# Influence of Major Environmental Parameters on Patulin Production by Penicillium expansum OM1 and Its Growth on Apple Puree Agar Media

## TL;DR

This study explores how environmental factors affect patulin production and growth of Penicillium expansum on apples, offering insights for reducing contamination.

## Contribution

The study identifies optimal environmental conditions for patulin production and growth of P. expansum on apple puree agar.

## Key findings

- Patulin production by P. expansum OM1 is highest at 15 °C, pH 4.0, and 98% RH.
- Growth rates are highest at 25 °C, pH 4.0–6.0, and 98% RH.
- Patulin contamination can be controlled by storing apples below 5 °C.

## Abstract

Patulin is a mycotoxin produced mainly by Penicillium expansum on apples. P. expansum is a fruit pathogen that can cause apple soft rot. However, much is unknown about the characteristics of P. expansum and influence of major environmental parameters on its patulin production and growth on apple puree agar media (APAM). In this study, we evaluated the influence of pH, temperature, and relative humidity (RH) on patulin production by P. expansum OM1 and its growth (colony diameter and mycelial dry weight) on APAM after isolation and identification of the patulin-producing fungal strain from an apple. The fungal isolate produced the largest quantity of patulin on APAM under 15 °C, pH 4.0, and RH 98%, while it had the highest growth rates on the same media under 25 °C, pH 4.0–6.0, and RH 98%. Our data demonstrated that three important physicochemical factors (pH, temperature, and RH) substantially influenced the patulin production by the fungal species and its growth on APAM. Moreover, our results revealed that patulin was not detected on APAM at 5 °C after 7 days of incubation and that a trace amount of patulin was produced by the fungal strain along with its slow growth on the same media at 5 °C after 14 days. It suggests that patulin contamination by P. expansum on apples could be controlled during postharvest storage below 5 °C. These findings could provide fundamental knowledge for development of efficient strategies to prevent the occurrence of apples contaminated with patulin produced by P. expansum on them during postharvest storage.