Abstract/Details

Homeostatic control of iron- and manganese-dependent bacterial physiology and the impact of these metals on multicellular interactions of <i>Agrobacterium tumefaciens</i>


2011 2011

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Abstract (summary)

Transition metals from the first row of the periodic table, including iron and manganese are critical micronutrients for nearly all forms of life. However, they are also generally limiting in the environment and toxic at high concentrations. I have used genetic and physiological approaches to define the regulatory systems that the plant pathogenic bacterium Agrobacterium tumefaciens uses to sense varying levels of environmental iron and manganese and control the expression of metal uptake and utilization systems. The regulation of these systems allows A. tumefaciens to maintain sufficient cellular levels of iron and manganese for growth while preventing the accumulation of toxic levels of either metal. Using microarray analysis, I showed that varied iron availability induces major alterations in the gene expression profile. This study of the transition metal physiology of A. tumefaciens included an examination of the role iron and manganese play in mediating biofilm formation. Limiting amounts of either iron or manganese were found to decrease the biofilm formation of A. tumefaciens. Interestingly, disruption of the iron-responsive regulatory circuitry did not alter or abolish the impact of iron on biofilms, whereas de-repression of the manganese uptake systems resulted in a slight increase in biofilm formation. Finally, iron mediates the interactions between A. tumefaciens and the environmental and opportunistically pathogenic bacterium Pseudomonas aeruginosa. Iron limitation stimulates P. aeruginosa to produce a secreted, soluble compound that inhibits the biofilm formation by A. tumefaciens and fosters biofilm dispersal.

Indexing (details)


Subject
Microbiology
Classification
0410: Microbiology
Identifier / keyword
Biological sciences; Agrobacterium tumefaciens; Biofilm formation; Diffusible inhibitors; Gene regulation; Manganese; Multicellular interactions; Pseudomonas aeruginosa; Transition metals
Title
Homeostatic control of iron- and manganese-dependent bacterial physiology and the impact of these metals on multicellular interactions of <i>Agrobacterium tumefaciens</i>
Author
Hibbing, Michael Einer
Number of pages
278
Publication year
2011
Degree date
2011
School code
0093
Source
DAI-B 73/04, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9781267078421
Advisor
Fuqua, Clay
Committee member
Brun, Yves; Kearns, Daniel B.; Parsek, Matthew R.; Velicer, Gregory J.
University/institution
Indiana University
Department
Biology
University location
United States -- Indiana
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3488073
ProQuest document ID
914707160
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/914707160
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