Amorphophallus paeoniifolius corm: A potential source of peroxidase for wide applications

Peroxidases have wide applications in different areas including chemical synthesis, medicine, food industry, bioremediation of wastewater, biosensing, and biotechnology. Amorphophallus paeoniifolius (elephant foot yam) is an attractive source of enzymes; however, no effort has been made to assess peroxidase enzyme from this source. Therefore, the objectives of this study were to evaluate and compare peroxidases from corms of elephant foot yam and roots of Dacus carota (carrot) and Aramoracia rusticana (horseradish). Elephant foot yam corm peroxidase (ECP) demonstrated 4.5 times higher specific activity compared with carrot root peroxidase (CRP). ECP showed retention of high activity over a broad pH range and had higher temperature optima and thermal stability compared with CRP and horseradish peroxidase (HRP). The calculated K_M values of ECP, CRP, and HRP for the substrates guaiacol and hydrogen peroxide were 4.5 mM and 307.8 µM, 4.6 mM and 55.5 µM, and 3.5 mM and 413.0 µM, respectively. Peroxidases are used for the bioremediation of wastewater contaminated with hazardous aromatic compounds. Heavy metals such as cadmium (Cd²⁺), lead (Pb²⁺), and toxic compounds such as sodium azide (NaN₃) are often present in wastewater along with aromatic compounds. Results showed activation of ECP and inhibition of HRP at 250 and 500 µM concentrations of Cd²⁺ and Pb²⁺. Treatment with 1 mM NaN₃ led to 8.4%, 55.5%, and 11.0% inhibition in the activities of ECP, CRP, and HRP, respectively. Overall, our results suggest that elephant foot yam can be used as a rich and convenient source of peroxidase for various applications including wastewater remediation.