Colorimetric method for determining hydrogen peroxide production in liquid media by filamentous fungi

Abstract

A semiquantitative assay to estimate rates of H₂O₂ produced in the liquid medium by fungi grown in a modified Georgiou-Petri dish growth apparatus in 9-cm Petri dishes is described. The method is based on the horseradish peroxidase-mediated oxidation of phenol red by H₂O₂ adapted to assay nmol amounts of H₂O₂ produced by fungal mycelial colonies in their own liquid media. We showed for the first time that the phytopathogen basidiomycete Sclerotium rolfsii produces H₂O₂ in the growth medium with the highest production rate of 250 nmol/min/g fungal dry weight at 3 d and with the highest accumulation rate of 235 nM/min at 8 d. The assay is simple and when properly adjusted can provide a reasonable in vitro assessment of the capacity of various fungi to produce H₂O₂, providing a valuable tool for studying its involvement in fungal phytopathogenicity and in microbial oxidative stress.

Key Words:

• Georgiou-Petri dish growth apparatus
• oxidative stress
• Sclerotium rolfsii