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Manchester Science Festival 2012

MadLab hosted four half-day public workshops that were suitable for teenagers and upwards as part of this year's Manchester Science Festival. Saturday morning participants got to fill Petri dishes with agar and nutrients including mushy peas and ice cream to see what bacteria these would encourage to grow. Those taking part in the afternoon got to create their own living paintings using bacteria. The Sunday morning workshop involved turning a USB webcam into a digital microscope with around 400x magnification, and that afternoon was spent culturing bioluminescent bacteria.


Zoom Asa Calow preparing the nutrients and agar for filling the Petri dishes

On arrival, Sunday afternoon participants were greeted with tea and biscuits and tables with neatly arranged stacks of empty Petri dishes, plastic tubs and disposable gloves and aprons, and a particularly fishy smell that pervaded the air. Once everyone was present we were given an explanation of the science behind bacteria that glow in the dark and were instructed as to the basic lab rules concerning use of gloves and aprons, hand washing and dealing with spills etc.

With the theory and safety instructions out of the way, Asa started the process of making a nutrient broth. This involved boiling fish heads for around 30 minutes before removing these and adding other simple ingredients such as yeast extract and glycerine, and then testing the acidity of the broth with a kit sold for use with aquariums, before adding bicarbonate of soda until the pH measured around 7 (neutral – neither acid nor alkali).


Zoom Filling the Petri dishes and small containers of spare agar to take home

Following this, shredded agar bought from a Chinese supermarket was added to the liquid, the lid was placed on the pressure cooker and the contents boiled under pressure for approximately 30 minutes. This sterilised the solution to kill any unwanted microbes in the agar mixture, with the pressure cooker providing a low cost alternative to a laboratory autoclave.

Lab Rules

At this point we switched to lab rules and participants had to put away any food and drinks and ensure that we were suitably gloved-up and wearing our aprons. This was not just for our safety, but also reduced the risk of inadvertently contaminating Petri dishes with our own bacteria and yeast. The hot agar solution was then dispensed in polystyrene cups, each Petri dish filled, and any spare solution placed into containers for us to take home, freeze and use to fill more dishes.


Zoom The glowing squid in a bucket

Once the agar had cooled and set we were invited in pairs to use a plastic tool to take a sample of glowing bacteria from a squid that had been stored overnight in a darkened room. The darkened room was in fact one of the toilets at MadLab and the squid was the source of the aforementioned fishy smell. Darkness was required in order to coax the bacteria of interest into glowing and to make it possible for us to identify a colony for scraping.

With a sample from the glowing squid in the plastic loop at the end of the tool we then scraped this across the agar surface of our Petri dishes, before wrapping them up in cling film to seal them and silver foil to keep light out, in preparation for taking them home.

Next: A waiting game

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