YEAST MANNITOL AGAR W/ 1.5% AGAR

Beijerinck was first to isolate and cultivate an aerobic gram negative rod-shaped microorganism from the nodules of legume. He named it Bacillus radicicola. which was subsequently placed under the genus Rhizobium. Bacteria belonging to the genus Rhizobium live freely in soil and in the root region of both leguminous and non-leguminous plants. However, they can enter into symbiosis only with leguminous plants by infecting their roots and forming nodules on them. Rhizobium present in these root nodules fixes atmospheric nitrogen i.e. gaseous nitrogen from air to organic nitrogen compounds, which is absorbed by plants. Thus role of Rhizobium is noteworthy for their major contributions to soil fertility. Yeast Mannitol Agar is used for the cultivation of symbiotic nitrogen fixing organisms viz. Rhizobium species.

for cultivation, enumeration and isolation of soil microorganisams like Rhizobium species