BIOREMEDIATION OF PHENOLIC-COMPOUNDS FROM WATER WITH PLANT-ROOT SURFACE PEROXIDASES

Peroxidases have been shown to polymerize phenolic compounds, thereby removing them from solution by precipitation. Others have studied the role of root surface associated peroxidases as a defense against funga l root pathogens; however, their use in detoxification of organic poll utants in vivo at the root surface has not been studied. Two plant spe cies, waterhyacinth [Eichhornia crassipes (C. Mart) Solms-Laub.] and t omato (Lycopersicon esculentum L.), were tested for both in vitro and in vivo peroxidase activity on the root surface. In vitro studies indi cated that root surface peroxidase activities were 181 and 78 nmol tet raguaiacol formed min-1 g-1 root fresh wt., for tomato and waterhyacin th, respectively. Light microscope studies revealed that guaiacol was polymerized in vivo at the root surface. Although peroxidase was evenl y distributed on tomato roots, it was distributed patchily on waterhya cinth roots. In vitro studies using gas chromatography-mass spectromet ry (GC-MS) showed that the efficiency of peroxidase to polymerize phen ols vary with phenolic compound. We suggest that plants may be utilize d as a source of peroxidases for removal of phenolic compounds that ar e on the EPA priority pollutant list and that root surface peroxidases may minimize the absorption of phenolic compounds into plants by prec ipitating them at the root surface. In this study we have identified a new use for root-associated proteins in ecologically engineering plan t systems for bioremediation of phenolic compounds in the soil and wat er environment.