Bacteria in their natural environments are continuously exposed to changing environmental conditions such as oxygen limitation. To survive and complete bacteria have developed methods to monitor the state of the environment and adapt accordingly. Understanding the processes of microbial persistence, competition, and colonization are of great importance when contemplating the use of beneficial microbes such as rhizobia in agriculture, or alternatively the control of harmful pathogens during infection and disease. The goal of this purpose is to identify and characterize novel regulatory pathways important in the response of the soil bacterium R. meliloti to oxygen limitation in order to examine the role of this response in survival, competition, and colonization. Towards this goal, a collection of previously isolated Tn5luxAB insertions fused to promoters expressed under microaerophilic conditions will be tested for regulation by the known oxygen sensing system, FixL/FixJ. Novel regulatory loci required for the oxygen-limitation response will be identified by second-site mutagenesis of strains containing Tn5luxAB fusions whose expression is FixL/FixJ independent. The importance of the novel regulatory loci and of fixL for survival and completion under microaerophilic conditions in nutrient-rich soil will be determined. A role for the loci in legume nodule formation and legume colonization will also be examined.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
1F32GM019412-01
Application #
2637508
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1998-09-30
Project End
Budget Start
1998-06-01
Budget End
1999-05-31
Support Year
1
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Michigan State University
Department
Other Basic Sciences
Type
Schools of Arts and Sciences
DUNS #
193247145
City
East Lansing
State
MI
Country
United States
Zip Code
48824
de Bruijn, Frans J; Rossbach, Silvia; Bruand, Claude et al. (2006) A highly conserved Sinorhizobium meliloti operon is induced microaerobically via the FixLJ system and by nitric oxide (NO) via NnrR. Environ Microbiol 8:1371-81
Trzebiatowski, J R; Ragatz, D M; de Bruijn, F J (2001) Isolation and regulation of Sinorhizobium meliloti 1021 loci induced by oxygen limitation. Appl Environ Microbiol 67:3728-31