Identification of saprophytic microorganisms and analysis of changes in sensory, physicochemical, and nutritional characteristics of potato and wheat steamed bread during different storage periods.

Due to its nutritional value and no gluten, potato flour has recently been used as a new type of material to make steamed bread. However, compared to traditional wheat steamed bread, its shelf life is considerably shorter, the dominant microorganisms and storage properties also differ. High-throughput sequencing combined with molecular biology assay revealed that Bacillus methylotrophic and Bacillus subtilis were the dominant bacteria in the crumb of potato and wheat steamed bread, respectively. Moreover, Meyerozyma, Penicillium chrysogenum, Penicillium citrinum, and Aspergillus parasiticus were the main fungi in the crusts. Ethanol was the most volatile compound in fresh potato and wheat steamed bread. Following storage for 48 h, 2,3-butanediol and 3-hydroxy-2-butanone were established as the most volatile compounds. Although decreased sourness was observed, the specific volume, brightness, and nutritional composition remained nearly unchanged. These findings provide a valuable theoretical basis for the development of potato and wheat steamed bread preservation technologies.

Combined application of antagonistic Wickerhamomyces anomalus BS91 strain and Cynara cardunculus L. leaf extracts for the control of postharvest decay of citrus fruit.

Combined use of biocontrol agents and plant extracts can be considered a viable and promising strategy for protecting plant tissues with different synergistic mechanisms of action that improve the antimicrobial activity of the mixtures. Treatments of citrus fruits with Wickerhamomyces anomalus BS91 have been previously reported as effective measures to reduce the incidence of green mold caused by Penicillium digitatum. On the opposite, the knowledge of the antifungal activity of cultivated cardoon (Cynara cardunculus L. var. altilis DC.) leaf extract, vegetable widespread in some Mediterranean areas, is still very limited. In this study, experimental trials were conducted to evaluate the effectiveness in vitro of leaf aqueous, methanolic and ethanolic extracts of C. cardunculus against seven fungal pathogens responsible for considerable food losses in the postharvest stage. In addition, biocontrol yeast W. anomalus BS91 and the three C. cardunculus extracts were tested in vivo both as a single treatment and in mixture, against Penicillium digitatum on 'Tarocco' oranges and 'Femminello' lemons. The combination of W. anomalus BS91 and leaf ethanolic extract reduced with the highest efficacy the incidence and severity of green mold on orange and lemon fruits with respect to the control, and was more effective than treatment with antagonistic yeast or leaf extracts applied alone. Incidence and severity of citrus decay were more consistently reduced when mixtures were applied 24 h before the inoculation of the pathogen, thus suggesting the relevance of preventive treatments. The mixtures of antagonistic W. anomalus BS91 and ethanolic leaf extract were more effective in controlling green mold decay on oranges than on lemons. These results indicate that biocontrol agents and leaf extracts, used in appropriate combination, can provide a stronger protection than when used singularly. However, compatibility between microbial antagonist and antimicrobial extract should be preliminary verified.

Enhancement of anti-acne effect of Scutellaria baicalensis extract by fermentation with symbiotic fungus Penicillium decumbens.

Inflammatory responses stimulated by Propionibacterium acnes have been shown to be major etiological factors in the pathogenesis of acne. Scutellaria baicalensis, a popular traditional Chinese medicine, has been widely shown to have anti-inflammatory effects. In this study, primary component analysis and primary effective component analysis were conducted. The results showed that wogonin (1.15 mg/g S. baicalensis extract) possessed better anti-acne effects than wogonoside (8.71 mg/g S. baicalensis extract) in inhibiting the up-regulation of IL-1ß and IL-8 level caused by P. acnes via inactivation of the MAPK and NF-κB signaling pathways. To enhance the anti-acne effects of S. baicalensis extract, an environmentally friendly and healthy plant fermentation strategy was used to efficiently convert glycoside-type constituents into bioactive aglycone. S. baicalensis extract was fermented by symbiotic fungus Penicillium decumbens f3-1 to transform wogonoside into wogonin with a conversion rate of 91.0% after 4 days. Fermented S. baicalensis extract (FSE) showed higher potential anti-acne effects than non-fermented S. baicalensis extract (NSE) by inhibiting the up-regulation of IL-1ß and IL-8. Thus, P. decumbens-fermented S. baicalensis Extract may be used for developing new anti-acne cosmetic ingredients.

Antimicrobial activity of endophytic fungi from the medicinal plants Mammea americana (Calophyllaceae) and Moringa oleifera (Moringaceae) / [Actividad antimicrobiana de hongos endófitos de las plantas medicinales Mammea americana (Calophyllaceae) y Moringa oleifera (Moringaceae)].

Introduction: Infectious diseases represent one of the leading causes of death worldwide. Considering the growing global challenge of antimicrobial resistance, research into new sources of potentially effective antimicrobial agents from natural origins is of great importance for world health. Objective: To evaluate the antimicrobial activity of endophytic fungi from Mammea americana and Moringa oleifera upon Staphylococcus aureus (ATCC 29213), S. aureus (resistant strain USb003), Escherichia coli (ATCC 25922), and E. coli (resistant strain USb007). Materials and methods: We isolated endophytic fungi from the leaves, seeds, and stems of the two plants under study. We evaluated their antimicrobial activity through the formation of sensitivity haloes in dual tests in vitro, as well as in trials using crude ethanolic extracts from the endophytes. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and cytotoxicity o the substances were analyzed. Results: Three ethanolic extracts of Penicillium sp., Cladosporium (001), and Cladosporium (002) exhibited the greatest inhibition halos in sensitive and resistant strains of E. coli and S. aureus. The MIC and CBM found were statistically significant (p≤0.05) compared with the gentamicin control. Furthermore, the cytotoxicity test results of CC50>1,000 demonstrated that the endophytic fungi studied exhibit bactericidal characteristics without causing unintended damage. Conclusion: The endophytic fungi M. oleifera and M. americana represent a source of active secondary metabolites with antimicrobial and non-toxic properties. In light of these findings, further research should proceed with chemical identification of the compounds and the study of their mechanisms of action, especially given the paucity of current scientific knowledge concerning the isolation of endophytes in these plants.

Introducción. Las enfermedades infecciosas son una causa importante de muertes en el mundo. La resistencia antimicrobiana es un problema global, por lo que es conveniente la investigación de nuevas fuentes de agentes antimicrobianos de origen natural potencialmente efectivos. Objetivo. Evaluar la actividad antimicrobiana de hongos endófitos de Mammea americana y Moringa oleifera en la cepa sensible (ATCC 29213) y en la cepa resistente (USb003) de Staphylococcus aureus, así como en la cepa sensible (ATCC 25922) y la cepa resistente (USb007) de Escherichia coli. Materiales y métodos. Se aislaron 14 hongos endófitos de las hojas, semillas y tallos de las dos plantas en estudio. Se evaluó su actividad antimicrobiana mediante la formación de halos de sensibilidad por ensayo dual in vitro y pruebas con extractos etanólicos crudos provenientes de los endófitos a los que se les evaluó la concentración mínima inhibitoria (CMI), la concentración bactericida mínima (CBM) y la citotoxicidad. Resultados. Tres extractos etanólicos de Penicillium sp., Cladosporium sp. (001) y Cladosporium sp. (002) presentaron mayores halos de inhibición en cepas sensibles y resistentes de E. coli y S. aureus. La CMI y la CBM halladas fueron estadísticamente significativas (p≤0,05), comparadas con el control de gentamicina. Las pruebas de citotoxicidad (concentración citotóxica, CC50>1.000) demostraron que los hongos endófitos poseen características bactericidas y no ocasionan daño alguno. Conclusión. Se halló una fuente de metabolitos secundarios activos con propiedades antimicrobianas y no tóxicas en los hongos endófitos de M. oleifera y M. americana; estos hallazgos son importantes para continuar con la identificación química de los compuestos y el estudio de sus mecanismos de acción en estas plantas en las que el aislamiento de endófitos ha sido escaso.

Effect of benzothiadiazole treatment on improving the mitochondrial energy metabolism involved in induced resistance of apple fruit during postharvest storage.

The effects of benzothiadiazole (BTH) on Penicillium expansum development, mitochondria energy metabolism, and changes in the number and structure of mitochondria in apple fruit were investigated after the fruit were immersed in 100 mg L-1 BTH for 10 min and then stored at 22 °C. The results indicated that BTH treatment significantly decreased the lesion diameter of fruit challenged with P. expansum; further, treatment enhanced the activities of mitochondrial respiratory metabolism-related enzymes, such as succinate dehydrogenase, cytochrome oxidase, H+-ATPase and Ca2+-ATPase, along with high ATP level and energy status in apple fruit during storage. Moreover, transmission electron microscopy results indicated that BTH treatment was beneficial for maintaining the number and structure of mitochondria during storage. The results suggested that BTH treatment enhanced ATP levels via mitochondrial energy metabolism, which might contribute to the induced resistance in apple fruit during storage.

Cold Plasma Treatment as an Alternative for Ochratoxin a Detoxification and Inhibition of Mycotoxigenic Fungi in Roasted Coffee.

Ochratoxin A (OTA) produced by mycotoxigenic fungi (Aspergillus and Penicillium spp.) is an extremely toxic and carcinogenic metabolite. The use of cold plasma to inhibit toxin-producing microorganisms in coffee could be an important alternative to avoid proliferation of mycotoxigenic fungi. Roasted coffee samples were artificially inoculated with A. westerdijikiae, A. steynii, A. versicolor, and A. niger, and incubated at 27 °C over 21 days for OTA production. Samples were cold plasma treated at 30 W input power and 850 V output voltage with helium at 1.5 L/min flow. OTA production in coffee was analyzed by high performance liquid chromatography coupled to a mass spectrometer (HPLC-MS). After 6 min of treatment with cold plasma, fungi were completely inhibited (4 log reduction). Cold plasma reduces 50% of OTA content after 30 min of treatment. Toxicity was estimated for extracts of artificially contaminated roasted coffee samples using the brine shrimp (Artemia salina) lethality assay. Toxicity for untreated roasted coffee was shown to be "toxic", while toxicity for cold plasma treated coffee was reduced to "slightly toxic". These results suggested that cold plasma may be considered as an alternative method for the degradation and reduction of toxin production by mycotoxigenic fungi in the processing of foods and feedstuffs.

Effects of hot air treatment in combination with Pichia guilliermondii on postharvest preservation of peach fruit.

BACKGROUND: Antagonistic yeast and hot air treatment are two promising methods for conferring resistance to pathogenic fungi. The study assessed the effectiveness of hot-air treatment (45 °C, 4 h) and antagonistic yeast (Pichia guilliermondii at 108 CFU mL-1 ) alone or in combination on the two major postharvest diseases (Rhizopus stolonifer and Penicillium expansum), as well as the quality and antioxidant parameters in harvested peaches. RESULTS: The combination of hot-air treatment and Pichia guilliermondii had notable inhibitory effects on infections in peach fruit wounds. In addition, the individual hot-air treatment or Pichia guilliermondii could improve quality indexes to varying degrees, but the combination of the above two treatments could achieve the highest efficacy. Furthermore, compared with other groups, the combined treatment induced the highest activities of superoxide dismutase and catalase, improved the content of total phenolics and reduced glutathione most obviously. Lastly, the most significant reductions in malondialdehyde content and relative electrical conductivity were observed in the combination-treated fruit. CONCLUSIONS: The combined treatment could control fungal diseases, besides delay the decline of quality and antioxidant parameters, so as to achieve the purpose of fresh keeping for harvested peach fruit. © 2018 Society of Chemical Industry.

A Novel Penicillium sp. Causes Rot in Stored Sugar Beet Roots in Idaho.

Penicillium vulpinum along with a number of other fungi can lead to rot of stored sugar beet roots. However, Penicillium isolates associated with necrotic lesions on roots from a recent sugar beet storage study were determined to be different from P. vulpinum and other recognized Penicillium species. Phylogenies based on sequencing of the internal transcribed spacer (ITS)-5.8S, ß-tubulin (BenA), and RNA polymerase II second largest subunit (RPB2) DNA regions indicate that these isolates are novel, but most closely related to the following Penicillium spp. in the section Fasiculata: P. aurantiogriseum, P. camemberti, and P. freii. Macro- and micromorphological data also support designating these isolates as a new species for which we propose the name, Penicillium cellarum sp. nov. Inoculation studies with the P. cellarum isolates on roots of the commercial sugar beet cultivar B-7 led to the formation of necrotic lesions 23 to 25 mm in diameter after 86 days in storage. These lesions were similar to those observed on sugar beet roots in commercial storage piles. These data indicate that P. cellarum is a pathogen which can cause root rot in stored sugar beet roots.

A new isoquinolone alkaloid from an endophytic fungus R22 of Nerium indicum.

A new isoquinolone alkaloid named 5-hydroxy-8-methoxy-4-phenylisoquinolin-1(2H)-one (3), together with two known quinolinone alkaloids 3-O-methylviridicatin (1) and viridicatol (2) were isolated from the fermentation of an endophytic fungus Penicillium sp. R22 in Nerium indicum. Their structures were elucidated by NMR, IR and MS data, and were also confirmed by comparing with the reported data in the literature. Meanwhile, the antibacterial and antifungal activities of all compounds were tested, and the results showed that three compounds had strong antifungal activity. Among them, compound 2 revealed potent antibacterial activity against Staphylococcus aureus with MIC value of 15.6 µg/mL.

Preparation and activity evaluation of chrysin-ß-D-galactopyranoside.

Chrysin-ß-D-galactopyranoside was efficiently synthesized, evaluated for its inhibitory activities against H22 cell lines compared with chrysin, the scavenging of hydroxyl radical, DPPH radical and superoxide anion, inhibitory effect against bacteria and fungi. The structures of all compounds were fully characterized by spectroscopic data (NMR, MS). The anti-tumor, antioxidant and antimicrobial activities of chrysin-ß-D-galactopyranoside were proved to be enhanced significantly compared with chrysin.

Antifungal activity of the ribosome-inactivating protein BE27 from sugar beet (Beta vulgaris†L.) against the green mould Penicillium digitatum.

The ribosome-inactivating protein BE27 from sugar beet (Beta vulgaris L.) leaves is an apoplastic protein induced by signalling compounds, such as hydrogen peroxide and salicylic acid, which has been reported to be involved in defence against viruses. Here, we report that, at a concentration much lower than that present in the apoplast, BE27 displays antifungal activity against the green mould Penicillium digitatum, a necrotrophic fungus that colonizes wounds and grows in the inter- and intracellular spaces of the tissues of several edible plants. BE27 is able to enter into the cytosol and kill fungal cells, thus arresting the growth of the fungus. The mechanism of action seems to involve ribosomal RNA (rRNA) N-glycosylase activity on the sarcin-ricin loop of the major rRNA which inactivates irreversibly the fungal ribosomes, thus inhibiting protein synthesis. We compared the C-terminus of the BE27 structure with antifungal plant defensins and hypothesize that a structural motif composed of an α-helix and a ß-hairpin, similar to the γ-core motif of defensins, might contribute to the specific interaction with the fungal plasma membranes, allowing the protein to enter into the cell.

Metabolites of the endophytic fungus Penicillium sp. FJ-1 of Acanthus ilicifolius.

Two new compounds, named as (2R,3S)-pinobanksin-3-cinnamate (1), and 15alpha-hydroxy-(22E,24R)-ergosta-3,5,8(14),22-tetraen-7-one (2), were isolated from the endophytic fungus Penicillium sp. FJ-1 of Acanthus ilicifolius Linn. Their structures were elucidated on the basis of spectroscopic analysis. Additionally, compound 1 exhibited potent neuroprotective effects on corticosterone-damaged PC12 cells, and compound 2 showed potent cytotoxicity on glioma cell lines.

Inhibitory effect of selenium against Penicillium expansum and its possible mechanisms of action.

Some organic and inorganic salts could inhibit the growth of many pathogens. Selenium (Se), as an essential micronutrient, was effective in improving the plant resistance and antioxidant capacity at a low concentration. Penicillium expansum is one of the most important postharvest fungal pathogens, which can cause blue mold rot in various fruits and vegetables. In this study, the inhibitory effect of Se against P. expansum was evaluated. The result showed that Se strongly inhibited spore germination, germ tube elongation, and mycelial spread of P. expansum in the culture medium. The inhibitory effect was positively related to the concentration of Se used. Fluorescence microscopy observation of P. expansum conidia stained with propidium iodide (PI) indicated that the membrane integrity decreased to 37 % after the conidia were treated with Se (20 mg/l) for 9 h. With the use of an oxidant-sensitive probe 2,7-dichlorofluorescin (DCHF-DA), we found that Se at 15 mg/l could induce the generation of intracellular reactive oxygen species (ROS). Furthermore, methane dicarboxylic aldehyde (MDA) content, hydrogen peroxide (H2O2), and superoxide anion (O2 (-)) production rate in P. expansum spores exposed to Se increased markedly. Compared with the control, the activities of superoxide dismutase (SOD) and the content of glutathione (GSH) were reduced, confirming that damage of Se to cellular oxygen-eliminating system is the main reason. These results suggest that Se might serve as a potential alternative to synthetic fungicides for the control of the postharvest disease of fruit and vegetables caused by P. expansum.

Photodynamic inactivation of mold fungi spores by newly developed charged corroles.

The photodynamic effect, originally used in photodynamic therapy (PDT) for the treatment of different diseases, e.g. of cancer, has recently been introduced for the inactivation of bacteria. Mold fungi, which provoke health problems like allergies and diseases of the respiratory tract, are even more resistant and their biology is also very different. This study presents the development of four new photosensitizers, which, in combination with low doses of white light, inhibit the germination of mold fungi spores. Two of them even cause lethal damage to the conidia (spores) which are responsible for the spreading of mold fungi. The photoactivity of the newly synthesized corroles was obtained by their application on three different mold fungi: Aspergillus niger, Cladosporium cladosporoides, and Penicillium purpurgenum. To distinguish between inactivation of germination and permanent damage, the fungi were first incubated under illumination for examination of photosensitizer-induced growth inhibition and then left in darkness to test the survival of the conidia. None of the compounds displayed dark toxicity, but all of them attenuated or prevented germination when exposed to light, and the positively charged complexes induced a complete damage of the conidia.

Penicillium oxalicum reduces the number of cysts and juveniles of potato cyst nematodes.

AIM: To test the biocontrol potential of Penicillium oxalicum, a biocontrol agent against fungal diseases and against the potato cyst nematodes (PCNs), Globodera pallida and Globodera rostochiensis. METHODS AND RESULTS: We tested the effect of P. oxalicum on the nematode cysts under laboratory conditions or in soil microcosms. A reduction in the rate of G. pallida juveniles hatching by P. oxalicum was observed when root diffusates from the 'Monalisa' and the 'Désirée' potato cultivar were used (98·6 and 74·1% reduction, respectively). However, the rate of G. pallida juveniles hatching was not significantly reduced when root diffusates from the 'San Pedro' tomato cultivar were used. Penicillium oxalicum also significantly reduced the ability of the G. rostochiensis juveniles to hatch (30·9% reduction) when root diffusates of the 'Désirée' potato cultivars were used. Penicillium oxalicum treatment of the soil significantly reduced the number of G. pallida cysts that were recovered from the soil of each pot that contained the 'Désirée' potato cultivar. CONCLUSIONS: Our results show that P. oxalicum is a potential biocontrol inoculant for protecting potato crops against PCNs. SIGNIFICANCE AND IMPACT OF THE STUDY: Penicillium oxalicum has potential to be used in order to reduce PCNs.

Interaction with Penicillium expansum enhances Botrytis cinerea growth in grape juice medium and prevents patulin accumulation in vitro.

Interactions between fungi occur when they grow on the same host plant. This is the case of Botrytis cinerea and Penicillium expansum on grape. P. expansum is also responsible for production of the mycotoxin patulin. In this study, the influence of the interaction between both fungi on fungal growth parameters was studied as well as the effect on the accumulation of patulin by P. expansum. For that purpose, spores of B. cinerea and P. expansum were inoculated together (mixed inoculum), and the parameters growth rate, time for growth and patulin accumulation were assessed. The presence of P. expansum conidia shortened the time for growth of mixed inoculum colonies which, at the end of incubation, were B. cinerea-like. Although some P. expansum growth was observed in mixed inoculum colonies, very low levels of patulin were observed. In assays carried out in patulin-spiked medium, B. cinerea was capable to metabolize the mycotoxin. The capabilities of B. cinerea to shorten time for growth and prevent patulin accumulation are competing abilities that facilitate grape colonization.

Biosolubilization of rock phosphate by three stress-tolerant fungal strains.

Three stress-tolerant phosphate-solubilizing fungal strains identified as Aspergillus niger, Aspergillus japonicus, and Penicillium simplicissimum were isolated from wheat rhizospheric soil. The strains demonstrated different capabilities of phosphate solubilization in National Botanical Research Institute's phosphate medium containing rock phosphate (RP) as sole phosphorus (P) source, and the solubilization of RP by P. simplicissimum was the most effective among these strains, followed by A. niger and A. japonicus. All the strains exhibited high levels of stress tolerance like 10∼45°C temperature, 4∼11 pH, 0∼3.5% NaCl, and 0∼35% PEG 10000. The strains also differed in their abilities to survive and release soluble P from RP under different stresses. A. niger showed significantly higher tolerance to temperature and pH over the other two strains. Higher amount of spores and content of soluble P in the medium were observed in the presence of 3.5% NaCl with P. simplicissimum, followed by A. niger and A. japonicus. P. simplicissimum could not solubilize RP in the presence of 35% PEG 10000, which exhibited the lowest tolerance to desiccation stress among the three strains.

Effect of heat shock treatment on stress tolerance and biocontrol efficacy of Metschnikowia fructicola.

The effect of high temperature and oxidative stress on the cell viability of the yeast antagonist, Metschnikowia fructicola was determined. A mild heat shock (HS) pretreatment (30 min at 40 °C) improved the tolerance of M. fructicola to subsequent high temperature (45 °C, 20-30 min) and oxidative stress (0.4 mol L⁻¹ hydrogen peroxide, 20-60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than nontreated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P<0.0001) biocontrol activity against Penicillium expansum and a significantly faster (P<0.0001) growth rate in wounds of apple fruits stored at 25 °C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was upregulated in response to HS and trehalose content also increased. Results indicate that the higher levels of trehalose induced by the HS may contribute to an improvement in ROS scavenging, stress tolerance, population growth in apple wounds and biocontrol activity of M. fructicola.

Tritirachium egenum, a thiamine- and siderophore-auxotrophic fungal species isolated from a Penicillium rugulosum.

Tritirachium egenum sp. nov., a biotrophic mycosymbiont, was found growing in association with a Penicillium rugulosum. This new species was unable to grow in axenic culture on traditional semi-synthetic culture media unless the growth medium was supplemented with a fraction of the culture filtrate of its host. The hot water extract of Alternaria alternata, containing the 'growth factor' of several contact mycosymbionts (biotrophic contact mycoparasites) also supported the growth of T. egenum. Signs, particularly the functional equivalence of this extract and ferrichrome on the T. egenum growth, suggested that this growth factor, referred to in the literature as mycotrophein, could actually be a hydroxamate-type siderophore. Moreover, it was shown that this siderophore-dependent organism had a deficient metabolism requiring, in addition, an exogenous source of thiamine or a precursor molecule of thiamine. Among mycosymbionts of fungi, the nutrient acquisition strategy of T. egenum is new, because it did not live in close association with the cytoplasm of its host. Indeed, it is neither a haustorial mycosymbiont nor a contact mycosymbiont, the two groups into which the biotrophic mycosymbionts of fungi are classified. Moreover, an interfungal association based on the utilization of siderophores has not yet been reported.

Cellular damage induced by a sequential oxidative treatment on Penicillium digitatum.

AIM: To investigate the cellular damage on Penicillium digitatum produced by a sequential oxidative treatment (SOT), previously standardized in our laboratory, to prevent the conidia growth. Lethal SOT consists of 2-min preincubation with 10 ppm NaClO followed by 2-min incubation with 6 mmol l(-1) CuSO(4) and 100 mmol l(-1) H(2)O(2) at 25°C. METHODS AND RESULTS: After the application of lethal SOT or sublethal SOT (decreasing only the H(2)O(2) concentration), we analysed several conidia features such as germination, oxygen consumption, ultrastructure and integrity of the cellular wall and membrane. Also, we measured the production of reactive oxygen species (ROS) and the content of thiobarbituric acid-reactive species (TBARS). With the increase of H(2)O(2) concentration in the SOT, germination and oxygen consumption of conidia became inhibited, while the membrane permeability, ROS production and TBARS content of conidia increased. Several studies revealed ultrastructural disorganization in P. digitatum conidia after lethal SOT, showing severe cellular damage without apparent damage to the cell wall. In addition, mycelium of P. digitatum was more sensitive than conidia to the oxidative treatment, because growth ceased and permeability of the membranes increased after exposure of the mycelium to a SOT with only 50 mmol l(-1) H(2)O(2) compared to a SOT of 100 mmol l(-1) for these effects to occur on conidia. CONCLUSION: Our insights into cellular changes produced by the lethal SOT are consistent with the mode of action of the oxidant compounds, by producing both alteration of membrane integrity and intracellular damage. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results allow the understanding of SOT effects on P. digitatum, which will be useful to develop a reliable treatment to control postharvest diseases in view of its future application in packing houses.