Author: mpolin

Dr Williams

Thrilling news! On Friday Steve has successfully defended his PhD thesis! Dr. Williams, as he’s now known, endured 3h of grilling by Giorgio Volpe (UCL) and Gareth Alexander (U Warwick)… and managed to emerge reasonably unscathed 😉 Steve has gracefully agreed to keep working with us as a postdoc for the next few months. Thanks Steve!

WMS Thesis prize for Iago

We’re very happy to announce that Iago has been awarded the Faculty Thesis Prize from Warwick Medical School, for his thesis “Biophysical mechanisms of antimicrobial resistance in swarming B. subtilis“. The thesis was co-supervised with our good friend Munehiro Asally. Well done Iago! You can read more about Iago’s work in his eLife publication and (hopefully soon) in a second follow-up article.

Iago is currently a postdoc in the Oxford Colloids Group (U. Oxford, UK).

The Narrow-Escape of a Microorganism

A microalga escapes one pool only to find itself in another.

Escaping through narrow apertures involves rare events and therefore is usually quite hard. It is also a classical problem for both Brownian and ballistic particles. Interestingly, microorganisms can find themselves having to find and go through a narrow aperture. Their case is peculiar as it bridges the Brownian and ballistic cases. Our new paper, just out in Physical Review Research, looks at this problem with a mix of experiments and simulations. As is often the case, we find an unexpected twist in the story…. A great collaboration with Antoine Allard, Mathieu Souzy, Jean François Louf, Matteo Contino and Idan Tuval.

Visit by Shilpa Khatri

We are very excited to welcome Shilpa Khatri, Assistant Professor at UC Merced (USA), who’s joined us at IMEDEA about 10 days ago for a 2-months visit. This is funded from a Visiting Fellowship from the University of the Balearic Islands. Between short trips to the continent and co-organising with us and others the 2022 MOB meeting, Shilpa will work with Steve Williams on a numerical project about phototaxis.

The curious case of confined active-passive systems

We’re excited to share a new arxiv preprint on the dynamics of mixed active-passive systems. In these systems, the passive particles are buffeted around by the active components like swimming microorganisms or synthetic active particles. These suspensions are fascinating both at a fundamental level (how can we describe/prescribe the average behaviour of the passive particles?) and -possibly- for future technological applications (directed transport at the microscopic scale). Here we show that confining an active-passive system leads to a non-uniform distribution of the passive species in a predictable way. We then use confinement to induce the mixed system to spontaneously un-mix and separate out the passive components! This is Steve’s first paper, in collaboration with Raphaël Jeanneret (LPENS Paris, France) and Idan Tuval (IMEDEA UIB-CSIC, Spain).

Eleonora Secchi’s visit

Over the last three weeks we were lucky enough to host Eleonora Secchi (ETH Zürich). Her visit was supported by a Visiting Fellowship from UIB (calls every 6 months: drop an email if interested!). We had lots of fun working on biofilm streamers by marine bacteria and in general exchanging ideas and learning from each other. Have a good fly back Eleonora and talk soon!

Yeast mating: here we go!

I am absolutely delighted to share the news that, together with Irene Stefanini (U. Torino), Daniel Segrè (Boston Uni) and Elizabeth New (U. Sydney), we have been awarded a grant from the Human Frontiers Science Program to work on the biophysics of yeast mating. This is a very intriguing subject involving mechanical stresses, metabolism, mixing flows and…. (surprisingly) the gut of wasps! In our group, this grant will finance a postdoctoral position and a lab technician with a starting date of 1st of Nov. (Ads coming out soon)

To sink or Not to sink

Micoorganisms are usually denser than the medium they live in, and therefore have the tendency to sediment. When they’re motile, this might not look like a big problem, but when they are not… well… they need to find a way to stay afloat. How do they do it? We are lucky to have been involved in a very interesting project led by Joseph Christie-Oleza on the sinking behaviour of cyanobacteria. It turns out that pili help cyanos stay afloat! And, surprisingly, help fend off grazers as well. The results have just been published in Nature Communications. Congrats to all and in particular to Joseph!

Swarming, Traffic Jams and Biofilms

Transient traffic jam within a monolayer bacterial swarm. Notice the cells being pushed out of the monolayer!

Absolutely delighted that Iago’s paper on the transition from bacterial swarming to biofilms is now out on eLife.

When the expansion of a B. subtilis swarm is hindered (even just by a simple barrier!) cells at the front pile up through a physical process similar to a traffic jam (a transient one in the movie!). This in turn leads to the emergence of a localised biofilm. This is the first direct report we could find of a transition between swarming and biofilm! Great work by Iago and fab collaboration with Munehiro Asally!

Ah! …here’s eLife‘s press release!