Spotlight on USDA-ARS Scientists

For nearly ten years, scientists at Purdue University and the USDA-ARS Eastern Regional Research Center have established a strong partnership and have collaborated on a number of research and outreach projects. We are proud of the relationship that has continually grown since we joined forces in 1999. For this annual report, we highlight two USDA-ARS scientists that have been instrumental in fostering our overall CFSE effort.

Dr. Andrew Gehring
Research Chemist

Dr. Andrew Gehring began his career with the USDA as a T.W. Edminster Postdoctoral Research Associate with the ARS's Eastern Regional Research Center located just outside of Philadelphia. His research focused on developing biosensor-based methods for rapid detection of foodborne bacterial pathogens, including immunomagnetic electrochemical methods for Salmonella spp. and E. coli O157:H7. Dr. Gehring later accepted a permanent position with the ARS as a leather chemist, a seemingly unrelated area of research. However, he eventually began working on rapid dehairing, a food safety initiative during the slaughter of cattle. Participation in this team-based research yielded the generation of a series of publications (one of which was selected to be paper of the year in the Journal of the American Leather Chemists Association), an international patent application, and a gold medal in private sector involvement awarded by the Philadelphia Federal Executive Board. He later returned to his earlier biosensor work on developing rapid methods for post-harvest food safety analysis where he currently applies multiplexed, antibody-based microarray technology to the rapid, high-throughput screening of foods for bacterial pathogens and associated toxins.

  • Gehring, A.G., Albin, D.M., Bhunia, A., Reed, S.A., Tu, S., Uknalis, J. Antibody microarray detection of Escherichia coli O157:H7: Quantification, assay limitations, and capture efficiency. Analytical Chemistry. 2006. v. 78. p. 6601-6607.
  • Gehring, A.G., Bailey, D.G., DiMaio, G.L., Crowther, J.C. Improved hide quality and rapid unhairing. Journal of the American Leather Chemists Association. 2002. v. 97. p. 339-348.

Dr. George Paoli
Research Microbiologist

Dr. George Paoli earned his Ph.D. from The Ohio State University studying the molecular biology, biochemistry, and physiology of carbon dioxide fixation in photosynthetic bacteria. He then went to the Air Force Research Laboratory as a National Research Council and Oak Ridge Institute for Scientific Education Postdoctoral Fellow to study the microbial biodegradation of nitroaromatic pollutants. After working for two years in the Microbial Biophysics and Residue Chemistry Research Unit at the USDA's Eastern Regional Research Center as a research associate, Dr. Paoli accepted a permanent position there as a research microbiologist. In his current research, Dr. Paoli employs modern molecular techniques, including antibody phage display, to develop reagents and methods for the detection of microbial pathogens in foods. In particular, Dr. Paoli and his coworkers selected a Listeria monocytogenes-specific phage displayed antibody fragment and used this antibody fragment to develop immunomagnetic beads, other immunoreagents, and an optical biosensor for the detection of L. monocytogenes. Dr. Paoli has also applied microbiological, immunological, and PCR-based methods for the detection and typing of Yersinia pestis, the causative agent of bubonic plague and a possible threat to food security.

  • Nanduria, V., Bhunia, A.K., Tu, S-I, Paoli, G.C., Brewster, J.D. SPR biosensor for the detection of L. monocytogenes using phage-displayed antibody. Biosensors and Bioelectronics. 2007. v. 23. p. 248-252.
  • Paoli, G.C., Kleina, L.G., Brewster, J.D. Development of Listeria monocytogenes specific immunomagnetic beads using a single-chain antibody fragment. Foodborne Pathogens and Disease. 2007. v. 4. p. 74-83.
  • Paoli, G.C., Bhunia, A.K., Bayles, D.O. Listeria monocytogenes. Fratamico, P.M., Bhunia, A.K., Smith J.L., editors. Caister Academic Press, Wymondham, Norfolk UK. Foodborne Pathogens: Microbiology and Molecular Biology. 2005. p. 295-325.

Dr. Gehring and Dr. Paoli

Since the inception of the Center for Food Safety Engineering, there has been a strong emphasis on interaction and collaboration with scientists from the UDSA-ARS Eastern Regional Research Center. This collaboration has been fostered through interaction between scientists during annual Purdue-CFSE/ARS-ERRC research planning workshops, annual participation by Purdue-CFSE and ARS-ERRC scientists in the Molecular Detection Symposium during the International Workshop on Rapid Methods and Automation in Microbiology at Kansas State University, and more recently, an invitation for Purdue-CFSE scientists to participate in an ARS-FSIS (Food Safety Inspection Service) research planning workshop, aimed at identifying specific FSIS needs.

In addition, ARS scientists have hosted Purdue students and post-doctoral fellows at ERRC who are conducting collaborative research. These collaborative research efforts have been presented at scientific meetings and have resulted in several publications in peer-reviewed journals.

Drs. Andrew Gehring and Arun Bhunia have interacted extensively on their mutual interest in the development of a mixed culture enrichment (Salmonella, E. coli O157:H7, Listeria monocytogenes, and Yersinia enterocolitica) in support of their work on multiplexed antibody-based microarray for detection of pathogenic bacteria from food. They have worked both independently and collaboratively on the development of the antibody-based microarray and have co-authored one publication on the subject. As part of her doctoral training, one of Dr. Bhunia's doctoral students, Kristen Nanchansky, spent a summer at ERRC working with Dr. Gehring developing a chemiluminescent immunoassay for the detection of L. monocytogenes. In addition, Drs. Bhunia and Gehring organized and co-chaired a symposium on Optical Technologies for Industrial, Environmental, and Biological Sensing-Food Safety and Agricultural Monitoring for the International Society for Optical Engineering Photonics East.

Drs. George Paoli and Arun Bhunia share an interest in studying the foodborne pathogen Listeria monocytogenes. Dr. Bhunia has developed and characterized a number of monoclonal antibodies against L. monocytogenes, and Dr. Paoli has applied antibody phage display to select a single-chain antibody specific to L. monocytogenes. In addition to co-authoring a chapter on the bacterium in a recently published book on the microbiology and molecular biology of foodborne pathogens, Drs. Paoli and Bhunia collaborated in supervising a post-doctoral study by Dr. Viswaprakash Nanduri on the development of a phage displayed antibody-based surface plasmon resonance optical biosensor for the detection of L. monocytogenes.

International Collaboration: CFSE goes to China

By invitation of Dr. Xianming Shi, the deputy director of the Bor-Luh Chinese Food Safety Center, Purdue scientists Arun Bhunia and Richard Linton joined USDA-ARS scientists (Shu-I Tu, Andrew Gehring, Yiping He, and George Paoli) and Dr. Jim Lindsay (ARS National Program Leader for Food Safety) in China in May 2008 to meet with representatives from Jiao-Tong University in Shanghai. At the meeting an agreement was signed forming a joint U.S.-Sino Food Safety Research Center between ARS and the Chinese Ministry of Science and Technology. We had a very productive meeting and already have plans to work together with USDA-ARS and Jiao-Tong University scientists in the near future. While in Shanghai, the group also attended and presented at the 10th World Congress on Biosensors.