Last month, Amelia gave us five great reasons to love plants. But plants aren’t the only species worked on at the John Innes Centre that lack the respect they deserve.


As a microbiologist I thought it was only fair to come up with my own ‘five answers’ – and show that microorganisms aren’t just here to cause us harm. In fact, they are essential for many processes, and have great potential for many more.


1. Antibiotics

The world is facing a crisis: antibiotic resistance. The best way to fight this is to treat antibiotics with a bit more respect – stop prescribing them when unnecessary, and follow treatment schedules properly. Until we solve this problem, however, we need to go out and find more to battle the strains that are multi-drug resistant.


Antibiotics are produced in nature as a defence against bacteria in the environment – such as streptomycin produced by Streptomyces, found in the soil. We are in a ‘drought’ of antibiotic discovery, with few breakthroughs in the past few decades. Scientists are now searching far and wide for new bacterial strains that can produce novel antibiotics to compete in the ‘arms race’ between humans and their pathogens.


We have barely scratched the surface with microbe discovery – and there may be more hiding away that we are unable to culture, or in environments we barely know. Examples of these are in deep sea trenches or the guts of insects. Some people even think there may be bacteria on Mars – and I’m sure if we do find them, people will be looking for antibiotics there too.


2. Genetic engineering

Microbes can be easily manipulated, and so have huge potential for genetic engineering. The best example of this is for the production of human insulin for treatment of diabetes.


Initially, diabetics were treated with insulin derived from animals – which often came with side-effects. As biology progressed the structure of insulin could be characterized (earning Fred Sanger a Nobel Prize), and entirely synthetic human insulin could be produced. Further developments meant that yeast could be engineered to produce human insulin – and this is how medical insulin is now produced.


Another example of a medicine produced by microbes is human growth hormone. Before we engineered microbes to make this, it would come from human cadavers!


Other potential uses for bacteria include developing them to clean up pollution (‘bioremediation’), fight tumours or detect arsenic in drinking water.


3. Food

If you say the words ‘microbes’ and ‘food’ to most people, they would probably think of food poisoning. However, some of our favourite foods wouldn’t exist without microbes.


Many industries rely on ‘fermentation’ – the ability of microorganisms to break down chemicals. Both brewing and baking require yeast fermentation (specifically Saccharomyces cerivisiae) to produce the gas bubbles that we need for beer and bread. Another example of fermentation is in the production of yoghurt, which uses a bacteria that converts lactose sugar in milk to lactic acid, giving yoghurt its sharp taste.


Bacteria aren’t the only microbes that are used in the food industry. Quorn, the popular meat alternative is produced from mycoprotein – produced from the fungus Fusarium venenatum.


Another use for fungi in food production is in cheese-making. Blue cheeses are treated with moulds which grow within, creating veins full of flavour. Soft cheeses such as brie have a bacteria growing on their outsides, allowing them to age from the outside in and allowing the interior to become runny.


4. Fuel

Our fossil fuel reserves are running out, and the race is on to find alternative sources of energy to sustain us.


Scientists are looking to bacteria for help. Like all organisms, bacteria are able to convert chemical energy (such as glucose) to other forms of energy (such as movement). In 1911 a scientist was able to produce an (albeit very small) electric current from E. coli. So the concept of microbial fuel cells was born.


Humans respire using oxygen, converting fuel (sugars) to energy, producing carbon dioxide and water. Many bacteria are able to respire without oxygen, and so instead of producing water in this reaction, produce protons and electrons. If we can harvest these electrons, then we have bacteria that produce electricity – a microbial fuel cell.


It is hoped that these fuel cells can be developed to be more efficient, and to use waste products such as those from industry as their fuel. If this can be achieved, it could have a huge impact on electricity production, as well as waste processing.


5. Symbiosis

The soil is a world full of microbes of all shapes and sizes – from bacteria to fungi to oomycetes. Although some aren’t friendly and can cause plant disease, many of them play quite the opposite role. Plants and specialised fungi can live together in harmony, and even help each other out. These beneficial relationships are known as symbioses.


There are two cases of soil symbioses that are particularly well-studied. The first of these (and the field in which my PhD falls) is the rhizobia-legume symbiosis – where bacteria convert nitrogen from the air into a form that plants can use in return for plant sugars.


The second is the case of mycorrhizal fungi, which associate with plant roots to get direct access to sugars. In return, the fungi scavenge through the soil for important nutrients and minerals such as phosphates.


There are many other cases of symbiosis that shape the world we live in – see this post from last year if you want to read more about rhizobia and some of our other favourite mutualistic relationships.


Interactions with plants aren’t the only case of bacteria living in harmony with other species. Our guts are full of bacteria with a wide range of benefits. They help us digest our food, stimulate cell growth, protect us from harmful microbes and help train our immune system to protect itself.

So, next time you think of microbes, don’t tarnish them all with the same brush. There is huge diversity across the microbe world – and huge potential for their use in many different areas of science.

To see Amelia’s answers to the question ‘why plants?’, click here

Izzy is a John Innes Centre PhD student. She’s on Twitter as @isabelwebb.


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