Responsibilities and Interests:

Soil microbiological analysis; characterization of microbial populations and communities in the soil and rhizosphere; application of molecular biology methods to soil microbial ecology.

Research Interests: Comparative microbial ecology of terrestrial systems; microorganisms involved in nitrogen cycling and retention; microbial ecology-based approaches to reducing nutrient losses from agriculture and forestry; DNA fingerprinting to track composition of microbial communities in soils and rhizospheres.

Education:

• Ph.D. Crop & Soil Sciences, Michigan State University, 1996
• M.A. Urban & Regional Planning, Environmental Sector, Univ. of Iowa, 1988
• M.S. Food Science & Technology, Univ. of Nebraska, 1978
• B.A. Microbiology, Univ. of Nebraska, 1974

CURRENT PROJECTS AND PLANNED COLLABORATIONS:

• Microbial hydrogen production (with Dr. Prabha Iyer, postdoctoral associate, Dr. Bruce Logan, Civil and Environmental Engineering, and BRIE graduate student Husen Zhang)
• Microbial processes and populations in naturally metalliferous soils (with Carolina Yanez, Dr. Carmen Enid Martinez, Soil Science, and BRIE Summer Undergraduate Fellow Krys Hamlett)
• Soil aggregate development and microorganisms (with Soils graduate student Jody Gibson and Dr. Henry Lin, Soil Science)
• Land management effects on soil microarthopod abundance and diversity (with Ecology graduate student Loren Byrne and Dr. K.C. Kim, Entomology)
• Microbial deodorization of livestock wastes (with Ecology graduate students Hugo Castillo and Masami Tonegawa, undergraduate student Erica Petre, Dr. Eileen Wheeler, Agricultural and Biological Engineering, and Dr. Jerzy Dec, Penn State Institutes of the Environment
• Molecular characterization of microbial mat communities (with Dr. Kate Freeman, Geosciences, and BRIE graduate student Courtney Turich)
• Impacts of biosolids on soil microbial communities in mine soils (with Rick Stehouwer, Soil Science.
• Characterization of perchlorate-reducing bacteria in engineered treatment systems (with BRIE graduate student Husen Zhang and Dr. Bruce Logan, Civil & Environ Engineering.
• Bacterial solubilization of phosphorus-containing minerals (with Soil graduate student Ann Widrig and Dr. Carmen Enid Martinez, Soil Science)
• Management effects on soil organic matter and microbial communities (with Dr. Doug Archibald and Dr. Heather Karsten, Crop Science, Dr. Mary Barbercheck, Entomology, Agroecosystem Science major Amber Lockawich, and Biology undergraduate student Summer Holmes.)

SOIL MICROBIAL ECOLOGY LABORATORY

A single gram of agricultural topsoil may contain at least one billion bacteria, a hundred thousand fungi, and thousands of protozoans and other microscopic organisms! Our ability to study such incredibly diverse microbial assemblages is hampered by the fact that most of these microorganisms will not grow under laboratory conditions. To get around this problem, M.A. Bruns's soil microbial ecology lab employs DNA fingerprinting of bacterial and eukaryotic communities to learn more about the key microorganisms involved in soil nutrient cycling and other important environmental processes. Basic steps involved in DNA fingerprinting are 1) extracting microbial DNA from soil; 2) polymerase chain reaction (PCR) amplification of ribosomal RNA genes; 3) separation of the PCR products by gel electrophoresis; and 4) computer-assisted analysis of the "fingerprints," or DNA band patterns produced in the gels. If we want to know more about the microbial populations that produce specific bands, we can cut these bands out of the gels, obtain their DNA sequence(s), and use the sequences for preliminary identification. We are interested in learning how soil microbial communities change over time when they are subjected to different environmental conditions and management treatments. We want to learn how to work with (not against!) the beneficial microorganisms that cleanse and improve our environment.

1. Hugo Castillo
2. Krys Hamlett
3. Ann Widrig
4. Dr. Prabha Iyer
5. Carolina Yanez
6. Erica Petre
7. Dr. Carmen Enid Martinez
8. Jody Gibson
9. Dr. Mary Ann Bruns
10. Amber Lockawich
11. Husen Zhang
12. Loren Byrne

PARTICIPATION IN OTHER PROGRAMS AT PENN STATE

• Huck Institute of Life Sciences (co-funder)
• BRIE, Biogeochemical Research Initiative for Education
• Intercollege Graduate Degree Program in Ecology (IGDPE)
• Penn State Institutes of the Environment (PSIE)
• WISER (Women in Science and Engineering Research)
• MURE (Minority Undergraduate Research Experience)
• H2E Center (Hydrogen Helping the Environment)

Professional Background:

• Soil Microbial Ecology Postdoctoral Researcher, Laboratory of Dr. Kate Scow, Dept. of Land, Air, and Water Resources, University of California, Davis, 1996-1999
• Congressional Fellow & Analyst, Food and Renewable Resources Program, Office of Technology Assessment, U.S. Congress, Washington, DC, 1988-90.
• Microbiologist, Schwan's Sales Enterprises, Salina, KS, 1982-85.
• U.S. Peace Corps Volunteer and Volunteer Leader, Cameroon, 1979-82.

Selected Publications:

1. 1. Zhang, H, MA Bruns, and BE Logan. 2002. Perchlorate reduction by a novel chemolithoautotropic, hydrogen-oxidizing bacterium. Environmental Microbiology 4:570-576.
2. Bruns MA, JR Hanson, J Mefford, and KM Scow. 2001. Isolate PM1 populations are dominant and novel methyl tert-butyl ether-degrading bacteria in compost biofilter enrichments. Environmental Microbiology 3:220-225.
3. Bruns MA, and DH Buckley. 2002. Isolation and purification of microbial community nucleic acids from environmental samples, pp 564-572. In C.J. Hurst (ed.), Manual of Environmental Microbiology, 2^nd ed., ASM Press, Washington, DC.
4. M.A. Bruns and K.M. Scow. 1999. DNA fingerprinting as a means to identify sources of soil-derived dust: problems and potential. In Integrated Assessment of Ecosystem Health. G. Fogg et al. (eds.), CRC Press, Boca Raton, FL.
5. M.A. Bruns, J.R. Stephen, G.A. Kowalchuk, J.I. Prosser, and E.A. Paul. 1999. Comparative diversity of ammonia oxidizer 16S rRNA gene sequences in native, tilled and successional soils. Applied and Environmental Microbiology 65:2994-3000.
6. M.A. Bruns, M.R. Fries, J.M. Tiedje, and E.A. Paul 1998. Functional gene hybridization patterns of terrestrial ammonia-oxidizing bacteria. Microbial Ecology 36:293-302.
7. Song XH, Hopke PK, Bruns MA, Graham K, and Scow KM. 1999. Pattern recognition of soil samples based on the microbial fatty acid contents. Environ. Sci. Technol. 33:3524-3530.
8. Stephen, J. R., G. A. Kowalchuk, M.A. Bruns, J.I. Prosser, T.M. Embley, and J. Woldendorp. 1998. Analysis of ß-subgroup chemolithotrophic ammonia oxidizer populations by DGGE, membrane transfer and hierarchical 16S rDNA oligonucleotide probing. Appl. Environ. Microbiol. 64:2958-2965.
9. Zhou J, Bruns MA, and Tiedje JM (1996) Rapid method for recovery of DNA from soils of diverse composition. Appl. Environ. Microbiol. 62:316-322.

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