Good bacteria – lactobaccilus

Collage (2) As part of our Dirty Stinky Children project we want to know all about microorganisms – the good, the bad and the ugly! We have learnt a lot about infections and diseases, rotting and decomposing and how our bodies protect themselves from disease but then we went to the lab to find out how some bacteria are useful.
We made yoghurt with lactobaccillus bacteria. The function of the lactobacillus is to ferment lactose (milk sugar) to produce lactic acid. The increase in lactic acid decreases pH and causes the milk to turn a bit more solid and into yoghurt.
First we had to measure out 400mLs of milk and add 30g of dried milk for added lactose. Then we heated it to kill any microorganisms that might have entered from the air. We waited for it to cool down to 40degC and added 30g of a starter culture. Our starter culture was a natural live yoghurt. Live yoghurt means that the bacterial cultures inside are still alive. Then we mixed it very well and put it in a water bath over night at 40degC. When we checked in the morning our milk solution had been converted into yoghurt!

About lab13network

Lab_13 is a space in a school managed by pupils for pupils to conduct their own research and experiments driven by their curiosity, imagination and enthusiasm, and under the watchful supervision of a Scientist in Residence (not a teacher!!).
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