What is a cellular microbiologist?

Do you want to know more about what a cellular microbiologist studies? Join me on an incredible journey where we'll explore the fascinating microscopic world of cell invasion by pathogens, and compare it to the thrilling concept of Earth invasion by aliens!

Artwork by Hiba Belkadi

When a non-scientist asks me what my job is, my typical answer is something very basic such as “I’m a researcher in biology”. If they want to know more, I add “I study how bacteria infect our gut through microscopy”. In other words, I can define myself as a cellular microbiologist! The problem is that when I use this term, most people look at me wide-eyed and feel they don't understand what I'm doing.

Cellular microbiologists are scientists who investigate how microscopic living things, called  microbes, overturn and subvert the cells of more complicated organisms, such as human beings. These types of studies are particularly important because they allow us to learn more about the process of infection, which can help to develop new therapeutic approaches to combat infectious diseases. Cellular microbiologists can also explore the functioning of human cells, allowing us to better understand and fight other diseases, such as neuropathologies (diseases of the nervous system) or cancer.

As a big fan of science fiction, I like to explain cellular microbiology using the metaphor of alien invasion, where the aliens represent the microbes and the Earth, with its constituent countries, represents the human body which is made up of many cells. My job is to study the strategies used by aliens to invade Earth. Just as countries have physical borders, human cells also have a plasma membrane which keeps out dangerous invading organisms that would damage the cell. However if these invaders are not recognized at the border, they can invade the cell and use its resources for their own benefits. Once the cell does detect this enemy, it can fight it from the inside, encapsulating the invading microbes and creating a toxic environment in order to destroy them. Sometimes, these enemies can be tough to fight, and just as one country under siege could call on its allies for support, immune cells can be summoned to help our infected cells to fight the microbes. That is how I see cellular microbiology and why I think my job is so exciting!

Therefore, I have interviewed four expert cellular microbiologists to share with us their vision of the field: Pr. Pascale Cossart, Dr. Olivier Neyrolles, Dr. Alice Lebreton and Dr. Guillaume Duménil. I ask them several questions regarding the role of a cellular microbiologist and their long experience in research.

Who is a cellular microbiologist?

All four of the researchers interviewed explained that a cellular microbiologist is interested in the dialogue between microbes and cells. Dr. Cossart went on to say that studying how a microbe infects its host “can help to better understand how a eukaryotic cell behaves”. It is worth remembering however that the interactions between microbes and other cells go beyond just infection, and encapsulate a range of host-microbe relationships as expressed by Dr. Neyrolles: “The interaction can be more or less beneficial for one of them. It can be symbiosis (beneficial to both) .. pure pathogenesis (where the microbe causes a disease in the host) or something in between”.

How do you study cellular microbiology?

All interviewees agreed  on the importance of using multi-disciplinary approaches, combining various modern tools to comprehensively address their research questions. These approaches include microscopy of microbes either live or fixed in time, which allows one to visualize the interaction between bacteria and cells.

Another key group of techniques used by microbiologists, including Drs. Lebreton and Neyrolles, are called omics approaches. These involve the collective characterization of the biological molecules at the basis of life such as DNA, proteins, lipids and carbohydrates which are responsible for the structure, function and dynamics of an organism. As Dr. Neyrolles explained, such global approaches “are useful to discover something completely unknown”. He described that his lab has taken advantage of these tools to identify “a new mechanism of innate immunity through bacterial intoxication by metals.”

Do you think cellular microbiologists need special qualities? Which ones?

For Dr. Duménil, it’s essential to appreciate the multidisciplinary dimension of cell biology, microbiology and medical health: “Keep in mind this global perspective, it is what makes the field interesting.” This emphasis on open-minded curiosity and versatility was echoed by the other researchers, with Dr. LeBreton commenting that “based on the question, you need to switch from one technique to the other and adopt new approaches.”

What is the most fun part of your job?

One word came back most often in response to this question - “discovery”. However revolutionary those discoveries are, bringing new knowledge to the field is clearly one of the things that most excites the researchers I spoke to. 

Dr. Lebreton added that a lovely part of her job is interacting with students and being able to see them grow and develop.

Do you have any anecdotes to share with us?

When a scientist wants to publish a paper,  they will choose a journal with a given level of prestige in their field, depending on how novel they judge the breakthrough of their research. After that, the article goes through a peer review process to ensure the veracity and quality of the content. Dr. Neyrolles shared an anecdote about this process, saying, "One of our papers was accepted in Cell Host & Microbe in just a few weeks without major revisions. Later, at an EMBO conference, a colleague complimented the work, calling it a beautiful story, and asked if we had considered submitting it to Cell. We hadn't. My advice: always dream big and aim high."

Dr. Duménil told us about his first conference presentation “My first congress was at the Institut Pasteur at the CIS auditorium. A famous cellular microbiologist was attending, and I had the chance to present him a poster of my PhD work. I told him that I was puzzled because my results were not showing what was previously published. He told me « stick to your guns ». When we start, we often doubt our results (sic), but he encouraged me to believe in them. One needs to be confident about his results.”

What would you recommend or advise to a young cellular microbiologist?

The answers to these questions were different and all insightful.

Dr Cossart said “Be on guard!”. For her it’s really important to stay read scientific papers, attend seminars and conferences, and not change project unless absolutely necessary. 

Dr Neyrolles recommends being equally strong in microbiology and cellular biology. 

Dr. Lebreton encourages students to write their lab-book (a diary of the experiments carried out) every evening. Similarly to the suggestion of Dr. Neyrolles, she also recommended  meeting people from both the microbiology and cell biology fields.

Dr Duménil comments “Keep in mind a global perspective. When we look at the cell scale, we can forget about the whole organism, we can make bad interpretations. It is the difficulty of cellular microbiology, which is multi-scale.”

What would you have become if you were not a cellular microbiologist? 

Most of them would still be scientists, but in different fields. Dr Cossart, if she could not have researched microbiology in any of its forms, would have studied chemistry.

Dr Neyrolles would have sought to become either a neurologist or a medical doctor in the countryside.

Dr. Lebreton would have been interested in various other scientific professions such as geology; palaeontology; chemistry; yeast genetics or RNA studies. However, besides these scientific endeavours, she could have seen herself as a baker or a scientific journalist. In fact, Dr. Lebeton has in many ways achieved this final possibility through her existing career, as she currently writes a regular scientific column for French newspaper Le Monde.

Dr. Duménil believes he would have been a biochemist, a structural biologist, or a journalist.

Why is cellular microbiology an important field?

“Cellular microbiology represents the heart of the infection process. It is also a gigantic source of information to better understand the cell, the microbe, and the organs” stated Dr. Duménil. 

Dr Lebreton added “Cellular microbiology is a precise way to find therapeutic targets...we push the cells to reveal their adaptive mechanism to new conditions.”

Anything else you would like to share with us? 

“Go towards the unknown.” Dr. Cossart

Conclusion

Now that you know more about who a cellular microbiologist is and what they do, I hope you can appreciate how fascinating this field is. Microbes subvert host cells in incredible ways, which are very fun to discover. Although we are supposed to root for the victory of our heroic host cells, often cellular microbiologists are amazed by the capacity of the villain microbes.

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This article was copy edited by Elena Capuzzo and Tom Cumming.

Meet the author: Nora Mellouk