Selection and application of endophytic bacterium Achromobacter xylosoxidans strain F3B for improving phytoremediation of phenolic pollutants.

While phytoremediation has been considered as an in situ bioprocess to remediate environmental contaminants, the application of functional endophytic bacteria within plants remains a potential strategy that could enhance the plants' efficiency in phytoremediation. In this study, 219 endophytes were isolated from plants that are predominantly located in a constructed wetland, including reed (Phragmites australis) and water spinach (Ipomoea aquatica). Twenty-five strains of the isolated endophytes utilize aromatic compounds as sole carbon source; Achromobacter xylosoxidans strain F3B was chosen for the in planta studies using the model plant Arabidopsis thaliana. Phylogenetic analysis indicated that those endophytic isolates of A. xylosoxidans formed a cluster within its species, and a specific real-time PCR detection method was developed for confirming the stability of the isolates in plants. In the presence of either catechol or phenol, inoculation of A. thaliana with F3B could extend into the root lengths and fresh weights to promote pollutants removal rates. These results demonstrate the potential of the endophytic F3B strain for helping plants to tolerate stress from aromatic compounds and to improve phytoremediation of phenolic pollutants.