Academic Faculty

Tiffany L. Weir, Ph.D.

Tiffany L. Weir, Ph.D.

Associate Professor

210 Gifford Building | (970) 491-4631 |

Research Interests:

The main goal of my research program is to understand the role of microbes in ecosystem functioning, with ecosystems ranging from soils to processed food products to the human gut. I currently conduct studies examining how fermentation of plant foods affects composition and bioavailability of phytochemicals beneficial for human health. Focus plants include rice bran and fermented Chinese tea, both of which have been used traditionally as medicines in Asian cultures and have shown activity in a number of chronic and infectious disease models. Another area of study is how dietary phytochemicals affect the composition of gut microbes. Our native microflora protects against pathogen infection, aids in digestion of dietary components to contribute to host energy status, and influences mucosal and systemic immune development. Thus, the ability to manipulate the gut microbiota through diet is a viable disease prevention strategy. I have focused my recent research efforts on identifying the inter-relationships between diet, microflora, and microbial metabolism to gain a better understanding of their underlying mechanisms. These studies have been highly interdisciplinary research efforts conducted in collaboration with Dr. Elizabeth Ryan (CSU-Clinical Sciences) and Dr. Melissa Wdowik (CSU-Food Science and Nutrition).


  • Ph.D. (2008): Cell and Molecular Biology. Colorado State University, Fort Collins, CO.
    Dissertation: Interactions between plants and the human opportunistic pathogen, Pseudomonas aeruginosa.
  • M.Sc. (1997): Plant pathology. Pennsylvania State University, State College, PA.
    Thesis: Investigation of the genetic variability in the fungal pathogens, Alternaria solani and Alternaria alternata.
  • B.S. (1995): Biology-Genetics and Development/Minor-Microbiology. Pennsylvania State University, State College, PA.

Professional Experience:

  • 08/2011-current: Assistant Professor, Dept. of Food Science and Nutrition, Colorado State University
  • 10/2008-7/2011: Assistant Professor, Dept. of Horticulture, Colorado State University
  • 8/2007-8/2008: Visiting Scientist, Institute of Environmental Studies, Pontifical Catholic University of Peru, Lima, Peru.
  • 9/2002-8/2007: Research Associate, Dept. of Horticulture, Colorado State University
  • 9/2002-11/2003: Risk analyst, USDA, APHIS, PPQ-Fort Collins, CO
  • 7/1998-8/2002: Plant Protection Officer, USDA, APHIS, PPQ-Jamaica, NY/Aurora, CO
  • 9/1994-5/1995: Research Assistant, Dept. of Plant Pathology, Pennsylvania State University
  • 5-8/1994: Research Assistant, Dept. of Entomology, Pennsylvania State University
  • 9/1993-5/1994: Research Assistant, Dept. of Plant Pathology, Pennsylvania State University

Professional Memberships and Activities:

  • 2008-present Consultant for El Pedregal, Agricola Chapi, Pantanos de Villa, INIA, USDA-FAS, Denver Diabetes Foundation, Golden Flower Trading Company
  • 2009-present Peace Corp Master’s International, Horticulture Advisor
  • 2009-present Conducting clinical trials at Poudre Valley Hospital in collaboration with the Depts. of Food Science and Nutrition and Clinical Sciences.
  • 2009-present Member of American Society of Microbiology
  • 2011 Member of the Phytochemical Society of North America
  • 2011 Member of the Association of Tropical Biology and Conservation
  • 4/2010 Conducted HPLC training workshop for Peruvian government officials
  • 2010-present CSU representative for Western Association of Agricultural Experiment Station Directors project W2122
  • 2011 Initiated and implemented IMOU with Hunan Agricultural University, Changsha, China

Awards and Honors:

  • 2015 An American Society of Microbiology Undergraduate Research Fellowship was awarded to Alyssa Whitney, an undergraduate in my laboratory. These are mentored awards and are chosen based on the student-mentor team. Alyssa was awarded a cash stipend to conduct summer research in my lab and we are both attending the 2015 ASM General meeting for a leadership workshop this spring as part of this award.
  • 2014 Future Leader Award -International Life Sciences Institute
  • 2012 International Program Faculty travel award to Rwanda
  • 2011 Biotropica paper featured in Science daily, New York Times Science section

Recent/Relevant Publications:

  • Whitney AK and Weir TL* (2015) Inhibitory activity of Fuzhuan tea fractions against Salmonella enterica and enteric pathogens. Current Topics in Phytochemistry (submitted).
  • Whitney AK and Weir TL* (2015) Interaction of Caffeine with the SOS Response Pathway in Escherichia coli. Gut Pathogens (under revision).
  • Cox-York K, Sheflin AM, Foster MT, Gentile CL, Kahl A, Koch L, Britton S, Weir TL (2015) Gut Ecology Associated With High Innate Aerobic Capacity Protects Against Ovariectomy-Induced Cardiometabolic Risk. Physiol Reviews (under revision).
  • Elamari AA, Weir TL, Abduelafez IM, Moragues M, Stromberger M (2015) Diversity and abundance of ACC Deaminase-positive bacteria associated with the rhizosphere of different winter wheat genotypes. Applied Soil Ecology (submitted).
  • Foster MT, Gentile CL, Cox-York K, Wei Y, Wang D, Estrada A, Reese L, Pagliassotti MJ, Weir TL*(2015) Fuzhuan tea consumption imparts hepatoprotective effects and alters intestinal microbiota in high saturated fat diet-fed rats. Molecular Nutrition and Food Research (submitted).
  • Kelly CJ, Zheng L, Campbell EL, Saeedi B, Scholz CC, Bayless AJ, Wilson KE, Glover LE, Kominsky DJ, Magnuson AM, Weir TL, Ehrentraut SE, Nguyen V, Taylor CT, Colgan SP (2015) Host-Microbe Crosstalk between Short-Chain Fatty Acids and Intestinal Epithelial HIF Provides a New Mechanism to Augment Tissue Barrier Function. Cell Host & Microbe DOI:
  • Sheflin AM, Borresen EC, Wdowik MJ, Rao S, Brown RJ, Heuberger AL, Broeckling CD, Weir TL*, Ryan EP (2015) Dietary intervention with heat-stabilized rice bran modulates gut microbiota and metabolites in healthy participants. Nutrients 7, 1282-1300.
  • Weir TL* (2014) Unraveling the mechanisms underlying associations between the microbiome and gastrointestinal malignancies. Transl Gastrointest Cancer doi: 10.3978/j.issn. 2224-4778.2014.07.09
  • Voreades N, Kozil A, Weir TL* (2014) Diet and the Evolution of the Intestinal Microbiome. Frontiers in Microbiology 5,494
  • Sheflin AM, Whitney A, Weir TL* (2014) Cancer Promoting Effects of Gut Microbial Dysbiosis. Current Oncology Reports 16, 406. 10.1007/s11912-014-0406-0
  • Gentile CL, Weir TL , Cox-York K , Yuren W, Wang D, Reese L, Moran G, Estrada A, Mulligan C, Pagliassotti M, Foster MT (2014) The Role of Visceral and Subcutaneous Adipose Tissue Fatty Acid Composition in Liver Pathophysiology Associated with NALFD. Adipocyte, doi=10.4161/21623945.2014.978662
  • Weir TL*, Manter DK, Sheflin AM, Barnett BA, Heuberger AH, Ryan EP (2013) Stool microbiome and metabolome differences between colorectal cancer patients and healthy adults. PLoS One 8(8): e70803. doi:10.1371/journal.pone.0070803
  • Keller AC, Weir TL*, Broeckling CD, Ryan EP (2013) Antibacterial activity and phytochemical profile of fermented Camellia sinensis (Fuzhuan tea). Food Research International 53, 945-949.
  • Bakker MG, Manter DK, Sheflin AM, Weir TL, Vivanco JM (2012) Marschner Review: Harnessing the rhizosphere microbiome through plant breeding and agricultural management. Plant and Soil 360, 1-13.
  • Borresen EC, Henderson AJ, Kumar A, Weir TL, Ryan EP (2012) Fermented foods: Patented approaches and formulations for nutritional supplementation and health promotion. Recent Patents on Food, Nutrition & Agriculture. 4,134-140.
  • Xu X, Hu Y, Xiao W, Huang J, He X, Wu J, Ryan EP, Weir TL* (2012) Effects of fermented Camilla sinensis, Fuzhuan tea, on egg cholesterol and production performance in laying hens. J. Int. Food and Agric. Res. 1:6-10.
  • Kumar A, Henderson A, Forster GM, Chen MH, Goodyear AW, Bauer JE, Weir TL, Leach JE, Dow SW, Ryan EP (2012) Dietary Rice Bran Promotes Resistance to Salmonella Colonization and Mucosal Invasion in Mice. BMC Microbiology. 12, 71;
  • Weir TL*, Hu Y, Ryan EP, Lin W, Murray P, Fu D, Snook R, Xiao W. (2012) Medicinal teas: a review to summarize health benefits and highlight fermented tea. Herbalgram. 94: 45-49.
  • Weir TL, Newbold TAS, Vivanco JM, van Haren M, Fritchman C, et al. (2012) Plant Inhabiting Ant, Pseudomyrmex triplarinus, utilizes chemical cues for host discrimination. Biotropica. 44: 246-253.
  • Xu X, Hu Y, Xiao W*, Weir TL*, Ryan EP, Huang J, He X, Wu J (2011) Effects of Fu Brick Tea consumption on the production performance, egg traits and the lipid metabolism in laying hens. J Agric. Food Chem. Under review.
  • Barnett BA and Weir TL* (2011) Bacterial secretion. In: Secretions and Exudates in Biological Systems (eds. Baluska F, Vivanco JM). Springer, Berlin, Germany. In press.
  • Kumar A, Duffy A, Forster G, Goodyear AW, Weir TL, Leach JE, Dow S, Ryan EP (2011) Dietary rice bran reduces susceptibility to Salmonella enteric Typhimurium infection in mice. PLOS Medicine. Under review
  • Weir TL*, Hu Y, Ryan EP, Lin W, Murray P, Fu D, Snook R, Xiao W. (2011) Medicinal teas: a review to summarize health benefits and highlight fermented tea. Herbalgram. Under review.
  • Fu D, Ryan EP, Huang J, Liu Z, Weir TL, Snook R, Ryan T (2011) Fermented Camellia sinensis, Fuzhuan Tea, regulates hyperlipidemia and transcription factors involved in lipid catabolism. Food Research International. In press.
  • Ryan EP, Heuberger AL, Weir TL, Barnett BA, Broeckling CD, Prenni JE (2011) Rice bran fermented with Saccharomyces boulardii generates novel metabolite profiles with bioactivity. J Food Agric Chem. 59, 1862-1870.
  • Weir TL, Newbold TAS, Vivanco JM, van Haren M, Fritchman C, et al. (2011) Plant Inhabiting Ant, Pseudomyrmex triplarinus, utilizes chemical cues for host discrimination. Biotropica. 43, DOI 10.1111/j.1744-7429.2011.00786.x
  • Weir TL, Manter DM, Kofer W. (2011) Microbes: A new frontier in tropical chemical biology. In: Chemical Biology of the Tropics: An interdisciplinary approach. (eds. Vivanco JM, Weir TL). Springer, Berlin, Germany. Pp114
  • Manter DK, Weir TL, Vivanco JM (2010) Sample pooling masks PCR-based estimates of soil microbial richness and community structure. Appl. Environ. Microbiol. 76, 2086-2090.

Book Chapters:
  • Pagliassotti MJ, Cox-York K, Weir TL (2014) Sugars and Metabolic Disorders in Animal Models Including Primates. In: Dietary Sugars and Health (eds. Goran MI, Tappy L, Le KA). CRC Press, London, UK.

Ongoing Research Support:

  • Weir T (PI) Broeckling, Zhou, Bellows, Auld, Baker (Co-PI’s) 2016-2021. Metabolomic Signature for Fruit and Vegetable Intake. NIH-NIDDK, NCAAM. $3 Million (Pending)
  • Weir T (PI) Foster M (Co-PI) 2015-2016, Association Between Dybiosis of Intestinal Microbiota and Post-Traumatic Headaches. DOD-CDRMP-IDEA. $150,000 (Pending)
  • ILSI-North America (Weir-PI) 2014-2016, Host microbial and genomic markers as predictors of response to a dietary intervention. $30K
  • Colorado Agriculture Experiment Station (PI) 2014-2016, Dietary phytoestrogens to prevent dysbiosis of intestinal microbiota due to estrogen loss. $50,000
  • Colorado Agriculture Experiment Station (Co-PI) 2013-2015, Expanded Food and Nutrition Education Program Related Research: Assessment of EFNEP Methods to Evaluate Dietary Quality and Nutrition Behavior Change. $50,000