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SUMMARY:Buckling instabilities in chaining bacterial colonies - Aidan Brow
 n\, Edinburgh University
DTSTART:20231123T140000Z
DTEND:20231123T150000Z
UID:TALK208765@talks.cam.ac.uk
CONTACT:Fulvio Forni
DESCRIPTION:Bacteria frequently grow together as colonies. Large\, complex
  colonies\, known as `biofilms’\, are often multi-species and exhibit co
 operative behaviour reminiscent of multicellular organisms\, such as signa
 lling and controlled cell death. However\, even at the early stages\, colo
 nies exhibit many different structures and morphologies\, which are contro
 lled by a dynamic interplay between cell growth and division\, the shape o
 f cells and the physical interactions between them. One type of interactio
 n\, called `chaining’\, consists of the maintenance of a physical\, usua
 lly protein\, link between sister cells following division. Chaining is co
 mmon in many bacterial species\, but is particularly well known in the rod
 -shaped Bacillus subtilis\, where buckling of single chains of bacteria le
 ads to convoluted\, open colonies with many pores and channels. This contr
 asts with the structure of non-chaining bacteria\, such as Escherichia col
 i\, which typically fracture into multiple small\, aligned domains. Here\,
  I will present 2D discrete-element simulations of growing bacterial colon
 ies\, where we continuously tune the probability and strength of chaining 
 between daughter cells. At the extremes\, we reproduce the behaviour of B.
  subtilis and E. coli -like colonies\, but for intermediate values of the 
 chaining parameters\, we identify a novel state\, where the whole colony b
 uckles collectively. A toy\, lattice model reproduces the shape of the tra
 nsition between the `aligned domains’ and `collective buckling’ states
 \, and enables us to show that the impact of chaining is to modify the rat
 e and probability with which these different mechanisms occur.\n\nThe semi
 nar will be held in LR4\, Baker Building\, Department of Engineering\, and
  online (zoom): https://newnham.zoom.us/j/92544958528?pwd=YS9PcGRnbXBOcStB
 dStNb3E0SHN1UT09
LOCATION:Department of Engineering\, JDB Seminar Room\, and online (Zoom)
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