Year of Award

2009

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Other Degree Name/Area of Focus

Microbiology and Biochemistry, Microbial Ecology

Department or School/College

Division of Biological Sciences

Committee Chair

William Holben

Committee Co-chair

Carol Brewer

Commitee Members

Matthias Rillig, James Gannon, Scott Miller

Keywords

microbial ecology

Subject Categories

Biochemistry | Integrative Biology

Abstract

Arbuscular mycorrhizal fungi (AMF) are soil fungi forming symbiotic associations with majority of land plants. AMF alter soil organic matter (SOM) directly through stabilization of soil aggregates and indirectly providing a path in which plant fixed C02 is transferred below-ground. Understanding contributions of AMF to SOM via protein production and stabilization of soil aggregates will greatly aid our understanding of soil carbon sequestration, nutrient cycling and mitigation of soil erosion. The work presented in chapter 2 challenges the glomalin extraction process and assesses the accuracy of the Bradford and monoclonal-antibody ELISA detection methods. My results clarify the contribution of glomalin to SOM: suggesting the extraction process is not eliminating all non-glomalin proteins. My results indicate that the Bradford is prone to overestimating the presence of glomalin when soils contain large concentrations of SOM, the ELISA is prone to retention and interference biases depending on the amount and type of organic matter. Chapter 3 determines the contribution of AMF colonized roots to Bradford Reactive Soil Protein (BRSP) and lmmunoreactive Soil Protein (IRSP) pools. I test the hypothesis that roots colonized by different species of AMF will produce different quantities of Bradford Root Protein (BRP) and Immunoreactive Root Protein (IRP). These differences could alter BRSP and IRSP pools. I further demonstrate that BRP and IRP concentrations are effective biomarkers in predicting the percentage of AMF root colonization. Chapter 4 assesses the influence of AMF on aggregate dynamics. This work uses Rare Earth Elements (REE) to track aggregate formation and breakdown in the presence of AMF. I confirm that AMF rapidly form and stabilize macroaggregates incorporating intermediate macro-and microaggregates into macroaggregates (> 2000 μm). In chapter 5 I assess the effect of Hieracium invasion and soil fertility on AMF and non-mycorrhizal fungal biomass, carbon mineralization and soil structure. Results from this study provide information essential to understanding how exotic species can alter soil processes. Chapter 6 is the product of my work with the ECOS program; set of investigations aimed at teaching middle school students the ecological importance of soil microbiology. The significance of this body of work is outlined in chapter 7.

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© Copyright 2009 Carl Lee Rosier