Professor and Chair
Office: BSF 131
Lab: BSF 243, BSF 245
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.
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.
Recent Journal Articles
Valerie J. Harwood
Honors and Award
Li X, Harwood VJ, Nayak B, Weidhaas JL. 2016. Ultrafiltration and Microarray for Detection of Microbial Source Tracking Marker and Pathogen Genes in Riverine and Marine Systems. Appl Environ Microbiol. 82(5):1625-35.
Ahmed W, Harwood VJ, Nguyen K, Young S, Hamilton K, Toze S. 2016. Utility of Helicobacter spp. associated GFD markers for detecting avian fecal pollution in natural waters of two continents. Water Res. 88:613-22.
Haugland RA, Siefring S, Varma M, Oshima KH, Sivaganesan M, Cao Y, Raith M, Griffith J, Weisberg SB, Noble RT, Blackwood AD, Kinzelman J, Anan'eva T, Bushon RN, Stelzer EA, Harwood VJ, Gordon KV, Sinigalliano C. 2016. Multi-laboratory survey of qPCR enterococci analysis method performance in U.S. coastal and inland surface waters. J Microbiol Methods 123:114-25.
Staley ZR, Harwood VJ, Rohr JR. 2015. A synthesis of the effects of pesticides on microbial persistence in aquatic ecosystems. Crit Rev Toxicol. 2015 Nov;45(10):813-36.
Li X, Harwood VJ, Nayak B, Staley C, Sadowsky MJ, Weidhaas J. 2015. A novel microbial source tracking microarray for pathogen detection and fecal source identification in environmental systems. Environ Sci Technol. 49:7319-29.
Nayak B, Weidhaas J, Harwood VJ. 2015. LA35 Poultry fecal marker persistence is correlated with that of indicators and pathogens in environmental waters. Appl Environ Microbiol. 81:4616-25.
Chase E, Young S, Harwood VJ. 2015. Sediment and Vegetation as Reservoirs of Vibrio vulnificus in the Tampa Bay Estuary and Gulf of Mexico. Appl Environ Microbiol. 81:2489-94. http://aem.asm.org/content/81/7/2489.full.pdf+html.
Solo-Gabriele H, Harwood VJ, João C. Brandão et al. 2015. Beach sand and the potential for infectious disease transmission: observations and recommendations. Journal of the Marine Biological Association of the United Kingdom 96:101-120.
Ahmed W, Harwood VJ, Gyawali P, Sidhu JP, Toze S. 2015. Concentration methods comparison for quantitative detection of sewage-associated viral markers in environmental waters. Appl Environ Microbiol. 81:2042-49.
Weidhaas J, Mantha S, Hair E, Nayak B, Harwood VJ. 2015. Evidence for extra-intestinal growth of Bacteroidales originating from poultry litter. Appl Environ Microbiol. 81:196-202.
Wanjugi P and Harwood VJ. 2015. Protozoan predation is differentially affected by motility of enteric pathogens in water vs. sediments. Microb Ecol. 2014 Nov;68(4):751-60.
Staley C and Harwood VJ. 2014. Differential expression of a sodium-phosphate cotransporter among Vibrio vulnificus strains. Microb Ecol. 2014 Jan;67(1):24-33.
Oliver DM, van Niekerk M, Kay D, Heathwaite AL, Porter J, Fleming LE, Kinzelman JL, Connolly E, Cummins A, McPhail C, Rahman A, Thairs T, de Roda Husman AM, Hanley ND, Dunhill I, Globevnik L, Harwood VJ, Hodgson CJ, Lees DN, Nichols GL, Nocker A, Schets C, Quilliam RS. 2014. Opportunities and limitations of molecular methods for quantifying microbial compliance parameters in EU bathing waters. Environ Int. 4;64C:124-128.
Ryu H, Elk M, Khan IU, Harwood VJ, Molina M, Edge TA, Domingo JS. 2014. Comparison of two poultry litter qPCR assays targeting the 16S rRNA gene of Brevibacterium sp. Water Res. 1;48:613-21.
Harwood VJ, Staley C, Badgley BD, Borges K, Korajkic A. 2014. Microbial source tracking markers for detection of fecal contamination in environmental waters: relationships to pathogens and human health outcomes. FEMS Microbiol Rev. 38:1-40.
J. Weidhaas, E. Garner, T. Basden, V. Harwood. 2014. Runoff studies demonstrate parallel transport behavior for a marker of poultry fecal contamination and Staphylococcus aureus. Journal of Applied Microbiology, 117(2):417-429.
R. L. Whitman, V. J. Harwood, T. A. Edge, M. B. Nevers, M. Byappanahalli, K. Vijayavel, J. Brandão, M. J. Sadowsky, E. W. Alm, A. Crowe, D. Ferguson, Z. Ge, E. Halliday, J. Kinzelman, G. Kleinheinz, K. Przybyla-Kelly, C. Staley, Z. Staley, H. M. Solo-Gabriele. 2014. Microbes in beach sands: integrating environment, ecology and public health. Reviews in Environmental Science and Bio-Technology, 13(3):329-368.
Z. R. Staley, E. Chase, C. Mitraki, T. L. Crisman, V. J. Harwood. 2013. Microbial water quality in freshwater lakes with different land use. Journal of Applied Microbiology, 115(5):1240-1250.
V. J. Harwood, A. B. Boehm, L. M. Sassoubre, K. Vijayavel, J. R. Stewart, T-T Fong, M-P Caprais, R. R. Converse, D. Diston, J. Ebdon, J. A. Fuhrman, M. Gourmelon, J. Gentry-Shields, J. F. Griffith, D. R. Kashian, R. T. Noble, H. Taylor, M. Wicki. 2013. Performance of viruses and bacteriophages for fecal source determination in a multi-laboratory, comparative study. Water Research 47(18):6923-6943.
V. J. Harwood, C. Staley, B. D. Badgley, K. Borges and A. Korajkic. 2013. Microbial source tracking markers for detection of fecal contamination in environmental waters: relationships to pathogens and human health outcomes. FEMS Microbiology Reviews 38(1):1-40.
P. Wanjugi and V. J. Harwood. 2013. The influence of predation and competition on the survival of commensal and pathogenic fecal bacteria in aquatic habitats. Environmental Microbiology 15(2):517-526.
C. Staley, E. Chase and V. J. Harwood. 2013. Detection and differentiation of Vibrio vulnificus and V. sinaloensis in water and oysters of a Gulf of Mexico estuary. Environmental Microbiology 15(2):623-633.
A. Korajkic, B. McMinn, V. J. Harwood, O. C. Shanks, G. S. Fout and N. J. Ashbolt. 2013. Differential decay of enterococci and Escherichia coli originating from two fecal pollution sources. Appl. Environ. Microbiol. 79(7):2488-2492.
A. Korajkic, P. Wanjugi, V. J. Harwood. 2013. Indigenous microbiota and habitat influence Escherichia coli survival more than sunlight in simulated aquatic habitats. Appl. Environ. Microbiol. 79(17):5329-5337.
K. V. Gordon, M. Brownell, S. Wang, J. E. Lepo, J. A. Mott, R. R. Nathaniel, M. Kilgen, K. N. Hellein, E. Kennedy, V. J. Harwood. 2013. Relationship of human-associated microbial source tracking markers with enterococci in Gulf of Mexico waters. Water Research 47:996-1004.
P. Wanjugi and V. J. Harwood. 2013. The influence of predation and competition on the survival of commensal and pathogenic fecal bacteria in aquatic habitats. Env. Microbiol. 15:517-26.
C. Staley, E. Chase and V. J. Harwood. 2013. Detection and differentiation of Vibrio vulnificus and V. sinaloensis in water and oysters of a Gulf of Mexico estuary. Environ Microbiol. 15:623-33.
E. Chase, C. M. Staley, J. Hunting and V. J. Harwood. 2012. Microbial source tracking to identify human and ruminant sources of fecal pollution in an ephemeral Florida river. J. Appl. Microbiol. 113:1396-406.
C. M. Staley, K. V. Gordon, M. E. Schoen and V. J. Harwood. 2012. Performance of two human-associated microbial source tracking qPCR methods in various Florida water types and implications for microbial risk assessments. Appl. Environ. Microbiol. 78:7317-26.
M. N. Byappanahalli, M. B. Nevers, A. Korajkic, Z. R. Staley, and V. J. Harwood. 2012. Enterococci in the environment. Microbio. Mol. Bio. Rev. 76(4):685-706.
C. M. Staley, K. V. Gordon, M. E. Schoen and V.J. Harwood. 2012. Performance of two human-associated microbial source tracking qPCR methods in various Florida water types and implications for microbial risk assessments. Appl. Environ. Microbiol. 78:7317-7326.
Z. R. Staley, J. K. Senkbeil, J. R. Rohr and V. J. Harwood. 2012. Lack of direct effects of agrochemicals on zoonotic pathogens and fecal indicator bacteria. Appl. Environ. Microbiol. 78(22):8146-50.
S. M. McQuaig, J. Griffith and V. J. Harwood. 2012. The association of fecal indicator bacteria with human viruses and microbial source tracking markers at coastal beaches impacted by nonpoint source pollution. Appl. Environ. Microbiol. 78:6423-6432.
O. C. Shanks, M. Sivaganesan, L. Peed, C. A. Kelty, A. D. Blackwood, M.R. Greene, R.T. Noble, R.N. Bushon, E.A. Stelzer, J. Kinzelman, T. Anan'eva, C. Sinigalliano, D. Wanless, J. Griffith, Y. Cao, S. Weisberg, V.J. Harwood, C. Staley, K. H. Oshima, M. Varma, R.A. Haugland. 2012. Interlaboratory comparison of real-time PCR protocols for quantification of general fecal indicator bacteria. Environ. Sci. Technol. 46(2):945-53.
K. N. Hellein, E. M. Kennedy, V. J. Harwood, K. V. Gordon, S. Y. Wang, J. E. Lepo. 2012. A filter-based propidium monoazide technique to distinguish live from membrane-compromised microorganisms using quantitative PCR. J Microbiol. Methods 89:76-78.
Z. R. Staley, J. R. Rohr and V. J. Harwood. 2011. A test of direct and indirect effects of agrochemicals on the survival of fecal indicator bacteria. Appl. Environ. Microbiol. 77:8765-74.
C. Staley, A. C. Wright, M. K. Jones and V. J. Harwood. 2011. Genetic and quantitative assessment of Vibrio vulnificus populations in oyster (Crassostrea virginica) tissues. Environ. Microbiol. Reports 3:543-549.
E. Chase and V. J. Harwood. 2011. Comparison of the effects of environmental parameters on growth rates of Vibrio vulnificus biotypes I, II and III by culture and quantitative PCR. Appl. Environ. Microbiol. 77:4200-4207.
B. S. Nayak, B. Badgley and V. J. Harwood. 2011. Comparison of genotypic and phylogenetic relationships of environmental Enterococcus isolates by BOX-PCR typing and 16S rRNA gene sequencing. Appl. Environ. Microbiol. 77:5050-5.
C. D. Cornelisen, P. A. Gillespie, M. Kirs, R. G. Young, R. W. Forrest, P. J. Barte, B. R. Knight and V. J. Harwood. 2011. Motueka River plume facilitates transport of ruminant faecal contaminants into shellfish growing waters, Tasman Bay, New Zealand. New Zealand. Aus. J Marine Freshwater Res. 45: 477-495.
C. M. Wapnick and V. J. Harwood. Urban and Suburban Watersheds. 2011. Microbial Source Tracking: Methods, Applications, and Case Studies. Springer-U.S., New York, NY.
J. Santo Domingo, H. Ryu and V. J. Harwood. 2011. Microbial Source Tracking. The Fecal Indicator Bacteria. M. J. Sadowsky and R. Whitman, Eds. ASM Press.
A. H. Shah, A. M. Abdelzaher, M. Phillips, R. Hernandez, H. M. Solo-Gabriele, J. Kish, G. Scorzetti, J. W. Fell, M. R. Diaz, T. M. Scott, J. Lukasik, V. J. Harwood, S. McQuaig, C. D. Sinigalliano, M. L. Gidley, D. Wanless, A. Ager, J. Lui, J. R. Stewart, L. R. Plano, L. E. Fleming. 2011. Indicator microbes correlate with pathogenic bacteria, yeasts and helminthes in sand at a subtropical recreational beach site. J Appl. Microbiol. 110(6):1571-1583.
J. L. Weidhaas, T. W. MacBeth, R. L. Olsen, and V. J. Harwood. 2011. Correlation of quantitative PCR for a poultry-specific Brevibacterium marker gene with bacterial and chemical indicators of water pollution in a watershed impacted by land application of poultry litter. Appl. Environ. Microbiol. 77:2094-2102.
B. D. Badgley, F. I. M. Thomas and V. J. Harwood. 2011. Quantifying environmental reservoirs of fecal indicator bacteria associated with sediment and submerged aquatic vegetation. Environ. Microbiol. 4:932-942.
A. Korajkic, M. J. Brownell and V. J. Harwood. 2011. Investigation of human sewage pollution and pathogen analysis at Florida Gulf Coast beaches. J Appl. Microbiol. 110:174-183.
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 44:5857-5866.
A. M. Abdelzaher, M. E. Wright, C. Ortega, A. R. Hasan, T. Shibata, H. M. Solo-Gabriele, J. Kish, K. Withum, G. He, S. M. Elmir, J. A. Bonilla, T. D. Bonilla, C. J. Palmer, T. M. Scott, J. Lukasik, V. J. Harwood, S. McQuaig, C. D. Sinigalliano, M. L. Gidley, D. Wanless, L. R. Plano, A. C. Garza, X. Zhu, J. R. Stewart, J. W. Dickerson, H. Yampara-Iquise, C. Carson, J. M. Fleisher, L. E. Fleming. 2011. Daily measures of microbes and human health at a non-point source marine beach. J Water Health 9(3):443-57.
Z. Stanley,V. J. Harwood, and J. R. Rohr. 2010. The effect of agrochemicals on indicator bacteria densities in outdoor mesocosms. Environ. Microbiol. 12(12):3150-3158.
B. A. Badgley, B. Nayak and V. J. Harwood. 2010. The importance of sediment and submerged aquatic vegetation as potential habitats for persistent strains of enterococci in a subtropical watershed. Water Research 44(20):5857-5866.
C. Staley and V. J. Harwood. 2010. The use of genetic typing methods to discriminate among strains of Vibrio cholerae, V. parahaemolyticus, and V. vulnificus. Journal of AOAC International. 93(5):1553-69.
B. A. Badgley, F. I. M. Thomas and V. J. Harwood. 2010. The effects of submerged aquatic vegetation on the persistence of environmental populations of Enterococcus spp. in outdoor mesocosms. Environ. Microbio. 12(5):1271-1281.
J. L. Weidhaas, T. W. Macbeth, R. L. Olsen, M. J. Sadowsky, D. Norat and V. J. Harwood. 2010. Identification of a poultry litter-specific DNA marker gene and development of a 16S rRNA-based quantitative PCR assay. J. Appl. Microbiol. 309(1):334-347.
A. Abdelzaher, M. Wright, C. Ortega, H. Solo-Gabriele, G. Miller, S. Elmir, X. Newman, P. Shih, J. A. Bonilla, T. D. Bonilla, C. J. Palmer, T. Scott, J. Lukasik, V. J. Harwood, S. McQuaig, C. Sinigalliano, M. Gidley, L. Plano, X. Zhu, J. D. Wang, L. Fleming. 2010. Presence of pathogens and indicator microbes at a non-point source subtropical recreational marine beach. Appl. Environ. Microbiol. 76:724-732.
S. D. Leskinen, M. Brownell, D. V. Lim and V. J. Harwood. 2010. 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.
V. J. Harwood, M. Brownell, S. Wang, J. Lepo, R. D. Ellender, A. Ajidahun, K. N. Hellein, E. Kennedy, X. Ye and C. Flood. 2009. Validation and field testing of library-independent microbial source tracking methods in the Gulf of Mexico. Water Research 43:4812-4819.
T.M. Scott, V. J. Harwood, W. Ahmed, Y. Masago, and J. B. Rose. 2009. 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.
A. Korajkic, B. A. Badgley, M. Brownell, V. J. Harwood. 2009. Application of microbial source tracking methods in a Gulf of Mexico field setting. J. Appl. Microbiol. 107:1518-1527.
S. M. Mcquaig, T. M. Scott, J. O. Lukasik and V. J. Harwood. 2009. 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.
B. Nayak, A. D. Levine, A. Cardoso and V. J. Harwood. 2009. Microbial population dynamics in solid waste bioreactors. J. Appl. Microbiol. 107(4):1330-1339.
S. Leskinen, V. J. Harwood and D. V. Lim. 2009. Rapid dead-end ultrafiltration concentration and biosensor detection of enterococci from beach waters of Southern California. J. Water Health 7:674-684.
A. Tatavarthy, K. Peak, W. Veguilla, T. Cutting, V. J. Harwood, J. Roberts, P. Amuso, J. Cattani, and A. Cannons. 2009. 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.
K. V. Gordon, M. C. Vickery, A. DePaola, C. Staley and V. J. Harwood. 2008. Real-time PCR assays for quantification and differentiation of V. vulnificus strains in oysters and water. Appl. Env. Microbiol. 74:1704-1709.
A. D. Levine, V. J. Harwood, S. Farrah, T. M. Scott, and J. B. Rose. 2008. Pathogen and indicator organism reduction through secondary effluent filtration: Implications for reclaimed water production. Water Environ. Research 80:596-608.
M. B. Brownell, V. J. Harwood, R. C. Kurz, S. M. McQuaig, J. Lukasik, and T. M. Scott. 2007. 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.
V. J. Harwood. 2007. Assumptions and limitations of microbial source tracking methods. J. Santo-Domingo and M. Sadowsky. Microbial Source Tracking. ASM Press, Washington, D.C.
D. M. Stoeckel and V. J. Harwood. 2007. Performance, design, and analysis in microbial source tracking studies. Appl. Environ. Microbiol. 73:2405-2415.
S. M. McQuaig, T. M. Scott, V. J. Harwood, S. R. Farrah and J. O. Lukasik. 2006. 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.
M. A. Anderson, J. E. Whitlock and V. J. Harwood. 2006. Diversity and Distribution of Escherichia coli Genotypes and Antibiotic-Resistant Phenotypes in Feces of Humans, Cattle and Horses. Appl. Environ. Microbiol. 72: 6914-6922.
M. Chatzidaki-Livanis, M. A. Hubbard, K. V. Gordon, V. J. Harwood, and A. C. Wright. 2006. Genetic distinctions among clinical and environmental strains of Vibrio vulnificus. Appl. Environ. Microbiol. 72:6136-6141.
A. Cardoso, A. D. Levine, B. S. Nayak and V. J. Harwood. 2006. Lysimeter comparison of the role of waste characteristics in the formation of mineral deposits in leachate drainage systems. Waste Management Res. 24:560-572.
K. L. (Hood) Anderson, J. E. Whitlock and V. J. Harwood. 2005. Persistence and differential survival of fecal indicator bacteria in subtropical waters and sediments. Appl. Environ. Microbiol. 71: 3041-3048.
V. J. Harwood, A. D. Levine, T. M. Scott, V. Chivukula, J. Lukasik, S. R. Farrah and J. B. Rose. 2005. Validity of the indicator organism paradigm:pathogen reduction and public health protection in reclaimed water. Appl. Environ. Microbiol. 71: 3163-3170.
D. F. Moore, V. J. Harwood, D. M. Ferguson, J. Lukasik, P. Hannah, M. Getrich and M. Brownell. 2005. Evaluation of antibiotic resistance analysis and ribotyping for identification of fecal pollution sources in an urban watershed. J. Appl. Microbiol. 99: 618-628.
S. D. Shehane, V. J. Harwood, J. E. Whitlock and J. B. Rose. 2005. The influence of rainfall on the incidence of microbial fecal indicators and the dominant sources of fecal pollution in a Florida river. J. Appl. Microbiol. 98:1127-1136.
A. D. Levine, V. J. Harwood, T. M. Scott and J. B. Rose. 2004. Factors influencing removal of bacteria, viruses and protozoan pathogens from wastewater for water reuse applications. H. H. Hahn, E. Hoffmann, H. Odegaard. Chemical Water and Wastewater Treatment VII. IWA Publishing.
J.E. Whitlock, D.T. Jones, V.J. Harwood. 2002. Identification of the sources of fecal coliforms in an urban watershed using antibiotic resistance analysis. Water Research 36(17): 4273-4282.
V. J. Harwood, J. Whitlock and V. H. Withington. 2000. Classification of the antibiotic resistance patterns of indicator bacteria by discriminant analysis: use in predicting the source of fecal contamination in subtropical Florida waters. Appl. Environ. Microbiol. 66: 3698-3704.