Assessing Soil Bacterial Diversity in Southwestern Pennsylvania

Ian Kohler, Peter Leehan, Kyle Yebernetsky


The environmental impact caused by the current expansion of gas drilling in the Marcellus shale region of Pennsylvania is poorly understood and undocumented. The diversity and abundance of soil bacteria, that serve essential functions in the environment, can be affected by this drilling. Studying soil bacterial communities, which have the metabolic and genetic capability to respond quickly to changes in environmental conditions, provide a window to overall ecosystem health. Therefore, it becomes paramount to profile and establish a baseline for the soil bacterial diversity in this region to thoroughly understand the environmental effects of drilling. To establish this sbaseline, soil bacteria were identified from within the mixed temperate forest of the 57-acre Abernathy Field Station in Southwestern Pennsylvania. Cultured bacteria were analyzed using molecular techniques involving the use of 16S rDNA sequences. Over 40 genera of soil bacteria were found, spanning across 30 families, with the phyla Firmicutes and Proteobacteria dominating. These results were comparable to other studies on culturable soil bacteria in other temperate forest ecosystems. The diversity among these isolates was assessed by various statistical methods including Shannon-Weaver and Chao1 indices. Rarefaction analysis indicated that sampling saturation was not reached, suggesting that more culturable species could be found. Diversity indices calculated were high suggesting that the soil in this region is nutrient rich. This was further supported by the relatively high numbers of β- Proteobacteria and Bacteriodetes, which are found in nutrient rich conditions. This study has been successful in profiling and establishing a baseline of soil bacterial diversity. From this, it now will be possible to monitor both the short and long term effects of Marcellus shale drilling on soil bacterial diversity and overall ecosystem health.


16S rDNA, Phylogeny, RFLP Analysis

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