Phytoremediation of phenol from wastewater, by peroxidases of tomato hairy root cultures

Phenolic compounds present in the drainage from several industries are harmful pollutants and represent a potential danger to human health. Here, we describe the removal of phenol from water using tomato hairy root cultures as source of enzymes, particularly peroxidases, which were capable to oxidise these compounds. Roots were able to remove phenol in the presence of H2O2 5 mM, from solutions containing 100 mg/l of pollutant. Removal reached high values within 1 h and over a wide range of pH (4.0–9.0) and temperatures (20–60 °C). After phenol treatment, peroxidase activity of hairy root extracts decreased and isoenzyme patterns were affected. Neutral and basic peroxidases isoenzymes were slightly inactivated while the activities of acidic peroxidase isoenzymes remained without changes. Removal assays and kinetic studies performed using root extracts and purified peroxidases suggest that basic peroxidase isoenzymes would be the main peroxidases implicated in removal processes and they could be inactivated during the treatment. However, acidic peroxidase isoenzymes seemed to have little participation and retained their activities. These findings contribute to a better understanding of the enzymatic processes involved in phytoremediation of phenol and might have important implications in the use of these roots or their enzymes as inexpensive systems for decontamination of polluted environments.