Recent changes to the classification of symbiotic, nitrogen-fixing, legume-associating bacteria: a review

Abdelaal Shamseldin, Ahmed Abdelkhalek, Michael J. Sadowsky

Research output: Contribution to journalReview articlepeer-review

20 Scopus citations


The Rhizobia are collectively comprised of gram negative soil bacteria that have the ability to form symbiotic nitrogen-fixing root and/or stem nodules in association with leguminous plants. The taxonomy of these bacteria is continually in a state of flux, in large part due to rapid development of refined molecular biology techniques. The isolation and characterization of new, and often different, legumes-nodulating bacteria on a variety of plant hosts has resulted in the naming of many new rhizobial species. Here we update the taxonomy of the legume-nodulating bacteria and describe newly identified rhizobia capable of nodulating edible legumes and legume trees. In 1990, there was only one bacterial species that was known to nodulate common bean worldwide (Rhizobium leguminosarum sv. phaseoli), one species that nodulated faba bean (Rhizobium leguminosarum sv. viciae), and two species that nodulated soybean (Bradyrhizobium japonicum and Rhizobium fredii). Today, nearly 14, 11, 6, 5, 5, 4, 3 and 2 species have been defined that are capable of nodulating common bean, soybean, cowpea, chickpea, peanut, lentils, faba bean and pea, respectively. The recent use of whole genome based taxonomy (genomotaxonomy) will surely change how we define this important group of bacteria. The identification of several rhizobial species that are able to nodulate and fix nitrogen with edible legumes may enhance the production of these crops and can compensate for worldwide deficiencies in human nutritional needs in the future.

Original languageEnglish (US)
Pages (from-to)91-109
Number of pages19
Issue number2
StatePublished - Feb 1 2017

Bibliographical note

Funding Information:
The authors thank the STDF of Egypt for funding this work through project no. 1268. This projected was also funded, in part, by the Minnesota Agricultural Experiment Station (to MJS).

Publisher Copyright:
© 2016, Springer Science+Business Media Dordrecht.


  • Classification
  • Legumes
  • Nitrogen fixation
  • Nodulation
  • Taxonomy


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