist, and somewhat granular in appearance, although mucoid forms occur; low convex; circular; margins are slightly irregular, grayish, cream-colored, yellowish brown, red, or rust brown to reddish; may or may not exhibit bioluminescence. Young colonies (24- to 48-h-old) on T-7+TTC agar are gray, but as the colonies age, bromothymol blue is absorbed from the medium and combines with pigments produced by the bacteria, causing the colonies to take on a characteristic coloration ranging from blue to shades of green and greenish blue. The reaction is alkaline, and the medium turns blue. Glutamic acid decarboxylase is produced. Lysine and ornithine decarboxylases, arginine dihydrolase, phenylalanine deaminase, urease, oxidase, and cytochrome oxidase are not produced. The methyl red and Voges-Proskauer tests are negative. Indole and H2S (triple sugar iron agar) are not produced. Nitrates are not reduced to nitrites. Lipase is generally not produced. Citrate is generally not utilized. Members of the genus may or may not be proteolytic (Loeffler blood serum and nutrient gelatin). Catalase may or may not be produced, but even apparently negative strains may occasionally show weakly positive results. The G+C content of the DNA is 43 to 44 mol%. Immunologically distinct from the marine luminescent bacteria, as well as from members of the genera Escherichia, Enterobacter, Serratia, Proteus, and Aeromonas (Paul Baumann, personal communication). The natural habitat for these bacteria is the intestinal lumen of entomogenous nematodes and the body cavity of infected host insects.
1: Gram-negative, asporogenous, peritrichous rods varying from 0.3 to 1.9 μm wide and from 2.3 to 21.9 μm long (average, 1.0 by 5.8 μm). Motile. In older cultures, crystalline inclusions (which are not poly-β-hydroxybutyrate) are formed within the cells; spherical cells, resulting from the disintegration of the cell wall, average 2.6 µm in diameter. Facultatively anaerobic. Nutrition is chemoorganotrophic; good growth occurs on meat extract and simple peptone agar. Metabolism is respiratory and fermentative. Acid, usually without gas, is produced from the fermentation of glucose, fructose, maltose, mannose, and ribose. Variable production of acid is obtained from cellobiose, glycerol, inositol, melezitose, amethylglucoside, saccharose, salicin, sorbitol, sucrose, trehalose, and xylose. Starch is not hydrolyzed. Colonies of primary forms of X. nematophilus subsp. nematophilus, X. nematophilus subsp. bovienii, and X. nematophilus subsp. poinarii on nutrient agar are about 1 mm in diameter after 24 to 48 h at 24°C; they may be smooth, moist, slightly mucoid, and somewhat granular in appearance. In addition, the colonies are low convex, circular with slightly irregular margins, and grayish, cream colored (X. nematophilus subsp. nematophilus), yellowish brown (X. nematophilus subsp. bovienii), or rust brown to reddish (X. nematophilus subsp. poinarii). Colonies of secondary forms differ in being somewhat translucent and flatter with spreading margins and less pigmentation. Primary colonies of X. luminescens on nutrient agar are more mucoid and more intensely pigmented than secondary forms. The latter also produce flatter colonies with spreading margins. Both forms are luminescent, but the primary form appears to be more strongly luminescent than the secondary form, although this has not been measured photometrically. On tergitol-7 agar supplemented with 0.04 mg of triphenyltetrazolium chloride per liter young colonies (24 to 48 h old) of primary forms of X. nematophilus subsp. nematophilus, X. nematophilus subsp. bovienii, and X. luminescens strains are gray, but as the colonies age, bro-mothymol blue is absorbed from the medium and combines with pigments produced by the bacteria, causing the colonies to take on a characteristic coloration. X. nematophilus subsp. nematophilus colonies become blue to deep purple, X. nematophilus subsp. bovienii colonies become greenish to blue green, and X. luminescens colonies become greenish with reddish brown centers. In all of the above strains, absorption of the bromothymol blue results in clearing zones in the agar surrounding the colonies. Secondary forms of the taxa described above do not absorb the bromothymol blue, the colonies take on various shades of red to rust, and clearing zones do not develop. Neither the primary nor secondary forms of X. nematophilus subsp. poinarii absorb the bromothymol blue from tergitol-7 agar supplemented with 0.04 mg of triphenyltetrazolium chloride per liter. Consequently, clearing zones do not develop, and the colonies become red to rust in color. Secondary forms of all species tend to produce flatter colonies with spreading and translucent margins. Glutamic acid, lysine decarboxylase, ornithine decarboxylase, arginine dihydrolase, oxidase, and cytochrome oxidase are not produced. Urease is not produced by X. nematophilus subsp. nematophilus, X. nematophilus subsp. bovienii, orX.nematophilus subsp.poinarii, but is produced by X. luminescens. The methyl red and Voges-Proskauer tests are negative. Indole is not produced by X. nematophilus subsp. nematophilus, X. nematophilus subsp. bovienii, or X. nematophilus subsp. poinarii. However, Akhurst found indole production in X. luminescens to be variable. Hydrogen sulfide (triple sugar iron agar) is not produced. Nitrates are not reduced to nitrites. Production of lipase and phenyalanine deaminase is variable. Citrate is generally not utilized in Simmons citrate agar, but is utilized on OY medium, as described by Dye. Tests for proteolysis by using Loeffler blood serum agar and nutrient gelatin have produced variable results. Catalase may or may not be produced, but even apparently negative strains may occasionally show weakly positive results. The G+C content of the DNA is 43 to 50 mol%. Species of X. nematophilus and X. luminescens are immunologically distinct from marine luminescent bacteria, as well as from members of the genera Escherichia, Enterobacter, Serratia, Proteus, and Aeromonas. The natural habitats for these bacteria are the intestinal lumina of entomogenous nematodes and the body cavities of infected host insects.
Subdivision(s)
MID | Name | Rank | Taxon ID |
---|---|---|---|
M022506080508002 | Xenorhabdus beddingii | Species | 40578 |
M022506080508003 | Xenorhabdus bovienii | Species | 40576 |
M022506080508004 | Xenorhabdus budapestensis | Species | 290110 |
M022506080508005 | Xenorhabdus cabanillasii | Species | 351673 |
M022506080508006 | Xenorhabdus doucetiae | Species | 351671 |
M022506080508007 | Xenorhabdus eapokensis | Species | 1873482 |
M022506080508008 | Xenorhabdus ehlersii | Species | 290111 |
M022506080508009 | Xenorhabdus griffiniae | Species | 351672 |
M022506080508010 | Xenorhabdus hominickii | Species | 351679 |
M022506080508011 | Xenorhabdus indica | Species | 333964 |
M022506080508012 | Xenorhabdus innexi | Species | 290109 |
M022506080508013 | Xenorhabdus ishibashii | Species | 1034471 |
M022506080508014 | Xenorhabdus japonica | Species | 53341 |
M022506080508015 | Xenorhabdus khoisanae | Species | 880157 |
M022506080508016 | Xenorhabdus koppenhoeferi | Species | 351659 |
M022506080508017 | Xenorhabdus kozodoii | Species | 351676 |
M022506080508018 | Xenorhabdus magdalenensis | Species | 995054 |
M022506080508019 | Xenorhabdus mauleonii | Species | 351675 |
M022506080508020 | Xenorhabdus miraniensis | Species | 351674 |
M022506080508001 | Xenorhabdus nematophila | Species | 628 |
M022506080508021 | Xenorhabdus poinarii | Species | 40577 |
M022506080508022 | Xenorhabdus romanii | Species | 351677 |
M022506080508023 | Xenorhabdus stockiae | Species | 351614 |
M022506080508024 | Xenorhabdus szentirmaii | Species | 290112 |
M022506080508025 | Xenorhabdus thuongxuanensis | Species | 1873484 |
M022506080508026 | Xenorhabdus vietnamensis | Species | 351656 |