Rhizobium bacterium is responsible for nitrogen fixation.
It is found in soil which lives in a symbiotic relationship with roots of leguminous plants like peas, groundnuts, lentil, peanuts, etc.
It produces nodules at the root of plants and converts the atmospheric nitrogen into ammonia which can be used in the growth and development of plants.
Plants provide the bacteria with organic compounds made by photosynthesis.
Thus, it lives in symbiotic relation with leguminous plants in which both the species are in a win-win situation and doesn’t harm anyone