It has long been known that the legume root-nodule bacteria produce a bacterial gum, but knowledge of the exact role of gum production in the metabolism of the organism is still rather incomplete. The results secured by a number of investigators indicate that gum production may be intimately connected in some way with the mechanism of symbiotic nitrogen fixation. In addition, some studies have shown that considerable differences exist in the quantity and chemical nature of the gum produced by different species of Rhizobium.
Anderson, Dean A.
"The production of gum by certain species of Rhizobium,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 13
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol13/iss158/1