Aseptic Technique This is how we grow bacteria and moulds without contaminating our cultures or ourselves. It is also called ‘sterile technique’. You must always read the ‘precautions sheet’ before you start. And do everything it tells you to!

How to prepare Turn the petri dish upside down. Stick a label on the base, with the date, your initials and the treatment written on it. Turn it back the right way up. Make sure you do not open it by accident. Collect a bunsen burner, mat and goggles. Put on the goggles, light the bunsen.

Pouring the agar Loosen the screw cap of a sterile bottle of agar. Tilt the bottle slightly so that..…………. ……………………………………………… Remove the cap and pass the neck of the bottle through the top part of a blue flame a few times. This will……………………………………… Lift and hold the petri dish lid over the base and quickly pour in the agar. Put the lid back and gently jiggle the dish to spread the agar across the base. Leave it to set. Rinse the bottle under the tap. Place it with the cap separate in the washing up tub.

Making a streak plate Heat an inoculating loop until it glows red. Let it cool and then pick up a little of the culture on the loop. Lift the petri dish lid and zig-zag the loop across the surface of the agar. Close the lid. Re-flame the loop to leave it sterile.

What we did Now draw on the outline what your dish looked liked after you added the soil streak. Remember we added 2 pieces of sticky tape. Say why …………… ……………………….

Our results After incubating the dishes at 25 o C for two days, the dish was sealed. Our dish looked like this >>> I estimate we had grown …… colonies of bacteria. What it looked like