Bacteria keep us healthy – but could they keep us young?

This article is taken from European research magazine Horizon as part of our partnership to share natural environment science stories with readers of More than a Dodo. Our Bacterial World exhibition is open until 28 May.

A study in mice has indicated that the make-up of bacteria in the gut is linked with learning abilities and memory, providing a potential avenue of research into how to maintain cognitive functioning as we age.

It’s part of a field of research looking at the link between gut bacteria and ageing to help people live healthier lives in old age. The proportion of the EU population aged 80 or over is predicted to more than double between 2017 and 2080, with those aged 65-plus rising from 20 to almost 30%.

However, the connection between the make-up of microbiota in the gut, brain functions and ageing has been unclear – with cause and effect difficult to establish. Dr Damien Rei, a postdoctoral researcher into neurodegenerative and psychiatric diseases at the Pasteur Institute in France, decided to examine the different types of microbiome that appear in younger and older mice to understand better what might happen in people too.

Coloured scanning electron micrograph (SEM) of Escherichia coli bacteria (red) taken from the small intestine of a child. E. coli are part of the normal flora of the human gut, though some strains cause illness.

He found that when he transferred gut bacteria in older mice to young adult mice, there was a strong effect on reducing learning and memory. And when the opposite was done, with older mice receiving microbiota from younger mice, their cognitive abilities returned to normal. The older mice were aged about a year and a half – equivalent to about 60-plus human years.

‘Despite being aged animals, their learning abilities were almost indistinguishable from those of young adult mice after the microbiota transfer,’ said Dr Rei – adding that this indicated strong communication between the gut and brain. ‘When I saw the data, I couldn’t believe it. I had to redo the experiment at least a couple of times.’

Furthermore, by seeing what was happening to the neuronal pathways of communication between the gut and brain when the aged microbiota was transferred to the younger mice, they were then able to manipulate these pathways. By doing this, he says they could block or mimic the effects of the aged microbiota.

Dr Rei’s study, which was carried out as part of a project called Microbiota and Aging, has not yet been published, but he hopes this could happen by the end of the summer. He is also looking into human gut microbiota in older people and those with Alzheimer’s disease, but said it is too early to reveal further details about this research.


However, Dr Rei pointed out that there is a big challenge in translating results in mice to people, not only because of the significant ethical barriers, but also the differences in physiology. ‘The immune system of a mouse is very different to one of a human. The gut microbiota is also very different because mice eat very different things to what we do,’ he said.

Image credit - Horizon

Research is still a long way off from making real inroads into using this type of research to combat neurodegenerative diseases such as Alzheimer’s, says Dr Rei. Indeed, he says, there is no convincing evidence yet that looking at the gut microbiota is the way to go. But he believes the mouse study opens doors to further investigation into mechanisms behind age-related changes.

‘The data on the mice was really the first stepping stone, and it was a way for us to understand the potential of manipulating the gut microbiota,’ said Dr Rei.

Pinning down the link between gut bacteria and ageing is not straightforward, according to Dr Thorsten Brach, a postdoctoral researcher at the University of Copenhagen in Denmark. ‘It’s known that ageing is a multifactorial process and it’s hard, especially when it comes to the microbiome, to separate the effects of ageing specifically from all other aspects,’ he said.

He worked on a project called Gut-InflammAge, which looked at the link between gut microbes, inflammation and ageing, led by associate professor Manimozhiyan Arumugam.

As part of their work, the team investigated the effects of mild periodic calorie restriction in mice to explore the potential impact of healthy-ageing diets involving fasting. Unexpectedly, calorie-restricted mice accumulated more body fat – which the researchers speculate may have been down to overeating between these periods – but also saw a mild ‘rejuvenation’ of their blood profile so it more closely resembled that of younger mice.

Despite being aged animals, their learning abilities were almost indistinguishable from those of young adult mice after the microbiota transfer.
Damien Rei, Pasteur Institute, France

The researchers did observe a difference between the microbiota composition in the different groups, but overall in the study the differences found were not big enough to suggest more than healthy variability between individuals. The study therefore supported the view that diet and lifestyle are more critical than age and gender in shaping the microbiota, said the researchers – though Prof. Arumugam said it would be more revealing to follow changes in individual people’s microbiomes over time.

The studies carried out so far indicate there is still a long way to go in painting an accurate picture of the link between microbiota and the ageing process. Prof. Arumugam also pointed out that microbiome analysis is lagging behind technologically compared with genetics research, with disease cause and effect harder to establish than with genes.

But research is gradually improving our understanding. Prof. Arumugam said that though his team’s study did not achieve a ‘breakthrough’, it helped give more insight into this area and raised questions over previous assumptions.

And research in this area could ultimately change how we view ageing, says Dr Rei, seeing it as more fluid than just ‘a totally one-way road with no turning back, except in the movies like Benjamin Button.’

The research in this article was funded by the EU.

Top image: Flickr/Pedro Simoes CC BY 2.0


This post Bacteria keep us healthy – but could they keep us young? was originally published on Horizon: the EU Research & Innovation magazine | European Commission.

Bacteria that changed the world: Alcanivorax

In our Bacterial World exhibition we offer a selection of ten bacteria that have changed the world, some in profound ways. In this series of short fact-file posts we present one of the ten each week. This week’s bacteria are…

Alcanivorax borkumensis
– the oil-eaters

Where they live
Seas around the world are host to small numbers of Alcanivorax borkumensis. But if there is an oil spill, its numbers skyrocket, as the species feeds on crude oil.

Why they are important
After the Deepwater Horizon oil spill, when the equivalent of 4.2 million barrels of oil gushed into the sea off Houston, Texas, Alcanivorax borkumensis unexpectedly helped reduce the environmental impact of the disaster.

How they are named
Alcanivorax borkumensis voraciously eats oil molecules called alkanes, giving the first part of the name. The second part recalls where scientists first spotted the species, around Borkum Island in the North Sea.

How they work
The species breaks down crude oil using a range of enzymes it produces naturally. It can consume a wider range of alkane molecules than other bacterial species, and so it becomes the dominant species in a contaminated area.

Top image: : Dr. Joanna Lecka, Tayssir Kadri, Prof. Satinder Kaur Brar (INRS)

Bacteria that changed the world: Prochlorococcus

In our Bacterial World exhibition we offer a selection of ten bacteria that have changed the world, some in profound ways. In this series of short fact-file posts we present one of the ten each week. This week’s bacteria are…

– the Oxygen-Makers

Where they live
Prochlorococcus bacteria grow anywhere damp, in salt water or fresh. They are similar to the blue cyanobacteria which thrived in the far-distant past on Earth.

Why they are important
2.3-2.4 billion years ago, cyanobacteria in the oceans began producing oxygen for the first time, changing the Earth’s environment completely.

How they are named
The Greek word for blue is cyan, giving the blue cyanobacteria their name. Until recently, they were known as blue-green algae, but cyanobacteria are actually an earlier and simpler form of life than algae.

How they work
Like all cyanobacteria, Prochlorococcus bacteria harvest energy from the Sun, absorb carbon dioxide and give out oxygen – the process called photosynthesis.

Top image: Transmission Electron Micrograph (TEM) image of Prochlorococcus coloured green
Copyright: Luke Thompson, Chisholm Lab; Nikki Watson, Whitehead (MIT), 2007

Bacterial Girl

We couldn’t resist. The moment we came up with the title of our special exhibition, Bacterial World, we were all humming Madonna’s 1985 hit. So here it is – a bacteria-themed version of Material Girl – written, performed and illustrated by the talented Museum team.

In place of “cold hard cash”, you’ll learn that bacteria were involved in the creation of life on Earth, and you’ll find DNA exchange and photosynthesis in place of kisses and hugs. Have a listen… and try to stop yourself dancing.

Of course, you’ll need the full lyrics to sing it in your bedroom with a hairbrush:


Some bugs make you feel unwell
And we’ve all heard of them
But look inside and you will find
That bacteria are your friend

They’ve been around since way back when
In the ocean life began
But nowadays they’re everywhere
So I think you’ll understand, that we are…

Living in a bacterial world
And I am a bacterial girl
You know that we are
Living in a bacterial world
And I am a bacterial girl

They spent some time in the sun
Began to photosynthesise
Put oxygen in the air we breathe
I’m telling you no lies

Now E. coli’s got a real bad rep
For causing people pain
But what you got to realise
Is it’s only one bad strain

’cause we are
Living in a bacterial world
And I am a bacterial girl
You know that we are
Living in a bacterial world
And I am a bacterial girl

Now some bugs love to snuggle up to
Exchange their DNA
Other cells are armed with spears
That wipe enemies away

Resistance to our medicines
You could call it evolution
But microbes might just hold the key
To a medical solution, ’cause we are

Living in a bacterial world
And I am a bacterial girl
You know that we are
Living in a bacterial world
And I am a bacterial girl

You know that we are

Living in a bacterial world
And I am a bacterial girl!

Bacterial World is open until 28 May 2019.

Credits for this little bit of brilliance go to:
Vocals, violin: Laura Ashby
Words, banjo, guitar, recording: Scott Billings
Illustrations: Chris Jarvis

Precision antibiotics – the future treatment of infections?

by Hannah Behrens

In our Bacterial World Science Short event series, researchers present their latest findings related to themes in the exhibition. At a recent Science Short, Hannah Behrens, a University of Oxford PhD student, explained how bacteria become resistant to antibiotics and how the species-specific antibiotics she studies might reduce the worrying rise in antimicrobial resistance.

Bacteria that are resistant to antibiotics present a huge problem. I work on developing new antibiotics that will slow the development of bacterial resistance.

But let’s not get ahead of ourselves. Your body is full of bacteria. In fact, there are more bacteria than human cells in your body. Most of these bacteria are good for you; they help you digest food and protect you from diseases.

But once in a while a harmful bacterium causes an infection. This could be a lung, wound, or bladder infection, or something with a fancy name like, Black Death, tuberculosis, leprosy, syphilis or chlamydia. The doctor will then prescribe you antibiotics to kill the offending bacteria.

Hannah Behrens delivers her Science Short talk at the Museum

The development of antibiotics in the 20th century was a major breakthrough. For the first time bacterial infections could be effectively and rapidly treated. Since 1942, when antibiotics first became available, we have discovered many new antibiotics which have saved millions of lives.

However, in the last 30 years we have not managed to develop any new antibiotics. During the same time, many bacteria have adapted to become resistant to the antibiotics we do have. In 2017, a woman in the US died because she had an infection with bacteria that were resistant to all available antibiotics. It is estimated that already 700,000 people in Europe alone die because of resistant bacteria per year. What is happening?

Bacteria are forming a lawn on this plate (light areas); where an antibiotic has been spotted on the bacteria they die and leave the surface blank (dark areas).

Every time we treat bacteria with antibiotics, most die, yet a few resistant bacterial cells survive. Like Rudolph the red nosed reindeer, the resistant bacteria are usually at a disadvantage until a special situation arises (a foggy night for Rudolph; treatment with antibiotics for resistant bacteria).

Under usual circumstances, producing a resistance mechanism is a disadvantage: it wastes energy and slows down growth, so very few bacteria are resistant. Only when all the non-resistant bacteria are killed by antibiotics do the resistant ones thrive. They have no more competition, and have all the resources, such as food and space, to themselves.

The more we use antibiotics, the more resistant bacteria we get. It is essential not to use antibiotics carelessly.

More antibiotics are used in animal farming than on humans. If we eat less meat, and so reduce the farming of livestock for food, we may reduce the growth of resistance bacteria. Another approach is to only take antibiotics when the doctor prescribes them. Antibiotics do not help against viral infections like colds. In many low and middle income countries, antibiotics are available in supermarkets and it is no coincidence that these countries have higher levels of resistant bacteria.

The precision antibiotics research group in the Department of Biochemistry at the University of Oxford

Apart from avoiding the unnecessary use of antibiotics, scientists – including me – are trying to develop better therapies against bacteria. I study precision antibiotics: drugs that specifically kill one species of bacteria. The advantage of this is that all good bacteria remain unharmed and only the disease-causing species is targeted. This also means that only resistant bacteria from this one species get an advantage to thrive.

I am interested in species-specific antibiotics against Pseudomonas aeruginosa. This bacterial species causes lung and wound infections and, according to the World Health Organization, is one of the three bacteria for which we most urgently need new antibiotics. Colleagues of mine tested different precision antibiotics against Pseudomonas and found one that is better than the others, called Pyocin S5.

Hannah’s painting of how researchers think pyocin antibiotics kill bacteria. The pink bacterium produces pyocins (pink balls), which enter the susceptible blue bacteria through pores (blue). The blue bacteria mistake the antibiotic for a nutrient and open the pore to let it in. Once inside the bacterium it forms a pore in the inner membrane which causes leakage of the cell contents and kills the cell.

I am now investigating how stable this antibiotic is, how it recognises this specific species of bacteria and how it enters the bacterial cells. This knowledge is important to decide on how to store, transport and administer the drug. I also hope that understanding why Pyocin S5 is more effective than the other antibiotics will allow us to design more effective, targeted antibiotics in the future.

My hope is that one day we will treat all bacterial infections with precision antibiotics and that antibiotic resistance will become a problem of the past.

Bacteria: captured and cultured

For our new exhibition, Bacterial World, we embarked an exciting science/art experiment to make visible the colonies of bacteria present on a wide range of our everyday items and belongings. Once cultured and photographed, eight of these colonies were captured by artist Elin Thomas as a set of crochet artworks that are on display in the exhibition. Our exhibitions officer Kelly Richards tells us more…

For every human cell in your body, a bacterial cell is also present. These bacteria are part of our microbiome, a vast array of microorganisms that use our body as a home and our food as a source of nutrients. In return, the bacteria help us to digest food, maintain our immune systems and keep dangerous bacteria at bay. In fact without these bacteria we would be very sick indeed.

It’s hard to see our microbiome because individual bacteria can easily be as small as 0.2 microns; you could fit over a thousand of these smallest bacteria on one side of a red blood cell. But if we can select and artificially grow the bacteria, their colonies become living, breathing cities visible to the naked eye.

Click the images above to find out more about culturing bacterial colonies

Colonies, both natural and artificial, can contain billions of bacteria as well as the materials that they secrete such as slime, which helps them to move across surfaces, and antibiotics, which kill off other bacterial colonies that could compete for food and space. In their attempts to dominate the space and food available, as well as get enough oxygen to live, colonies can create beautiful, complex structures.

We had a go at visualising the bacteria that live invisibly alongside us by asking visitors to take part in a simple experiment. With the help of microbiologist Rachael Wilkinson, we took items such as coins, keys and jewellery and touched them lightly against agar plates – dishes containing a nutrient-rich jelly that aids bacterial growth. The agar plates were then given to Nicole Stoesser, a clinical microbiologist at the John Radcliffe Hospital, who grew them in the safe environment of the laboratory.

Many different types of colonies grew from the objects we printed. In the collage above, eight of these colonies have been represented as crocheted Petri dishes by artist Elin Thomas. These artworks are on display in the Bacterial World exhibition until 28 May 2019.

In the gallery below is a photograph of every participant’s plate, whether anything grew in it or not. Click on an image to see a larger version. If you took part in the experiment you will be able to identify your own plate from its number.

The results go to show that we really are living in a bacterial world!