Term of Award

Fall 2014

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Tiehang Wu

Committee Member 1

John Scott Harrison

Committee Member 2

Subhrajit Saha

Abstract

This study compared the soil microbial communities of three vegetation types in the coastal plain of Georgia: 1. crop land actively in use for agricultural production, 2. transitional grassland in early stages of secondary succession, and 3. pristine unmanaged forest land. Microbial species diversity and quantities of microbial DNA were determined from each of these vegetation types at three separate locations near Statesboro, Georgia. Length heterogeneity PCR(LH-PCR) methods and subsequent analysis of fungal, bacterial, and metazoan communities by analysis of similarity (ANOSIM) revealed high within-group similarity by vegetation type, indicating land management intensity and vegetation cover is a strong determining factor in community similarity. Further analysis of fragments obtained by LH-PCR revealed that fungal and metazoan communities in crop soil included the highest number of common operational taxonomic units (OTUs) represented in all treatments, while forest soils contained the least number of common OTUs of animal and fungi. This trend is not observed in bacterial communities, and may be a function of organism size. Quantitative PCR (qPCR) detection of fungal and bacterial DNA revealed significantly higher concentrations of both fungal and bacterial DNA in forest soils than concentrations in both crop and transitional soils. Despite differences in microbial communities and DNA concentrations, these soils exhibited no significant difference in their suppression of the soil-borne pathogen Sclerotium rolfsii in the context of a greenhouse experiment. S. rolfsii inoculum was successfully detected through qPCR based methods, however, S. rolsfii DNA concentrations lack correlation with Southern Blight disease incidence. In conclusion, vegetation and land management intensity significantly affect soil microbial communities. Forest soils host a fewer number of common animal and fungal OTUs than crop soils. Bacteria had no difference in the occurrence of common OTUs between vegetation types. qPCR methods were successfully employed to detect S. rolfsii inoculum. Although S. rolfsii DNA concentrations lacked correlation with disease severity, these methods are capable of detecting the potential of soil-borne disease development.

Download

Share

COinS