Azotobacter
Azotobacter aids to boost plant development and increase soil nitrogen level through nitrogen fixation by using carbon for its metabolism. Optimal calcium nutrient concentrations are required for Azotobacter to develop more rapidly and have the capacity to fix nitrogen (Iswaran and Sen, 1960) but higher nitrogen concentrations have a negative impact on Azotobacter activity (Soleimanzadeh and Gooshchi, 2013). Since more than a century ago, the genus Azotobacter has been utilised as a biofertilizer (fertiliser that contains living microorganisms) (Gerlach & Vogel, 1902).