Member SpotlightsDevelopment of Biosensors for Microorganism Detection Srinivasan Durairaj, Ph.D. A Science Advisory Board Member Since 2002  Srinivasan Durairaj, Ph.D., is a Research Associate at Michigan State University (MSU) where he develops biosensors used in microbe detection in food and water sources. Durairaj received his Ph.D. at Bharathiar University, India (1997), before pursuing a research position at MSU. His main project concerns the development of a biosensor for detection of bovine viral diarrhea virus (BVDV). Durairaj belongs to the Association of Microbiologists of India, the International Mentoring Program of the American Society for Microbiology, and the Bacteriology and Teaching committees of the American Phytopathological Society. He’s also an Associate Editor for the Internet Journal of Microbiology and the Research Journal of Microbiology. Academic & Professional Background I received my Ph.D. from Bharathiar University, India in 1997. After completing my Ph.D., I started my career as a Lecturer in Microbiology and worked in India for five years. During that period I was instrumental in initiating a postgraduate program in microbiology and then moved to a research department in microbiology, where I conducted a University Grants Commission sponsored national level seminar on microbial technology. This was a great experience, being able to interact with scientists from all over India as an organizing secretary, and students from my department got great exposure by this seminar. The following year I received an appointment as a Lecturer in the Department of Biology at the University of South Pacific, Suva, Fiji Islands. I am basically a traditional microbiologist and I always want to learn about molecular techniques and their use in microbiology. After this, I got a chance to work as a Research Associate with Dr. Lee Kroos’s Lab at Michigan State University. All of my research background obtained in the past years has helped me to advance without any major difficulties, and at the same time I have acquired new skills and other techniques. I have been enjoying my research here at Michigan State University for the past six years. Current Research My main research interest is to develop a portable and disposable biosensor for the detection of pathogenic microorganisms in food and water. Health care professionals, bioterrorism rapid-response teams, food-safety personnel and water treatment authorities can use the biosensor for early detection and ensuring the public’s safety. Current methods for the detection of pathogens are based on conventional microbiological culturing techniques followed by biochemical identification. These techniques are time consuming and may take 2 to 7 days for confirmation, and may include costly and laborious sample preparation. Analysis of large volumes of samples is also a great challenge with current methods. It is clear that monitoring pathogenic microorganisms in food and water is a difficult and expensive task. The new technologies developed by laboratories have not been sufficiently validated in the field conditions for general use at this point in time. This indicates the need for a new standard method that is accurate, quick, portable and inexpensive. Hence, I would like to develop and evaluate an innovative combination of rapid, sensitive, specific, and quantitative detection methods to meet these current needs. My current role in the lab is validation of our current biosensors in field samples, writing reports and research papers, coordinating graduate and undergraduate student activities, supervising laboratory activities and helping the lab in ways that will facilitate the successful implementation of research projects. Career Motivations & Expectations My father was a major influence in my pursuit to work in research. My childhood consisted of a traditional rural Indian village with an agricultural emphasis. Later my education in the city atmosphere made me think about the complexity and diversity of life and the human influences on it. When I was younger, I would go with my father to the fields and he would use different kinds of soils and manures to grow the crops. Even though I was young, I knew there was something unique in the soils that made it better or worse for a particular crop and this is when my curiosity for research started to grow. It was my undergraduate microbiology lecture that made me interested in identifying the microscopic organisms. These microorganisms play a major role in food quality and safety, which has a great influence on human health. My father’s influence as a role model and mentor in my life was very profound. I wanted my career to develop in the area of microbiology, especially in detecting pathogenic microorganisms. I learned during my graduate studies that the traditional microbial methods alone are not good enough to achieve my goals. The time I spent in Dr. Kroos’s lab helped me to learn the basic molecular techniques. Now in my present lab I am using those techniques and advancing my research in the same area using biosensor technology. Future Endeavors My goal is to work in an academic environment, so that I can develop a biosensor-based program to solve some of the challenging problems and then take this technology to the common man. Also, I want to train students in this highly interdisciplinary area of research and finally establish my lab as a well-known group for biosensors so I can be helpful in improving the lives of people around the world. My goal is to continue enjoying the nature of my work, to spread the enthusiasm I have, and encourage others to fulfill their potential. Life Outside the Lab I live in East Lansing, MI with my wife Sangeetha and daughter Vidhula. My hobbies are watching Spartan football games and taking my daughter swimming. Other interests include reading history books and organizing our community group gathering. I like running inside the beautiful MSU campus and cycling with my daughter on the weekends in the spring. Please describe your research interests in more detail. My Ph.D. thesis is on the antimicrobial activity of microorganisms. I started my career as a lecturer, but I was always interested in doing research in pathogenic microorganism’s contamination in food and water. Besides that primary goal, I’m also interested in identifying the pathogens from different environments. When I was using microbial techniques, molecular methods were gaining momentum. But after learning those methods, I was not satisfied. I think that biosensors can make a big impact on the identification of pathogens, if it is successful. What was your previous background in working with biosensors before deciding to develop a sensitive, specific, and rapid field-based biosensor to detect BVDV? My previous experience focuses around the pathogens and the techniques used for their identification. My molecular biology background helped me know and analyze the pathogenic genes and how to use molecular techniques for proper experiential design. My background on the engineering of the biosensor is relatively new with a great deal of potential for growth. I now understand how much the field has grown and much potential lies in it. What achievements/failures have you experienced thus far? What challenges have you run into? So far we are able to use our biosensors to detect the pathogen from pure cultures. The major challenge we are facing is using the real sample from the original matrix. The work is progressing and we are seeing great improvements. The challenges I am seeing are the keystone challenges the field faces, using original sample materials for field based detections; particularly, aged samples and decreased volumes. For my control experiments, the low concentrations of the virus in the sample make detection of the virus by RT-PCR very difficult. In addition to extracting pathogens from the sample matrix, other challenges include: increasing sensitivity of the biosensor, improving reliability/reproducibility of test results, reducing risk of false readings (particularly false negatives), ensuring specificity, and reducing response time of the sensor. How did you design the mechanism responsible for singling out the target? What is the detector element? There has been considerable interest in the development of biosensors based on electrochemical immunoassays using conductive polymers, like polyaniline, polypyrrole, polyacetylene, and polythiophene for analytical and industrial purposes. The conductive polymer acts as an electrochemical transducer to convert the biological signal to an electrical signal. Polyaniline in particular, has been one of the most extensively investigated conducting polymers, due to its excellent stability in liquid form, promising electronic properties, and strong bimolecular interactions. Our lab has developed a novel magnetic polyaniline, which is used as a label for the electrochemical sandwich biosensor assay for the detection of microorganisms. In addition, the magnetic property of the polyaniline allows for magnetic separation of captured cells from their surrounding matrix. The biosensor is connected to a multi-meter and resistance measurements are recorded for 6 minutes, at 2-minute intervals. A drop in resistance will be determined from the difference between the resistance output of the blank and the resistance output of the samples. The resistance drop is due to the electron transfer facilitated by the polyaniline-labeled antibody between the electrodes. The change in resistance is proportional to the concentration of cells in the sample. Are you directly involved in the bioengineering of the biosensor or the application of the biosensor for BVDV detection? My role is mostly involved in the microbiology and molecular biology part of the project. I manage the cell lines all the way until sample pre-processing. I use culturing and plating techniques to monitor viral counts in sample fluids, which are then correlated with biosensor outputs in order to “calibrate” the biosensor. What technology is used to display the results? Currently results are read as resistance measurements from a digital multi-meter, connected to electrodes on the biosensor. Resistance values are then manually transferred into Microsoft Excel and manipulated for clear display of test results. In the future, the resistance meter could be wired directly to the computer and a program could be written to perform data collection and manipulation automatically. What applications would your biosensor be used for outside the lab? The World Health Organization has indicated that terrorists may try to contaminate the food supplies and has urged all countries to strengthen their surveillance. An increased demand for high throughput screening, especially in the clinical and pharmaceutical industries, has produced several technological developments for detecting biomolecules. Some of these technologies include ELISA, PCR, flow cytometry, spectroscopy, etc. These detection methods are good for laboratory purposes, but they are time consuming, require specialized training, and have complicated processing steps to culture or extract the pathogen from samples. A field-ready biosensor, however, is inexpensive, easy to use, portable, and gives results in minutes. Health care professionals, bioterrorism rapid-response teams, food-safety personnel, and water treatment authorities can use biosensors. If you'd like to comment on this article, or join in discussion on other topics with SAB members, please visit our community forums. Publications T. Suresh, A.A.M. Hatha, D. Srinivasan, Sangeetha Nathan and P. Lakshmanaperumal Samy (2006). Prevalance and antimicrobial resistance of Salmonella enteritidis and other salmonellas in the eggs and egg-storing trays from retails markets of Coimbatore, South India. Food Microbiolgy (23): 294-299. D. Srinivasan and Lee Kroos (2005). Mutational Analysis of the fruA Promoter Region Demonstrates that C box and 5-bp Elements are Important for Expression of an Essential Developmental Gene of Myxococcus Xanthus. Journal of Bacteriology (186):17:5961-5967. T. Suresh, A.A.M. Hatha, D. Srinivasan, Sangeetha Nathan and P. Lakshmanaperumal Samy (2004). Salmonella cross-contamination in retail chicken outlets and the efficacy of spice extracts on Salmonella enteritidis growth Inhibition on various surfaces. Microbes and Environment (19):4: 286-291. ### << Previous Next >> [ View All Member Spotlights ] |
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