Powdered Culture Media - Nutrient Agar
Nutrient agar is a general purpose medium containing beef extract, peptone and agar and is used for the examinations of water, sewage and food products. Other uses include maintaining stock cultures, cultivating samples and isolating organisms into a pure culture.
Method of Preparation:
Suspend 23 grams of dehydrated Nutrient Agar media into 1 liter of distilled or deionized water. Boil until completely dissolved. Sterilize in an autoclave for 15 minutes at 15 pounds of pressure. When pouring into plates, it is usually not necessary to fill the bottom of the petri dish completely. While holding the lid over the petri dish, pour, so that, 2/3 to 3/4 of the bottom of the petri dish is covered. Place the top back and gently swirl the dish until the bottom is completely covered. If the plates are going to remain refrigerated and stored for 2+ months, pouring the plate thicker will prevent dehydration.
When calculating the amount of media necessary, plan on 10-15 ml of nutrient agar for each petri dish. Therefore, a liter will produce 70-100 plates depending on the thickness of the pour.
100 grams will make 280-400 plates.
500 grams will make 1400-2000 plates.