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Ralph Mitchell

Faculty
  • Gordon McKay Research Professor of Applied Biology
    Ralph Mitchell

    Contact Information

    Office: Pierce Hall 127
    Email: mitchell [ AT ] seas [ DOT ] harvard [ DOT ] edu
    Office Phone: (617) 496-3906
    Office Fax: (617) 496-1471
    Lab Name: Laboratory of Applied Microbiology
    Lab Room: Engineering Sciences Lab 301
    Lab Phone: (617) 496-3906

    Recruitment Status

    Not accepting graduate students

    Websites

    Education

    1. B.A., 1956, Microbiology, Trinity College, Dublin
    2. Ph.D., 1961, Microbiology, Cornell University

    Research Interests

      • Energy & Environmental Systems
      • Environmental Chemistry and Microbiology

    Primary Teaching Area

    Environmental Science & Engineering

    Profile

    In recent years the field of microbiology has made dramatic advances. New tools and methods are being employed to investigate fundamental microbial processes, and new biotechnological techniques are being used to induce microorganisms to produce an extraordinary range of pharmaceutical, agricultural, and industrial substances. Professor Mitchell's laboratory is engaged in research on microbial processes in natural habitats and in applied microbiology, on subjects that include control of the deterioration of materials by microorganisms and the development of targeted pesticides.

    Professor Mitchell's laboratory is currently involved in extensive research on the ability of microbes to attack nonliving materials, including metals, concrete, stone and artificial polymers. His research has shown that materials used in electronics, on buildings, and in industrial processes are susceptible to microbial "diseases."

    Professor Mitchell's group is particularly interested in the association between increased pollution and the acceleration in recent years in the biodeterioration of ancient buildings and monuments. One current project involves a study of the role of microorganisms in the accelerated deterioration of historic limestone by atmospheric pollutants. In another investigation, his research group is investigating the biodeterioration of consolidants used to protect archeological sites, with the goal of developing environmentally acceptable binding materials for historic buildings, which are capable of resisting biodegradation.

    A major project of the Mitchell laboratory concerns the microbiology of surfaces. Studies of the complex chemical and biochemical interactions that occur at the interface between an aqueous phase and a living or nonliving surface provide insight into the chemical transformations mediated by microorganisms found on the surfaces of both living and artificial materials. Professor Mitchell's group has identified biochemical cues produced by surface-active bacteria that induce the development of invertebrate organisms. Their observations help explain how developing organisms use external biochemical triggers and provide new means for controlling undesirable insects and other pests.

    Positions & Employment

    Harvard School of Engineering and Applied Sciences

    • Present: Gordon McKay Research Professor of Applied Biology

    Selected Publications

    1. Na, C., C. McNamara, N. Konkol, K. Bearce Lee, S.T. Martin and R. Mitchell. Correlation of bacterial attachment with both interfacial and adhesive forces measured by force volume microscopy. Environmental Science and Technology, submitted.
    2. Konkol, N., C. McNamara, J. Sembrat, M. Rabinowitz, and R. Mitchell. Enzymatic decolorization of bacterial pigments from culturally significant marble. Journal of Cultural Heritage, submitted.
    3. Nick R. Konkol, Christopher J. McNamara, Robert Blanchette, Eric May, and Ralph Mitchell. Sticks and Stones: Microbial Deterioration of Culturally Significant Wood and Stone Artifacts and the Potential for Bioremediation. Microbe, accepted.
    4. McNamara, C.J., K.A. Bearce Lee, M.A. Russell, L.E. Murphy, and R. Mitchell. Analysis of the Bacterial Community in Concretions Formed on Metal Submerged in a Marine Environment. Journal of Cultural Heritage, accepted.
    5. McNamara, C.J., C. Anastasiou, V. O. Flaherty, and R. Mitchell. 2008. Microbial remediation of olive mill wastewater. International Biodeterioration and Biodegradation 61:127-134.
    6. Tarnowski, A., X. Zhang, C. McNamara, S. Martin, and R. Mitchell. 2007. Biodeterioration and performance of anti-graffiti coatings on sandstone and marble. The Journal of the Canadian Association for Conservation 32:3-16.
    7. McNamara, C.J., T.D. Perry, K. Bearce, G. Hernandez-Duque, and R. Mitchell. 2006. Epilithic and endolithic bacterial communities in limestone from a Maya archaeological site. Microbial Ecology 51:51-64.
    8. McNamara, C.J., K. Bearce, T.D. Perry IV, and R. Mitchell. 2006. Microbial biofilms inside historic stone. In: R. Fort, M. Alvarez de Buergo, M. Gomez-Heras and C. Vazquez-Calvo (Editors), Proceedings of the International Conference on Heritage, Weathering and Conservation, HWC-2006, 21-24 June 2006, Madrid, Spain. Taylor and Francis, London.
    9. McNamara, C.J., T.D. Perry, R. Leard, J. Dante, and R. Mitchell. 2005. Microbial corrosion of aluminum alloy 2024 in aircraft fuel tanks. Biofouling 21:257-265.
    10. Perry, T.D., V. Klepac-Ceraj, X.V. Zhang, C.J. McNamara, M.F. Polz, S.T. Martin, N. Berke, and R. Mitchell. 2005. Binding of harvested bacterial exopolymers to the surface of calcite. Environmental Science and Technology 39:8770-8775.
    11. McNamara, C.J. and R. Mitchell. 2005. Microbial deterioration of historic stone. Frontiers in Ecology and the Environment 8:445-451.
    12. McNamara, C.J., T.D. Perry IV, K. Bearce, G. Hernandez-Duque, and R. Mitchell. 2005. Measurement of limestone biodeterioration using the Ca2+ binding fluorochrome Rhod-5N. Journal of Microbiological Methods 61:245-250.
    13. Perry, T.D., C.J. McNamara, and R. Mitchell. 2005. Biodeterioration of stone. In: Scientific Examination of Art: Modern Techniques in Conservation and Analysis. National Academy of Sciences, Washington, D.C., pp 72-84.
    14. McNamara, C.J., M. Breuker, M. Helms, T.D. Perry, and R. Mitchell. 2004. Biodeterioration of Incralac used for the protection of bronze monuments. Journal of Cultural Heritage 5:361-364.
    15. Perry, T.D., O.W. Duckworth, C.J. McNamara, S.T. Martin, and R. Mitchell. 2004. Effects of the biologically produced polymer alginic acid on macroscopic and microscopic calcite dissolution rates. Environmental Science and Technology 38:3040-3046.
    16. Perry, T.D., O.W. Duckworth, C.J. McNamara, S.T. Martin, M. Breuker, and R. Mitchell. 2004. Biologically produced polymers affect calcite dissolution. In: Proceedings of the 11th International Symposium on Water-Rock Interaction. R.B. Wanty and R.R. Seal (eds.). Saratoga Springs, NY.
    17. Tarnowski, A., C. McNamara, K. Bearce, and R. Mitchell. 2004. Sticky microbes and dust on objects in historic houses Objects Specialty Group Postprints for the American Institute for the Conservation of Historic and Artistic Works 11:11-28.
    18. Breuker, M., C. McNamara, L. Young, T. Perry, A. Young, and R. Mitchell. 2003. Fungal growth on synthetic cloth from Apollo spacesuits. Annals of Microbiology 53:47-54.
    19. McNamara, C.J., T.D. Perry, M. Zinn, M. Breuker, G. Hernandez-Duque, and R. Mitchell. 2003. Microbial processes in the deterioration of Mayan archaeological buildings in southern Mexico. In: Art, Biology, and Conservation: Biodeterioration of Works of Art. R.J. Koestler, V.H. Koestler, A.E. Charola, and F.E. Nieto-Fernandez (eds.). The Metropolitan Museum of Art, New York.
    20. Perry, T.D., C.J. McNamara, R. Mitchell, and G. Hernandez-Duque. 2003. An investigation of bacterial dissolution of Maya limestone: biodiversity and functional analysis. In: Molecular Biology and Cultural Heritage. C. Saiz-Jimenez (ed.). Swets and Zeitlinger, Lisse.
    21. McNamara, C.J., T.D. Perry, N. Wolf, R. Mitchell, R. Leard, and J. Dante. 2003. Corrosion of aluminum alloy 2024 by jet fuel degrading microorganisms. Corrosion 2003, Paper No. 03568, NACE International, Houston, TX.