Medium 73: AZOSPIRILLUM MEDIUM

    Potatoe extract*             950 ml 
    L-Malic acid                 2.5 g 
    KOH                            2 g 
    Sucrose                      2.5 g 
    Vitamin solution**             1 ml 
    Bromthymol blue
    (0.5% alcoholic solution)      1 ml 
    Agar                          20 g 
    pH 6.8 
 
*Potatoe extract:
200 g potatoes (washed, peeled and sliced) are 
placed in a gauze bag, boiled in 1 liter of water 
for 30 min., filtred through cotton, saving the 
filtrate.
 
    **Vitamin solution:
    Biotin                       10 mg
    Pyridoxin                    20 mg 
    Distilled water             100 ml

The malic acid is dissolved in 50 ml of water and 
BTB is added. KOH is added until the malic 
solution is green (pH 7.0). This solution with 
sucrose and vitamin solution is added to the 
potatoe extract. Add agar, boil and sterilize.