| Over the past 50 years, the field of microbial ecology has evolved into one of the most exciting sub-disciplines of biology and has produced many important revelations in the areas of ecology and biotechnology. Much of the recent work in this field has focused on providing a better understanding of how environmental conditions influence microbial communities and the resulting impacts of those changes on ecosystem function and stability. The studies detailed within this dissertation explored the relationship between microbial communities and environmental factors. Although the two environments studied (filters within a pilot scale municipal drinking water treatment facility in Birmingham, AL, and soils of the Atacama Desert, Chile) exhibited dissimilar conditions, I employed a variety of comparable molecular and microbiological techniques for their examination. Microbial community structure within the drinking water treatment filters was influenced by filter type (granular activated carbon or anthracite), colonization time (early or late), and depth distribution within the filter (top or bottom), but was not significantly influenced by chlorinated backwashing. The filters were colonized by common soil and freshwater bacteria, and did not appear to be colonized by known human pathogens. In contrast, the microbial communities within soils of the Atacama Desert were primarily influenced by carbon, nitrogen, and soil organic matter concentrations, as well as pH, nitrate concentration, and soil conductivity. The effects of these environmental conditions varied with latitude, with the northern hyperarid soils supporting less abundant, viable, and diverse microbial communities, and soils of the arid southern desert supporting communities with higher microbial abundance, activity, viability, and diversity. Cultivation experiments revealed that soil microbial communities of the Atacama were not primarily limited by water availability. Combined, these studies provide an assessment of the factors that influenced microbial communities within these disparate systems and a better understanding of the relationship between microbial communities and environmental conditions. |
