Degradation, Phytoprotection and Phytoremediation ofPhenanthrene by EndophytePseudomonas putida,PD1

ABSTRACT:Endophytes have been isolated from a large diversity of plants and have beenshown to enhance the remediation efficiency of plants, but little information is available on theinfluence of endophytic bacteria on phytoremediation of widespread environmentalcontaminants such as polycyclic aromatic hydrocarbons (PAHs). In this study we selected anaturally occurring endophyte for its combined ability to colonize plant roots and degradephenanthrene in vitro. Inoculation of two different willow clones and a grass withPseudomonasputidaPD1 was found to promote root and shoot growth and protect the plants against thephytotoxic effects of phenanthrene. There was an additional 25−40% removal of phenanthrenefrom soil by the willow and grasses, respectively inoculated with PD1 when compared to theuninoculated controls. Fluorescent microscopy usingfluorescent protein tagging of PD1confirmed the presence of bacteria inside the root tissue. Inoculation of willows with PD1consistently improved the growth and health when grown in hydroponic systems with highconcentrations of phenanthrene. To our knowledge this is thefirst time that the inoculation ofwillow plants has been shown to improve the degradation of PAHs and improve the health of the host plants, demonstrating thepotential wide benefit to thefield of natural endophyte-assisted phytoremediation.