Volatile organic compounds from Pichia kluyveri inhibit the cacao pathogen Moniliophthora roreri.

Moniliophthora roreri is a major fungal pathogen that significantly reduces cacao yields in Colombia. Currently, farmers rely solely on fungicides for its control, and environmentally friendly alternatives remain limited. The objective of this study was to assess the antagonistic potential of yeasts isolated from diverse niches in Colombia against M. roreri as a first step toward developing sustainable biocontrol strategies. Initially, the pathogen was identified at the molecular level. Subsequently, seven yeast strains belonging to the genera Wickerhamomyces, Naganishia, Pichia, and Metschnikowia were assessed for antifungal activity against M. roreri, volatile organic compounds (VOCs) production, and enzymatic activities. Although none of the strains inhibited fungal growth through direct confrontation, VOC-mediated antagonism in dual-culture assays resulted in pathogen growth inhibition ranging from 38% to 98%. Glucanase, protease, and cellulase activities were detected to varying degrees among the isolates. Pichia kluyveri Lv125, which exhibited the strongest inhibitory effect, was selected for VOC characterization using gas chromatography-mass spectrometry (GC-MS). Antagonistic VOCs produced after 15 days of incubation included 1-butanol, 3-methylbutanoic acid, butanoic acid, 3-methyl-1-butanol, 3-methyl acetate, and phenylethyl alcohol. These findings highlight the potential of yeasts as biological control agents and support their use as an alternative management strategy against M. roreri in cacao plantations.