Due to the oxidation of sulfides, The first considerable development was that of aerobic bacteria which could now utilize Mo. As oxygen began to accumulate in the atmosphere and oceans, the reaction of MoS to MoO also increased. This reaction made the highly soluble molybdate ion available for incorporation into critical metalloenzymes, and may have thus allowed life to thrive. It allowed organisms to occupy new ecological niches. Mo plays an important role in the reduction of dinitrogen to ammonia, which occurs in one type of nitrogenases. These enzymes are used by bacteria that usually live in a symbiotic relationship with plants; their role is nitrogen fixation, which is vital for sustaining life on earth. Mo enzymes also play important roles in sulfur metabolism of organisms ranging from bacteria to humans.
