On the Behavior of the Root Nodule Bacteria of Leguminous Plants on Nitrate and Nitrite.

Abstract

Experiments were made in which utilization and reduction of nitrate or nitrite by several kinds of root nodule bacteria were conducted in the mannitol liquid culture at various periods of growth. As far as possible, five per cent yeast water was added on the basis of bacterial activity to support their good growth. The results are as follows : a. Although the organism from "Genge" is not able to attack potassium nitrate, most of rhizobia except alfalfa bacteria break down or reduce nitrate to nitrites distinctly. b. The reduction process is exceedingly retarded by clover bacteria as well as bean and wood's clover bacteria, when grown in ammonium nitrate media. c. No change in total nitrogen of the flasks containing potassium nitrate media, in which clover, bean and wood's clover bacteria have respectively grown, are shown for fourteen days incubation, while a remarkable decreases in the cultures of cowpea, lupine and alfalfa organisms. d. It is suggestible that an ability in utilizing nitrite by rhizobia is noticed and that a species from alfalfa attack nitrite in particular to produce large amounts of gaseous nitrogen.