for isolation,cultivation and identification of sucrose positive Azotobacter species from soil.
Azotobacter is a group of heterotrophic and aerobic bacteria and their main property is the ability to fix nitrogen non-symbiotically. Their agronomic importance is due to the capability of synthesizing antibiotics, plant growth promotion substances, vitamins, exopolysaccharides and pigment production, besides their antagonist effect against pathogens. They also have the ability to solubilize phosphates in aquaculture systems, vermi-compost production and potato grown soils. Azotobacter Agar (Sucrose) is a selective solid medium for the separation and enrichment of nitrogen-fixing bacteria Azotobacter from the soil. The nitrogen-enriched sucrose agar medium is suitable for nitrogen-fixing bacteria that can use sucrose as the sole carbon source and nitrogen as the sole nitrogen source in the air. Phosphates are used as buffering agents. Yeast extract acts as a source of vitamins, minerals and other essential nutrients. Magnesium presumably functions as an activator of phosphorylation, and may therefore be active at several different stages in the respiration. Equal concentrations of calcium are necessary for growth with free nitrogen, nitrate, ammonia, and asparagine. The actual physiological function of calcium is unknown. In addition, some important microelements such as iron and molybdenum are necessary for nitrogen fixation.