Understanding Plant-Microbe Interactions for Phytoremediation ofPetroleum-Polluted Soil

摘要

Plant-microbe interactions are considered to be important processes determining the efficiency of phytoremediation of petroleum pollution, however relatively little is known about how these interactions are influenced by petroleum pollution. In this experimental study using a microcosm approach, we examined how plant ecophysiological traits, soil nutrients and microbial activities were influenced by petroleum pollution in Phragmites australis, a phytoremediating species. Generally, petroleum pollution reduced plant performance, especially at early stages of plant growth. Petroleum had negative effects on the net accumulation of inorganic nitrogen from its organic forms (net nitrogen mineralization (NNM)) most likely by decreasing the inorganic nitrogen available to the plants in petroleum-polluted soils. However, abundant dissolved organic nitrogen (DON) was found in petroleum-polluted soil. In order to overcome initial deficiency of inorganic nitrogen, plants by dint of high colonization of arbuscular mycorrhizal fungi might absorb some DON for their growth in petroleum-polluted soils. In addition, through using a real-time polymerase chain reaction method, we quantified hydrocarbon-degrading bacterial traits based on their catabolic genes (i.e. alkB (alkanemonooxygenase), nah (naphthalene dioxygenase) andtol (xylene monooxygenase) genes). This enumeration oftarget genes suggests that different hydrocarbon-degrading bacteria experienceddifferent dynamic changes during phytoremediation and a greater abundance ofalkB was detected during vegetative growth stages. Becausephytoremediation of different components of petroleum is performed by differenthydrocarbon-degrading bacteria, plants’ ability of phytoremediatingdifferent components might therefore vary during the plant life cycle.Phytoremediation might be most effective during the vegetative growth stages asgreater abundances of hydrocarbon-degrading bacteria containingalkB and tol genes were observed at thesestages. The information provided by this study enhances our understanding of theeffects of petroleum pollution on plant-microbe interactions and the roles ofthese interactions in the phytoremediation of petroleum-polluted soil.