Microbes: bacteria

Public summary: 

Bacteria are living things made from only one cell. You've probably heard about how they cause disease, but you might not know about some of the friendlier ones that are useful to us. Come and investigate our extra large cuddly microbe collection!

Cuddly bugs, props from a lab, and a hand-washing experiment
Useful information
Kit List: 

A small grey box labelled "microbes (bacteria)".

In the box:

• 8 x cuddly bacteria
• 1 x cuddly penicillin bug (to talk about antibiotics)
• 1 x cuddly yeast (to say that not all microbes are bacteria)
• 1 x plate of plastic bacteria (E.coli)
• 2 x bacteria viewers (look a bit like small microscopes)
• 3 x slides sets for bacteria viewers
• 1 x flask for growing bacteria
• Packets of tools for growing bacteria
• Laminated fact sheets for cuddly bacteria
• Laminated instructions sheets for hand washing activity
• UV hand wash cream (this is £15 per bottle, so use only minimum amount per group)
• UV light for hand wash activity

If you want to do the hand wash activity you'll need a soap, warm water and bowl and some paper towels to dry hands on.

Packing Away: 

Please make sure that we have all the cuddly microbes, and that they go back in the right box.

Frequency of use: 


There are several things to do: lots of cuddly bacteria to talk about (everyone loves these), UV hand-washing experiment (good for younger kids) and bacteria viewers and lab props (better for older kids).

The three microbes experiments were new for the 2011 Summer Roadshow, so are still being developed. Let us know if there’s anything else you’d like to include!

Element one: cuddly bugs

The kit:
• 9 x cuddly bacteria
• 1 x cuddly penicillin bug (to talk about antibiotics)
• 1 x cuddly yeast (to say that not all microbes are bacteria)

Tips for demonstrating:
- Lay them out on the table (possibly with the slide viewers described below)
- Let children pick them up and ask you what they are
- Ask questions to see what the kids know about bacteria - "germs" is a common answer!
- You might find it easier to keep most of them in the box and bring them out one at a time if your experiment is busy, which can make it easier to control the questions

Talking about bacteria:
- Most bacteria are harmless: there are actually 10 times as many bacterial cells in your body than your own cells.
- Some of them produce toxins or invade your cells, which can make you ill.
- Bacteria are made up of just one cell, unlike us and other animals/ plants, which are made up of millions of millions of cells
- They're a few micrometres in length, which means if you could line them up, you'd get a million in a metre...

The following explanations are also found on laminated sheets in the box, and there is some additional information on labels attached to the cuddly bacteria:

1) E. coli (Escherichia coli): Gram negative, rod shaped
*SLIDE in microscope box*
Found in the intestines of most mammals- it’s there inside you only hours after you’re born! There are lots of bacteria in our digestive system that are harmless to us – in fact they stop harmful bacteria from living and growing there instead. Sometimes E.coli can make us ill; some unusual strains produce toxins which can give us food poisoning. Biologists like E. coli: It’s very easy to grow in the lab and can make lots of proteins and DNA very quickly.

2 ) Salmonella (Salmonella enterica): Gram negative, rod shaped
*SLIDE in microscope box*
Can infect humans and animals, so sometimes infects people of food isn’t cooked properly (particularly chicken or eggs). Causes gastroenteritis (diarrhoea and vomiting…) The bacterium itself can actually live inside certain types of white blood cell, which is a very effective way of hiding from the cells of the immune system that circulate in the blood.

3 ) Typhoid Fever (Salmonella typhimurium): Gram negative, rod shaped
Very closely related to the Salmonella bacteria that cause food poisoning. Typhoid fever is a lot worse than food poisoning however: its symptoms include a high fever, abdominal pain, a skin rash and headaches. Some people can be infected without having symptoms, but can still pass it to other people making them carriers of the disease. 'Typhoid Mary' (Mary Mallon) was the first recognised asymptomatic carrier and spread typhoid around New York in the early 1900s in her work as a cook, over 50 have fatalities have been linked to her. It is spread by drinking water or eating food contaminated with the bacterium. Typhoid fever is most common in India and its spread can be prevented by good hygiene.

4 ) Diarrhoea (Campylobacter jejuni): Gram negative, spiral shaped
Most common cause of food poisoning in the UK, linked to handling raw chicken. It produces a toxin that kills certain human cells, which helps the bacteria to survive, without being attacked by the immune system.

5 ) TB (Mycobacterium tuberculosis): ‘Acid fast’ will not gram stain
Infects the lungs when the bacterium is breathed in. Here it gets contained by the immune system in a tough shell. Only about 1 in 10 people who have the bacterium get ill: this usually happens when the immune system is weak and cannot contain the bacterium. The disease can cause damage to the lungs and in really bad cases it can spread to other parts of the body.

6 ) Cholera (Vibrio cholerae): Gram negative, comma shaped
Usually spread when water is contaminated by the bacterium. Produces a toxin that stops you absorbing water through your intestines. This causes really bad diarrhoea, which can be fatal as you lose too much water and salt from your body.

7 ) Listeria (Listeria monocytogenes): Gram positive, rod shaped
Causes fever and muscle pains. If the bacterium can get to the brain this can cause meningitis. Pregnant women are the most commonly infected – the mother usually gets a mild fever but the baby might be badly affected or born early. The source of the infection is often food – pasteurising dairy foods helps kill the bacteria and reduce the numbers of infections.

8 ) Stomach Ache (Shigella): Gram negative, rod shaped
Very closely related to E. coli. When the bacterium is ingested it can get inside the cells of your intestine. It produces some toxins that can also make you ill.

9 ) Yogurt (Lactobacillus bulgaricus): Gram positive, rod shaped
One of a number of species of bacteria that can be used to make yoghurt.
What Wikipedia has to say about the use of L. bulgaricus in the manufacture of yoghurt:
“Lactobacillus delbrueckii subsp. bulgaricus is commonly used alongside Streptococcus thermophilus as a starter for making yoghurt. The two species work in synergy, with L. bulgaricus producing amino acids from milk proteins, which are then used by S. thermophilus. Both species produce lactic acid, which gives yoghurt its tart flavour and acts as a preservative. The resulting decrease in pH also partially coagulates the milk proteins, such as casein, resulting in yoghurt's thickness. While fermenting milk, L. bulgaricus produces acetaldehyde, one of the main yoghurt aroma components. Some strains of bulgaricus also produce bacteriocins which kill undesired bacteria. It is often helpful to sufferers of lactose intolerance, whose digestive systems lack the enzymes to break down lactose to simpler sugars.”

10) gonorea, syphilis, chalmydia

(Yes, we know that they're not bacteria, but we'd found that people ask about antibiotics, so we think that they're a nice bonus to have in the box)

Penicillin (Penicillium chrysogenum)
This is a fungus that makes penicillin, an antibiotic that kills some types of bacteria. It does this to kill off the bacteria that are competing for the food it needs for growth, but we have used penicillin from this fungus to treat bacterial infections in humans.

Yeast for bread and beer
Also a kind of fungus. It's one cell, just like the bacteria, though the cell is much bigger. In bread the yeast can use the sugars in the dough for its growth; it breaks them down in a reaction that produces the gas carbon dioxide, which make the bread rise. In beer the yeast converts the sugars to alcohols.

Element two: growing bacteria in a lab

The kit:
• 1 x plate of plastic bacteria (E. coli)
• 1 x flask for growing bacteria
• Packets of tools for growing bacteria

NB. The kit we have has not been used in a lab and the 'bacteria' on the plate are not real!

Under sterile (no other bacteria) conditions:
1) You can grow some types of bacteria in the lab. E. coli is happy to grow on agar plates, as long as it has all the nutrients it might need. The L-shaped spreader is used when you put the cells on the new plate, to make sure that the bacteria aren't too close together.
2) If you want more cells than this, get some bugs you're interested in with the green tool.
3) The plastic flask can be used to grow bacteria in a growth medium/ broth. (Extra detail: For E. coli you'd usually use Luria-Bertani medium (LB) at 37 degrees C to provide the necessary nutrients. This contains 10g Tryptone (enzymatically digested milk protein casein - supplies amino acids), 5g of Yeast Extract (supplies lots of nutrients), 1g glucose, 10g NaCl pH ~7.2, deionized, distilled water to 1 litre.)

Element three: bacteria viewers

The kit:
• 2 x bacteria viewers (look a bit like small microscopes)
• 3 x slides sets for bacteria viewers

These are essentially a more durable version of a set of slides and a microscope. In the set of slides (which come with a booklet for information) you can see various different shapes of bacteria - just like in the cuddly bugs:
1) Round (1= "coccus", 2+ = "cocci")
2) Rod (1= "baccilus", 2+ = "baccili")
3) Spiral

These shapes are determined by the cell wall (the tough outer layer) and the cytoskeleton (internal "scaffolding"). They matter because they affect how the cells can absorb nutrients from its environment, how they can attach to surfaces and how they're able to move.

Element four: handwashing activity

Why should we bother washing our hands? This activity uses glow in the dark stuff to show how easy it is to miss the bits of your hands where bacteria are...

The kit:
• Laminated instructions sheets for hand washing activity
• UV hand wash cream (this is £15 per bottle, so use only minimum amount per group)
• UV light for hand wash activity
*Also needs a bowl and paper towels that are not supplied in the box*

There is a set of laminated instructor notes in the box, taken from the Wellcome Trust. A full version can be viewed online here: http://www.yourgenome.org/downloads/pdf/teachers/handshake/handshake_tno...

• No hand washing: Form a ‘line’ around your group of children. Squirt UV cream on the first child’s hand and get them to rub their hands together, then shake the hand of the next person in the group, then they shake the next person’s hand... Shine the UV torch onto each of the kids’ hands to show up the ‘bacteria’. All should now wash their hands thoroughly.
• Compare the results with hand washing: Repeat the procedure but get each person to wash their hands in the bowl after the UV cream has been rubbed in but before they shake the hand of the next person.
• If the group activity isn’t suitable, you could always compare before and after hand washing on the same child.
• This should show that washing hands helps to remove microbes – and washing with soap does this better than with just water as the soap breaks down some of the natural oils on your hands that help the bacteria to stick. Look at where the bacteria were found – it’s easier for bacteria to stay between our fingers and under our nails – and that’s why it’s important to wash your hands properly!

Risk Assessment
Date risk assesment last checked: 
Mon, 08/01/2018
Risk assesment checked by: 
Date risk assesment double checked: 
Fri, 02/02/2018
Risk assesment double-checked by: 
Risk Assessment: 
Hazard Risk Likelihood Severity Overall Mitigation Likelihood Severity Overall
Microbe toys and accessories Trip hazard if dropped on the floor. Likelihood score Severity score Overall Keep all props in contained area. Call first aider in case of injury. Likelihood again Severity again New overall (hopefully better than the first)
UV cream UV cream in eyes. Likelihood score Severity score Overall When giving UV cream to children, tell them not to put their fingers near their eyes and ensure they rinse it off.
Call first aider in case of injury. If washing up liquid gets into an eye, demonstrator must call a first aider and may perform an eye wash if trained and confident to do so.
Likelihood again Severity again New overall (hopefully better than the first)
UV cream Slip hazard if spilled. Likelihood score Severity score Overall All spills should be cleared up immediately. Call first aider in case of injury. Likelihood again Severity again New overall (hopefully better than the first)
UV cream Possible allergic reaction to cream? (Widely used in teaching, so severe reaction is likely to be rare). Likelihood score Severity score Overall Suggest that volunteer from group isn't one who is known to have sensitive skin.
Call first aider in case of allergic reaction, then seek further medical advice where appropriate.
Likelihood again Severity again New overall (hopefully better than the first)
Publicity photo: