Nutrient Agar Preparation

NUTRIENT AGAR

Nutrient agar is a commonly used food medium for microbial cultures. Nutrient agar contains:
• beef extract (provides carbohydrates, nitrogen, vitamins, salts)
• peptone (helps control pH)
• agar (a carbohydrate used as a solidifying agent)
• distilled water (an agent for distributing food materials to growing colonies of micro-organisms)

Materials:

Agar Powder
distilled water
flask or beaker
glass stir rodlab thermometer
sterile petri dishes (plastic)
flame or boiling mixture
heat resistant hand protection

Measure agar and distilled water into clean flask or beaker

Recipe: Agar(4.6g) + Distilled Water(200ml) = Yield(10 plates)

Add agar powder into beaker fill with distilled water

Stir the mixture constantly

Boil the mixture for 1 minute. Remove from heat.Place a sterile lab thermometer in the mixture and monitor the temperature until it falls to approximately 45 - 50° C or if a lab thermometer is not available, cover and let stand a few minutes.

Pour enough melted agar into each sterile petri dish to cover the bottom - about 1/8" to 1/4" deep. Replace the lid immediately.

Note: Keep sterile petri dishes closed until ready to pour agar into them. Air-borne contaminants can easily invade an open petri dish.

Place agar plates on a counter top to cool and set. Agar medium will set like stiff gelatin at room temperature. The agar medium is now ready for storage or use.

Storage: Stack agar plates upside down in the refrigerator. Do Not Freeze! The purpose of placing the plates upside down is to prevent condensation from dripping down onto the agar surface which could then facilitate movement of organisms between colonies.

Penyediaan agar-agar nutrien ini adalah untuk pelajar tingkatan 5 menjalankan eksperimen mengkaji kesan pertumbuhan mikroorganisma pada suhu 37oC , 60oC dan 5oC. Penyediaan dilakukan bersama pembantu makmal. Mungkin untuk pelajar yang akan datang penyediaan agar nutrien dilakukan oleh pelajar sendiri.