Experiments using bacterial cultures are quite dangerous because if any unwanted bacteria mixes in with the experiment or gets on our hands it can contaminate experiments. Therefore we must use aseptic techniques. Everything must be sterilized and precautions must be taken to stop bacteria from the air getting in.
First we made sure that all the equipment was ready in front of us and all labels were prepared so that we didn’t have to waste time getting things and risk contaminating it. We made sure that the syringe used to pick up the culture was sterile by using a new one and putting it straight into disinfectant when we had finished with it. Each time we used a piece of equipment we dipped it into alcohol then burned it off to burn of anything that might be contaminating it. We did this with the necks of all the test tubes, the glass spreader used to spread the culture around the agar surface, and the forceps. While putting the culture in we made sure that we only lifted the lid very slightly so as to allow as little air as possible into it. We sealed the lids of the petri dishes with sealing tape to make sure that the lids didn’t come off and none of the culture could escape.
To get the best results possible we made sure that the culture was spread around the whole petri dish by keeping the rod still and turning the dish all the way round. When we put the antibiotic disk in we pressed it down lightly to make sure that it was in contact with the agar and culture. When we stuck our label on we made sure that it was in the centre of the disk so that it wouldn’t get in the way of measuring.
We washed our hands before and after the experiment.