Effect of magnetic field as abiotic elicitor on growth and antioxidant activities of Ganoderma lucidum mycelium

Ganoderma lucidum, commonly called reishi (Japan) and Ling Zhi (China) is a medicinal fungus, and generally observed on dead trees and timbers of deciduous forest trees such as Quercus castaneifolia, Carpinus betulus, Parrotia persica. Ganoderma lucidum owes its anti-disease properties to presence of secondary metabolites in the fruiting body, mycelium and spores. The aim of present study was to investigate the possibility of increasing the antioxidant activity of Ganoderma lucidum by using a magnetic field as an abiotic elicitor. Mushroom samples were collected from Dr. Bahramnia's Forest Management project- Golestan- Iran. One cm cultured mycelia in PDA medium were exposed to magnetic field with under ۲۰, ۴۰ and ۶۰ milli tesla levels for ۳۰, ۶۰ and ۹۰ minutes. The experiment was conducted as completely randomized design arrangement in factorial with three replications. The growth of the mycelia was measured over ten days. The results showed that there was no significant difference between mycelial growth trends in different treatments. The average growth of treated mycelium was ۸.۰۵ mm per day compared to the average growth of ۷.۴ mm per day for control. According to the results mycelium of Ganoderma lucidum grows "very fast" with a growth of more than ۵ cm during ۳-۴ days. To investigate the effect of magnetic field levels on the antioxidant activities, the grown mycelium were cultured in PDB medium for ۱۴ days and then filtered. The Extracellular methanolic extract was used to evaluate the antioxidant properties by DPPH method. Effect of magnetic field levels on the antioxidant activities of the treatments was significant but it did not make sense at different times (۳۰, ۶۰ and ۹۰ minutes). Antioxidant activities were ۲۱.۵۴, ۲۵.۳۶ and ۲۸.۳۴ for ۲۰, ۴۰ and ۶۰ mili tesla treatments respectively while was ۱۸.۵۶in control. So, according to the results of antioxidant properties, ۶۰ milli tesla in ۹۰ minutes treatment was selected as the best treatment for future experiments about secondary metabolites.

Keywords:

Ganoderma lucidum , magnetic field , mycelial growth , antioxidant properties