Novel MR Selective Imaging of Transport and Growth in Biofilms

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Understanding the coupling of hydrodynamics and chemical reaction lies at the heart of many chemical processes. This project aims to implement and develop chemically-specific, spatially-resolved magnetic resonance (MR) measurement techniques, that are able to quantify, unambiguously, transport (both flow and diffusion) and chemical composition/conversion within an optically opaque complex pore structure. The case studies to be addressed in this context are of biofilm control, metabolism and mineralization, which provide relatively 'MR friendly' (in terms of signal relaxation times) test systems upon which to develop and apply appropriate MR measurement methods based on nuclei other than 1H. Biofilms consist of micro-organisms encased in an excreted polymeric substances (EPS) matrix, the purpose of which is to anchor them onto the solid support surface. They are widely encountered in engineering capacities, ranging from bioreactors and subsurface biofilm barriers for pollution control (in which biofilm growth and retention is desirable) to bio-fouling (in which case micro-organism retention is highly undesirable) of process equipment, water courses and rock near oil-recovery wells, as well as in various medical applications (e.g. urinary catheters). Transport/accumulation of nutrients into, and metabolic products away from, the micro-organisms is crucial to their growth, while penetration of biocides into biofilms is a major factor which limits their efficacy. A major limitation in our ability to either control or exploit biofilm formation lies in there being no easily accessible quantitative description of the meso- and macro-scale transport and chemistry occurring within these complex systems. Multi-nuclear MR, by virtue of its non-invasive, chemically-selective nature, in addition to its ability to quantify transport, will be developed to provide such a quantitative description. Various aspects of the MR technique are, as yet, unproven. However the ground broken in this study will be widely applicable in reaction, reservoir and tissue engineering, and materials processing, as well as providing vital information that could be used to tackle an unglamorous but important medical problem (catheter bio-fouling) which is a contributory cause of death for many of our ageing population and susceptible spinal injury patients.