Sam Brown

Whole-tissue imaging reveals intrastrain diversity shapes the spatial organization of Pseudomonas aeruginosa in a murine infection model | mSphere Intrastrain genetic and phenotypic diversity within Pseudomonas aeruginosa populations is common in chronic pulmonary infections. While this intrastrain heterogeneity is a hallmark of chronic infection, its consequences for the spatial organization of P. aeruginosa within the airways remain unclear. Here, we demonstrate that the loss of O-specific antigen in a subpopulation of P. aeruginosa significantly alters the spatial architecture of P. aeruginosa, without changing the total population size or composition. Using a combination of tissue clearing and hybridization chain reaction RNA-FISH in a murine lung infection model, we mapped the localization of genetically distinct P. aeruginosa variants in mixed populations in vivo. These findings reveal that genetic diversification within a strain can reshape the infection landscape at the micron scale, highlighting the overlooked role of intrastrain dynamics in shaping the microbiogeography of infections and influencing host-pathogen interactions.

Recent work from the lab showing how presence of O-antigen deficient Pseudomonas variants change aggregate assembly and microbiogeography of infection

journals.asm.org/doi/10.1128/...

16.12.2025 14:18 — 👍 13    🔁 10    💬 2    📌 0

Halobacteriovorax halts disease progression in endangered Caribbean corals Abstract. Predation is a top-down regulator of ecosystem integrity and a key driver of community structure and evolution in plants and animals. Despite our

A bacterial predator, Halobacteriovorax, acts as a living "probiotic" that halts Vibrio-induced disease progression in endangered Caribbean corals. This shows microbial predators are promising new tools for coral disease therapy! #CoralReefs #MicrobialEcology #ISMEJ academic.oup.com/ismej/advanc...

16.12.2025 16:41 — 👍 6    🔁 5    💬 0    📌 0

Bacterial immune systems as causes and consequences of microbiome structure Bacterial immune systems have evolved in response to diverse molecular "parasites", yet their ecological roles remain poorly understood. This Essay explores how interactions between mobile genetic ele...

Very happy to see this piece out in @plosbiology.org, on the bacterial immune systems and microbial communities. It was a great team effort with Rafael Custodio, @brockhurstlab.bsky.social , @brownlab.bsky.social, and Edze Westra! 🦠🧫 #phagesky #mevosky

journals.plos.org/plosbiology/...

19.11.2025 18:35 — 👍 93    🔁 48    💬 0    📌 0

Bacterial immune systems as causes and consequences of microbiome structure Bacterial immune systems have evolved in response to diverse molecular "parasites", yet their ecological roles remain poorly understood. This Essay explores how interactions between mobile genetic…

The ecological roles of bacterial #immune systems are poorly understood. Rafael Custodio @ellinoralseth.bsky.social @brockhurstlab.bsky.social @brownlab.bsky.social & Edze Westra explore how mobile genetic elements and bacterial defenses shape #microbiome structure and function 🧪

20.11.2025 13:55 — 👍 6    🔁 4    💬 0    📌 0

Thanks Andrew, @jrchandler.bsky.social and @ajaidandekar.bsky.social for great commentary! I totally agree, so much more to do. One exciting prospect is using regulatory wiring knowledge to improve our abilities to predict bug behaviors 'in the wild'. Our fig 7B is encouraging start, IMO.

17.09.2025 17:37 — 👍 1    🔁 0    💬 0    📌 1

The las and rhl QS systems have a reciprocal, synergistic, and unequal relationship. Top: Single-signal models demonstrate that the summed effects of single signals (3 oxo C12 HSL alone, red; C4 HSL alone, orange) cannot account for the maximal expression of lasI or rhlI. The upper green, flat surfaces in the plots indicate the maximum mean expression level measured across all combinations of signal concentrations while the lower semi-transparent surfaces mark the sum of single signal effects. The plotted points represent observed expression levels when C4 HSL is withheld (red) and when 3 oxo C12 HSL is withheld (yellow). Lines indicate the model predictions. Bottom: Multi-signal non-linear models capture the synergistic effects of both signals and match observed expression levels. Model estimates are shown as grid lines. Horizontal bars show the mean value of expression observed at each combination of signal concentrations. Lines extend from these mean values to the relevant grid point for clarity. Right: Data show that relationship of the las and rhl systems is reciprocal, and the multi-signal model quantifies the strength of those interactions. In particular, it reveals the contribution of both signals to the maximum fold-change in expression of both synthases. The charts in this panel summarize the contribution of 3 oxo C12 HSL (red), C4 HSL (yellow), and the synergistic combination of both (orange).

Bacterial #QuorumSensing is often assumed to follow a strict hierarchy. @brownlab.bsky.social &co find that #Pseudomonas aeruginosa instead uses a reciprocal, cooperative system that enhances responsiveness to population density & environmental changes @plosbiology.org 🧪 plos.io/3I7DhRG

08.09.2025 07:55 — 👍 15    🔁 7    💬 1    📌 0

Microbial Primers | Microbiology Society In the constantly evolving world of microbiology, new research and discoveries can often be overwhelming. ‘Microbial Primers’ is a series of short articles designed to simplify and illuminate intricat...

Latest Microbial Primer on 'polymicrobial infections' from @jenniferfarrell.bsky.social @brownlab.bsky.social and published by the @microbiologysociety.org. Check out all Primers which are useful introductions to topics and they are good for teaching. www.microbiologyresearch.org/content/micr...

20.06.2025 16:00 — 👍 8    🔁 4    💬 0    📌 0

pKJK5 vs RP4 cartoon sketch on plasmid competition

I *finally* get to share our work on plasmid competition– super proud to now have this on bioRxiv:

CRISPR-Cas is beneficial in plasmid competition, but limited by competitor toxin-antitoxin activity when horizontally transferred

www.biorxiv.org/content/10.1...

1/6 👇

12.05.2025 05:11 — 👍 38    🔁 15    💬 3    📌 2

Opportunities

Hello world! I'm starting out on bluesky with a job posting - we're looking for lab research tech who shares our love of bugs. More info here brownlab.biology.gatech.edu/opportunities/

17.01.2025 18:35 — 👍 41    🔁 38    💬 1    📌 2