Malt Extract Agar, 500g

Malt Extract Agar is used for the cultivation of fungi and is not intended for use in the diagnosis of disease or other conditions in humans. An acidic medium that will support the growth of most yeasts and molds while inhibiting most bacteria. It was first described by Thom and Church in 1926 in a study of Aspergillus spp., claiming the high carbohydrate content ensured rapid growth. Selectivity can be increased by further lowering the pH with the addition, after sterilization, of Lactic Acid (X037). It should be noted that excess heating of this medium, together with its low pH, can easily result in hydrolysis of the agar gel, producing soft plates.

Typical Formulation

Formula Litre
Malt Extract 30.0 g/L
Peptone 5.0 g/L
Agar 15.0 g/L

Preparation

Suspend 50 grams of the medium in one liter of purified water.
Heat with frequent agitation to boiling to completely dissolve the medium.
Autoclave at 121°C for 15 minutes.
Cool to 45–50 °C 5. If the addition of NCM4011, Lactic Acid 10%, is required, this should be done after sterilization.
The addition of a 5 mL vial of NCM4011 will lower the pH of 250 mL of medium to 3.5–4.0.