Enhancement of pyrene removed from contaminated soils by Bidens maximowicziana

The research utilized Bidens maximowicziana along with pyrene-degrading bacteria to evaluate their potential in cleaning up pyrene contamination. The removal of pyrene from the planted soil was obviously higher than that from the unplanted soils. After 50 d of B. maximowicziana growth, the average removal ratio of pyrene in planted soil was 79%, which was 28% higher than that of pyrene in unplanted soil. In contrast to other plants, both roots and shoots of B. maximowicziana could accumulate a large amount of pyrene from the soil and pyrene uptake increased with the soil pyrene concentration. Through analysis of pathways of pyrene removal, this enhanced removal of pyrene by plant–microbial association might be mainly the result of B. maximowicziana-promoted microbial degradation. Both the catalase and polyphenol oxidase activities in soil were higher in planted soil than those in unplanted soil. And the bacteria populations in soil, especially in rhizosphere, were also inspired by the growth of B. maximowicziana. These could be explained by the rhizosphere effect. Therefore, bio-removal of pyrene in the contaminated soils was feasible using B. maximowicziana.