Katharine Field
Environmental Microbiology, Fecal Source Detection, Molecular Evolution
Research Interests:
Novel applications of molecular techniques to water quality problems caused by microbial contamination.
Host-specific and geographic distribution of fecal bacteria.
Persistence and fate of microbiological contaminants in water, including anaerobes, indicators, antibiotic resistance genes and pathogens.
Spread of antibiotic resistance through the fecal environmental route.
Office: 354 Nash Hall
Courses Taught: MB 302 General Microbiology, MB 330 Disease and Society
Degrees: B.A. Yale University, M.A., Boston University, Ph.D., University of Oregon
Research
Research in my laboratory addresses fundamental questions in environmental microbiology and microbial evolution. Projects involve studying the effects of microbial contamination in water, developing markers to track the sources of fecal contamination, tracing pathogen contamination in water, correlating different types of fecal contamination with public health outcomes through epidemiological studies, tracking the spread of antibiotic resistance genes from fecal bacteria in natural environments, and phylogenetic analysis of coevolution of fecal anaerobic bacteria with vertebrate hosts. My laboratory is involved in the development of bridging technologies that can be utilized by industry and water quality laboratories to take advantage of new, rapid methods to identify fecal contamination and pathogens.
Pathogen contamination and fecal source discrimination. Pathogens and nutrients from fecal pollution impact the integrity of aquatic ecosystems, pose health risks and affect both recreational and fisheries use of the waters. Often the source of fecal contamination in water cannot be determined. My lab developed a PCR-based indicator system utilizing 16S rDNA markers from the Bacteroidales group of fecal anaerobic bacteria. The method rapidly detects fecal contamination and distinguishes its source. Real-time quatitative PCR allows us to quantify these markers. This method is being tested by the US EPA in epidemiological studies to supplement or replace current methods of detecting fecal contamination. We are interested in understanding the survival and spread of fecal pathogens, anaerobes, and public health indicators in natural waters. Labeling fecal bacteria with BrdU, a thymidine analog, allows us to follow their persistence and survival in natural waters in a culture-independent manner.
Novel methods of probe development. We recently developed a subtractive hybridization approach to empirically determine host-specific differences in fecal bacteria, resulting in unique sequence tags to use for primer design. This approach when linked to standard ribosomal gene identification has the potential to uncover important functional differences among microbial communities; we are pursuing this to compare and characterize the fecal microbial communities in cattle, humans and gulls.
Bacteroidales conjugative transposons, antibiotic resisitance and horizontal evolution. We recently showed that bacteroidales bacteria conjugate and transfer antibiotic resistance under environmental conditions in cold aerobic seawater, when oysters are present to facilitate contact. In addition, we showed that many different species of wild animals (e.g. coyote, deer, fox) carry either a human or ruminant-type gene for tetracycline resistance, tetQ. A likely source for this gene is from fecally-contaminated water; an alternate hypothesis is that the gene occurs naturally in vertebrates. An ongoing study comparing levels of antibiotic resistance in Oregon and Alaskan coyotes attempts to distinguish these hypotheses.
Coevolution of Bacteroidales with host species. The concept of "endemism" is usually applied to macroorganisms. Commensal bacteria may be the best models for endemic distribution among microorganisms. We found that most groups of animals have very different phylogenetic groups of Bacteroidales. This suggests that unique clades of Bacteroidales have coevolved with host groups. Dogs, cats, and gulls, however, have Bacteroidales sequences that are closely related to groups found in humans, suggesting that horizontal transfer between hosts has also played a role in the evolution of fecal bacterial communities. Recently we have discovered an isolated Native American community in Alaska whose residents do not have the human-specific bacterial clade found elsewhere. We are interested in testing whether the distribution of these fecal anaerobes is geographic and related to geographic isolation, is related to diet, or perhaps is a record of population history and movements, as are genetic markers in Heliocobacter pylori.
Improtance of research. Our techniques have been successfully applied for rapid assessment of microbial water quality, and for microbial source tracking, in the United States and elsewhere. in addition, the Bacteroidales system presents an excellent model for the study of bacterial evolution by horizontal gene transfer and vertical inheritance, and our work will contribute to a fundamental understanding of the way bacteria evolve.
Selected Publications
Pub Med
Walters, S.P., V.P. Gannon, and K.G. Field. 2006 (in press). Detection of Bacteroidales fecal indicators and the zoonotic pathogens E. coli 0157:H7, Salmonella, and Campylobacter.
Shanks, O.C., C. Nietch, M.t. Simonich, M. Younger, D. Reynolds and K.G. Field. 2006. Basin-wide analysis of the dynamics of fecal contamination and fecal source idenfication in Tillamook Bay, Oregon. Appl. Environ. Microbiol. 72: 5537-5546.
Walters, S.P. and K. G. Field. 2006. Persistence and growth of fecal Bacteroidales assessed by bromodeoxyuridine immunocapture. Appl. Environ. Microbiol. 72:4532-4539.
Amogan, H.P., J.P. Martinex, L.M. Ciuffetti, K.G. Field and P.W. Reno 2006. Karyotype and genome size of Nadelspora canceri determined by pulsed field gel electrophoresis. Acta Protozoologica 45:249-254.
Devereux, R., P. Rublee, J.H. Paul, K.G. Field and J.W. Santo Domingo. 2006. Development and Applications of Microbial Ecogenomic Indicators for Monitoring Water Quality. Environmental Monitoring and Assessment 116:459-479.
Dick, L.K. and K.G. Field 2005. Microplate subtractive hybridization to enrich for source-specific Bacteroidales fecal pollution indicators. Appl. Environ. Microbiol. 71:3179-3183.
Dick, L.K. A.E. Bernhard, T.J. Brodeur, J.W. Santo Domingo, J.M. Simpson, S.P. Walters, and K.G. Field 2005. Host distributions of uncultivated fecal Bacteroidales reveal genetic markers for fecal source idenfication. Appl.Environ. Microbiol. 71:3184-3191.
Bernard, A.E., D. Colbert, J. McManus, and K.G. Field 2005. Microbial community dynamics based on 16S rDNA profiles in a Pacific Northwest estuary and its tributaries. FEMS Microbiol. Ecol. 52:115-128.
Dick, L.K. and K.G. Field 2004. Rapid estimation of numbers of fecal Bacteroidetes by use of a quantitative PCR assay for 16S rRNA genes. Appl.Environ. Microbiol. 70:5695-5697.
Till, D., K.G. Field and A.P. Dufour. 2004. Managing risk waterborne zoonotic disease through water quality surveillance. In "Waterborne Zoonoses: Identification, Causes and Control", J.A. Cotruvo, A. Dufour, G. Rees, J. Bartram, R. Carr, D.O. Cliver, G.F. Craun, R. Fayer, and V.P.G. Gannon, eds., pp. 338-348. World Health Organization, IWA Publishing Alliance House, London.
Field, K.G. 2004. Fecal Source Identification. In "Waterborne Zoonoses: Identification, Causes and Control", J.A. Cotruvo, A.Dufour, G. Rees, J. Bartram, R. Carr, D.O. Cliver, G.F. Craun, R. Fayer, and V.P.G. Gannon, eds., pp. 349-366. World Health Organization, IWA Publishing Alliance House, London.
Field, K.G., E.C. Chern, L.K. Dick, J.A. Fuhrman, J.f. Griffith, P.A. Holden, M.G. LaMontagne, J.Le, B.H. Olson, M.T. Simonich, 2003. A comparative study of culture-independent, library-independent genotypic methods of fecal source tracking. J.Wat. Health 1 (4): 181-194.
Kim, S.-H., H. An, K.G. Field, C.-I Wei, J.B. Velasquez, B. Ben-Gigirey, M.T. Morissey, R.J. Price, and T.P. Pitta. 2003. Detection of Morganella morganii, a prolific histamine former, by the PCR assay using 16S rDNA targeted primers. J. Food Protect. 66:1385-1392.
Bernhard, A.E., T. Goyard, M.T. Simonich, and K.G. Field. 2003. Application of a rapid method for identifying fecal pollution sources in a multi-use estuary. Water research 37: 909-913.
Field, K.G., A.E. Bernhard, and T.J. Brodeur. 2003. Molecular approached to microbiological monitoring: fecal source detection. Environ. Monitor. Assess. 81: 313-326.
Ream, W., B. Geller, J. Trempy and K.G. Field. 2003. Molecular Microbiology Laboratory: A Writing Intensive Course. Academic Press, San Diego. 268 pp.
Kim, S.-H., R. J. Price, M.t. Morissey, K.G. Field, C.I. Wei, and H. An. 2002. Histamine production by Morganell morganii in mackerel, albacore, mahi-mahi and salmon at various storage teperatures. J. Food Sci. 67:1522-1528.
Kim, S.-H., R.J. Price, M.T. Morissey, K.G. Field, C.I. Wei, and H. An. 2002. Occurrence of histamine-forming bacteria in albacore and histamine accumulation in muscle at ambient termperature. J. Food Sci. 67: 15-1521.
Kim, S.-H., K.G. Field, D.-S. Chang, C.-I Wei, and H. An. 2001. Identification of bacteria crucial to histamine accumulation in Pacific Mackerel during storage. J. Food Protect. 64:1556-1564.
Kim, S.-H., K.G. Field, M.T. Morrissey, R.J. Price, C.-I Wei, and H. An. 2001. Source and identification of histimine-producing bacteria from fresh and temperature-abused albacore. J. Food Protect. 64: 1035-1044.
Bonnichsen, R., L. Hodges, W. Ream, D.L. Kirner, K. Selsor, R.E. Taylor, and K.G. Field. 2001. Methods for the study of ancient hairs: radiocarbon dates and gene sequences from individual hairs. J. Archeological Science 28: 777-787.