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The good bacteria

Bacteria get a lot of bad press but they don’t deserve it all – there are lots of bacteria that are very important for all living things on earth!  Bacteria have learnt to live in every part of the earth, from the hottest, to the coldest, no matter how dangerous, so they have no problem living inside or on you!  Many of the bacteria you come into contact with every day are actually helpful!  But how do they help?

Your body is full of helpful bacteria!  Many different bacteria live inside your gut and your body is happy to have them there.  Bacteria in your gut make lots of copies of themselves.  In fact, they make so many copies of themselves, that there is no room for any of the bad bacteria to grow!  The good bacteria don’t grow too big because there is only a certain amount of resources, the things like food, space and so on, that they need to grow.  When they reach the limit of the resources, they are in equilibrium with your gut.  Equilibrium is the balance where the bacteria are happy because they have somewhere to live and get their dinner every day and your gut is happy because there aren’t lots of bad bacteria! 

Our friend GI Jake is another type of good bacteria that lives in your gut – he is a bifido-bacterium.  The word bifido just means ‘split into two’ – you can see from the picture that GI Jake is shaped like a ‘Y’ and has two ears called ‘lobes’ – and bacterium just means a single bacteria!

GI Jake - a bifidobacterium!
You can tell bacteria are working in your gut because you can sometimes smell the gas they produce.  The gas builds up in your intestines, it is a waste product from the bacteria as the work to digest your food.  When there is too much gas for your intestines, it escapes from your body as flatulence – which is also called a fart!  If you eat certain types of foods, like beans, the bacteria make lots of gas. 

The gas gets really smelly though is you eat a lot of processed foods or if you don’t chew your food really well before you swallow it. 

Outside of your body, bacteria like lactic acid and streptococcus bacteria are also very useful in producing food.  Bacteria are used to make dairy products like cheese, yoghurts, sour cream and crème fraîche!  These bacteria are added to milk and they grow and ferment the milk.  The different types of bacteria that are added to make the different types of dairy products give each of them the taste you love!  If you ferment milk with bacteria, the products change and get a little thicker.  This is because the main protein in milk, casein, cannot dissolve in the acid that is produced by the bacteria during the fermentation process.  It is lucky this happens – it would be very difficult to drink the cheese in your sandwich!


Bacteria are used a lot in the making of yoghurt and cheese.  Yoghurt is just fermented milk, made by adding good bacteria that you can find in the ‘natural’ yoghurts in the supermarket, and heating for several hours.  Cheese can be made from the milk of lots of animals, but they all need bacteria to turn the milk into cheese.  The different types of bacteria give the different cheeses their own taste and texture (if they are runny or hard, for example).  Both yoghurt and cheese come in a huge amount of flavours – you’ll definitely fine one that suits you!

If you look closely at the labels of dairy products of yoghurts, you will see that some of them have had probiotics added.  This means that good bacteria are added that, if you eat enough of them, they will be good for your health.  GI Jake is a probiotic – he helps to keep you gut healthy and fight off invaders!

It isn’t only dairy products that can be fermented.  – you can ferment vegetables too using bacteria!  If you add lactic acid bacteria to thin strips of white cabbage, they ferment the cabbage to give sauerkraut (which just means, sour cabbage).  These bacteria are also involved in the pickling of foods like onions, gherkins the production of vinegar and the curing of meats.

Bacteria have lots of other uses other than making sure we don’t get hungry!  Scientists have been using bacteria for a long time to produce medicines like vaccines.  Now they are going even further and they are making bacteria work for humans!  Scientists at the APC are using good bacteria to help to understand ho bacteria work in the gut and how they can be used to fight diseases of the gut.  Find out more at:  http://apc.ucc.ie

Bacteria have learnt to live anywhere so they have learnt to eat whatever is closely by to survive.  For some bacteria their diet is not very different from yours because they live in your mouth or digestive system and eat the food you eat.  There are bacteria out there however who will eat anything!  Bacteria have been found that will eat dangerous or harmful substances, like oil.  These have been used to clean up oil spills but unfortunately they don’t work very quickly so it is still best not to have spills in the first place.  Other bacteria eat anything that is decaying.  This sounds quite nasty but it makes sure that decomposing plants and animals don’t become environmental waste.  Bacteria are also great recyclers – they are the new clean-up crew!

Instead of cleaning up fuel, some bacteria make fuel!  Methane makes up a large part of the natural gas found in the earth.  Methane is make by bacteria that live deep underground and sometimes underwater, wherever there is no oxygen.  Natural gas is used as fuel to keep our homes warm.

So, how do you get some good bacteria?  Well, the easiest way is to eat some!  Look at the labels on foods like yoghurt, dairy drinks and cheeses to see which contain good bacteria the next time you are in the supermarket.  Bacteria are good for you – make them work for you!


Did you know…?

Bacteria make the holes in Swiss cheese!  There are three types of bacteria used but only two of them make lactic acid as a waste product.  At the end of the cheese-making, the third bacteria eats the lactic acid and makes lots of carbon dioxide gas as its waste product.  This gas makes bubbles that are the holes you see in the finished cheese!


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