Analysis of PAH-degrading bacteria associated with phytoremediation

Phytoremediation, the use of plants to clean up organic and inorganic pollutants, is an emerging remediation technology considered to be a cost effective, aesthetically pleasing, and more environmentally compatible alternative to engineering-based methods. Plant-microbe rhizosphere interactions are considered the major mechanism for phytoremediation of some organic contaminants, including polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). This research study is focused on the soil microbial community response in the rhizosphere of different plant species in phytoremediation field trials in PAH contaminated soils. We hypothesized that different plant species have different effects in the abundance and diversity of bacterial PAH degraders. We utilized a direct PAH metabolism technique, the "Spray Plate Assay", to quantify culturable and PAH-degrading soil bacteria from five different field treatments: planted with Aster novae-angliae, Eupatorium purpureum, Lobelia cardinalis, and Spartina pectinata, and an unplanted control. It was shown that A. novae-angliae and S. pectinata increased total soil bacteria relative to the other treatments. A. novae-angliae and E. purpureum were observed to enrich PAH-degrading bacteria up to 4 times compared to the other treatments. In summary, this study demonstrated that appropriate plant selection is a critical factor for design of an effective phytoremediation treatment.