Kosakonia radicincitans and Cryptococcus laurentii controlled Penicillium expansum rot and decreased patulin production at 4 and 25 °C.

In the present work, we evaluated the effects of a mixture of biocontrol agents against two toxigenic strains of Penicillium expansum isolated in Argentine Patagonia from pome fruits. The two strains, INTA-5 and INTA-10, were previusly selected among ten strains coming from the Alto Valle (Rio Negro-Argentina) for their high production of patulin. For the biocontrol, Kosakonia radicincitans, Cryptococcus laurentii, and Rhodosporidium fluviale were tested in vitro experiments on Potato Dextrose Agar (PDA) dishes against the INTA-5 and INTA-10 strains. The bacterium K. radicincitans and the yeast C. laurentii were selected to be used in a mixture due to their capacity to control the fungus and reduce the mycotoxin severely. In vitro assays with the mixture showed a high antagonism against P. expansum INTA-5 and INTA-10, at 21 d of incubation at 25 °C and a patulin reduction of 98%. The mixture of microorganisms was also effective in apples stored at 25 °C for 10 d and 4 °C for 30 d. At cold storage, the mixture controlled moderately the development of rot and decreased patulin concentration. At 25 °C, the pathogen's optimal growth temperature, the mixture of Biological Control Agent (BCAs) assured both the control of rot and decrease of patulin concentration. The combination of two microorganisms, with different requirements and abilities, resulted in a mix with a strong antagonism against P. expansum with the capability to decrease the patulin concentration. Treatment with the selected mixture could be a good option for controlling strains with different behaviours and in different environmental conditions.

The brlA Gene Deletion Reveals That Patulin Biosynthesis Is Not Related to Conidiation in Penicillium expansum.

Dissemination and survival of ascomycetes is through asexual spores. The brlA gene encodes a C2H2-type zinc-finger transcription factor, which is essential for asexual development. Penicillium expansum causes blue mold disease and is the main source of patulin, a mycotoxin that contaminates apple-based food. A P. expansum PeΔbrlA deficient strain was generated by homologous recombination. In vivo, suppression of brlA completely blocked the development of conidiophores that takes place after the formation of coremia/synnemata, a required step for the perforation of the apple epicarp. Metabolome analysis displayed that patulin production was enhanced by brlA suppression, explaining a higher in vivo aggressiveness compared to the wild type (WT) strain. No patulin was detected in the synnemata, suggesting that patulin biosynthesis stopped when the fungus exited the apple. In vitro transcriptome analysis of PeΔbrlA unveiled an up-regulated biosynthetic gene cluster (PEXP_073960-PEXP_074060) that shares high similarity with the chaetoglobosin gene cluster of Chaetomium globosum. Metabolome analysis of PeΔbrlA confirmed these observations by unveiling a greater diversity of chaetoglobosin derivatives. We observed that chaetoglobosins A and C were found only in the synnemata, located outside of the apple, whereas other chaetoglobosins were detected in apple flesh, suggesting a spatial-temporal organization of the chaetoglobosin biosynthesis pathway.

Molecular basis and regulation of pathogenicity and patulin biosynthesis in Penicillium expansum.

Penicillium expansum is a necrotrophic plant pathogen with a wide range of fruit hosts. It causes blue mold rot during fruit storage, transport, and sale, resulting in huge economic losses to the fruit industry. Moreover, this pathogen is also the main producer of patulin, a toxic secondary metabolite that contaminates fruit and fruit-derived products and impairs human health. Therefore, understanding molecular basis of the pathogenicity and patulin biosynthesis of the fungal pathogen has important scientific significance and also plays an important guiding role in the research and development of new control technologies. Here, we comprehensively summarize the recent research progress, particularly regarding the molecular aspects of pathogenicity, patulin biosynthesis, and the related regulatory mechanisms, as well as control technologies for blue mold rot in the fruit industry.

Dissection of patulin biosynthesis, spatial control and regulation mechanism in Penicillium expansum.

The patulin biosynthesis is one of model pathways in an understanding of secondary metabolite biology and network novelties in fungi. However, molecular regulation mechanism of patulin biosynthesis and contribution of each gene related to the different catalytic enzymes in the biochemical steps of the pathway remain largely unknown in fungi. In this study, the genetic components of patulin biosynthetic pathway were systematically dissected in Penicillium expansum, which is an important fungal pathogen and patulin producer in harvested fruits and vegetables. Our results revealed that all the 15 genes in the cluster are involved in patulin biosynthesis. Proteins encoded by those genes are compartmentalized in various subcellular locations, including cytosol, nucleus, vacuole, endoplasmic reticulum, plasma membrane and cell wall. The subcellular localizations of some proteins, such as PatE and PatH, are required for the patulin production. Further, the functions of eight enzymes in the 10-step patulin biosynthetic pathway were verified in P. expansum. Moreover, velvet family proteins, VeA, VelB and VelC, were proved to be involved in the regulation of patulin biosynthesis, but not VosA. These findings provide a thorough understanding of the biosynthesis pathway, spatial control and regulation mechanism of patulin in fungi.

Evaluation of the activity of the antifungal PgAFP protein and its producer mould against Penicillium spp postharvest pathogens of citrus and pome fruits.

Postharvest fungal diseases are among the main causes of fresh fruit losses. Chemical control is against claims for "natural" or "chemical-free" products. Biocontrol agents, such as antifungal proteins or their producing moulds, may serve to combat unwanted pathogens. Since the effectiveness of these bioprotective agents depends on the food substrate, their effect must be tested on fruits. The objective of this work was to study the effect of the antifungal protein PgAFP and its producer, Penicillium chrysogenum, against Penicillium expansum and Penicillium digitatum growth on apple and oranges respectively, and the PgAFP effect on eleven P. expansum, Penicillium italicum, and P. digitatum strains in vitro, and on patulin production on apple substrate. The sensitivity upon PgAFP was P. digitatum > P. expansum > P. italicum. In oranges, broadly, no inhibitory effect was obtained. PgAFP and P. chrysogenum did not inhibit the P. expansum CMP-1 growth on Golden Delicious apples, however, a successful effect was achieved on Royal Gala apples. On apple substrate, patulin production by P. expansum CMP-1 rose in parallel to PgAFP concentrations, linked with high reactive oxygen species levels. PgAFP cannot be proposed as a bioprotective agent on apple. However, P. chrysogenum is a promising agent to be used on Royal Gala apples.

The pH-responsive PacC transcription factor plays pivotal roles in virulence and patulin biosynthesis in Penicillium expansum.

The PacC (loss or reduction in phosphatase activity at acid but not at alkaline pH [Pac]) transcription factor regulates environmental adaptation, secondary metabolism and virulence in many fungal pathogens. Here, we report the functions of PacC in Penicillium expansum, a postharvest pathogenic fungus in horticultural crops, and ascertain that the gene expression and proteolytic processing of PePacC are strictly pH-dependent. Loss of PePacC resulted in an obvious decrease in growth and conidiation of P. expansum cultured in both acidic and alkaline conditions. The ΔPePacC mutant lost the ability of patulin production at pH values above 6.0 because expressions of all the genes in patulin cluster were significantly down-regulated. Additionally, virulence of the ΔPePacC mutant was obviously reduced in pear and apple fruits. Proteome analysis revealed that PePacC could function as an activator or repressor for different target proteins, including calreticulin (PeCRT) and sulfate adenylyltransferase (PeSAT), which were further proved to be involved in virulence of P. expansum. Our results demonstrate important roles for PePacC in patulin biosynthesis via limiting expressions of the genes in the cluster, and in pathogenesis via mediating a known virulence factor glucose oxidase (PeGOD) and new virulence factors, such as PeCRT and PeSAT.

Patulin transformation products and last intermediates in its biosynthetic pathway, E- and Z-ascladiol, are not toxic to human cells.

Patulin is the main mycotoxin contaminating apples. During the brewing of alcoholic beverages, this mycotoxin is degraded to ascladiol, which is also the last precursor of patulin. The present study aims (1) to characterize the last step of the patulin biosynthetic pathway and (2) to describe the toxicity of ascladiol. A patE deletion mutant was generated in Penicillium expansum. In contrast to the wild strain, this mutant does not produce patulin but accumulates high levels of E-ascladiol with few traces of Z-ascladiol. This confirms that patE encodes the patulin synthase involved in the conversion of E-ascladiol to patulin. After purification, cytotoxicities of patulin and E- and Z-ascladiol were investigated on human cell lines from liver, kidney, intestine, and immune system. Patulin was cytotoxic for these four cell lines in a dose-dependent manner. By contrast, both E- and Z-ascladiol were devoid of cytotoxicity. Microarray analyses on human intestinal cells treated with patulin and E-ascladiol showed that the latter, unlike patulin, did not alter the whole human transcription. These results demonstrate that E- and Z-ascladiol are not toxic and therefore patulin detoxification strategies leading to the accumulation of ascladiol are good approaches to limit the patulin risk.

Effects of temperature, pH, and relative humidity on the growth of Penicillium paneum OM1 isolated from pears and its patulin production.

Patulin is a mycotoxin produced by several species of Penicillium sp., Aspergillus sp., and Byssochlamys sp. on apples and pears. Most studies have been focused on Penicillium expansum, a common postharvest pathogen, but little is known about the characteristics of Penicillium paneum. In the present study, we evaluated the effects of temperature, pH, and relative humidity (RH) on the growth of P. paneum OM1, which was isolated from pears, and its patulin production. The fungal strain showed the highest growth rate at 25 °C and pH 4.5 on pear puree agar medium (PPAM) under 97 % RH, while it produced the highest amount of patulin at 20 °C and pH 4.5 on PPAM under 97 % RH. Moreover, RT-qPCR analysis of relative expression levels of 5 patulin biosynthetic genes (patA, patE, patK, patL, and patN) in P. paneum OM1 exhibited that the expression of the 4 patulin biosynthetic genes except patL was up-regulated in YES medium (patulin conducive), while it was not in PDB medium (patulin non-conducive). Our data demonstrated that the 3 major environmental parameters had significant impact on the growth of P. paneum OM1 and its patulin production. These results could be exploited to prevent patulin contamination by P. paneum OM1 during pear storage.

Effects of aliphatic aldehydes on the growth and patulin production of Penicillium expansum in apple juice.

The effects of 16 aliphatic aldehydes with 3-10 carbons on the growth and patulin production of Penicillium expansum were examined. When P. expansum spores were inoculated into apple juice broth, some alkenals, including 2-propenal, (E)-2-butenal, (E)-2-pentenal, and (E)-2-hexenal, inhibited fungal growth and patulin production. Their minimal inhibitory concentrations were 5, 50, 80, and 80 µg/mL respectively. Vital staining indicated that these alkenals killed mycelia within 4 h. Treatment of the spores with these aldehydes also resulted in rapid loss of germination ability, within 0.5-2 d. On the other hand, aliphatic aldehydes with 8-10 carbons significantly enhanced patulin production without affecting fungal growth: 300 µg/mL of octanal and 100 µg/mL of (E)-2-octenal increased the patulin concentrations in the culture broth by as much as 8.6- and 7.8-fold as compared to that of the control culture respectively. The expression of the genes involved in patulin biosynthesis in P. expansum was investigated in mycelia cultured in apple juice broth containing 300 µg/mL of octanal for 3.5, 5, and 7 d. Transcription of the msas gene, encoding 6-methylsalicylic acid synthase, which catalyzed the first step in the patulin biosynthetic pathway was remarkably high in the 3.5-d and 5-d-old cultures as compared with the control. However, octanal did not any increase the transcription of the msas in the 7-d-old culture or that of the other two genes, IDH and the peab1, in culture. Thus the enhanced patulin accumulation with supplementation with these aldehydes is attributable to the increased amount of the msas transcript.

Native pears of Sardinia affect Penicillium expansum pathogenesis.

Penicillium expansum causes blue mould rot, a serious post-harvest disease of pome fruits and is the main producer of the mycotoxin patulin. The occurrence of natural resistance against different hostpathogens, has been evidenced in some pear accessions of the Sardinian germoplasm. The aim of this research was to correlate P. expansum growth and patulin production on these indigenous pear accessions. In vitro and in vivo experiments were carried out with seven accessions ('Sarmentina', 'Vacchesa', 'De Puleu', 'De su Duca', 'Natalina', 'Oliena', 'Laconi 5') belonging to the CNR-ISPA ex situ collection and one national control cultivar ('Abate'). A wild type P. expansum from our collection was isolated from blue mould-decayed Sardinian pear fruit and selected for its aggressiveness and patulin production. The in vivo assay was carried out using 5 x 2 cm (Ø x thickness) sterilized fruit discs wounded and inoculated by a 10(5)UFC/mL concentration of P. expansum. Fruit discs were incubated at 23 degrees C for 7 days before analysis. The in vitro experiments, aimed at monitoring over time P. expansum mycelial growth and patulin accumulation, were performed with a standard medium (PDA) and a pear puree Agar Medium (PAM). Petri dishes with PDA and PAM were inoculated centrally with P. expansum conidia (10(5)UFC/ml) and then incubated at 23 degrees C for 7 days. Mycelial growth on Sardinian PAMs was inhibited in comparison to 'Abate' PAM and PDA. In particular, the accessions 'Sarmentina' and 'Vacchesa' showed the maximum inhibitory activity both in vitro and in vivo. Patulin production was detected by high-pressure liquid chromatography-mass spectrometry. The mycotoxin concentration in Sardinian PAMs was lower than that detected in PDA medium, pointing out a positive correlation between fungal growth inhibition and patulin production. The lowest concentration of patulin was found in 'Sarmentina' PAM. Based on these findings, some of Sardinian pear accessions seems to affect P. expansum pathogenesis and inhibit patulin production. Further researches are necessary to assess the mechanism of this biocontrol activity.

Histone H3K4 Methyltransferase PeSet1 Regulates Colonization, Patulin Biosynthesis, and Stress Responses of Penicillium expansum.

Fruit blue mold disease and patulin contamination caused by Penicillium expansum lead to huge economic losses and food safety concerns worldwide. Many genes have been proven to be involved in the regulation of pathogenic and toxigenic processes of P. expansum. Histone H3 lysine 4 (H3K4) methylation is well recognized for its association with chromatin regulation and gene transcription. However, it is not clear whether H3K4 methylation is related to infection and patulin biosynthesis in Penicillium. Here, we characterized PeSet1, which is responsible for H3K4me1/me2/me3 in P. expansum. The deletion of PeSet1 caused severe defects in hyphal growth, conidiation, colonization, patulin biosynthesis, and stress responses. Moreover, we demonstrated that PeSet1 is involved in the regulation of patulin biosynthesis by mediating the expression of patulin cluster genes and crucial global regulatory factors. Likewise, PeSet1 positively regulated key genes in ß-1,3-glucan biosynthesis and the reactive oxygen species scavenging process to modulate cell wall integrity and oxidative stress responses, respectively. Collectively, we have proven for the first time the function of Set1 in patulin biosynthesis and the crucial role of Set1 in colonization and stress responses in P. expansum. IMPORTANCE Penicillium expansum is one of the most important plant fungal pathogens, which not only causes blue mold rot in various fruits, leading to huge decay losses, but also produces mycotoxin patulin, posing a threat to human health. Both pathogenesis and patulin biosynthesis in P. expansum are regulated by complex and sophisticated networks. We focused on the epigenetic modification and identified a conserved histone H3K4 methyltransferase PeSet1 in P. expansum. Our work revealed the important role of PeSet1 in growth, development, colonization, patulin production, and stress responses of P. expansum. In particular, we originally described the regulation of Set1 on patulin biosynthetic pathway. These findings will provide new targets for the prevention and control of blue mold disease and patulin contamination.

Development of real-time PCR methods to quantify patulin-producing molds in food products.

Patulin is a mycotoxin produced by different Penicillium and Aspergillus strains isolated from food products. To improve food safety, the presence of patulin-producing molds in foods should be quantified. In the present work, two real-time (RTi) PCR protocols based on SYBR Green and TaqMan were developed. Thirty four patulin producers and 28 non-producers strains belonging to different species usually reported in food products were used. The patulin production was tested by mycellar electrokinetic capillary electrophoresis (MECE) and high-pressure liquid chromatography-mass spectrometry (HPLC-MS). A primer pair F-idhtrb/R-idhtrb and the probe IDHprobe were designed from the isoepoxydon dehydrogenase (idh) gene, involved in patulin biosynthesis. The functionality of the developed method was demonstrated by the high linear relationship of the standard curves constructed with the idh gene copy number and Ct values for the different patulin producers tested. The ability to quantify patulin producers of the developed SYBR Green and TaqMan assays in artificially inoculated food samples was successful, with a minimum threshold of 10 conidia g(-1) per reaction. The developed methods quantified with high efficiency fungal load in foods. These RTi-PCR protocols, are proposed to be used to quantify patulin-producing molds in food products and to prevent patulin from entering the food chain.

[Research on patulin biosynthesis and infection of Chinese medicinal materials by its producing strains].

OBJECTIVE: To investigate the effect of patulin producing strains on the different Chinese medicinal materials and the toxin biosynthesis mechanism. METHOD: Microbiology and HPLC analytical methods were adopted in this paper. RESULT: It was showed that the materials rich in starch and other polysaccharides were easily polluted by the patulin producing strain. This strain grew well and produced more toxins under 25 degrees C, 95% moisture content and bulk package. And the effect of low illumination intensity on the strain growth and toxin biosynthesis was not notable. Sample stability, precision, repeatability and rate of recovery were studied. HPLC analytic method was established and it revealed that the test method was suitable. CONCLUSION: The pollution of Chinese medicinal materials by toxin producing microbes will be effectively controlled through establishing the suitable storage methods. So the study on the growing characteristics and toxin biosynthesis mechanism of toxin producing strains will be an important practical significance for controlling the toxin pollution of herbal medicines and contribute to establish the evaluation system of Chinese medicine safety.

Targeting mitochondrial metabolite transporters in Penicillium expansum for reducing patulin production.

There is an increasing need of alternative treatments to control fungal infection and consequent mycotoxin accumulation in harvested fruits and vegetables. Indeed, only few biological targets of antifungal agents have been characterized and can be used for limiting fungal spread from decayed fruits/vegetables to surrounding healthy ones during storage. On this concern, a promising target of new antifungal treatments may be represented by mitochondrial proteins due to some species-specific functions played by mitochondria in fungal morphogenesis, drug resistance and virulence. One of the most studied mycotoxins is patulin produced by several species of Penicillium and Aspergillus genera. Patulin is toxic to many biological systems including bacteria, higher plants and animalia. Although precise biochemical mechanisms of patulin toxicity in humans are not completely clarified, its high presence in fresh and processed apple fruits and other apple-based products makes necessary developing a strategy for limiting its presence/accumulation. Patulin biosynthetic pathway consists of an enzymatic cascade, whose first step is represented by the synthesis of 6-methylsalicylic acid, obtained from the condensation of one acetyl-CoA molecule with three malonyl-CoA molecules. The most abundant acetyl-CoA precursor is represented by citrate produced by mitochondria. In the present investigation we report about the possibility to control patulin production through the inhibition of mitochondrial/peroxisome transporters involved in the export of acetyl-CoA precursors from mitochondria and/or peroxisomes, with specific reference to the predicted P. expansum mitochondrial Ctp1p, DTC, Sfc1p, Oac1p and peroxisomal PXN carriers.

Effect of Ambient pH on Growth, Pathogenicity, and Patulin Production of Penicillium expansum.

Penicillium expansum is an important postharvest pathogen of pomaceous fruit and a causal agent of blue mold or soft rot. In this study, we investigated the effect of ambient pH on growth, ultrastructure alteration, and pathogenicity of P. expansum, as well as accumulation of patulin and expression of genes involved in patulin biosynthesis. Under different pH, the fungus was routinely cultured and collected for growth, pathogenicity, patulin production, and gene expression studies using transmission electron microscopy, apple inoculation, HPLC, and RT-qPCR methods. Different ambient pH had significant impact on expression of genes and growth factors involved in patulin biosynthesis. Under same range of pH, gene expression profile, growth factors, and patulin accumulation (in vivo and in vitro) all showed similar changing trends. A well-developed cell was observed in addition to upregulation of genes at pH between pH 5.0 and 7.0, while the opposite was observed when pH was too basic (8.5) or too acid (2.5). Additionally, ambient pH had direct or indirect influence on expression of PecreaA, PelaeA, and PepacC. These findings will help in understanding the effect of ambient pH on growth, pathogenicity, and patulin production and support the development of successful methods for combating P. expansum infection on apple fruits.

Ecophysiology of Penicillium expansum and patulin production in synthetic and olive-based media.

Olives and their derivatives, in particular olive oil, represent one of the most significant agricultural products in the Mediterranean basin. Storage under inadequate conditions poses serious problems concerning fungal contamination, with consequent defects and potential mycotoxin production in olives and olive oils. Penicillium expansum represents one of the most significant postharvest pathogens in several fruits, including olives. Not only it causes blue mold but also is one of the most relevant patulin producing species of the genus Penicillium. The aim of this research was to evaluate the ecophysiological conditions governing growth and PAT production by P. expansum strains previously isolated from Tunisian olives. For this purpose, four P. expansum isolates were tested in a synthetic medium (Czapek Yeast Autolysate, CYA) and in olive-based medium (OM) for their ability to grow and produce PAT under different temperatures (4 °C, 15 °C and 25 °C) for 10 and 20 d. The mycotoxin was analysed by HPLC-UV. Results showed that all isolates were able to grow on tested media at different temperatures. Different PAT production profiles were found, showing that at 25 °C P. expansum isolates were able to produce PAT on CYA and OM medium. At 15 °C the production of PAT was only detected on CYA medium, while no PAT production was detected at 4 °C for the two media.

Luteolin-induced activation of the phenylpropanoid metabolic pathway contributes to quality maintenance and disease resistance of sweet cherry.

Redox imbalance and fungal infection are major causes for quality deterioration and postharvest decay of fruit. Therefore, it is crucial to activate intrinsic antioxidative capacity and disease responses for fruit quality maintenance. Although plant-derived flavonoids have been reported for health-promoting benefits, their roles in the maintenance of fruit quality remains largely unexplored. Here, we exogenously applied luteolin, a flavonoid substance, and further examined its efficacy in maintaining fruit quality and inhibiting fungal diseases in sweet cherry. The results showed that 100 or 200 mg/L luteolin maintained better organoleptic quality and decreased disease incidence during storage. Biochemical assays revealed that luteolin activated the phenylpropanoid metabolic pathway and improved antioxidative capacity, thereby elevating total anthocyanin and flavonoid contents. Notably, luteolin inhibited mycelial growth of fungal pathogens and reduced patulin yield by Penicillium expansum. Collectively, these results suggest that luteolin is a promising alternative for maintaining better fruit quality and ameliorating disease resistance.

First morphomolecular identification of Penicillium griseofulvum and Penicillium aurantiogriseum toxicogenic isolates associated with blue mold on apple.

Postharvest blue mold decay caused by Penicillium spp. is the most important disease of fresh apple fruit in the world, which extend from the field to the store. Two new Penicillium spp. responsible for apple fruit decay were recovered. The morphological and molecular features of Penicillium griseofulvum and Penicillium aurantiogriseum isolated from apple fruits were characterized morphologically and molecularly. Pathogenicity test exhibited that both P. griseofulvum and P. aurantiogriseum were responsible for blue mold decay in storage apple fruits. Lesion diameter indicated that P. aurantiogriseum was more aggressive than P. griseofulvum. All tested isolates were able to synthesize citrinin in addition to patulin. Not all of the isolates belonging to the same species showed the same profile of secondary metabolites. Microsatellite-primed polymerase chain reaction was able to differentiate these isolates at the species level and divided the analyzed isolates into two genetically different groups. Little intraspecific variability was evident. Microsatellite-primed polymerase chain reaction analysis proved to be an objective, rapid, and reliable tool to identify Penicillium spp. involved in blue mold of apple. This is the first report of occurrence of P. griseofulvum and P. aurantiogriseum on imported apple fruits in Saudi Arabia.

Some factors influencing patulin production by Penicillium expansum in pome fruits.

BACKGROUND: The objective of our study was to examine the effects of Penicillium expansum on patulin production in relation to isolates, species and cultivar type, incidence and severity of decay. In addition, patulin production at different incubation times and its diffusion were also investigated. These factors were evaluated in pome fruits inoculated with P. expansum and kept at 20 °C for short periods of time. RESULTS: The ability of five P. expansum isolates to grow and produce patulin in inoculated Golden Delicious apples varied among the strains from below the limit of quantification to 662 µg kg(-1). Variety and species of pome fruits influenced patulin production. P. expansum isolate PE97.IT produced a higher patulin content in apples than in pears. The highest patulin production was 386 µg kg(-1) in Golden Delicious. No blue mould symptom appeared in pears inoculated with P. expansum and no patulin was detected after 3 days at 20 °C. However, patulin increased with incubation time after 6 and 8 days. No patulin was detected in healthy pear tissue but it was high in the decayed area. CONCLUSION: Since patulin production is associated primarily with infected rotten tissue, patulin control is possible by using healthy fruits, sorting damaged and rotten fruits before processing.

Production and migration of patulin in Penicillium expansum molded apples during cold and ambient storage.

The ability of three Penicillium expansum isolates to produce patulin was first evaluated in YES medium after incubation at 25 °C to select a high patulin producer. Then, a spore suspension of the selected P. expansum 3.78 strain was inoculated onto the surface of Golden delicious apples and incubated at 8 or 20 °C until the mold lesion reached a diameter of 1, 2 or 3 cm. For each lesion size, patulin was quantified from apple samples cut into 1 cm depthwise fractions and widthwise sized cylinders. Maximum patulin concentration, about 80,000 ng/g apple, was obtained at 8 °C for the center and surface sample of the 3 cm diameter lesion. Patulin was systematically found at the highest concentration in the lesions, but still quantified up to one centimeter next to the lesion. Patulin concentrations were not significantly different between the 8 and 20 °C incubation temperature, except for the 3 cm large lesions. Based on these findings, and for lesions less than or equal to 3 cm in diameter, we recommend to consumers to cut off at least 1 cm around and below the mold spot to limit patulin exposure. Apples should also be stored at cool temperatures, below 8 °C, to delay lesion development.