Ashby's Mannitol Agar is recommended for isolation of Azotobacter species from soil that can use mannitol and atmospheric nitrogen as source of carbon and nitrogen respectively. Azotobacter is a non-symbiotic nitrogen fixing bacteria, also known as biofertilizer. Dipotassium phosphate provides buffering to the medium. Various essential ions required for promoting growth of Azotobacter are also available in this medium.
- Appearance: White to cream homogeneous free flowing powder
- Gelling: Firm, comparable with 1.5% Agar gel
- Color and Clarity of prepared medium: Whitish opalescent gel forms in Petri plates
- Reaction of 4.07% w/v aqueous solution at 25°C. pH : 7.4±0.2
- Cultural characteristics observed after an incubation at 35-37°C for upto 5 days