Starch Agar Plates

Hi Guys,

I'm making starch agar for the first time and was wondering if anybody had any tips? My CLEAPSS password has expired so I can't access their guide until I hear back from them but have found this 'recipe' online:

Starch agar

Suspend 15 g of nutrient agar in 100 cm³ distilled water. Bring to the boil to dissolve completely. Heat 40 g of soluble starch in 100 cm³ of distilled water to form a suspension. Allow to cool and then mix with the nutrient agar solution.

Just wondering if there's anything I should be careful of or any tips and tricks before I start.

That's similar to a recipe I have used before. 0.2g starch in 100ml dist water - heat until dissolved then add 1.5g agar and heat until dissolved.


Lvl 37 Alchemist
The recipe I use for starch agar (from School Science Handbook not CLEAPSS)

Add 2g agar to 100cm3 of cold 1% starch solution
Bring to the boil and pour into plates
Alternatively you could autoclave prior to pouring

It turns blackest black when the iodine is added so must be doing something right :)
I find it easier to add the starch to a beaker, add a small amount of cold water to make a paste then make it up to volume with hot water from a kettle so the starch dissolves, then add the agar and heat until it dissolves