Ability of free-living nodule bacteria to fix atmospheric nitrogen

Literature material is presented on the ability of free-living nodule bacteria for asymbiotic nitrogen fixation, detected for the first time in 1975. Necessary components of the nutrient medium in the use of which the nitrogen-fixing ability of rhizobia in pure cultures is manifested, proved to be sugars and intermediates of the citric acid cycle, as well as small quantities of bound nitrogen. The experimental data available in the literature are evidence of the presence of a complete assortment of genes for the synthesis of the nitrogenase enzyme complex in free-living nodule bacteria.