Cross Index	Rhizobium
SuperSet	Prokaryote, Eubacteria Gram-Negative Aerobic/ Microaerophilic Rods and Cocci
Compare	Acetobacter, Acidiphilium, Acidomonas methanolica, Acidothermus cellulolyticus, Acidovorax, Acinetobacter, Afipia, Agrobacterium, Agromonas oligotrophica, Alcaligenes, Alteromonas, Aminobacter, Aquaspirillum, Azomonas, Azorhizobium caulinodans, Azotobacter, Bacteroides, Beijerinckia, Bordetella, Bradyrhizobium japonicum, Brucella, Chromohalobacter marismortui, Chryseomonas luteola, Comamonas, Cupriavidus necator, Deleya, Derxia gummosa, Ensifer adherans, Erythrobacter longus, Flavimonas oryzihabitans, Flavobacterium, Francisella, Frateuria aurantica, Gluconobacter, Halomonas, Hydrogenophaga, Janthinobacterium lividum, Kingella, Lampropedia hyalina, Legionella, Marinobacter hydrocarbonoclasticus, Marinomonas, Mesophilobacter marinus, Methylobacillus glycogenes, Methylobacterium, Methylococcus, Methylomonas, Methylophaga, Methylophilus, Methylovorus glucosotrophus, Moraxella, Morococcus cerebrosus, Neisseriaceae, Neisseria, Oceanospirillum, Ochrobactrum anthropi, Oligella, Paracoccus, Phenylobacterium immobile, Phyllobacterium, Pseudomonas, Psychrobacter immobilis, Rhizobacter daucus, Rhizobium, Rhizomonas suberifaciens, Rochalimaea, Roseobacter, Rugomonas rubra, Serpens, Sinorhizobium, Sphingobacterium, Taylorella equigenitalis, Thermoleophilum, Thermomicrobium, Thermus, Variovorax paradoxus, Volcaniella eurhalina, Weeksella, Wolinella, Xanthobacter, Xanthomonas, Xyella fastidiosa, Xylophilus ampelinus, Zoogloea ramigera
Contrast	Archaea
Subset

 

Morphology

Rhizobium

CELLULAR

Staining	Gram-negative
Morphology	Rods 0.5-0.9 x 1.2-3.0 um. Commonly pleomorphic under adverse growth conditions
Motility	Motile by one polar or subpolar flagellum or two to six peritrichous flagella
Specialized structures	Fimbriae have been described on a few strains Usually contain granules of poly-B- hydroxybutyrate which are refractile by phase-contrast microscopy. Nonsporeforming

Division

COLONIAL

Solid surface

Colonies are circular, convex, semitranslucent, raised and mucilaginous, usually 2-4 mm in diameter within 3-5 days on yeast-mannitol-mineral salts agar.

Liquid

Pronounced turbidity develops after 2 or 3 days in agitated broth

 

Growth Parameters

Rhizobium

PHYSIOLOGICAL

Tropism	Chemoorganotrophic, utilizing a wide range of carbohydrates and salts of organic acids as carbon sources, without gas formation
Oxygen	Aerobic, possessing a respiratory type of metabolism with oxygen as the terminal electron acceptor. Often able to grow well under oxygen tensions less than 1.0 kPa (Wilson 1940).
pH	Optimum pH, 6-7
Temperature	Optimum temperature, 25-30`C
Requirements	Cellulose and starch are not utilized. Produce an acidic reaction in mineral-salts medium containing mannitol or other carbohydrates. Growth on carbohydrate media is usually accompanied by copious extracellular poly-saccharide slime. Ammonium salts, nitrate, nitrite and most amino acids can serve as nitrogen sources. Some strains will grow in a simple mineral salts medium with vitamin-free casein hydrolysate as the sole source of both carbon and nitrogen. Peptone is poorly utilized. Casein and agar are not hydrolyzed. Some strains require biotin or other water-soluble vitamins. 3- Ketoglycosides not produced (Bernaerts and De Ley 1963).
Products
Enzymes
Unique features

ENVIRONMENTAL

Habitat	The organisms are characteristically able to invade the root hairs of temperate- zone and some tropical-zone leguminous plants (family Leguminosae) and incite production of root nodules wherein the bacteria occur as intracellular symbionts. All strains exhibit host range affinities (host "specificity"). The bacteria are present in root nodules as pleomorphic forms (bacteroids) which are normally involved in fixing atmospheric nitrogen into a combined form (ammonia) utilizable by the host plant.
Lifestyle
Pathogenicity

Distribution

 

Genome

Rhizobium

G+C Mol %

59-64

 

Reference

Rhizobium

First citation	Frank,B. (1889) Ueber die Pilzsymbiosis der Leguminosen Ber. Deut. Bot. Ges. 7:332-346
The Prokaryotes	p
Bergey's Systematatic	p 235 D. C. Jordan
Bergey's Determinative	p 95

References