Mechanism of action of some microbial antagonists against fungal pathogens

Abstract

The present work reviews the mechanisms of action of some microorganisms antagonistic to pathogenic fungi (Penicillium digitatum, Penicillium italicum, Penicillium expansum, Botrytis cinerea, Monilinia fructicola, Rhizophus stolonifer and others). The most important modes of inhibition include antibiosis, parasitism, competition and host resistance induction. The antagonists under consideration often bring different mechanisms into play against a single pathogen and sometimes inhibitory activity can vary according to the fungus involved. In particular, the antagonist bacteria (Bacillus subtilis, Pseudomonas cepacia, Pseudomonas fluorescens and others) and the fungi (Trichoderma harzianum and others) act mainly by antibiosis and occasionally by parasitism and competition. The antagonist yeast (Pichia guilliermondii, Candida famata and others) are presently considered the most effective for postharvest use, given their particular mechanism of inhibition based on space and nutrient competition and host resistance induction by eliciting phytoalexins only in the wounds, without producing antibiotics