Toxicity elimination of phenanthrene to wheat mediated by enhanced Pseudomonas sp. JM2-gfp biofilm degradation

Biofilm mediated degradation of polycyclic aromatic hydrocarbons is effective and environmentally safe. In this study, the bioactivity of a Pseudomonas sp. JM2-gfp formed biofilm on the uptake and toxicity of phenanthrene onto wheat roots were investigated and the biofilm degradation efficiency was enhanced by adding natural organic compounds. Dense biofilm habitat at entire root zone of the wheat root except the cap position. Interface phenanthrene adsorption was attenuated after the biofilm formation on the surface of the wheat root and phenanthrene accumulation in wheat roots and stems were deceased during the treatment period. Phenanthrene degradation rate were also evaluated and biofilm colonized wheat had higher rate than that of the wheat itself. The addition of citric acid and humic acid enhanced the bioactivity of the Pseudomonas sp. JM2-gfp formed biofilm on phenanthrene adsorption, accumulation and degradation, achieving over 80% degradation efficiency. Citric acid and humic acid were able to benefit the formation of the biofilm by increasing the secretion base hydrophobicity surrounding the wheat root to facilitate the toxicity elimination of phenanthrene.