5e de Duve Lecture: Voici le podcast!
Pascale Cossart nous éclaire sur les bases moléculaires et cellulaires des infections bactériennes.
Bdellovibrio bacteriovorus is a strange little bacterium with an atypical life cycle. ‘It attacks gram-negative bacteria, which have the distinction of having a double cell membrane’, explains Dr Géraldine Laloux, an FNRS researcher in microbiology. ‘B. bacteriovorus interferes and maintains a small niche between the two membrane layers. From there, it secretes enzymes to eat and digest the contents of the host bacterium. Thanks to this food, it grows and takes the form of a long filament that subdivides into small daughter cells, rupturing the host bacterium. These new B. bacteriovorus in turn go in search of another victim in order to reproduce.’
B. bacteriovorus is found everywhere in nature, especially in aqueous media. It even seems to exist in our intestines. This predatory bacterium is of great interest to researchers. And for good reason: harmless to humans, it’s a threat to certain pathogenic and antibiotic-resistant bacteria. But while several laboratories around the world are studying it for this purpose (1), Dr Laloux is more interested in its life cycle. ‘Usually,’ she says, ‘a mother bacterium breeds by dividing into two daughter cells. In B. bacteriovorus, the number of daughter cells is both greater and variable. The purpose of my research is to understand the ins and outs of this particular life cycle. How does it do it? Using what enzymes? How do its genes express themselves? In what way and at what point in its development and in what area do the proteins that control the bacterial life cycle and that are well known in other species interact in such a way that B. bacteriovorus behaves as it does?’
To address these issues, Dr Laloux was awarded an ERC Starting Grant (2). ‘We only understand a few bacteria and their life cycles’, she says. ‘There are still many things to explore and discover! Moreover, a growing number of laboratories are turning away from the most well-known bacteria in order to look at more atypical microorganisms.’ The ERC Starting Grant will allow Dr Laloux to hire staff (doctoral, postdoctoral, technical) and purchase the advanced microscope she needs for her work. ‘For five years, I’ll be able to devote myself entirely to my research without having to seek funding! It's important to conduct fundamental research on bacteria. If we want to use some of them at the therapeutic level, we’ll have to be able to manipulate them. But to do so, we must understand exactly how they work.’
In 2013, back in Belgium, she joined the de Duve Institute. In the laboratory of Prof. Jean-François Collet, she learned more about bacterial envelopes, which led her to study B. bacteriovorus. ‘I’d like to present my first results in 2019. Ultimately, I hope the laboratory the ERC Starting Grant will allow me to mount will become recognised in the field of bacterial biology’.
(1) Several laboratories are trying to confirm its safety for humans and its antibiotic effectiveness.
(2) ERC Starting Grants of €1.5 million are intended for young European researchers.
2005: Master’s Degree in Cellular and Molecular Biology, Université de Namur
2009: PhD in Science, Université de Namur
2010-13: Researcher, Department of Molecular, Cellular and Developmental Biology, Yale University
2013-17: Researcher, de Duve Institute, UCLouvain (FNRS Postdoctoral Researcher, 2014-17)
2017: Winner of the Prix Alvarenga de Piauhy, Belgian Royal Academy of Medicine
Since 2017: Professor and FNRS Research Associate, UCLouvain
2018: Recipient of ERC Starting Grant