Design of a real time biorecognition system to detect foodborne pathogens- DNA Biosensor Vijayalakshmi Velusamy a , Khalil Arshak a1 , Olga Korostynska a , Kamila Oliwa b , Catherine Adley b2 a Electronic and Computer Engineering Department, University of Limerick, Limerick, Ireland b Microbiology Laboratory, Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland 1 khalil.arshak@ul.ie , 2 catherine.adley@ul.ie Abstract—In recent years, there has been numerous research papers reported on the use of DNA biosensors for the detection of foodborne pathogens. However, none of the papers to date reflect the detection of foodborne pathogens directly in food using a handheld DNA biosensor. It has been shown in our recent work that DNA sequences named BCFomp1/BCRomp1 can be used for the specific detection of the Bacillus cereus (B. cereus) group species (spp). Analysis of these DNA probes using standard PCR analysis showed that the minimum level of detection was 10 3 CFU/ml. The lowest number of bacterial cell per reaction tube that can be amplified was 5 CFU and the minimum quantity of DNA that can be amplified was found to be 1pg. The prime intention of this paper was to pioneer the design and fabrication of a single-strand (ss) DNA biosensor for the detection of the B. cereus group spp. Cyclic voltammetry (CV) was used to develop and test a model DNA-based biosensor. The electrically conducting polymer, polypyrrole was used as a platform for immobilizing DNA on the gold electrode surface. The model DNA biosensor generated unique CV signals between complementary and noncomplementary oligonucleotides and it proved to be effective. Keywords: Bacillus cereus spp; foodborne pathogen detection; DNA; cyclic voltammetry; biosensor; conducting polymers. I. INTRODUCTION Foodborne diseases are a worldwide growing health problem involving a wide spectrum of illnesses caused by microbial, viral, parasitic or chemical contamination of food. Food diarrhoeal diseases can lead to serious illnesses and in some cases to death. Some diseases are caused by toxins from the “disease-causing” microbe, others by the human body’s reactions to the microbe itself. Apart from Clostridium botulinum, Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spps, Shigella spps, the most frequently isolated bacterial foodborne pathogens are the B. cereus group spp [1], which include: Bacillus cereus, Bacillus mycoides, Bacillus pseudomycoides, Bacillus weihenstephanensis, Bacillus thuringiensis, Bacillus anthracis [2, 3]. Growth of B. cereus results in production of several highly active toxins. Therefore, consumption of food containing >10 6 bacteria/gm may result in emetic and diarrhoeal syndromes. The most common source of this bacterium is found in liquid food products, milk powder, mixed food products and is of particular concern in the baby formula industry [4]. However, they can also be found in other foods such as turkey, beef, rice and noodles. The emetic toxin type is also known to grow well in mashed potatoes, rice dishes and vegetable sprouts [5]. Although the safety of food has dramatically improved overall, the progress is uneven and foodborne outbreaks from microbial contamination, chemicals and toxins are common in many countries [6]. International trade statistics (2007) by World Trade Organization (WTO) reported that Europe has accounted for 46% of world exports of agricultural products, where food represents 80% of agricultural exports [7]. Trading of contaminated food between countries increases the potential for outbreaks and consequently, health risks posed by microbial pathogens in food are of major concern to all governments. In November 2007, the U.S. Food and Drug Administration (FDA) developed a comprehensive ‘Food Protection Plan’, in which it was outlined that food must be considered as a potential vehicle for intentional contamination [8]. Such intentional contamination of food could result in human or animal illnesses and deaths, as well as economic losses. It has been reported in EU legislation on microbiological criteria for foodstuffs, that “foodstuffs should not contain micro-organisms or their toxins or metabolites in quantities that present an unacceptable risk for human health”, as laid down in Regulation (EC) No 2073/2005 [9]. Recently, the World Health Assembly (WHA) established a global surveillance system for public health emergencies of international concern by adopting the International Health Regulations (IHR) which came into force in June 2007 [10]. These current legislations on food and health provide an enhanced scientific activity into the area of food pathogen detection. The role of pathogen detection technology is vital and is the key to the prevention and identification of problems related to health and safety. Therefore, giving importance to develop a DNA biosensor for the rapid detection of bacterial pathogens in food, we first designed DNA probes, which are SAS 2009 – IEEE Sensors Applications Symposium New Orleans, LA, USA - February 17-19, 2009 9781-4244-2787-1/09/$25.00 ©2009 IEEE Authorized licensed use limited to: IEEE Xplore. Downloaded on April 15, 2009 at 11:18 from IEEE Xplore. Restrictions apply.