Monday, November 13, 2006
92-14

A Quantitative Measure of Total Bacterial Community Diversity in Disturbed and Undisturbed Soil Ecosystems.

Sougata Bardhan, The Ohio State University, 1680 Madison Avenue, 1680 Madison Avenue, Wooster, OH 44691, United States of America and Barry Jacocks, School of Natural Res.-OSU, Wyffels Hybrids, 18 Oakington Drive, Geneseo, OH 61254-9203.

Evaluating and monitoring soil ecological aspects is arguably one of the most difficult objectives of soil scientists. Soil is primarily composed of mineral materials embedded with plant roots, microbial and animal biomass, decomposed organic matter, gas, water etc. Bacteria are microbial organisms in soil that are involved in several key soil processes and are found in large numbers in a healthy soil. They respond greatly to any disturbance. But unfortunately identifying and quantifying bacterial diversity was very difficult until recently. With the advent of molecular tools, studies can now be conducted that measure bacterial community diversity. Many researchers have concluded that the functional roles played by suites of species are more relevant to ecosystem processes than individual species for that particular system. Thus the proper functioning of these ecological interactions is measured by the degree of diversity; in other words proper functioning is often proportional to the complexity of the system. Higher diversity is generally considered to indicate better soil health. In this study, I compared bacterial diversity in soils under different management conditions. The sites selected for the study included a chronosequence of reclaimed coal mines maintained as pasture or grass, unreclaimed abandoned coal mines, and undisturbed tree remnants and grasslands. Three replicated soil samples (0-7.5 cm depth) were collected. Bacterial DNA was extracted and purified and DNA melting and reassociation profile was used to link bacterial community diversity with soil health from the standpoint of different management practices. After melting, 50% re-association was measured by the decrease in optical density and Cot plot were calculated to express bacterial diversity. Initial results indicate that bacterial diversity is related to the richness of the system meaning that unreclaimed coalmines had considerably less number of bacterial species when compared to the number of bacterial species quantified in an organic farm.