Assessing Microbial Diversity in Central Iowa Using DNA Fingerprinting

Abstract

The vast majority of biological diversity resides in the microbial world, and the number of differing species in kingdoms Bacteria, Fungi, Protista, and Archaea are predicted to be several million. Moreover, the diversity within bacteriophage, plant viruses, and animal viruses is thought to exceed what is found in any one of the major kingdoms of life. These microbes play important roles in the ecosystems they occupy and one hypothesis is that this microbial diversity can be utilized as a metric to assess the status or health of an ecosystem. Conventional microbiological techniques used to assay microbial populations have largely been supplanted with molecular techniques that enable investigators to capture a more true and wider diversity and to avoid culture bias. Over the course of a four month period, soil samples taken from Walnut Woods State Park and water samples taken from the Raccoon River were assayed by tRFLP analysis. Bulk DNA was purified from soil and water and total 16S ribosomal subunit genes were amplified and genotyped. Microbial diversity was evaluated over time, across locations, and in consideration of abiotic factors such as temperature, soil moisture, and soil depth. Conventional microbial characterization methods were performed as comparisons. The experiments revealed a very rich microbial diversity present in the water and soil samples that were tested.