The structure of a dense colony of motile rod-like bacteria can be represented by a swarm, or active nematic fluid, while the longer motile chains of cells formed by filamentous algae may show additional emergent properties, arising from possibilities such as entangling in space with each other or with their surroundings. The physics of the self-organised dynamical states of active matter have typically been studied only in highly simplified geometries. However, life thrives in confined geometries, which are instead dominated by dense, complex surfaces. Roots burrow through the soil, extreme algae can colonize even the dry inhospitable rock walls of Antarctic valleys, lichens break down stone, damaging cultural works like marble statuary, and even simple yeast can exert amazing pressures, of several atmospheres, on their surroundings. These are the environments in which micro-biotic motility has evolved, and these are the kinds of environments, therefore, in which their mobility must be apprehended.
In this project you will focus on elucidating the common physics to all the above situations through the question: How do microbes invade, proliferate in, and how can they ultimately break, rock or soil?
Specifically, you will study how yeasts and algae grow in confined spaces, like the pores of soil or rock, and how they interact with their environment. Experiments will develop using microfluidic techniques, or the so-called ‘lab-on-a-chip’ technology to make model porous media where the positions and sizes of every one of thousands of individual elements are designed. These experiments will be coupled to 3D observations of growing microbial colonies, in and on loosely consolidated granular media (i.e. model dirt, or artificial sandstone). Here, measurements will be made by optical coherence tomography (OCT). The algae grow as filaments, one cell wide, that move in a gliding motion, like an active polymer. You will look at how this allows them to jam, either by entangling with other filaments, or their environment, and how this modifies their macroscopic properties. You will also look at how they develop internal structure, like a fabric of co-aligned elements, and how that structure is important in building up the properties of a biofilm or biomat.
The work is collaborative, and will involve regular work with, and visits to, the world-leading Max Planck Institute for Dynamics and Self-Organisation, in Göttingen, Germany.
Applicants should have a background in physics, or a related discipline, with at least a 2:1 Honours degree (or equivalent). Relevant experience (e.g. project work, placements or research internships) involving microfluidics, image processing, or fluid dynamics would be valuable.
Fees and funding
The studentship will pay UK/EU tuition fees. It will also provide a maintenance stipend of approximately £14,777 per year for three years (the stipend is linked to the RCUK rate, starting in 2018).
Applications from non-EU students are welcome, but a successful candidate would be responsible for paying the difference between non-EU and UK/EU fees. Fees for 2017/18 are £13,250 for non-EU students and £4,260 for UK/EU students.
Guidance and support
Further information on guidance and support can be found on this page.