Julie Le Bris

Some #Pseudomonas aeruginosa strains naturally lack the major virulence system T3SS. 🦠 @inaattree.bsky.social & @cbuch.bsky.social labs reveal that avirulent isolates still produce valuable metabolites (e.g. rhamnolipids, elastase, pyoverdine)—making them promising for #biotech use.
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Phages are promising against antibiotic-resistant bacteria—but resistance can emerge. 🦠 New work from @baerboletta.bsky.social lab shows E. coli can resist phages in the lab, but in the gut that resistance comes at a cost: context is crucial for #PhageTherapy success.
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Cyril Anjou, 2e candidat au prix de thèse nous a présenté ses travaux sur les rôles physiologiques des systèmes thioredoxine de Clostridioides difficile, impliqués dans les étapes du cycle de vie de la bactérie, ainsi que sur l’intérêt thérapeutique potentiel de la modulation de leur expression.🦠

🦠 Mycobacteria aren't just tough, they're interior designers! 🦠 Check out our latest #preprint 🚨, led by our PhD student @camimille.bsky.social , where we show that #Mycobacterium tuberculosis builds secret cytoplasmic membranes to adapt its metabolism and sneak past immunity 🤫

Thread coming soon!

New tool alert! 🚀 MCAAT uses de Bruijn graphs to detect #CRISPR arrays in #metagenomes, capturing data lost in assemblies. A step forward in uncovering the hidden diversity of CRISPR-Cas systems. By Talibli & Voß
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Archaea thrive in harsh niches that challenge DNA integrity. 🧬 In H. volcanii, Sailer et al. revealed Cas1 & Hel308a as new Microhomology-Mediated End Joining (MMEJ) players, expanding the toolkit for archaeal genomes repair.
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Phage provoke growth delays and SOS response induction despite CRISPR-Cas protection | Philosophical Transactions of the Royal Society B: Biological Sciences Bacteria evolve resistance against their phage foes with a wide range of resistance strategies whose costs and benefits depend on the level of protection they confer and on the costs for maintainance....

How do bacteria choose what type of defences to use against phages? We explored that question in the last paper I worked on as a postdoc at the Uni of Exeter @uniofexeteresi.bsky.social with Stineke van Houte, Stefano Pagliara and Edze Westra (not on Bluesky)
doi.org/10.1098/rstb...

Thanks Basile! 😊

Huge thanks to everyone involved : Hugo Varet @pasteur.fr, @epcrocha.bsky.social social and my amazing PhD director @olayarendueles.bsky.social

Here, we show a clear example of plug-and-play dynamics in the bacterial chromosome.
It explain the success and versatility of the Klebsiella capsule, giving insights into how complex traits can be repeatedly mobilized without extensive cellular rewiring.

🏥 We show that the capsule’s modular architecture enables seamless horizontal transfer with preserved functionality. Specifically, K1 serotype acquisition drives hypermucoviscosity even without rmpA.

We observed minimal transcriptomic changes, minimal fitness costs and convergent adaptation to a specific environment rather than serotype-specific solutions, hinting for capsule locus modularity. 🧬

🦠 We found that capsule production is highly hierarchical, determined by the capsule type and the genetic background independently.

We swapped capsular loci in five different genetic backgrounds of the nosocomial pathogen Klebsiella pneumoniae. #phagesky #AMR

🧬 Beyond virulence, capsule changes shape host evolution and is tied to core metabolism. This suggests epistasis, yet their diversity and turnover argue for modularity. @klebclub.bsky.social #microsky

Serotype swapping in Klebsiella spp. by plug-and-play Understanding how complex, multi-gene systems evolve and function across genetic backgrounds is a central question in molecular evolution. While such systems often impose costs through epistatic inter...

How complex functions, with important physiological and evolutionary impacts get repeatedly and efficiently transferred across genomes?
That’s what we explored using one of the fastest-evolving loci in Bacteria: the capsule locus.
The paper: www.biorxiv.org/content/10.1...
Thread👇

Check out @julielebris.bsky.social’s thread on our latest manuscript describing phenotypic heterogeneity in capsule production in Klebsiella & Acinetobacter @klebclub.bsky.social

This work started when I was still in @pasteur.fr & got finished in @cbitoulouse.bsky.social
#microsky #phagesky

A big shout out to my PhD director @olayarendueles.bsky.social

And congratulations to everyone involved in this fascinating project! Sara, Lilibeth, Amandine and @epcrocha.bsky.social

Capsule heterogeneity appears as a bet-hedging strategy that could play a major role in shaping the alternation of the bacterial life cycle between the environment and pathogenesis by giving a small subpopulation reversible, useful traits.

🏥 Such heterogeneity is also found in Acinetobacter spp.

Capsule production heterogeneity enables a subpopulation to escape from phages, relevant for phage therapy strategies but also impacting gene flow. 🧬

🦠 Such heterogeneity varies across environment and contributes to increase the strain fitness.

We developed a method to quantify this capsule production heterogeneity in more than 150 Klebsiella spp. strain and found it widespread (mostly in classical strains!). 🕵

🔬Microscopy with India ink staining showed clonal cells make varying amounts of capsule—unlike P. fluorescence’ ON/OFF switch, it’s a continuous phenotype.

Phenotypic heterogeneity of capsule production across opportunistic pathogens | mBio The polysaccharidic capsule is present in ~50% of species across the bacterial phylogeny, including all ESKAPE microorganisms, the six most significant multidrug-resistant (MDR) nosocomial pathogens. It is also an important virulence factor and a major ...

Delighted to share our recently published work!
Ever wondered how Klebsiella (and others) deals with capsule production’s costs ?
The paper: journals.asm.org/doi/10.1128/...
Thread👇

#CRISPR is more than Cas9 ✂️ 🧬 @BeiselLab reveals a short tracrRNA from S. pyogenes is toxic in L. paracasei, even without Cas9, underscoring challenges of using CRISPR-Cas9 in non-native hosts.
#microsky
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#phagesky

I am looking for phages infecting Streptococcus pneumoniae to test a phenotype - does anyone have some and willing to share ?

Repost appreciated :)

Looking forward to #ESEB2025 Day 1!
In this meeting, the team has two talks:
I’ll present coevolutionary dynamics between bacteria & their prophages in S43 Tuesday PM & @julielebris.bsky.social will speak on Thursday AM, S34, on phenotypic heterogeneity of capsule expression.

🔬 We’re past the midpoint of the year; perfect time to look back at what’s been discovered so far. From how Salmonella slows its escape from immune cells to the microbes thriving in oil reservoirs, these are the most-read #microLife papers of 2025 so far: buff.ly/TfhOvEc

Manuscript accepted just in time for #ESEB2025 @eseb2025.bsky.social
@julielebris.bsky.social will present phenotypic heterogeneity in some #ESKAPE pathogens 🧫 !
S34.01 - Mechanisms of adaptation to changing conditions in microorganisms
Those not going to Barcelona, stay tuned for details!