Glucose oxidase as a control agent against the fungal pathogen Botrytis cinerea in postharvest strawberry

Abstract

Botrytis cinerea is an economically devastating necrotrophic fungus with many host species, and the fungicides commonly used to control it cause serious food and environmental safety problems. It is therefore urgent to develop alternative control measures for these pathogen fungicides. The glucose oxidase enzyme (GOX) is an oxido-reductase that catalyzes the oxidation of glucose to hydrogen peroxide (H2O2) and gluconic acid. GOX has been widely used as a food additive because of its safety and oxidation properties, but little is known about its antifungal effects against B. cinerea, and there have been no reports of its application for pathogen control of postharvest fruit. Here, we examined the antimicrobial activity of GOX against B. cinerea spores and developed a GOX-glucose (10 g/L) system that can significantly restrict fungal growth on postharvest strawberry fruit. A variety of optical and electron microscopy investigations revealed that GOX inhibits B. cinerea growth by altering the morphology of mycelial membranes, among other deleterious effects. Biochemical analyses supported the observation that GOX-mediated growth inhibitory effects result from its competition of carbon and enzymatic production of H2O2 and from the acidifying influence of gluconic acid. Our demonstration of this GOX-glucose system as a control agent to protect postharvest fruit opens the door for the application of this technology to other crops and for further investigation of the mechanisms that can interrupt B. cinerea growth.