New Capability for Bacterial Testing in the Food Production Environment

This Follow on Fund programme of research involves the development of an innovative bionanosensor with superior performance for the detection of bacterial pathogens in a sensitive, quantitative and multiplexed manner for use in chilled food production. This involves further development of a nanoparticle based analytical technology for the detection of Listeria, in particular L. monocytogenesis following on from previous BBSRC funding (BB/M018652/1, BB/R00899X/1). Current methods for detecting bacteria are time consuming (1-2 days in the case of bacteria culturing on selective media, but in reality 7 day turnaround for food production facilities where laboratories are located offsite), is expensive and requires specialised personnel and equipment. Therefore, there is a real need for faster, simpler and reliable isolation and detection of bacterial pathogens that can be carried out in the food production environment. To address this need we will develop a simple, portable protype device capable of point of use (POU) detection of bacteria, specifically Listeria. The research involves the use of an optical detection technique called Raman scattering which will be developed for the POU detection of bacterial pathogens. If light of a particular wavelength is directed onto a molecule then some of the scattered light will change wavelength. This change in wavelength is related to the structure of the molecules and provides a molecular fingerprint that can be used for definitive identification. However, Raman scattering is a weak process and the signal can be greatly enhanced if the molecule is coloured and adsorbed onto a roughened metal surface (surface enhanced resonance Raman). In this case we will use gold nanoparticles as the gold metal surface will amplify the Raman scattering from a molecule on the surface producing a fingerprint unique to the molecule allowing the composition of mixtures to be easily identified without separation steps. A novel bionanosensor for the detection of multiple Listeria pathogens in one assay combined with enhanced Raman detection will be developed. This will use magnetic nanoparticles which have a biomolecule on the surface which will bind to the surface of the bacteria. This will allow isolation and separation of bacteria from the surrounding medium upon application of a magnetic field. Additionally, gold nanoparticles which are functionalised with a coloured molecule or label, resulting in intense surface enhanced Raman signals, and an antibody which will bind specifically to a particular strain of bacteria will be added. When the correct bacteria are present, binding will occur resulting in magnetic isolation and concentration of the bacteria from the matrix. By using a different label for each bacteria, a unique spectrum will be produced allowing multiple species to be detected simultaneously. A portable Raman spectrometer will be used to detect the bacteria present at the POU. We will partner with The Samworth Brothers Group (family-owned food manufacturing business with 12 production sites, generating an annual turnover of c. £ 1 bn) and Wasatch Photonics Inc to further develop our initial research towards prototype development. This will allow the technology to be moved further along the translational pathway with a view to developing the laboratory based approach into POU detection that can be used directly in food production areas. Our future aim, pending successful demonstration of POU detection, is to form a spin out company to commercialise the technology having already established a clear need through our partners Samworth Brothers and their customer network, as well as a market assessment report.