The efficacy of a yeast, Aureobasidium spp. strain UC14 isolated during the winter season, against Penicillium expansum growth was tested by in vitro assays and on apples during the cold storage. The antagonism of UC14 was further demonstrated by the low amount of pathogen DNA detected in treated fruits by qPCR analysis and also by the reduction of patulin. Results displayed interesting aspects of the strain as candidate for use in the postharvest phase.

Abstract

Penicillium expansum is a fungal pathogen of pome fruit, causing the economically important disease of apple blue mould. The fungus is also important due to its ability to produce the mycotoxin patulin. A strain of Aureobasidium spp. (UC14) was assessed for controlling P. expansum and patulin production in a series of in vitro antibiosis experiments. Volatile and non-volatile metabolites reduced growth of P. expansum on average by 50%. To assess UC14 efficacy on apples in vivo, different concentrations of cellular suspension were assayed. The concentration 1 × 10⁸ cells/mL was the most effective, completely suppressing apple fruits blue mould symptoms. The antagonism of UC14 was further demonstrated by the very low amount of pathogen DNA in treated fruits detected by qPCR. During cold storage, Aureobasidium strain UC14 persisted on fruits and reduced disease severity by 82.5% and 89.8%, for ‘Golden delicious’ and ‘Fuji’ apples, respectively. Aureobasidium strain UC14 reduced patulin on ‘Golden delicious’ and ‘Fuji’ apples by 98.1% and 96.2% with respect to the control, demonstrating good efficacy as a potential biological control agent (BCA), so becoming an interesting candidate for use as BCA in the postharvest phase.