Valerie Harwood

Valerie Harwood
Professor

Contact

Office: BSF 131
Phone: 813-974-1524
Fax: 974-3263
Email: vharwood@usf.edu

Education

1992 Ph.D. in Biomedical Sciences. Old Dominion University and Eastern Virginia Medical School.

1983 B.A. in Biology. State University of New York at Plattsburgh.

1980 B.A. in French. Iowa State University.

Research

Water quality microbiology and microbial ecology

Work in my laboratory focuses on water quality. Microorganisms that enter the water via sewage contamination can sicken entire communities and cause death. We are trying to find better ways to determine the source(s) of fecal contamination in water, whether it originates from human sewage, pets, agricultural animals, or wild animals. My lab is best known for its work on microbial source tracking (MST), described below.

Fecal indicator bacteria, such as fecal coliforms, E. coli and Enterococcus species are used extensively in the US and throughout the world as signals, or “red flags” for fecal contamination in water, yet these organisms can enter the water in the feces of animals as diverse as cattle, birds and humans. In subtropical waters such as those found in Florida, there is potential for growth of these indicator organisms. If growth occurs after indicator organisms enter water, sediments and soil, the indicator organism will tend to be present at high levels in the absence of pathogens, nullifying its use as an indicator of water quality and its predictive value for risk to human health. The goal of microbial source tracking (MST) is identification of the source of fecal indicator bacteria, and possibly pathogens, in environmental waters. These studies have implications for how stormwater is managed, how beach water quality is monitored, and how water quality is maintained or improved throughout the U.S. and in other countries.

We employ state-of-the-science methods such as quantitative PCR (qPCR) to quantify genes of bacteria and viruses that indicate contamination from specific sources. We work with state and federal agencies such as the Florida Department of Environmental Protection, the U.S. Environmental Protection Agency and the U.S. Department of Agriculture to develop new methods and test emerging ones in locations ranging from Florida to Arkansas, California, Colorado, New Mexico, Oklahoma, Virginia and New Zealand.

We are also investigating the potential for growth of E. coli, Enterococcus and other indicator organisms in Florida sediments and waters, and the stability of genomic fingerprints for these organisms under environmental conditions. The effect of agrochemicals such as fertilizer, malathion and chlorothalonil on indicator bacteria and pathogens is also under investigation. Community structure and indicator diversity in anthropogenically impacted vs. disturbed environments constitutes another area of ongoing research.

Other research interests also include qPCR quantification and population biology of the marine bacterium Vibrio vulnificus, an opportunistic pathogen that can cause septicemia and rapid death. V. vulnificus is a significant cause of illness and death in Florida and other states, generally due to consumption of raw shellfish but also from wound infections.

Specialty Area

Environmental Microbiology

Recent Publications

Z. Stanley,V.J. Harwood, and J.R. Rohr. The effect of agrochemicals on indicator bacteria densities in outdoor mesocosms. Environmental Microbiology. In Press.

2010. B.A. Badgley, B. Nayak and V.J. Harwood. The importance of sediment and submerged aquatic vegetation as potential habitats for persistent strains of enterococci in a subtropical watershed. Water Research. In Press.

2010. C. Staley and V.J. Harwood. A review of genetic typing studies of Vibrio cholera, V. parahaemolyticus and V. vulnificus. Journal of AOAC International. In Press.

2010. B.A. Badgley, F.I.M. Thomas and V.J. Harwood. The Effects of Submerged Aquatic Vegetation on the Persistence of Environmental Populations of Enterococcus spp. in Outdoor Mesocosms Environmental Microbiology, In Press.

2010. J.L. Weidhaas, T. W. Macbeth, R. L. Olsen, M. J. Sadowsky, D.Norat and V. J. Harwood. Identification of a poultry litter-specific DNA marker gene and development of a 16S rRNA-based quantitative PCR assay. J. Appl. Microbiol. Epub ahead of print.

2010. Abdelzaher A, Wright M, Ortega C, Solo-Gabriele H, Miller G, Elmir S, Newman X, Shih P, Bonilla JA, Bonilla TD, Palmer CJ, Scott T, Lukasik J, Harwood VJ, McQuaig S, Sinigalliano C, Gidley M, Plano L, Zhu X, Wang JD, Fleming L. Presence of pathogens and indicator microbes at a non-point source subtropical recreational marine beach. Appl. Environ. Microbiol. 76:724-732.

2010. S.D. Leskinen, M. Brownell, D.V. Lim and V.J. Harwood. Hollow-fiber ultrafiltration and PCR detection of human-associated genetic markers from various types of surface water in Florida. Appl. Environ. Microbiol. 76:4116-4117.

2009. V. J. Harwood, M. Brownell, S. Wang, J. Lepo, R.D. Ellender, A. Ajidahun, K. N. Hellein, E. Kennedy, X. Ye and C. Flood. Validation and field testing of library-independent microbial source tracking methods in the Gulf of Mexico. Water Research. 43:4812-4819.

2009. T.M. Scott, V.J. Harwood, W. Ahmed, Y. Masago, and J.B. Rose. Comment on “Environmental occurrence of the enterococcal surface protein (esp) gene is an unreliable indicator of human fecal contamination. Env. Sci. Technol. 43:6434-6435.

2009. A. Korajkic, B.A. Badgley, M. Brownell, V.J. Harwood. Application of microbial source tracking methods in a Gulf of Mexico field setting. J. Appl. Microbiol. 107:1518-1527.

2009. S.M. Mcquaig, T.M. Scott, J.O. Lukasik and V.J. Harwood. Development and validation of a sensitive Taqman® quantitative PCR assay for the specific detection and quantification of two human polyomaviruses (JCV and BKV) in fecal waste. Appl. Environ Microbiol. 75:3379-3388.

2009. B. Nayak, A.D. Levine, A. Cardoso and V.J. Harwood. Microbial population dynamics in solid waste bioreactors. J. Appl. Microbiol. 107(4):1330-1339.

2009. S. Leskinen, V.J. Harwood and D.V. Lim. Rapid dead-end ultrafiltration concentration and biosensor detection of enterococci from beach waters of Southern California. J. Water Health. 7:674-684.

2009. A. Tatavarthy, K. Peak, W. Veguilla, T. Cutting, V.J. Harwood, J. Roberts, P. Amuso, J. Cattani, and A. Cannons. An accelerated method for isolation of Salmonella enterica serotype Typhimurium from artificially contaminated foods, using a short preenrichment, immunomagnetic separation, and xylose-lysine-desoxycholate agar (6IX Method). J. Food Protect. 72:583-590.

2008. K. V. Gordon, M. C. Vickery, A. DePaola, C. Staley and Valerie J. Harwood. Real-time PCR assays for quantification and differentiation of V. vulnificus strains in oysters and water. Appl. Env. Microbiol. 74:1704-1709.

2008. A.D. Levine, V.J. Harwood, S. Farrah, T.M. Scott, and J.B. Rose. Pathogen and indicator organism reduction through secondary effluent filtration: Implications for reclaimed water production. Water Environment Research: 80:596-608.

2007. Brownell, M.B., V.J. Harwood, R.C. Kurz, S.M. McQuaig, J. Lukasik, and T.M. Scott . Confirmation of putative stormwater impact on water quality at a Florida beach by microbial source tracking methods and structure of indicator organism populations. Water Research 41: 3747-3457.

2007. Stoeckel, D.M. and V.J. Harwood. Performance, design, and analysis in microbial source tracking studies. Appl. Environ. Microbiol. 73:2405-2415.

2006. Shannon M. McQuaig, Troy M. Scott, Valerie J. Harwood, Samuel R. Farrah and Jerzy O. Lukasik. Novel method for the detection of human derived fecal pollution in environmental waters using a PCR based human polyomavirus assay. App. Environ. Microbiol. 72: 7567-7564.

2006. M. A. Anderson, J.E. Whitlock and V.J. Harwood. Diversity and Distribution of Escherichia coli Genotypes and Antibiotic-Resistant Phenotypes in Feces of Humans, Cattle and Horses Appl. Environ Microbiol. 72: 6914-6922.

2006. M. Chatzidaki-Livanis, M. A. Hubbard, K.V. Gordon, V. J. Harwood, and A.C. Wright. Genetic distinctions among clinical and environmental strains of Vibrio vulnificus. Appl. Environ. Microbiol. 72:6136-6141.

2006. A Cardoso, A.D. Levine, B.S. Nayak and V.J. Harwood. Lysimeter comparison of the role of waste characteristics in the formation of mineral deposits in leachate drainage systems. Waste Management Res. 24:560-572.

Valerie Harwood Professor