AGAR

What is agar?

• Agar is a gelatinous substance derived from seaweed.

• In the past century agar has been used as a solid substrate to contain culture medium for microbiological work.

Instructions for Making Agar

1. Measure 70 mL of distilled water using a graduated cylinder. Pour the water

into a 250 mL beaker.

Instructions for Making Agar

2.Obtain 2.0 g of nutrient agar powder and place into the beaker. Stir well.

3. Heat until boiling. When it starts to boil, take it off of the hot plate.

Instructions for Making Agar4. Obtain two petri dishes and mark four

quadrants on the bottom of one petri dish as shown below (use a permanent marker & a ruler). Also mark your initials on each of the petri dishes.

2.

3. 4.

1.

Instructions for Making Agar

5. Carefully pour enough hot agar to cover the bottom of the two petri dishes to a depth of 0.75 cm.

(Uncover the lid slightly – don’t put the lid down)

6. Replace the lid and wait for the agar to solidify.

What is agar?• The gelling agent is an unbranched

polysaccharide obtained from the cell walls of some species of red algae, primarily from the genera Gelidium and Gracilaria, or seaweed (Sphaerococcus euchema).