Patulin production byPenicillium expansum isolates from apples during different steps of long-term storage

Abstract

Penicillium expansum is the principal cause of blue mould rot and associated production of patulin, a weak mycotoxin, in apples worldwide. P. expansum growth and patulin production is observed during improper or long-term storage of apples. We have investigated the extent to which each successive step during long-term storage contributes to patulin production in various P. expansum isolates. Fungal isolates collected on apples from several Belgian orchards/industries were identified to species level. Random amplification of polymorphic DNA (RAPD) analysis and beta-tubulin gene sequencing identified P. expansum and Penicillium solitum as the most prevalent Penicillium species associated with Belgian apples. All 27 P. expansum isolates and eight reference strains were characterised for their patulin production capacity on apple puree agar medium for five days under classical constant temperature and atmosphere conditions. Under these conditions, a large range of patulin production levels was observed. Based on this phenotypic diversity, five P. expansum isolates and one reference strain were selected for in vitro investigation of patulin production under representative conditions in each step of long-term apple storage. Patulin accumulation seemed highly strain dependent and no significant differences between the storage steps were observed. The results also indicated that a high spore inoculum may lead to a strong patulin accumulation even at cold temperatures (1 degrees C) combined with controlled atmosphere (CA) (3% O-2, 1% CO2), suggesting that future control strategies may benefit from considering the duration of storage under CA conditions as well as duration of deck storage

Effect of quorum sensing and quenching molecules on inter-kingdom biofilm formation by Penicillium expansum and bacteria

“…These microorganisms were chosen based on different characteristics: their ability to form mature single-species biofilms between 48 and 72 h growth, and because they have been assessed while forming inter-kingdom biofilms (Simões et al 2010;Afonso et al 2019). P. expansum, in particular, was also selected due to its well-known ability to produce patulin as a secondary metabolite (Santos et al 2002;Reddy et al 2010;De Clercq et al 2016). However, it produces this mycotoxin in certain favourable conditions (i.e.…”

Patulin in Apples and Apple-Based Food Products: The Burdens and the Mitigation Strategies

“…In a French apple orchard, the density of Penicillium was less than 50 spores/m 3 , however, 2500 spores/m 3 of Penicillium were detected in the atmosphere of previously disinfected warehouses, where P. expansum and Penicillium solitum accounted for 20.0–65.6% and 6.0–47.1%, respectively [ 31 ]. An isolation of the fungal species in long-term stored “Jonagold” apples in Belgium also indicated that P. expansum and P. solitum were the dominating species [ 44 ]. Although P. solitum is unable to produce patulin, it acts as a predisposing agent, which allows the entry of P. expansum and causes more destructive infections [ 37 , 45 ].…”

“…The highest production level of patulin by P. expansum isolates from Vineland, Woodstock, and Georgian Bay in Ontario, Canada, was around 0.66 mg/kg [ 50 ]. While the P. expansum isolate FC116 from Belgian “Jonagold” apple orchards was able to produce 747 mg/kg patulin in vitro [ 44 ]. More intriguing, there was no correlation between patulin accumulation in actual apples and in the potato dextrose agar, even by the same P. expansum isolate [ 51 ].…”

“…In a model of apple puree agar media, the effect of reducing the O 2 level from 20% to 3% on patulin production by P. expansum was strain-dependent; while a consistent suppression of patulin production was observed in all of the tested P. expansum strains when the O 2 was dropped from 3% to 1% [ 86 ]. In different stages of apple storage, no significant variation of the patulin content was observed, although the content of oxygen changed significantly [ 44 ]. Similarly, limited O 2 storage failed to reduce patulin in the “Galaxy” and “Fuji Kiku” apples from Brazil [ 46 ].…”

“…Recently, controlled atmospheres (1.00–3.00% O 2 and 0.03–5.00% CO 2 ) and/or ethylene content adjustments through the spraying of 1-methylcyclopropene have been coupled with cold storage practices to better extend the shelf-lives of apples and to inhibit P. expansum spreading [ 46 , 153 , 154 ]. Although patulin is commonly found during a later storage phase, a high density of P. expansum spores could result in a large amount of patulin accumulating in apples, even at an earlier onset of cold storage [ 44 , 155 ]. Therefore, a new trend of applying biocontrol agents (i.e., antagonistic yeast cultures) in cold and hypoxic warehouses has been tested, showing their ability to synergistically inhibit P. expansum growth and patulin accumulation [ 156 , 157 ].…”