Bradyrhizobium japonicum

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Bradyrhizobium japonicum
Bradyrhizobium japonicum USDA 110 on TY agar.JPG
Bradyrhizobium japonicum strain USDA 110 on an agar plate
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Alphaproteobacteria
Order: Rhizobiales
Family: Bradyrhizobiaceae
Genus: Bradyrhizobium
Species: B. japonicum
Binomial name
Bradyrhizobium japonicum
(Kirchner 1896) Jordan, 1982

Rhizobium japonicum Buchanan 1926
Rhizobacterium japonicum Kirchner 1896[1]

Bradyrhizobium japonicum is a species of legume-root nodulating, microsymbiotic nitrogen-fixing bacteria. The species is one of many Gram-negative, rod-shaped bacteria commonly referred to as rhizobia.[2] Within that broad classification, which has three groups, taxonomy studies using DNA sequencing indicate that B. japonicum belongs within homology group II.[3]



B. japonicum is added to legume seed to improve crop yields,[4] particularly in areas where the bacterium is not native (e.g. Arkansas soils).[5] Often the inoculate is adhered to the seeds prior to planting using a sugar solution.[6]


A strain of B. japonicum, USDA110, has been in use a model organism since 1957.[2] It is widely used to study molecular genetics, plant physiology, and plant ecology due to its relatively superior symbiotic nitrogen-fixation activity with soybean (i.e. compared to other rhizobia species). Its entire genome was sequenced in 2002, revealing that the species has a single circular chromosome with 9,105,828 base pairs.[7]


B. japonicum is able to degrade catechin with formation of phloroglucinol carboxylic acid, further decarboxylated to phloroglucinol, which is dehydroxylated to resorcinol and hydroxyquinol.[citation needed]

B. japonicum possess the nosRZDFYLX gene, which aides in denitrification and has two catalytic subunits - Cu-a and Cu-z (with several histidine residues). It manages an expression cascade that can sense oxygen gradients, termed 'FixJ-FixK2-FixK1.' FixJ positively regulates FixK2, which activates nitrogen respiration genes, as well as FixK1. FixK1 mutants are unable to respire from nitrogen due to a defective catatylic copper subunit (Cu-z) in nosRZDFYLX.[8]


  1. ^ "to Bradyrhizobium gen. nov., a genus of slow-growing, root nodule bacteria from leguminous plants". Int. J. Syst. Bacteriol. 32: 136–139. 1982. doi:10.1099/00207713-32-1-136. 
  2. ^ a b Board, James E. (2012). A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen Relationships (1st ed.). Rijeka, Croatia: InTech. pp. 5–6. doi:10.5772/53728. ISBN 9789535108764. 
  3. ^ A. B. Hollis, W. E. Kloos & G. E. Elkan (1981). "DNA:DNA hybridization studies of Rhizobium japonicum and related Rhizobiaceae". Journal of General Microbiology. 123: 215–222. doi:10.1099/00221287-123-2-215. 
  4. ^ Purcell, Larry C.; Salmeron, Montserrat; Ashlock, Lanny (2013). "Chapter 5" (PDF). Arkansas Soybean Production Handbook - MP197. Little Rock, AR: University of Arkansas Cooperative Extension Service. p. 5. Retrieved 21 February 2016. 
  5. ^ Purcell, Larry C.; Salmeron, Montserrat; Ashlock, Lanny (2000). "Chapter 7" (PDF). Arkansas Soybean Production Handbook - MP197. Little Rock, AR: University of Arkansas Cooperative Extension Service. pp. 2–3. Retrieved 21 February 2016. 
  6. ^ Bennett, J. Michael; Rhetoric, Emeritus; Hicks, Dale R.; Naeve, Seth L.; Bennett, Nancy Bush (2014). The Minnesota Soybean Field Book (PDF). St Paul, MN: University of Minnesota Extension. p. 79. Retrieved 21 February 2016. 
  7. ^ Kaneko, T; Nakamura, Y; Sato, S; Minamisawa, K; Uchiumi, T; Sasamoto, S; Watanabe, A; Idesawa, K; Iriguchi, M; Kawashima, K; Kohara, M; Matsumoto, M; Shimpo, S; Tsuruoka, H; Wada, T; Yamada, M; Tabata, S (2002). "Complete genomic sequence of nitrogen-fixing symbiotic bacterium Bradyrhizobium japonicum USDA110". DNA Research. 9 (6): 189–197. doi:10.1093/dnares/9.6.189. PMID 12597275. 
  8. ^ D. Nellen-Anthamatten, P. Rossi; et al. (1998). "Bradyrhizobium japonicum, FixK2, a Crucial Distributor in the FixLJ-Dependent Regulatory Cascade for Control of Genes Inducible by Low Oxygen Levels". [Journal of Bacteriology]. 180 (19): 5251–5255. 

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