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David W. Emerich

Professor of Biochemistry
Associate Chair
Director, Undergraduate Studies

Email:	emerichd@missouri.edu
Phone:	(573) 882-4252
Lab:	(573) 771-9076
Fax:	(573) 882-5635
Office:	226 Schweitzer Hall
Mailing Address:	Biochemistry 117 Schweitzer Hall University of Missouri-Columbia Columbia, MO 65211
Research Areas:	Enzymology, physiology and genomics of biological nitrogen fixation and related metabolic activities.

Educational Background

BS		University of Wisconsin	Madison, Wis.	Biochemistry
PhD		University of Wisconsin	Madison, Wis.	Biochemistry

Notable Honors and Service

Associate Chair, Department of Biochemistry
Herman Frasch Foundation Research Fellow, 1981-86
Gamma Sigma Delta Teaching Award, 1983
CAFNR Teaching Award, Biochemistry Unit, 1993
Alumni Faculty Development Incentive Award, 1993
CAFNR Outstanding Advisor Award, 1994
Member, Gamma Sigma Delta, 1995
Faculty Technology Teaching Grant, 1995
William T. Kemper Fellowship for Excellence in Teaching, 2000

Research Description

Biochemical regulation of Bradyrhizobium japonicum during symbiotic development

Current Projects - Biochemical and genetic regulation of the metabolic processes that are required for symbiotic nitrogen fixation is the focus of this research program. Rhizobium-leguminous plant symbioses are unique associations in which both the bacteria and the plant undergo complex metabolic and morphological changes. My laboratory is attempting to identify these processes and to elucidate the mechanisms by which these changes are controlled. The primary goal is to determine which factors, genetic and/or biochemical, limit nitrogen fixation and thus plant growth and development. After these limitations are defined, the appropriate generic alterations will then be attempted to enhance plant productivity.

Specific projects include (1) genomic analysis using oligonucleotide microarrays of the Bradyrhizobium japonicum genome (2) proteomic analysis of the proteins expressed during symbiotic development and (3) metabolic analysis using ¹³C-NMR and combined chromatographic/mass spectral analyses. A recent focus of the laboratory has been the elucidation of malate metabolism by the symbiotic form of B. japonicum which are referred to as bacteroids and the role of alanine excretion by bacteroids. Malate is the primary compound provided to the bacterorid by the plant and is believed to be metabolized via the citric acid cycle, but we have shown that neither α-ketoglutarate dehydrogenase nor isocitrate dehydrogenase are required for symbiotic nitrogen fixation. Thus, the pathway of malate metabolism to provide energy for reduction of atmospheric dinitrogen remains to be determined. Recently, we have shown that alanine, not ammonium, is the principle nitrogen compound provided to the plant by the bacteroid. The metabolism of B. japonicum is being characterized via DNA microarray and proteomic analysis.

Selected Publications

N.W. Oehrle, D.B. Karr, R.J. Kramer and D.W. Emerich. 2000. Enhanced attachment of Bradyrhizobium japonicum to soybean through reduced root colonization of internally-seedborne microorganisms. Can. J. Microbiol. 46:600-606.

D.B. Karr, R-T. Liang, B. Rheus and D.W. Emerich. 2000. Altered exopolysaccharides of Bradyrhizobium japonicum mutants correlate with impaired soybean lectin binding, but not effective nodule formation. Planta, 211:218-226.

L.S. Green, J. K. Waters, S. Ko, and D.W. Emerich. 2003. Comparative analysis of the Bradyrhizobium japonicum sucA region. Can. J. Microbiol. 49:237-243.

D.B. Karr, N.W. Oehrle and D.W. Emerich. 2003. Recovery of nitrogenase from aerobically isolated soybean nodule bacteroids. Plant and Soil. 257:27-33.

N.W. Oehrle, L.S. Green, D.B. Karr and D.W. Emerich. 2004. The HFC/HCFC breakdown product of trifluoroacetic acid (TFA) and its effects on the symbiosis between Bradyrhizobium japonicum and soybean (Glycine max). Soil Biol. Biochem. 36:333-342.

Employment Opportunities

Post-Doctoral Opportunities

Electronic submission is encouraged, e-mail to biochemsearch@missouri.edu

Applicants should send CV and names of two references to:
Dr. David Emerich
Postdoctoral Application
Biochemistry
117 Schweitzer Hall
University of Missouri-Columbia
Columbia, MO 65211

Enzymology, physiology and genomics of biological nitrogen fixation and related metabolic activities.