As an Early Career Fellow, Dr Alessia Lepore studies how microbes cope with stresses in the food chain.

“Since joining the Quadram Institute as an Early Career Fellow, I’m studying the tricks that food pathogens, microbes that cause disease, use to adapt to multiple stresses across the food chain, potentially jeopardising food safety.

What stresses do microbes experience?

Think of a pathogen living on a salad plant. As the salad plant goes through the food chain, from the farm to the store, it experiences different stresses. Washing can move water in or out of microbial cells, which is called osmotic stress, refrigeration is a form of cold stress and packaging changes oxygen availability, leading to a build up of unstable molecules which is called oxidative stress.

It’s a good thing that food pathogens are exposed to stresses, because we want to eliminate bad microbes from our food. What is less good is that these pathogens can sometimes survive and adapt, so it’s important to understand how microbes cope with these stresses so that we find new ways to help keep food safe.

How do we study microbes’ responses to stress?

Since microbes face multiple stresses along the food chain, studying their responses to combined stresses, rather than individual stresses, is necessary to reflect real-world farm-to-fork conditions. Replicating this complexity in the lab, however, remains a real challenge.

My research approach involves different experiments like microfluidics, single-cell imaging and super-resolution microscopy techniques.

Microfluidics mimics food production methods

Using microfluidics, I create controlled environments, tiny chambers filled with liquid, that can be tweaked to mimic food companies’ varying production methods.

For example, I can apply heat shock to the system, change how much nutrient is available or introduce multiple pathogens to see how pathogens respond and whether they survive.

Microscopy zooms in on stress survivors

I use single-cell microscopy to watch how microbes respond as they are exposed to different stresses. With fluorescence microscopy, I can see how individual cells switch on stress-response genes, such as heat shock response genes.

This matters because some microbes cope with stress better than others. The ones that cope best are the ones that survive, multiply and potentially spread infection. It’s the stress survivors that we don’t want on our plate.

Super-resolution techniques reveal stress-busting tactics

I also investigate in more detail what’s happening inside the microbes as they adapt. That means looking at molecular processes in real-time.

For example, some pathogens produce heat shock proteins that help against heat shock. Heat will usually cause tightly folded proteins to loosen and change shape. The heat shock proteins act as helpers to ‘close’ the proteins back into their usual shapes.

Techniques like single-molecule microscopy, a higher-resolution microscopy technique, allow me to go into more detail and focus on and track these individual proteins within microbes. That way I can better understand their role in pathogen stress-busting tactics.

My early career research fellowship journey

Combining techniques during my fellowship here at the Quadram Institute, I want to develop a farm-to fork platform to monitor pathogen survival and adaptation in real-time.

It’s my curiosity towards complex stress environments that’s brought me to the Quadram Institute Early Career Fellowship. I started out studying bacteria during my physics PhD and then focused on how bacteria stay alive following exposure to stresses like antibiotics during my postdoctoral research.

Before joining the Quadram Institute, I was a Marie Curie fellow at Ecole Polytechnique’s Laboratory of Optics and Biosciences, where I studied how bacteria respond and adapt to infection stressors like high temperatures.

Now, I’m looking forward to gaining research independence and leadership skills. I’m enjoying the collaborative atmosphere at the Quadram Institute and the research culture.

The Institute’s focus on real-world problems and expertise in reducing foodborne illness and antimicrobial resistance is a real draw for me and will help me learn more about the link between how microbes cope with stress and food safety.”