The process by which bacteria convert nitrogen gas into a usable form is called nitrogen fixation. This biological process is primarily carried out by specific bacteria, such as Rhizobium, which live symbiotically with plants, particularly legumes. Nitrogen fixation is vital for ecosystems, as it makes atmospheric nitrogen accessible to plants, facilitating growth and supporting food webs. This process is essential in agricultural practices, as it enhances soil fertility and reduces the need for synthetic fertilizers.