Petri dishes

Hannah re-plates out Petri dish cultures from 22/10/2017 to obtain single organism cultures and adding penicillin to existing Petri dishes 29/10/2017

Our Petri dish cultures of air born bacteria and fungi and mouth swabs from Rhys and Hannah from 22/10/2017 are now covering whole of Petri dishes. The air born cultures (open Petri dishes left outside for 4 hours to collect sample) show wide range of organisms – bacterial and fungal cultures – and the mouth swabs show much more limited number bacteria mainly (with smaller areas occupied by fungi). Interesting the swabs from the two children appear to have grown quite different bacteria, if the macroscopic view of the Petri dish is anything to go by. Rhys’ mouth swab has brown a gelatinous yellow-coloured shiny organism, whereas Hannah’s a rougher looking dry appearance to her culture.

Today, Hannah used a bent sterile needle on a diabetic syringe to attempt to plate out new cultures from the old ones on new Petri dishes – the idea is to obtain a single culture. She used her mouth swab culture Petri dish for this purpose.

After that, she poured some Benzylpenicillin powder (out of date penicillin from my surgery) into the old Petri dishes (her swab culture and one of air cultures) to see over this next week what effect that will have on the organisms present – she tried to get a straight line on the mouth swab – difficult to achieve as she did not want to touch the penicillin and contaminate it! – and more liberally splatter-gunned the air culture as this has lots different organisms and she wanted to see what the pencillin’s effect was on different ones.

As we do not know what we have grown here, there is a risk that some of these organisms are pathogenic (could lead to disease) so Hannah used sterile technique and gloves and we cleaned everything thoroughly afterwards!