Karl R. Matthews Associate Professor Rutgers University Department of Food Science 65 Dudley Road School of Env & Biol Sciences Rutgers University New Brunswick. NJ 08901-8520 (732) 932-9611 x219 FAX - 6776 matthews@aesop.rutgers.edu

Use of tools of biotechnology to address questions of virulence and survival of foodborne pathogens

Through support from USDA grants we are addressing the role that fertilization with manure may play in the contamination of fresh produce and about the extent to which contamination can arise from irrigation with contaminated water. This project complements an additional project addressing the microbial safety of alfalfa sprouts. We utilize marker bacteria expressing green fluorescent protein (GFP) to study behavior of bacteria in plants and other food matrix's.

Marker bacteria are visualized using fluorescence microscopy and images captured with a CCD camera. Alfalfa seeds are contaminated with marker bacteria. germinated. and sprouts grown to maturity in specially constructed chambers. The sprouts are harvested and processed for imaging to determine spatial location of marker bacteria.

Research investigating membrane vesicles released by E. coli O157:H7 lead to the discovery that such vesicles contain chromosomal. plasmid. and phage DNA. Although other researchers have demonstrated vesicles contain DNA. and that DNA can be transferred: transformation and expression has not been demonstrated previously. Our research demonstrates that shiga toxin is not only produced. but expressed in an active form based on verocytotoxicity studies.

Microorganisms use many methods to ensure their survival including entering a viable but non-culturable state to prolong survival under adverse growth conditions. We demonstrate E. coli O157:H7 enter the VNC state. alone this finding is significant. However. our research demonstrates that E. coli O157:H7 do not enter the VNC state in ground beef . but can exist in the VNC state in ground beef.

Finally. as stated we are interested in development of methods for identifying foodborne pathogens. Currently we are developing an RT-PCR assay for screening samples for the presence of only viable E. coli O157:H7 in food samples. The assay is particularly beneficial for detecting cells. which grow poorly or not at all when standard growth conditions are used.

Selected Publications

Pang HJ, Lo CY, Matthews KR. (2007) Influence of immunomodulation on the development of Listeria monocytogenes infection in aged guinea pigs. FEMS Immunol Med Microbiol. 49(3):415-24.

Tabak M, Scher K, Hartog E, Romling U, Matthews KR, Chikindas ML, Yaron S. (2007)
Effect of triclosan on Salmonella typhimurium at different growth stages and in biofilms.
FEMS Microbiol Lett. 267(2):200-6.

Solomon EB. Matthews KR. (2005) Use of fluorescent microspheres as a tool to investigate bacterial interactions with growing plants. J Food Prot. 68(4):870-3.

Golding SS. Matthews KR. (2004) Intrinsic mechanism decreases susceptibility of Escherichia coli O157:H7 to multiple antibiotics. J Food Prot. 67(1):34-9.

Solomon EB. Pang HJ. Matthews KR. (2003) Persistence of Escherichia coli O157:H7 on lettuce plants following spray irrigation with contaminated water. J Food Prot. 66(12):2198-202.

Gandhi M. Matthews KR. (2003) Efficacy of chlorine and calcinated calcium treatment of alfalfa seeds and sprouts to eliminate Salmonella. Int J Food Microbiol. 87(3):301-6.

Yaron. S.. and Matthews. K.R. (2002). A reverse transcriptase-PCR assay for detection of viable Escherichia coli O157:H7. J. Appl. Microbiol. 92:663-640.

Solomon. E. B.. Potenski. C.J. and Matthews. K.R. (2002). Effect of irrigation method on transmission to and persistence of Escherichia coli O157:H7 on lettuce. J. Food Prot. 65:673-676.

Solomon. E.B.. Yaron. S. and Matthews. K.R. (2002). Transmission and internalization of Escherichia coli O157:H7 from contaminated manure and irrigation water into lettuce plant tissue. Appl. Environ. Microbiol. 68:397-400.

Kolling. G.. and Matthews. K.R. (2001). Examination of recovery in vitro and in vivo of nonculturable Escherichia coli O157:H7. Appl. Environ. Microbiol. 67:3928-3933.

Gandhi. M.. Golding. S.. Yaron. S. and Matthews. K.R. (2001). Use of green fluorescent protein expressing Salmonella Stanley to investigate survival. spatial location. and control on alfalfa sprouts. J. Food Prot. 64:1891-1898.

Zhao. L.. and Matthews. K.R. (2000). Influence of starvation. temperature. and pH on culturability of Escherichia coli O157:H7. J. Food safety. 20:191-205.

Yaron. S.. Kolling. G.L.. Simon. L. and Matthews. K.R. (2000). Vesicle transfer of virulence genes from Escherichia coli O157:H7 to other enteric bacteria. Appl. Environ. Microbiol.66:4414-4420.

Kolling. G.L.. and Matthews. K.R. (1999). Export of virulence genes and shiga toxin by membrane vesicles of Escherichia coli O157:H7. Appl. Environ. Microbiol. 65:1843-1848.