Peter Bergholz

Assistant Professor

Van Es 152
701 231 5946
Bergholz Lab Website


  • Ph.D. in Microbiology and Molecular Genetics from Michigan State University (2007)

Professional Experience

  • Research Associate in Food Science at Cornell University (2011)
  • Research Associate in Crop and Soil Sciences at Cornell University (2010-2011)
  • Postdoctoral Associate in Crop and Soil Sciences at Cornell University (2007-2010)
  • National Science Foundation Training Course (2005-2006): Integrative Biology and Adaptation of Antarctic Marine Organisms, McMurdo Station, Ross Island, Antarctica

Teaching Interests

  • MICR 481/681-Microbial Genomics
  • SAFE 401/601-Food Safety Information and Flow of Food
  • SAFE 402/602-Foodborne Hazards
  • SAFE 403/603-Food Safety Risk Assessment

Research Interests

Our laboratory researches the adaptive value of genomic variation in microbial populations and the ecological mechanisms that maintain and spread adaptive variants in nature. Microbial genomes diversify rapidly due to a combination of fast mutation rates, infrequent homologous recombination and acquisition of accessory genes through horizontal gene transfer. Natural selection is thought to prune away unfit lineages with near equal speed, but successful genomic variants may expand the niche dimension of the species. With advances in geographic information systems (GIS) as a framework for describing the world, scientists are more capable of linking data on genomes to patterns and processes in the environment than ever before. However, scientists haven’t yet deciphered the extent to which large scale patterns and processes, including patterns of land-management or climate, play a role in the distribution of genomic variation within the tiniest of species.

We seek to understand adaptive variation in microbial populations using genome-wide association studies that integrate two approaches. First, a new analytical framework has been proposed to link adaptive genomic variation with quantitative landscape characteristics. Landscape genomics combines GIS modeling, population genomics, and spatial analysis to yield quantitative insights into large-scale processes that generate and maintain adaptive variation in species. Second, a reverse ecology approach seeks to use genomic information as a model-generating tool to discover the phenotypic and genomic basis for adaptive divergence of microbial populations.

Currently, my laboratory uses enteric bacteria, especially those involved in foodborne illness, as subjects of this research. The genomics of these populations are interesting, because they: a) remain a major health concern all over the world, b) exhibit enormous genomic diversity, and c) must adapt for life both within and outside the host. Perhaps most importantly, many knowledge gaps surrounding their population dynamics, dispersal pathways and adaptation to extrahost environments remain which may be filled by research on their genomes.

Most Recent Publications

  • Wongsuntornpoj, S., AI Moreno-Switt, PW Bergholz, M Wiedmann, and S Chaturongakul. Salmonella phages isolated from dairy farms in Thailand show wider host range than a comparable set of pahges isolated from US dairy farms. VETERINARY MICROBIOLOGY. 172 (1-2): 345-352 AUG 2014.
  • Falbo, K, RL Schnieder, DH Buckley, MT Walter, PW Bergholz, and BP Buchanan. Roadside ditches as conduits for fecal indicator organisms and sediment: Implications for water quality management. JOURNAL OF ENVIRONMENTAL MANAGEMENT. 128: 1050-1059 OCT 2013
  • Strawn, LK, ED Fortes, EA Bihn, KK Nightingale, YT Gröhn, RW Worobo, M Wiedmann, PW Bergholz. Landscape and Meterological Factors Affecting Prevalence of Three Foodborne Pathogens in Fruit and Vegetable Farms. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. 79 (2): 588-600 JAN 2013. doi:10.1128/AEM.02491-12.
  • Bergholz, PW, JD Noar, DH Buckley. Environmental patterns are imposed on the population structure of Escherichia coli after fecal deposition. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. 77 (1): 211-219 JAN 2011.
  • Davis, DA, MD Gamble, CE Bagwell, PW Bergholz, CR Lovell. Responses of salt marsh grass diazotroph assemblages to changes in marsh elevation, edaphic conditions, and host-plant species. MICROBIAL ECOLOGY 61 (2): 386-398 FEB 2011.
  • Ayala-del-Río, HL, PS Chain, MA Ponder, JJ Grzymski, N Ivanova, PW Bergholz, G Bartolo, L Hauser, M Land, C Bakermans, D Rodrigues, J Klappenbach, D Zarka, F Larimer, P Richardson, AE Murray, MF Thomashow and JM Tiedje. The genome sequence of Psychrobacter arcticus 273-4, a psychroactive Siberian permafrost bacterium reveals mechanisms for adaptation to low temperature growth. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 76 (7): 2304-2312 APR 2010.
  • Gamble, MM, CE Bagwell, J LaRocque, PW Bergholz, CR Lovell. Seasonal variability of diazotroph assemblages associated with the salt marsh cordgrass, Spartina alterniflora. MICROBIAL ECOLOGY. 59 (2): 253-265 FEB 2010.
  • Bergholz, PW, C Bakermans, and JM Tiedje. Psychrobacter arcticus 273-4 uses resource efficiency and molecular motion adaptations for subzero temperature growth. JOURNAL OF BACTERIOLOGY 191 (7): 2340-2352 APR 2009.
  • Ponder, MA, SJ Gilmour, PW Bergholz, CA Mindock, R Hollingsworth, MF Thomashow, JM Tiedje. Characterization of potential stress responses in ancient Siberian permafrost psychroactive bacteria. FEMS MICROBIOLOGY ECOLOGY 53 (1): 103-115 JUN 2005.