Ammonia is processed by Rhizobium bacteria using different enzymes depending on the conditions. When there is a lack of glucose and excess nitrogen, the bacteria use glutamate dehydrogenase. In contrast, when there is a shortage of ammonia or nitrate, they use glutamine synthetase and glutamate synthase. Different Rhizobium species have different enzyme preferences. Bacteroids in root nodules of certain plants also use these enzymes for ammonia assimilation, but not all plants show the same enzyme activity. Overall, the study shows that the plant system, not the bacteria, is responsible for assimilating ammonia in root nodules.