Antimicrobial Efficacy of Soy Isoflavones against Listeria Monocytogenes

Food-borne pathogenic biofilms in food processing and manufacturing industries have led to food spoilage, bio fouling, and food-borne illnesses. Antimicrobial coatings and films serve as a barrier against bacterial contamination. Chemical or synthetic antimicrobial coatings are widely used today which are not necessarily safe. The demand for antimicrobial coatings in food applications is estimated to reach USD 2.7 billion in the year 2018. With an increased demand for antimicrobial coatings and a need to effectively inhibit microbial biofilms, new coatings need to be developed. The unique properties of soy isoflavones such as biodegradability, biocompatibility and edibility over artificial polymer or chemical based coatings could make it an ideal antimicrobial agent to prevent bacterial growth in a variety of environments.  This research explores the effectiveness of soy isoflavones for use in the food industry by assessing their antimicrobial efficacy against Listeria monocytogenes using microtiter plate assay (MPA) and imaging techniques. The end results of this research would help the food industry to develop natural, novel, eco-friendly, edible, biocompatible, biodegradable, multi-purpose antimicrobial coatings or agents to inhibit the growth of microbial biofilm and provide food safety to the consumers. It would also result in a significant contribution to Ontarian soy growers by increasing their opportunities and adding value to their crop. It would be very significant to the Government in reducing the cost spent on health sector and help in the mission of providing “health and wellness” to the citizens of Canada.

Understanding the Adhesion Kinetics of Biofilms on Food Contact Surfaces using Nanotechnology

Biofouling on food industry equipment leads to economic losses from corrosion, equipment impairment, and reduced heat transfer efficiency.  Common food contact surfaces such as stainless steel are robust; however, they can encourage bacterial attachment and subsequent biofilm formation.  Attachment of bacteria on food contact surfaces is the first step towards biofilm development.  The overall goal of this research is to better understand the interaction between the microorganisms, Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA), and substrates on which these microorganisms adhere.  The relation between the bacterial cell surface electrokinetic potential at the nanoscale, and the ability of these microorganisms to attach to stainless steel and gold surfaces was assessed through Atomic Force Microscopy and Kelvin Probe Force Microscopy.

AFM results showed that no microbial attachment occurred after 3 hours of incubation on non-functionalized surfaces while poly-L-lysine functionalized surfaces showed microbial attachment after 30 minutes.  Poly-L-lysine is a common food preservative and can act as a microbial attachment factor depending on bond orientation.  KPFM data revealed positive surface potentials on stainless steel compared to negative surface charges on gold surfaces.  Pseudomonas aeruginosa showed larger membrane potentials than MRSA, with MRSA showing noticeably different membrane potentials between gold and stainless steel surfaces.

Microstructure of food matrix determines the physical, textural and sensory properties of end products. For predicting moisture transport and viscoelastic stresses during sorption and drying of wheat grains it is crucial to determine the  precise internal structure of wheat. Lack of 3-dimensional morphology of the internal features of wheat kernel at the micro-nano scale is a constraint to understand the structure-function relationship, and the coupling between the heat and the mass-transfer processes during drying, cooking and processing. Micro X-ray computed tomography (X-ray CT) is a powerful tool for non-invasive high resolution 3-D visualisation and characterization of the internal micro-structure of cellular food products.

The goals of this study are:(i) to accurately investigate the 3-dimensional spatial distribution of the internal microstructure of insect and sprout damaged wheat kernels using X-ray micro CT images, and (ii) to determine the morphometric parameters such as porosity, anisotropy (3D symmetry) and absolute permeability of the matrix structures inside the insect and sprout damaged wheat kernels.

Cross contamination of food by pathogens via surfaces increases the risk of the propagation of infectious diseases. E.Coli and Listeria species are the predominant bacterium that causes fouling on food processing surfaces, chutes, cutting tables, tube systems, pipes and conveyor belts. The knowledge of the ability of the material surface for bacterial colonization is essential for selecting and designing surfaces for food processing. Characterization and optimization of surface pre-treatment with anti-microbial coatings will prevent the biofilm formation, and thereby will ensure food safety. Silver zeolite (SZ) acts as a smart surface coating. Upon contact with moisture, silver and highly reactive oxygen ions are released from the crystalline structure. The silver ions interact with the bacteria’s proteins and DNA. The oxygen acts as a free radical oxidizing components within the bacteria. The objectives of this project are (i) To investigate the interaction of the food pathogenic bacteria with various surfaces, and (ii) To assess the rate of antimicrobial activity of selected disinfectants against the pathogenic bacteria.

Nanomedicine is the technology that uses nanoscale or nanostructured materials such as bionanorobots in medicine that according to their structure have unique medical effects. A Nanorobot is defined as any smart structure which is capable of actuation, sensing, signaling, information processing, intelligence, manipulation and swarm behaviour at the nano scale. Bio-nanorobots are nanorobots designed and inspired by harnessing properties of biological materials such as DNAs and peptides. Bionanorobots made using bio-instrumentation have several clinical advantages including targeted drug delivery, nano sized hybrid therapeutics (low dosage) and early diagnosis at cellular level. Realizing Bionanorobots for biomedical applications raises several challenges. The objective of this project is to design an intelligent system using fuzzy logic and neural networks for diagnosis and treatment of tumours in humans using bionanorobots.

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