Is agar alone sufficient for growing bacteria?
Bacteria need vitamins, proteins and minerals not found in agar and so we add a nutrient broth, which is also referred to as ‘media’ by microbiologists, to the Petri dishes. What else do bacteria need? Because we want to make a cream that destroys bacteria living in or on humans, we need to provide the bacteria with an environment which is broadly similar to that found in or on our bodies. Our mouths are a good home for bacteria. They tend to be humid and at a temperature of about 37oC, so it’s logical to grow bacteria at the same temperature. If it gets too hot (say over 40oC) the bacteria will die but if it gets too cold the bacteria simply won’t grow. We are nearly ready to collect our bacteria. We have agar on which bacteria can grow, suitable nutrients and a bug-friendly environment but there is one last step before catching the bugs themselves: all equipment that could be in direct contact with the bacteria or the media has to be sterilised. The best methods of sterilisation are
