Penicillium Verrucosum Research Articles

Antimicrobial activity of fumarprotocetraric acid, lecanoric acid, protocetraric acid and stictic acid isolated from different species of lichen

The antimicrobial activity of fumarprotocetraric acid, lecanoric acid, protocetraric acid and stictic acid isolated from the lichens Cladonia furcata (Huds.) Schrad., Ochrolechia androgyna (Hoffm.) Arn., Parmelia caperata (L.) Ach. and Parmelia conspresa (Ach.) Ach. was studied for the following microorganisms: Bacillus mycoides, Bacillus subtilis, Staphylococcus aureus, Enterobacter cloaceae, Escherichia coli, Klebsiella pneumoniae, Aspergillus flavus (ATCC 9170), Aspergillus fumigatus, Botrytis cinerea, Candida albicans, Fusarium oxysporum, Mucor mucedo (ATCC 52568), Paecilomyces variotii (ATCC 22319), Penicillium purpurescens, Penicillium verrucosum, Trichoderma harsianum. Aspergillus flavus, Mucor mucedo and Paecilomyces variotii are ATCC type, and the other microorganisms are clinical isolates. The antimicrobal activity was estimated by determining the minimum inhibitory concentration (MIC) by the Broth tube Dilution method. The tested lichen components ihibited growth of all the tested microrganisms. The bacteria showed a bigger sensitivity relative to fungi. The lowest MIC value (0.031mg/mL) was measured for the fumarprotocetraric acid related to the Klebsiella pneumoniae species. The weakest antimicrobial activity was found in stictic acid, which inhibited most of the tested microorganisms in significantly higher concentrations. Generally, all the components had relatively strong antimicrobial activity against the tested microorganisms.

Verrucine F, a Quinazoline from Penicillium verrucosum

Verrucine F (3), a quinazoline similar to verrucines A (1) and B (2), contains one anthranilic acid residue, one L-glutamine residue, and one alpha,beta-unsaturated phenylalanine residue, as determined by NMR, MS, and chemical methods. Compounds 1 and 3, but not 2, were produced by Penicillium verrucosum J255 and eight additional P. verrucosum strains. Verrucines were typically more concentrated in the inner (older) parts of the colony, and 3 peaked 4-8 days after 1, but at 10-fold lower concentrations (approximately 200 microg/g). Verrucine F (3) formed spontaneously from 1 in buffered water solutions, probably by oxidation at C-1 followed by water elimination.

Production and partial characterization of lipase from Penicillium verrucosum obtained by submerged fermentation of conventional and industrial media

The growing interest in lipase production is related to the potential biotechnological applications that these enzymes present. Current studies on lipase production by submerged fermentation involve the use of agro-industrial residues aiming at increasing economic attractiveness. Based on these aspects, the objective of this work was to investigate lipase production by Penicillium verrucosum in submerged fermentation using a conventional medium based on peptone, yeast extract, NaCl and olive oil, and an industrial medium based on corn steep liquor, Prodex Lac (yeast hydrolysate), NaCl and olive oil, as well as to characterize the crude enzymatic extracts obtained. Kinetics of lipase production was evaluated and the highest enzymatic activities, of 3.15 and 2.22 U.mL-1, were observed when conventional and industrial media were used, respectively. The enzymatic extract showed optimal activity in the range from 30 to 40 °C and at pH 7.0. Although the industrial medium presents economical advantages over the conventional medium, the presence of agro-industrial residues rich in nitrogen and other important nutrients seemed to contribute to a reduction in lipase activity.

Stress induction of mycotoxin biosynthesis genes by abiotic factors

Systematic expression analysis of mycotoxin biosynthesis genes by real-time PCR and microarray was carried out to examine the relationship between growth and general expression patterns in relation to single environmental factors such as temperature, water activity (a(w)) and pH and water activity x temperature interactions. For single parameters, one major peak of expression occurred close to optimum growth conditions. However, a second minor peak was observed under suboptimal growth conditions, when intermediate environmental stress was imposed on Aspergillus parasiticus (afl genes), Penicillium verrucosum (ota genes) and Fusarium culmorum (tri genes). This expression profile pattern was more pronounced in relation to changes in temperature and a(w) than to pH. In a two-factorial experimental design with temperature xa(w) regimes, again two peaks of expression were observed for cluster genes after microarray analysis, one close to those giving optimal growth and one under imposed stress conditions. Interestingly, when the activity of single genes of the microarray data were plotted in relation to the two parameters, again a two-peak expression profile became obvious independently for both parameters. Expression of the mycotoxin biosynthesis genes was followed exactly by phenotypic mycotoxin production. This expression profile appears to be generic across the mycotoxigenic fungi examined.

Effect of ochratoxin A on redox-regulated transcription factors, antioxidant enzymes and glutathione-S-transferase in cultured kidney tubulus cells

Ochratoxin A (OTA), a mycotoxin mostly produced by Aspergillus ochraceus and Penicillium verrucosum, is a worldwide contaminant of food and feedstuff. OTA is nephrotoxic and a renal carcinogen in rodents. The underlying molecular and cellular mechanisms by which OTA exhibits its toxicity have yet not been fully clarified. In the present study the effects of ochratoxin A on the activity of redox-regulated transcription factors, antioxidant enzymes, as well as glutathione-S-transferase (GST) have been studied in cultured kidney tubulus cells (LLC-PK1). Confluent LLC-PK1 cells were incubated with increasing concentrations of OTA for 24 h. OTA decreased SOD activity and enhanced intracellular levels of reactive oxygen species (ROS) as measured by flow cytometry. Furthermore OTA resulted in a down-regulation of GST mRNA and activity levels. Lower GST levels were accompanied by a decreased transactivation of activator protein-1 (AP-1) and NF-E2-related factor-2 (Nrf2), which mediate GST gene transcription. Present data indicate that enhanced ROS production and an impairment of GST activity, possibly due to an AP-1 and Nrf2 dependent signal transduction pathway, may be centrally involved in OTA induced nephrotoxicity.

Occurrence of Penicillium verrucosum in retail wheat flours from the Spanish market

In Spain, low ochratoxin A (OTA) levels have been detected in wheat and different wheat products but no information has been published about the fungi involved in this OTA contamination. Some species of the genera Penicillium and Aspergillus are known to form OTA but few of them are known to contaminate foods with this mycotoxin. Penicillium verrucosum, an important OTA producer typical of temperate and cold climates, is much more frequently found on cereals in countries where they occasionally have OTA problems as in North European countries compared with South Europe, where levels of OTA generally seem to be lower or is not detected. The aim of this study was to determine, identify and characterize the occurrence of potential OTA-producing Aspergillus spp. and Penicillium spp. from retail wheat flours purchased in the Spanish market and used for human consumption. A total of 105 Aspergillus isolates were analyzed in order to know whether they are able to produce OTA and/or citrinin (CIT). None of these isolates were able to produce these mycotoxins. However, 17 suspected P. verrucosum isolates were recovered and confirmed by RAPD analyses. Eleven isolates were OTA producers and 14 isolates produced CIT. Our results confirm the potential risk of OTA and CIT production in wheat flours if stored improperly and the occurrence of P. verrucosum in South European countries. This was the only species able to produce these mycotoxins.

Study of the Ochratoxin A effect on Aspergillus parasiticus growth and aflatoxin B 1 production

Aflatoxin B 1 (AFB 1) is a carcinogenic metabolite produced by certain Aspergillus species. Ochratoxin A (OTA) is a metabolite of Aspergillus ochraceus and Penicillium verrucosum. AFB 1 and OTA are amongst the most frequent combinations of mycotoxins found in plant products. Thus, synergistic effects or interactions between the two mycotoxins could be taking place. The aim of the present study was to investigate the effect of OTA on Aspergillus parasiticus growth and AFB 1 production in yeast extract sucrose (YES) medium at concentrations of 0.16, 1.6 and 16 ng OTA flask −1. The AFB 1 extracted from cultures and purified with immunoaffinity columns was then quantitated by HPLC. The recovery and detection limit of the method were 95.3% and 0.02 ng AFB 1 mL −1, respectively. Maximum AFB 1 productions in cultures with OTA were observed from 9 to 12 days (76.09–82.52 ng AFB 1 flask −1) while in control cultures (without OTA) maximum production (197.2 ng AFB 1 flask −1) was observed on 14th day. Maximum AFB 1 levels in cultures with OTA were reduced by a percentage of 58–61% compared to control cultures. Furthermore AFB 1 levels in cultures with OTA were practically (92%) degraded after 18 days of incubation. Conclusively when OTA is present the production of AFB 1 by A. parasiticus in YES medium is inhibited.

Environmental factors and preservatives affect carbon utilization patterns and niche overlap of food spoilage fungi

Nutrient assimilation by two mycotoxigenic spoilage fungi ( Penicillium verrucosum , Aspergillus ochraceus ) and four other food spoilage fungi ( Penicillium coryolophilum , P. roqueforti , Cladosporium herbarum , Eurotium repens ), of 32 key C-sources in wheat bread were examined in relation to abiotic factors of water availability, pH, temperature and the presence/absence of a preservative, potassium sorbate. These studies were to understand the relative potential co-existence, nutritional partitioning and niche exclusion in bread-based matrices. The niche size decreased significantly with decrease in water availability, temperature and pH. There were also significant interactive effects between pH and the preservative. The data were used to determine the niche overlap indices (NOI) of competing fungi relative to the two ochratoxigenic species. These showed that P. verrucosum and A. ochraceus were nutritionally dominant over the other species. The NOIs showed that potential co-existence and/or niche exclusion was influenced by environmental factors. Overall, the addition of the preservative increased the interspecific competition for nutrients. The level of co-existence and nutritional partitioning was significantly modified by abiotic factors, and this can help explain the dominance of specific fungal species in food matrices. This approach could also be useful for understanding competitiveness and dominance of fungal species in other ecosystems, especially in relation to impacts of abiotic and biotic factors.

Antifungal activity of lemon ( Citrus lemon L.), mandarin ( Citrus reticulata L.), grapefruit ( Citrus paradisi L.) and orange ( Citrus sinensis L.) essential oils

The objective of this work was to study the effect of the essential oils of lemon ( Citrus lemon L.), mandarin ( Citrus reticulata L.), grapefruit ( Citrus paradisi L.) and orange ( Citrus sinensis L.) on the growth of moulds commonly associated with food spoilage: Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum and Penicillium verrucosum, using the agar dilution method. All the oils showed antifungal activity against all the moulds. Orange essential oil was the most effective against A. niger, mandarin essential oil was most effective at reducing the growth of Aspergillus flavus while grapefruit was the best inhibitor of the moulds P. chrysogenum and P. verrucosum. Citrus essential oils could be considered suitable alternatives to chemical additives for use in the food industry.

Environmental factors affect efficacy of some essential oils and resveratrol to control growth and ochratoxin A production by Penicillium verrucosum and Aspergillus westerdijkiae on wheat grain

This study determined the efficacy of three essential oils (bay, clove and cinnamon oil) and the antioxidant resveratrol (0–500 μg g −1) on the control of growth and ochratoxin A (OTA) production by Penicillium verrucosum and Aspergillus westerdijkiae (= A. ochraceus) under different water activity ( a w, 0.90, 0.95, 0.995), and temperature (15, 25 °C) conditions on irradiated wheat grain. The most effective treatment (resveratrol) was then tested on natural grain. The ED 50 values for growth inhibition by the oils were 200–300 μg g −1 at the a w and the temperatures tested. For resveratrol, this varied from <50 μg g −1 at 0.90–0.95 a w to >350 at 0.995 a w at both temperatures. The ED 50 values for the control of OTA were slightly lower than for control of growth, with approx. 200 μg g −1 required for the oils and 50–100 μg g −1 of the antioxidant, at 0.90/0.95 a w and both temperatures. In wet grain (0.995 a w), higher concentrations were required. For growth there were statistically significant effects of single-, two- and three-way interactions between treatments except for concentration×temperature and concentration×temperature×essential oil/antioxidant treatment. For OTA control, statistically significant treatments were a w, temperature× a w, concentration×temperature, treatment×concentration, and three-way interaction of concentration× a w×treatment for P. verrucosum and A. westerdijkiae. Subsequent studies were done with the best treatment (resveratrol, 200 μg g −1) on natural wheat grain with either P. verrucosum or A. westerdijkiae at 0.85–0.995 a w and 15/25 °C over 28 days storage. This showed that the populations of the mycotoxigenic species and OTA contamination could be reduced by >60% by this treatment at the end of the storage period.

The Antimicrobial Activity of the Lichen Substances of the Lichens Cladonia Furcata, Ochrolechia Androgyna, Parmelia Caperata and Parmelia Conspresa

ABSTRACTAntimicrobial activity of fumarprotocetraric acid, lecanoric acid, protocetraric acid and stictic acid isolated from the lichen of Cladonia furcata, Ochrolechia androgyna, Parmelia caperata and Parmelia conspresa was studied in relation to the following species of microorganiosms: Bacillus mycoides, Bacillus subtilis, Staphylococcus aureus, Enterobacter cloaceae, Escherichia coli, Klebsiella pneumoniae, Aspergillus flavus, Aspergillus fumigatus, Botrytis cinerea, Candida albicans, Fusarium oxysporum, Mucor mucedo, Paecilomyces variotii, Penicillium purpurescens, Penicillium verrucosum, Trichoderma harsianum. The antimicrobal activity was estimated by determining the minimal inhibited concentration (MIC) by the Broth tube Dilution method. The researched lichen components ihibited the growth of all the tested microrganisms. The bacterias showed a highrer sensitivity relative to fungi. The lowest MCI value (0.031 mg/mL) was measured for the fumarprotocetraric acid related to the Klebsiella pneumoniae species. The weakest antimicrobial activity was found in stictic acid, which inhibited most of the tested microorganisms at significantly higher concentrations. Generally, all the components had relatively strong antimicrobal activity against the tested microorganisms, among which were the ones that caused deseases in men and animals, which could be of significance for their use for pharmaceutical purposes.

Survey on ochratoxin A in Indian green coffee destined for export

Ochratoxin A (OTA) is a toxic metabolite, produced by Aspergillus spp. and Penicillium verrucosum, that is nephrotoxic and possibly carcinogenic to humans. The aim of this study was to evaluate OTA contamination in batches of green coffee destined for export. Analysis of 80 green coffee samples indicated that, although a high incidence (74%) of OTA contamination (0.2–13.5 ng g−1) was recorded, the overall mean OTA level (2.17 ± 2.45 ng g−1) was low. The highest recorded OTA concentration was 13.5 ng g−1 in a robusta cherry sample and only five samples had OTA above 5 ng g−1 level. The mean OTA level was higher in cherry (range: 1.63 ± 0.97–4.8 ± 3.90) than parchment (0.56 ± 0.35–1.10 ± 0.28), indicating a correlation between processing method and OTA contamination.

Mycobiota of Czech wine grapes and occurrence of ochratoxin A and Alternaria mycotoxins in fresh grape juice, must and wine.

The aim of this study was to monitor the mycobiota of wine grapes, occurrence of ochratoxigenic microfungi in wine grapes and occurrence of ochratoxin A and Alternaria mycotoxins in fresh grape juice, must and wine from domestic crops in the year 2004. Thirteen samples of wine grapes (white /nine samples/ and red /four samples/) were collected during harvesting in the Znojmo wine region, SE Moravia. One sample of a wine grape variety was represented by three subsamples of wine grapes, which were sampled in left, middle and right part of the vineyard. Five wine grape berries per bunch were randomly selected, plated onto Dichloran Rose Bengal Chloramphenicol (DRBC) agar, and incubated for 5–7 days at 25 °C. Alternaria alternata, Cladosporium herbarum, C. cladosporioides, Penicillium expansum, P. aurantiogriseum, P. spinulosum and Rhizopus nigricans were isolated from the samples. Ochratoxigenic microfungi, e. g. Aspergillus carbonarius, and other species of section Nigri, A. ochraceus, Penicillium verrucosum and P. nordicum, were not found in the samples. The HPTLC method for quantification of ochratoxin A (OTA) and Alternaria mycotoxins (alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT), and tenuazonic acid (TeA)) in fresh grape juice (13 samples), must (13 samples) and wine (13 samples) was used. The limit of quantification (LoQ) was 8 ng/l for OTA, 1.5 μg/l for AOH, 1.5 μg/l for AME, 1.5 μg/l for ALT and 7.5 μg/l for TeA. Occurrence of OTA and Alternaria mycotoxins in fresh grape juice, must and wine was not proved.

Potential for detection and discrimination between mycotoxigenic and non-toxigenic spoilage moulds using volatile production patterns: A review

There has been interest in the development of techniques for the rapid early detection of mycotoxigenic moulds in the food production chain. The development of sensor arrays that respond to the presence of different volatiles produced by such moulds has been examined as a potential method for the development of such detection systems. Commercial devices based on such sensor arrays, so-called ‘electronic noses’, have been examined extensively for the potential application of determining the presence of mycotoxigenic moulds in food raw materials. There is also interest in using the qualitative volatile production patterns to discriminate between non-mycotoxigenic and mycotoxigenic strains of specific mycotoxigenic species, e.g. Fusarium section Liseola, Penicillium verrucosum and Aspergillus section Nigri. This paper reviews the technology and available evidence that the non-destructive analysis of the headspace of samples of food raw materials or the discrimination between strains (mycotoxigenic and non-mycotoxigenic) can be determined using volatile fingerprints.

Physiological relationship between food preservatives, environmental factors, ochratoxin and otapksPV gene expression by Penicillium verrucosum

There is significant interest in trying to understand the relationship between environmental factors, preservative concentration and expression of genes involved in mycotoxin production. However, little information is available on the link between physiological stress factors and expression of genes responsible for mycotoxin production. This study has examined the effect of interactions between ionic and non-ionic water availability modified with glycerol or NaCl ( a w, 0.98, 0.95 and 0.93) and sub-optimal concentrations of calcium propionate and potassium sorbate (150, 300 ppm) at 25 °C on growth, ochratoxin A (OTA) and otapksPV gene expression by the mycotoxigenic species Penicillium verrucosum. Growth was inhibited between 25–35% by the preservatives at each a w level. However, OTA production was stimulated by 150 and 300 ppm of both preservatives, especially at 0.95 and 0.93 a w. If water activity as a single stress factor was changed, a typical OTA production and otapksPV expression profile occurred, indicating that OTA biosynthesis is activated under two conditions, i.e., under optimal growth conditions and under weak stress conditions. Temporal analysis of otapksPV expression showed that there was an optimum after 8–9 days incubation. Statistical analyses indicated good correlation between sub-optimal concentrations of preservatives, intermediate a w levels and genotypic and phenotypic gene and toxin production. This is the first time that genotypic information has been linked to phenotypic mycotoxin production in relation to such interacting stress factors.

Response surface method to optimize the production and characterization of lipase from Penicillium verrucosum in solid-state fermentation

Current studies about lipase production by solid-state fermentation involve the use of agro-industrial residues towards developing cost-effective systems directed to large-scale commercialization of enzyme-catalyzed processes. In this work, lipase production and partial characterization of the crude enzymatic extracts obtained by Penicillium verrucosum using soybean bran as substrate was investigated. Different inductors were evaluated and the results showed that there is no influence of this variable on the lipase production, while temperature and initial moisture were the main factors that affected enzyme production. The optimized cultivation temperature (27.5 degrees C) and initial moisture of substrate (55%) were determined using the response surface methodology. Kinetics of lipase production was followed at the optimized growth conditions. Optimum lipase yield was 40 U/g of dry bran. The crude enzymatic extract showed optimal activity in the range from 30 to 45 degrees C and in pH 7.0.

An overview of ochratoxin A in beer and wine

Ochratoxin A (OTA) is a mycotoxin produced mainly by several fungal species of the genera Aspergillus and Penicillium. This mycotoxin has been shown to be nephrotoxic, hepatotoxic, teratogenic and carcinogenic to animals and has been classified as a possible carcinogen to humans. OTA occurs in a variety of foods, including beer and wine. Reports on OTA occurrence in beer indicate that this is a worldwide problem due to the widespread consumption of this beverage. At present, the European Union (EU) has not set a maximum allowable limit (MAL) for this mycotoxin in beer, although there is a limit in barley and malt. Studies carried out in different countries agree in the high proportion of samples contaminated with OTA although levels are, usually, below 0.2 ng/ml. OTA occurrence has been related to the contamination of malt barley with ochratoxigenic species, particularly Penicillium verrucosum. OTA produced in grains is carried to wort and, although fermentation decreases the concentration, the toxin is not eliminated. Reducing the fungal contamination of malt barley is the most promising strategy for reducing OTA in beer. With regard to wine, surveys on the presence of OTA have been conducted worldwide. The proportion of wines in which OTA is detected is very high (above 50%) in some countries (especially in the Mediterranean basin) although only a few wines contained concentrations exceeding the MAL laid down by the EU (2.0 ng/ml). A gradient of concentration is usually recognized; OTA levels decrease in the order red, rosé, and white wine but also with increasing latitude of the producing countries. OTA presence in wines is due to the black aspergilli, mainly A. carbonarius, which can grow on grapes in the vineyards and produce the toxin. At grape crushing, the juice can be contaminated with the toxin which is carried over into wine, where it persists due to its stability. Pre- and post-harvest treatments are being investigated to diminish contamination of wines as much as possible.

Post-harvest control strategies: Minimizing mycotoxins in the food chain

Contamination of cereal commodities by moulds and mycotoxins results in dry matter, quality, and nutritional losses and represents a significant hazard to the food chain. Most grain is harvested, dried and then stored on farm or in silos for medium/long term storage. Cereal quality is influenced by a range of interacting abiotic and biotic factors. In the so-called stored grain ecosystem, factors include grain and contaminant mould respiration, insect pests, rodents and the key environmental factors of temperature, water availability and intergranular gas composition, and preservatives which are added to conserve moist grain for animal feed. Thus knowledge of the key critical control points during harvesting, drying and storage stages in the cereal production chain are essential in developing effective prevention strategies post-harvest. Studies show that very small amounts of dry matter loss due to mould activity can be tolerated. With < 0.5% dry matter loss visible moulding, mycotoxin contamination and downgrading of lots can occur. The key mycotoxigenic moulds in partially dried grain are Penicillium verrucosum (ochratoxin) in damp cool climates of Northern Europe, and Aspergillus flavus (aflatoxins), A. ochraceus (ochratoxin) and some Fusarium species (fumonisins, trichothecenes) on temperate and tropical cereals. Studies on the ecology of these species has resulted in modelling of germination, growth and mycotoxin minima and prediction of fungal contamination levels which may lead to mycotoxin contamination above the tolerable legislative limits (e.g. for ochratoxin). The effect of modified atmospheres and fumigation with sulphur dioxide and ammonia have been attempted to try and control mould spoilage in storage. Elevated CO 2 of > 75% are required to ensure that growth of mycotoxigenic moulds does not occur in partially dried grain. Sometimes, preservatives based on aliphatic acids have been used to prevent spoilage and mycotoxin contamination of stored commodities, especially feed. These are predominantly fungistats and attempts have been made to use alternatives such as essential oils and anti-oxidants to prevent growth and mycotoxin accumulation in partially dried grain. Interactions between spoilage and mycotoxigenic fungi and insect pests inevitably occurs in stored grain ecosystems and this can further influence contamination with mycotoxins. Effective post-harvest management of stored commodities requires clear monitoring criteria and effective implementation in relation to abiotic and biotic factors, hygiene and monitoring to ensure that mycotoxin contamination is minimised and that stored grain can proceed through the food chain for processing.

Guttation droplets of Penicillium nordicum and Penicillium verrucosum contain high concentrations of the mycotoxins ochratoxin A and B

Eight of eleven ochratoxigenic isolates of Penicillium nordicum and Penicillium verrucosum produced guttation droplets when grown on Czapek yeast extract (CYA) agar for 10-14 days at 25 degrees C. Parallel cultivation of one strain each of P. nordicum and P. verrucosum on malt extract agar demonstrated that higher volumes of exudate are produced on this agar. However, HPLC analyses revealed higher concentrations of ochratoxin A (OTA) and B (OTB) in droplets originating from cultures on CYA. For quantitative determination of the mycotoxin contents, triplicates of three isolates each of P. nordicum and P. verrucosum were grown as single spot cultures on CYA for up to 14 days at 25 degrees C. Guttation droplets were carefully collected between day 11 and 14 with a microliter syringe from each culture. Extracts from exudates and corresponding mycelia as well as fungal free agar were analyzed by HPLC for the occurrence of ochratoxin A (OTA) and B (OTB). Mean concentrations ranging between 92.7-8667.0 ng OTA and 159.7-2943.3 ng OTB per ml were detected in the guttation fluids. Considerably lower toxin levels were found in corresponding samples of the underlying mycelia (9.0-819.3 ng OTA and 4.5-409.7 ng OTB/g) and fungal free agar (15.3-417.0 ng OTA and 12.7-151.3 ng OTB/g). This is the first report which shows that high amounts of mycotoxins could be excreted from toxigenic Penicillium isolates into guttation droplets.

Occurrence of ochratoxin A and ochratoxigenic mycoflora in corn and corn based foods and feeds in some South American countries

Cereals and cereal- derived products constitute the base of human and animal feeding in South American countries. This review attempts to give an overview of the ochratoxin A (OTA) occurrence and potential sources of OTA contamination in those products. The environmental conditions as humidity and temperature in the colonization of the substrates by Aspergillus section Nigri isolated from corn kernels were also discussed. The available information on the ochratoxigenic mycoflora and OTA presence in corn, corn based food and feed is limited. Only few surveys have been carried out in Argentina, Ecuador and Brazil; which showed that Aspergillus niger aggregate and A. ochraceus species would be the main source of OTA. It's possible to emphasize that, the species A. carbonarius has not been isolated from these substrates and Penicillium verrucosum was isolated only from pig feeds of Argentinean samples in low percentage. Studies about the ecophysiology of ochratoxigenic fungi and OTA occurrence are in progress in Latin America to reduce the impact of this toxin in the food chain.