Current importance of ochratoxin A-producing Aspergillus spp

Analyzing the quality differences between healthy and moldy cigar tobacco leaves during the air-curing process through fungal communities and physicochemical components

Introduction

The air-curing process of cigar tobacco, as a key step in enhancing the quality of cigars, is often susceptible to contamination by mold spores, which severely constrains the quality of cigar tobacco.

Methods

This study employed high-throughput Illumina sequencing technology and a continuous flow analysis system to analyze the differences between the microbial communities and physicochemical components of moldy and healthy cigar tobacco leaves. Furthermore, correlation analysis was performed to reveal the impact of mold on the quality of cigar tobacco.

Results

The differences between the microbial flora and physicochemical compositions of moldy (MC) and healthy (HC) tobacco leaves were analyzed, revealing significant disparities between the two groups. Aspergillus spp. represented the dominant mold in MC, with nine out of twelve isolated molds showing higher quantities on MC than on HC. Mold contamination notably decreased the total nitrogen (TN), total phosphorus (TP), total alkaloids (TA), starch, protein, and flavor constituents while increasing the total fatty acid esters (TFAA), which was accompanied by a shift towards weakly acidic pH in the leaves. Fungal community analysis indicated a significant reduction in the fungal operational taxonomic unit (OUT) numbers and diversity indices in MC, contrasting with the bacterial trends. Aspergillus exhibited significantly higher relative abundance in MC, with LEfSe analysis pinpointing it as the primary driver of differentiation. Furthermore, significant negative correlations were observed between Aspergillus and TP, starch, TA, and protein, while a significant positive association was evident with TFAA. Network analysis underscored the pivotal role of Aspergillus as the species influencing disparities between HC and MC, with its abundance serving as a critical determinant during the air-curing process.

Discussion

This study elucidated substantial quality distinctions between MC and HC during air-curing, with Aspergillus emerging as the key species contributing to leaf mold.

Ultra-sensitive determination of Ochratoxin A in coffee and tea samples using a novel semi-automated in-syringe based coagulant-assisted fast mycotoxin extraction (FaMEx) technique coupled with UHPLC-MS/MS

In this study, we demonstrated a novel semi-automated in-syringe-based coagulant-assisted liquid-liquid microextraction (IS-CGA-LLME) as fast mycotoxin extraction (FaMEx) technique coupled with ultra-high-performance liquid chromatography connected with a tandem-mass spectrometer (UHPLC-MS/MS) for the quantification of mycotoxin (Ochratoxin A, OT-A) in coffee and tea samples. IS-CGA-LLME is a three-step extraction process that includes extraction of OT-A from sample matrix using low-volume solvent extraction, then the extractant was cleaned-up using a coagulation process, and finally, the decolorized/matrix removed sample solution was processed for LLME for target analyte's pre-concentration. The final extractant was analyzed using UHPLC-MS/MS for OT-A quantification. Under the optimized experimental conditions, highly sensitive detection and quantification limits were obtained at 0.001 and 0.003 ng g^-1 for OT-A with excellent extraction recovery (93-111%) and precision <10%. These results proved that the developed method is a simple, highly sensitive, semi-automated, low-matrix effect and efficient procedure for the determination of mycotoxins in food samples.

An Immunoenzymatic Method for the Determination of Ochratoxin A in Biological Liquids (Colostrum and Cow's Milk)

Ochratoxins are mycotoxins that have been extensively studied lately due to the multiple toxic effects such as nephrotoxicity, hepatotoxicity, and carcinogenicity. These toxins contaminate plant and animal foods and after ingestion they reach into body fluids. The method of competitive direct enzyme immunoassay, in the solid phase, was validated through the determination of specific parameters (performance, linearity, recovery percentage, limit of detection, limit of quantification). The validated method was used to determine ochratoxin A in colostrum and cow’s milk. The method applied for the determination of ochratoxin A was linear for the concentration range of 0.0–0.5 ng/mL, the value for the regression coefficient (r) was 0.9838. Ochratoxin A was present in 91.67% of the colostrum and in 93.33% of cow’s milk samples. The linearity of the method, demonstrated for very low concentrations of analyte, the detection limit as well as the limit of quantification recommend the method for the determinations of micro-pollutants from foods, including biological fluids.

Antimicrobial Actions and Applications of Chitosan

Chitosan is a naturally originating product that can be applied in many areas due to its biocompatibility, biodegradability, and nontoxic properties. The broad-spectrum antimicrobial activity of chitosan offers great commercial potential for this product. Nevertheless, the antimicrobial activity of chitosan varies, because this activity is associated with its physicochemical characteristics and depends on the type of microorganism. In this review article, the fundamental properties, modes of antimicrobial action, and antimicrobial effects-related factors of chitosan are discussed. We further summarize how microorganisms genetically respond to chitosan. Finally, applications of chitosan-based biomaterials, such as nanoparticles and films, in combination with current clinical antibiotics or antifungal drugs, are also addressed.

Recent Progress and Development of G-Quadruplex-Based Luminescent Assays for Ochratoxin A Detection

Ochratoxin A (OTA) is a mycotoxin that is widespread throughout the world. It contaminates foods such as vegetables, fruits, and rice. It harms human health and has potential carcinogenic effects. The G-quadruplex (G4) is a tetraplexed DNA structure generated from guanine-rich DNA that has found emerging use in aptamer-based sensing systems. This review outlines the status of OTA contamination and conventional detection methods for OTA. Various G4-based methods to detect OTA developed in recent years are summarized along with their advantages and disadvantages compared to existing approaches.

Diversity, Application, and Synthetic Biology of Industrially Important Aspergillus Fungi

The filamentous fungal genus Aspergillus consists of over 340 officially recognized species. A handful of these Aspergillus fungi are predominantly used for food fermentation and large-scale production of enzymes, organic acids, and bioactive compounds. These industrially important Aspergilli primarily belong to the two major Aspergillus sections, Nigri and Flavi. Aspergillus oryzae (section Flavi) is the most commonly used mold for the fermentation of soybeans, rice, grains, and potatoes. Aspergillus niger (section Nigri) is used in the industrial production of various enzymes and organic acids, including 99% (1.4 million tons per year) of citric acid produced worldwide. Better understanding of the genomes and the signaling mechanisms of key Aspergillus species can help identify novel approaches to enhance these commercially significant strains. This review summarizes the diversity, current applications, key products, and synthetic biology of Aspergillus fungi commonly used in industry.

Influence of temperature, water activity and incubation time on fungal growth and production of ochratoxin A and zearalenone by toxigenic Aspergillus tubingensis and Fusarium incarnatum isolates in sorghum seeds

The major objective of this study was to describe the effect of water activity and temperature on radial growth and production of ochratoxin A (OTA) and zearalenone (ZEA) on sorghum grains of three Aspergillus tubingensis and three Fusarium incarnatum isolates. The water activity range was 0.91-0.99 a_w for F. incarnatum isolates and 0.88-0.99 a_w for A. tubingensis isolates. Temperatures of incubation were 15, 25 and 37°C for both species. Mycotoxin production was determined after 7, 14, 21 and 28days depending on the growth rate of the six isolates. Maximum growth rates (mm/day) were observed at 37°C and 0.99 a_w for A. tubingensis isolates and at 0.99 a_w and 25°C for F. incarnatum isolates. A. tubingensis was able to grow at 15°C only at the highest a_w levels (0.97 and 0.99 a_w). However, at this temperature F. incarnatum grew at 0.94 a_w. Optimum ochratoxin A production was observed at 0.97 a_w×37°C whereas optimal conditions for ZEA production varied from one isolate to another. Moreover, isolates of F. incarnatum from Tunisia do not require high a_w and temperature levels to yield maximum levels of ZEA. In general, our results showed that there is no correlation between the growth and production of ZEA in the case of F. incarnatum. This is the first study on the water activity and temperature effect on growth rate and ZEA production of F. incarnatum. Our results show that sorghum grains not only support growth but also OTA and ZEA production by A. tubingensis and F. incarnatum, respectively.

Comparative study of growth responses and screening of inter-specific OTA production kinetics by A. carbonarius isolated from grapes

The aim of this work was to assess OchratoxinA (OTA) production of different Aspergillus carbonarius isolates, evaluate their growth profile through different growth measurements, and reveal any underlying correlation between them. Ten different isolates of A. carbonarius isolated from Greek vineyards located in different geographical regions were examined in vitro for their OTA production potential after an incubation period of up to 11 days. All fungal isolates grew on a synthetic grape juice medium (SGM) similar to grape composition at optimum conditions of temperature and water activity (25°C and 0.98 a_w). Samples for OTA determination were removed at 3, 5, 7, 9, and 11 days of growth and analyzed by HPLC. Based on OTA measurements the isolates were characterized by diverse OTA production ranging from 50 to 2000 ppb at day 11. The different fungal growth responses (colony diameter, colony area, biomass, biomass dry weight, and colony density) have been measured and correlated with toxin production by means of principal components analysis (PCA), confirming satisfactory correlation and explained over 99% of data variability. Leudeking-Piret model was also used to study OTA production with time, revealing a mixed-growth associated trend and pointing a fail-safe model with slightly better prediction through colony area. This approach contributes to the assessment of correlation between mycotoxin production and different methods of fungal growth determination in relation to time.

Ochratoxin A in stored U.S. barley and wheat

Ochratoxin A (OTA) is a mycotoxin of significant health concern that is present in a variety of cereal grains and other foods around the world. Although OTA contamination can occur prior to harvest, it is largely considered a storage issue that can be controlled through the implementation of proper storage practices. Barley, durum, and hard red spring wheat samples that had been stored for various lengths of time were collected (n = 262) over a period of 2 years by multiple commercial grain companies located in the northwestern and northern Great Plains regions of the United States. Samples were analyzed for OTA concentration using high-performance liquid chromatography with fluorescence detection. OTA was detected in 12.2% of the samples, and of those samples, 81.3% had been stored for ≥6 months. One sample of barley and four samples of wheat exceeded 5 ng/g of OTA.

Ochratoxin A levels in spices and dried nuts consumed in Tunisia

A total of 112 samples of spices (24 caraway, 20 coriander, 25 curcuma, 20 black pepper and 23 red pepper) and 110 samples of dried nuts (44 almonds, 42 peanuts and 24 pistachio) purchased from popular markets in 24 regions of Tunisia were analyzed for ochratoxin A (OTA) by fluorescence HPLC. The average levels of contamination of OTA found in spice samples were 244, 206, 290, 274 and 203 µg/kg, respectively, for caraway, coriander, curcuma, black pepper and red pepper. Concerning dried nut samples, the average levels were 61, 60 and 89 µg/kg, respectively, for almonds, peanuts and pistachio. Contamination levels were higher than the usual norms (10.0 OTA µg/kg) established by the European Commission in 2005 . This survey is the first to be carried out on the natural occurrence of OTA in the main spices and dried nuts consumed by the Tunisian population.

Exposure assessment to ochratoxin A in Chinese wine

A rapid, sensitive, reproducible, and inexpensive method of high-performance liquid chromatography with fluorescence detection after an anion-exchange solid-phase extraction cleanup step for the analysis of ochratoxin A (OTA) in Chinese wine was developed. The average recovery rate and the average RSD of recovery were 97.47% and about 4%. The relative standard deviations of both the interday and intraday precision were 6.7 and 12.6%, respectively. The limits of detection and quantitation were determined to be 0.01 and 0.03 μg/L, respectively. A total of 223 samples from the major wine-producing areas of China were analyzed for OTA. OTA was detected at levels of 0.01-0.98 μg/L. The mean was 0.15 μg/L. Then, participants as representative inhabitants were invited to answer the designed questionnaire about the quantity and frequency of wine consumption. All data were simulated by the point evaluation for the risk assessment of OTA contamination from wine. Those results indicated that daily intake (DI) of OTA for the average adult consumer varies between 0.86 and 1.08 ng/kg bw per week, which was lower than all the reference standards. However, the DI value (4.38-5.54 ng/kg bw per week) in the high percentile (97.5) was slightly above 5% PTWI (100 ng kg(-1) week(-1)) of the JECFA. In conclusion, OTA exposure from Chinese wine has no risk of harm. This research will provide the scientific basis for determining the maximum limit of OTA content in Chinese wine.

Survey of ochratoxin A in freshly harvested durum and hard red spring wheat in the United States, 2011 and 2012

Ochratoxin A (OTA) is a toxin produced by some Penicillium and Aspergillus species around the world in a variety of food and feed, especially cereal grains, before harvest but primarily during storage. Durum and hard red spring (HRS) wheat samples were collected right after harvest as part of the U. S. regional crop quality survey in both 2011 (n = 560) and 2012 (n = 654) from the upper Great Plains. All samples were analyzed for OTA contamination using high-performance liquid chromatography with fluorescence detection. Overall, 2.1% of the samples were positive for OTA. In 2011, OTA was detected in 1.0% of the durum wheat samples but was not found in HRS wheat. In 2012, 8.3 and 1.4% of the durum and HRS wheat samples, respectively, were positive for OTA. Of the 25 samples that had detectable OTA, 3 samples (12%), all of which were durum wheat, had OTA that exceeded 5 ng/g.

Natural occurrence of mycotoxins in medicinal plants: a review

Medicinal plants are widely used as home remedies and raw materials for the pharmaceutical industries. Herbal remedies are used in the prevention, treatment and cure of disorders and diseases since ancient times. However, use of medicinal herbs may not meet the requirements of quality, safety and efficacy. During harvesting, handling, storage and distribution, medicinal plants are subjected to contamination by various fungi, which may be responsible for spoilage and production of mycotoxins. The increasing consumption of medicinal plants has made their use a public health problem due to the lack of effective surveillance of the use, efficacy, toxicity and quality of these natural products. The increase in use of medicinal plants may lead to an increase in the intake of mycotoxins therefore contamination of medicinal plants with mycotoxins can contribute to adverse human health problems and therefore represents a special hazard. Numerous natural occurrences of mycotoxins in medicinal plants and traditional herbal medicines have been reported from various countries including Spain, China, Germany, India, Turkey and from Middle East as well. This review discusses the important mycotoxins and their natural occurrences in medicinal plants and their products.

Multilocus sequence analysis of Aspergillus Sect. Nigri in dried vine fruits of worldwide origin

Dried vine fruits may be heavily colonized by Aspergillus species. The molecular biodiversity of an Aspergillus population (234 strains) isolated from dried vine fruit samples of worldwide origin were analyzed by investigating four housekeeping gene loci (calmodulin, β-tubulin, elongation factor 1-α, RPB2). Aspergillus Sect. Nigri was dominant and the strains were identified as A. tubingensis (138), A. awamori (38), A. carbonarius (27), A. uvarum (16) and A. niger (11). Four Aspergillus flavus strains were also identified from Chilean raisins. Two clusters closely related to the A. tubingensis species with a significant bootstrap (60% and 99%) were identified as distinct populations. Among the four loci, RPB2 showed the highest genetic variability. This is the first complete study on the worldwide distribution of black Aspergilli occurring on dried vine fruits identified by a molecular approach.

Molecular diagnosis of ochratoxinogenicAspergillus species

Toxigenic and non-toxigenic black aspergilli belonging to theAspergillus niger aggregate and toA. carbonarius were compared to each other and to strains of other species by DNA fingerprinting. AFLPs showed a clear separation ofA. niger andA. carbonarius. However, no clear correlation between the genetic similarity of the strains and the ability to produce ochratoxin A (OTA) was detected. Based on AFLP, marker sequences were chosen for the construction of SCAR-PCR primers for the detection ofA. carbonarius. A similar approach was used forA. ochraceus, another fungus of concern regarding ochratoxin A contamination of coffee. Cluster analysis ofA. ochraceus isolates mainly from Brazilian coffee showed a very close genetic similarity. Three species specific primer pairs were developed and one of these was used for the PCR and realtime PCR (RT-PCR) based detection of the mould in green coffee.A. ochraceus was specifically and rapidly detected and quantified in green coffee. A positive correlation between the amount of DNA and OTA content was established.

Ochratoxin A management in vineyards by Lobesia botrana biocontrol

Grape berries attacked by Lobesia botrana larvae are more easily infected by Aspergillus section Nigri (black aspergilli) ochratoxigenic species. Two-year field trials were carried out in Apulia (Italy) to evaluate a bioinsecticide control strategy against L. botrana and the indirect effect on reducing ochratoxin A (OTA) contamination in vineyards. A commercial Bacillus thuringiensis formulate and an experimental Beauveria bassiana (ITEM-1559) formulate were tested in two vineyards cultivated with the same grape variety, Negroamaro, but with two different training systems (espalier and little-arbor techniques). In both years and training systems the treatments by B. bassiana ITEM-1559 significantly controlled L. botrana larvae attacks with effectiveness similar to B. thuringensis (more than 20%). A significant reduction of OTA concentrations (up to 80% compared to untreated controls) was observed only in the first year in both training systems, when the metereological parameters prior to harvest were more favorable to the insect attack. Results of field trials showed that B. bassiana ITEM-1559 is a valid bioinsecticide against L. botrana and that grape moth biocontrol is a strategy to reduce OTA contamination in vineyard in seasons with heavy natural infestation.

Fungi and Mycotoxins from Pre- and Poststorage Brewer's Grain Intended for Bovine Intensive Rearing

The aim of the study was to determine the mycobiota and natural levels of mycotoxins such as aflatoxin B₁ (AFB₁), ochratoxin A (OTA), fumonisin B₁ (FB₁), and deoxynivalenol (DON) present in brewers grains pre- and poststored intended for bovine intensive rearing. Poststored (80%) samples had counts higher than 1 × 10⁴ colony-forming units (CFU/g). Cladosporium spp. and Aspergillus spp. were isolated at high frequencies. Aspergillus flavus was the prevalent isolated species. Prestored (70%) and poststored (100%) samples showed AFB₁ levels over the recommended limits (20 μg/Kg), and OTA levels were below the recommended limits (50 μg/Kg) while pre- and poststored samples did not show FB₁ and DON natural contamination levels. The presence of mycotoxins in this substrate indicates the existence of contamination. Regular monitoring of feeds is required in order to prevent chronic and acute toxic syndromes related to this kind of contamination.

Effect of yearly conditions and management practices on ochratoxin A production in Sultana Seedless vineyards

Sun drying of seedless grapes (Vitis vinifera cv. Sultanina) is widely practised in the western Aegean Region providing Turkey with a significant share in the world trade of sultanas. Research was initiated in 1998 to determine the incidence of ochratoxin A (OTA), to identify the major factors resulting in contamination and to develop techniques to reduce or prevent contamination. This paper assesses OTA formation in five experimental vineyards located in Manisa province of Turkey between 1998 and 2003. The cultural practices recorded were tillage (type and timing), fertilisation, plant protection, irrigation, trellising, pruning, GA(3) application, harvest maturity and date, and drying practices (type of drying yard, dipping into alkaline solution, length of drying period). In the experimental vineyards, no OTA was found at veraison. OTA levels in grapes harvested at fresh maturity ranged between <LOD and 8 ng g(-1), whereas in dried sultanas they were between <LOD and 35 ng g(-1). The frequency of OTA-positive samples increased in dried grapes compared with fresh. The number and timing of tillage, number of damaged berries, and removal of damaged/infected berries prior to sun drying were identified as the major good practices that may contribute to the reduction of OTA in sultanas.

Ochratoxigenic black species of Aspergilli in grape fruits of northern Italy identified by an improved PCR-RFLP procedure

A collection of 356 isolates of Aspergillus spp. collected during 2006 and 2007 from grapevines in northern Italy were identified through Internal Transcribed Spacer based Restriction Fragment Length Polymorphism (ITS-RFLP) and tested for ochratoxin A (OTA) production. Restriction endonuclease digestion of the ITS products using the endonucleases HhaI, HinfI and RsaI, distinguished five different RFLPs. From each pattern, three samples were sequenced and the nucleotide sequences showed different species corresponding to Aspergillus niger, A. carbonarius, A. tubingensis, A. japonicus and A. aculeatus. By comparing the sequences of the ITS regions, also the uniseriate species A. japonicus and A. aculeatus could be differentiated by HinfI digestion of the ITS products. Among the aspergilli, A. niger was the major species associated with grapes during 2006 (57.4%), while A. carbonarius was the major species during 2007 (46.6%). All the strains of Aspergillus were tested for their ability to produce OTA on Yeast extract sucrose medium (YES), as it was tested as an optimal substrate for the evaluation of OTA production by black aspergilli. Out of 356 isolates, 63 (17.7%) isolates produced OTA ranging from 0.05 to 3.0 µg mL(-1). Most of the ochratoxigenic isolates were A. carbonarius (46) in both years, but also some strains of A. tubingensis (11) and A. japonicus (6) produced lower amounts of OTA.

Application of isotope dilution mass spectrometry: determination of ochratoxin A in the Canadian Total Diet Study

Analytical methods are generally developed and optimized for specific commodities. Total Diet Studies, representing typical food products 'as consumed', pose an analytical challenge since every food product is different. In order to address this technical challenge, a selective and sensitive analytical method was developed suitable for the quantitation of ochratoxin A (OTA) in Canadian Total Diet Study composites. The method uses an acidified solvent extraction, an immunoaffinity column (IAC) for clean-up, liquid chromatography-tandem mass spectrometry (LC-MS/MS) for identification and quantification, and a uniformly stable isotope-labelled OTA (U-[(13)C(20)]-OTA) as an internal recovery standard. Results are corrected for this standard. The method is accurate (101% average recovery) and precise (5.5% relative standard deviation (RSD)) based on 17 duplicate analysis of various food products over 2 years. A total of 140 diet composites were analysed for OTA as part of the Canadian Total Diet Study. Samples were collected at retail level from two Canadian cities, Quebec City and Calgary, in 2008 and 2009, respectively. The results indicate that 73% (102/140) of the samples had detectable levels of OTA, with some of the highest levels of OTA contamination found in the Canadian bread supply.

Exploration of Islamic medicine plant extracts as powerful antifungals for the prevention of mycotoxigenic Aspergilli growth in organic silage

BACKGROUND

Feed contamination with mycotoxins is a major risk factor for animals and humans as several toxins can exist as residues in meat and milk products, giving rise to carry-over to consumers via ingestion of foods of animal origin. The starting point for prevention, in this chain, is to eliminate the growth of mycotoxigenic fungi in the animal forage. Ten plant extracts, recommended in Islamic medicine, were evaluated as antifungal agents against mycotoxigenic Aspergilli, i.e. Aspergillus flavus and A. ochraceus, growth in organic maize silage.

RESULTS

Most extracts had remarkable antifungal activities using both qualitative and quantitative evaluation methods. Cress (Lepidium sativum) seed extract was proven to be the most powerful among the plants examined. Blending of the most effective extracts (garden cress seed, pomegranate peel and olive leaf extracts), individually at their minimal fungicidal concentrations, with maize silage resulted in the reduction of inoculated A. flavus colony counts by 99.9, 99.6 and 98.7%, respectively, whereas silage blending with the combined extracts completely prohibited fungal growth for up to 30 days of incubation under aerobic conditions.

CONCLUSION

Besides the health promoting effects, silage blending with the bioactive plant extracts examined could lead to the required protection from pathogenic and mycotoxigenic fungi.

OCORRÊNCIA DE ASPERGILLUS SPP., PENICILLIUM SPP. E AFLATOXINAS EM AMOSTRAS DE FARINHA DE MILHO UTILIZADAS NO CONSUMO HUMANO, PIAUÍ, BRASIL

RESUMO Esse trabalho teve como objetivo avaliar a presença de fungos e de aflatoxinas em um produto à base de milho, destinado ao consumo humano na Cidade de Teresina, Piauí, Brasil. Foram utilizadas 30 amostras (500 g) de farinha de milho a partir de seis diferentes marcas vendidas em supermercados dessa cidade. A coleta foi realizada entre janeiro e março de 2009. A avaliação micológica foi realizada imediatamente e, em seguida, foram armazenadas a -4º C, alíquotas para, posteriormente, ser realizada a análise de aflatoxinas. As contagens fúngicas variaram entre 2,42 e 4,10 UFC/g. Não houve diferença significativa a p < 0,05 entre as marcas utilizadas. As principais espécies de Aspergillus isoladas foram: A. flavus (32,73 %), A. oryzae ( 14,54%). A. niger agregado (10,91%), A. parasiticus (5,45%), A. fumigatus (5,45%) e A. carbonarius (1,81%), já as de Penicillium foram P. citrinum (28,88%), P. funiculosum (25,67%) e P. verrucosum (16,22%). Não foi detectada a presença de aflatoxina. Conclui-se que espécies fúngicas potencialmente capazes de produzir micotoxinas como Aspergillus e Penicillium são encontradas em farinha de milho, porém, não foi detectada a presença de aflatoxinas nesse produto utilizado para alimentação humana.

Detection of ochratoxin A and cis- and trans-resveratrol in red wines and their musts from Calabria (Italy)

The natural occurrence of ochratoxin A (OTA) and cis- and trans-resveratrols in red wines has been widely reported. The aim of this work was to evaluate the ochratoxin A (OTA) and both cis- and trans-resveratrol content of red wine (from must to wine) in a pilot-scale vinification process in Calabria (Italy). Eleven samples were collected at different stages of vinification and analysis was carried out by HPLC. Wine from manufacturer 3 contained the highest amount of trans-resveratrol (3.41 mg l(-1)). This wine was characterized by an Aglianico-Magliocco grape variety. Interestingly, data regarding OTA showed that the value of this contaminant was low in all analyzed samples and, in each case, below the legal limit (2.0 mg l(-1) (ppb)). Overall, the results demonstrated the high quality of wines produced in Calabria.

Natural occurrence of fumonisin B2 in red wine from Italy

The potential risk of exposure to fumonisin B(2) (FB(2)) in the grape-wine chain has recently been revealed after a report of Aspergillus niger in grapes and its ability to produce FB(2) and FB(4). The occurrence of these two fumonisins in wine was investigated by LC/MS/MS in 51 market samples (45 red, five white and one rose wine) produced in various Italian regions. Nine samples of red wine were found to be contaminated by fumonisin B(2) at levels ranging from 0.4 to 2.4 ng/ml, while FB(4) was not detected in any of the tested samples. This is the first report on the natural occurrence of FB(2) in wine, indicating that, although at low levels, there is a potential risk of FB(2) exposure for the wine-consumer.

Ochratoxin A in roasted coffee from French supermarkets and transfer in coffee beverages: comparison of analysis methods

The OTA content of 30 roasted coffees purchased in French supermarkets was evaluated by two validated different methods: one using immunoaffinity column (IAC) clean-up after alkaline extraction; the second using toluene extraction under acidic conditions. OTA recoveries (0.5 to 5 µg/kg) ranged from 16-49% with the alkaline extraction method and 55-60% with the acidic method. OTA recoveries from prepared beverages were similar with all methods (75-80%). All samples containing OTA ranged from trace (<LOQ) to 11.9 µg/kg. About 20 to 140% of OTA passed through the beverages. Recoveries of over 100% of OTA in beverages were due to three types of interferences: (i) formation of open-ring OTA (OP-OA) during alkaline extraction, (ii) isomerization of OTA during roasting, and (iii) presence of the nonchlorinated analogue OTB. The first two types of interference generate OTA derivatives that are not recognized by OTA antibodies, while OTB cross-reacts with OTA-antibodies. These analytical problems will seriously impact the amount of OTA detected, especially at the levels close to the limits from the EU legislation. Underestimation of OTA could be highly dangerous for health.

Fungi and mycotoxins in feed intended for sows at different reproductive stages in Argentina

The aim of this study was to evaluate fungi and contamination levels of aflatoxin B₁, ochratoxin A, fumonisin B₁, and zearalenone in raw materials and finished feed intended for sows at different reproductive stages. Total fungi, Aspergillus, Penicillium, and Fusarium species occurrence, were examined. Aspergillus flavus, A. niger aggregate spp., and F. verticillioides were the prevalent species. Fungal counts exceeded the levels proposed as feed hygienic quality limits (1 × 10⁴ colony forming units) at all reproductive stages. Aflatoxin B₁, ochratoxin A, fumonisin B₁, and zearalenone were detected by high-pressure liquid chromatography. Aflatoxin levels in 80% samples of finished sow feeds were over the permitted levels of 0.02 μg g⁻¹ (mean 228.2 ± 95 μg Kg⁻¹). Fumonisin B₁ was detected in all tested raw materials at levels that varied from 50.3 to 1137.64 μg Kg⁻¹ and finished feed samples at levels that ranged from 99.8 to 512.4 μg Kg⁻¹. Aflatoxin B₁, zearalenone, and ochratoxin A were not detected in raw materials. All finished feeds were negative for zearalenone contamination whereas all nonpregnant gilt samples were contaminated with low OTA levels (mean 0.259 ± 0.123). This fact requires periodic monitoring to prevent the occurrence of mycotoxicosis in animal production, to reduce the economic losses, and to minimize hazards to human health.

Occurrence of black aspergilli and ochratoxin A on grapes in Italy

Ochratoxin A (OTA) in wine is linked to contamination by several Aspergillus species. In 2003–2007, grape samples collected in Italy were surveyed for the presence of OTA and OTA-producing fungi. A. niger aggregate was the prevalent species. A. carbonarius, which is considered the main source of OTA in grapes, was mostly found in Southern Italy. The year and the environment had an important influence on the development of the black Aspergillus populations. Testing with ELISA showed OTA to be present in about 30% of the samples. Samples from Southern Italy showed the highest occurrence (45%) and also the highest OTA concentration, sometimes higher than 2 μg/L. The values decreased progressively the further North the samples were taken.

Ochratoxin a: general overview and actual molecular status

Ochratoxin A (OTA) is a mycotoxin produced by several species of Aspergillus and Penicillium fungi that structurally consists of a para-chlorophenolic group containing a dihydroisocoumarin moiety that is amide-linked to L-phenylalanine. OTA is detected worldwide in various food and feed sources. Studies show that this molecule can have several toxicological effects such as nephrotoxic, hepatotoxic, neurotoxic, teratogenic and immunotoxic. A role in the etiology of Balkan endemic nephropathy and its association to urinary tract tumors has been also proved. In this review, we will explore the general aspect of OTA: physico-chemical properties, toxicological profile, OTA producing fungi, contaminated food, regulation, legislation and analytical methods. Due to lack of sufficient information related to the molecular background, this paper will discuss in detail the recent advances in molecular biology of OTA biosynthesis, based on information and on new data about identification and characterization of ochratoxin biosynthetic genes in both Penicillium and Aspergillus species. This review will also cover the development of the molecular methods for the detection and quantification of OTA producing fungi in various foodstuffs.

Ochratoxin A and β2-microglobulin in BEN patients and controls

Ochratoxin A (OTA) is a mycotoxin naturally occurring in different foods. OTA is arguably a risk factor for Balkan endemic nephropathy (BEN). The aims of this study are to (1) test the OTA-BEN association in BEN-groups and controls and (2) determine whether urine β2-microglobulin, a marker of impaired ability of the kidneys to re-absorb, is related to OTA. BEN patients had significantly higher OTA serum levels. Within the offspring, OTA was significantly related to higher β2-microglobulin excretion. OTA (2005/2006) was related to a higher incidence of BEN after 2008, providing further evidence that OTA is a risk factor for BEN.

Predicting Growth–No Growth of Listeria monocytogenes on Vacuum-Packaged Ready-to-Eat Meats

Compliance with U.S. Department of Agriculture (USDA) composition-based labeling standards often has been regarded as evidence of the shelf stability of ready-to-eat (RTE) meats. However, the USDA now requires further proof of shelf stability. Our previous work included development of equations for predicting the probability of Staphylococcus aureus growth based on the pH and aw of an RTE product. In the present study, we evaluated the growth–no-growth during 21°C storage of Listeria monocytogenes on 39 vacuum-packaged commercial RTE meat products with a wide range of pH (4.6 to 6.5), aw (0.47 to 0.98), and percent water-phase salt (%WPS; 2.9 to 34.0). Pieces of each product were inoculated with a five-strain cocktail of L. monocytogenes and vacuum packaged, and L. monocytogenes levels were determined immediately after inoculation and after storage at 21°C for up to 5 weeks. L. monocytogenes grew on 13 of 14 products labeled “keep refrigerated” but not on any of the 25 products sold as shelf stable. Using bias reduction logistic regression data analysis, the probability of L. monocytogenes growth (Pr) could be predicted as a function of pH and aw:Pr = exp[−59.58 + (4.67 × pH) + (35.05 × aw)]/{1 + exp[−59.58 + (4.67 × pH) + (35.05 × aw)]}. Pr also could be predicted as a function of pH and %WPS: Pr = exp[−20.52 + (4.10 × pH) − (0.51 × %WPS)]/{1 + exp[−20.52 + (4.10 × pH) − (0.51 × %WPS)]}. The equations accurately predicted L. monocytogenes growth (Pr values of 0.68 to 0.99) or no growth (Pr values of &lt;0.01 to 0.26) and with our equations for predicting S. aureus growth will be useful for evaluating RTE meat shelf stability.

Effect of temperature and water activity on growth and ochratoxin A production boundaries of two Aspergillus carbonarius isolates on a simulated grape juice medium

AIMS

To develop and validate a logistic regression model to predict the growth and ochratoxin A (OTA) production boundaries of two Aspergillus carbonarius isolates on a synthetic grape juice medium as a function of temperature and water activity (a(w)).

METHODS AND RESULTS

A full factorial design was followed between the factors considered. The a(w) levels assayed were 0.850, 0.880, 0.900, 0.920, 0.940, 0.960, 0.980 and the incubation temperatures were 10, 15, 20, 25, 30, 35 and 40 degrees C. Growth and OTA production responses were evaluated for a period of 25 days. Regarding growth boundaries, the degree of agreement between predictions and observations was >99% concordant for both isolates. The erroneously predicted growth cases were 3.4-4.1% false-positives and 0.7-1.4% false-negatives. No growth was observed at 10 degrees C and 40 degrees C for all a(w) levels assayed, with the exception of 0.980 a(w)/40 degrees C, where weak growth was observed. Similarly, OTA production was correctly predicted with a concordance rate >98% for the two isolates with 0.7-1.4% accounting for false-positives and 2.0-2.7% false-negatives. No OTA production was detected at 10 degrees C or 40 degrees C regardless of a(w), and at 0.850 a(w) at all incubation temperatures. With respect to time, the OTA production boundary shifted to lower temperatures (15-20 degrees C) as opposed to the growth boundary that shifted to higher temperature levels (25-30 degrees C). Using two literature datasets for growth and OTA production of A. carbonarius on the same growth medium, the logistic model gave one false-positive and three false-negative predictions out of 68 growth cases and 13 false-positive predictions out of 45 OTA production cases.

CONCLUSIONS

The results of this study suggest that the logistic regression model can be successfully used to predict growth and OTA production interfaces for A. carbonarius in relation to temperature and a(w).

SIGNIFICANCE AND IMPACT OF THE STUDY

The proposed modelling approach helps the understanding of fungal-food ecosystem relations and it could be employed in risk analysis implementation plans to predict the risk of contamination of grapes and grape products by A. carbonarius.

Ochratoxin A production by Aspergillus westerdijkiae in orange fruit and juice

To evaluate the incidence of fungi producing ochratoxin A in orange fruit and juice a survey was carried out by challenge test with ochratoxin A producing strains of Aspergillus westerdijkiae used as the model system. A. westerdijkiae grew into experimental lesions caused on orange surfaces, in orange natural medium and in orange juice and produced OTA in all environments. The higher temperature of 26 degrees C had a greater influence than temperatures of 20 degrees C and 4 degrees C on the growth of the mould, and OTA production. The environmental temperature of 20 degrees C, slows down but does not prevent toxin production. At the lowest temperature of 4 degrees C no growth was observed.

Influence of Lobesia botrana field control on black aspergilli rot and ochratoxin A contamination in grapes

The grape berry moth Lobesia botrana is a key pest in vineyards in southern Europe. Damage caused by L. botrana larvae may encourage growth of black aspergilli, leading to ochratoxin A (OTA) accumulation in grapes. Field trials were conducted during three grape growing seasons (2005 through 2007) in Apulia, Italy, to evaluate an insecticide control strategy for L. botrana in the vineyard as an indirect method of reducing OTA contamination by reducing black aspergilli on the grapes. In the 2005 field trials, the insecticide treatment controlled attacks by L. botrana larvae and reduced OTA concentrations by up to 66% in the must samples of Negroamaro and Primitivo grape varieties. Significant differences (P < or = 0.05) also were observed in the incidence of black aspergilli. Environmental conditions in 2006 and 2007 resulted in a natural low level of infestation by L. botrana, low levels of OTA in both treated and untreated samples, and no significant differences between treated and nontreated samples. The results of our field study confirm previous reports that L. botrana is an important risk factor for OTA accumulation and are consistent with the hypothesis that controlling L. botrana in vineyards reduces OTA concentrations in grapes.

Study of the phenotypic and genotypic biodiversity of potentially ochratoxigenic black aspergilli isolated from grapes

Ochratoxin A (OTA) is a mycotoxin with nephrotoxic, carcinogenic, teratogenic and immunotoxic effects, naturally found in agricultural products including grapes and wine. Black Aspergillus species (Section Nigri) are mainly responsible for OTA accumulation in wine grapes and in particular Aspergillus carbonarius and Aspergillus niger aggregate. The biodiversity of potentially ochratoxigenic strains of black aspergilli from different French vineyards in the southern Mediterranean region of Languedoc-Roussillon was studied. One hundred and eighty nine black strains were isolated from grapes and studied according to harvest year, production zone, grape variety and pre-harvest treatment of grapevines. The strains were identified and classified in two groups according to macroscopic and microscopic characters; these were called the A. carbonarius representative group and the A. niger aggregate representative group. Members of each group were classified in subgroups based on macroscopic morphological colony characters. Strain biodiversity was studied according to phenotypic and genotypic characterization and to the OTA production of selected strains on PDA medium. After identification was confirmed by specific PCR using primer pair ITS1/CAR and ITS1/NIG, 24 potential ochratoxigenic strains belonging to A. carbonarius and A. niger aggregate were discriminated by RAPD-PCR using 8 different OPC primers. The use of specific primers supported the identification based on phenotypic and morphological characters. RAPD-PCR patterns demonstrated a considerable diversity among the strains. Clustering among A. niger aggregate strains was associated with production zone and harvest year, but not grape variety or pre-harvest treatment. Clustering among A. carbonarius strains was not associated with any of the above parameters. OTA production of strains on culture medium seemed to correlate better with morphological characters than with genotypic profiles. No clear relation could be established between phenotypic and genotypic characters of the studied black aspergilli.

Predicting growth-no growth of Staphylococcus aureus on vacuum-packaged ready-to-eat meats

U.S. Department of Agriculture (USDA) composition-based labeling standards for various ready-to-eat (RTE) meat products typically specify maximum product pH and/or moisture:protein ratio and less often maximum water activity (a(w)). Compliance with these standards often has been regarded as proof of shelf stability. However, the USDA now requires additional proof, e.g., challenge study results, of shelf stability. The pathogen most likely to grow on vacuum-packaged, reduced-moisture products is Staphylococcus aureus. Therefore, vacuum-packaged RTE products that do not support S. aureus growth at room temperature could be considered shelf stable. We developed mathematical equations for predicting whether S. aureus would grow under such conditions. Twenty-four commercial RTE meat products and 10 intentionally misprocessed products (insufficient drying, fermentation, and/or salt) were inoculated with a five-strain cocktail of S. aureus, vacuum packaged, and stored at 21 degrees C. Initial, 7-day, and 28-day S. aureus counts were recorded. Product pH, a(w), moisture:protein ratio, and percentage of water-phase salt (%WPS) also were determined. S. aureus grew only in the intentionally misprocessed products and in some commercial products labeled "keep refrigerated." Using bias reduction logistic regression data analysis, the probability of S. aureus growth (Pr) could be predicted by either of two equations. The first was based on pH and a(w) values: Pr = exp[-59.36 + (5.75 x pH) + (28.73 x a(w))]/{1 + [exp(-59.36 + (5.75 x pH) + (28.73 x a(w))]}. The second was based on pH and %WPS: Pr = exp[-26.93 + (5.38 x pH) + (-0.61 x %WPS)]/{1 + exp[-26.93 + (5.38 x pH) + (-0.61 x %WPS)]}. These equations accounted for observed S. aureus growth-no growth results and will be a useful tool for evaluating the shelf stability of RTE meats.

Mycoflora of maize harvested from Iran and imported maize

The natural occurrence of fungal contamination was evaluated in stored maize in three different agro-ecological zones (Iran, Brazil and China). A total of 45 samples were analyzed and 685 fungal isolates were identified. The most frequent isolated fungi from maize originated from Iran, Brazil and China were Fusarium sp. (17.3, 17.9 and 37.1%), Aspergillus sp. (9.3, 17.4 and 19.7%),Penicillium sp. (5.8, 15.2 and 17.6%), Rhizopus sp. (2.4, 3.2 and 3.5%), Mucor sp. (1.1, 1.6 and 1.3%), Cladosporium sp. (1.6, 1.9 and 1.9%), Alternaria sp. (1.1, 1.6 and 1.3%), Geotrichum sp. (0, 0 and 0.3%), Acromonium sp. (0.5, 0.8 and 0%) and Absidia sp. (0, 0.8 and 0.5%), respectively. Significant difference was observed between the frequency of fungal isolates of Iranian maize and foreign products (p < 0.0005). Maize mycoflora profiles showed that Fusarium verticillioides and Aspergillus flavus prevailed in 30.7 and 13.3% of the samples from China, in 12 and 5.3% of the samples from Iran and 11.7 and 11.5% of the samples from Brazil, respectively. There were significant differences in the frequency of Fusarium verticillioides in Chinese maize with other countries products (p < 0.0005) and that of Aspergillus flavus in Iranian maize with other countries (p < 0.002). The results emphasize that farmers and consumers should be alerted to the danger of fungal contamination in maize.

Mycological survey and ochratoxin A natural contamination of swine feedstuffs in Rio de Janeiro State, Brazil

Mycotoxin contamination of animal feeds represents a hazard to human and animal health due to potential transmission to meat and milk. Barley by-products are alternative feeding supplies for animal production. The aims of this assay were to study the mycobiota of feedstuffs and finished swine feed, to determine the ability of Aspergillus and Penicillium isolates to produce ochratoxin A (OTA) and to evaluate OTA occurrence in these substrates. Corn, brewers' grains and finished swine feed samples were collected from different factories. Fungal counts were higher than 2.8x10(4)CFU g(-1). Fusarium, Aspergillus and Penicillium genera were isolated at high levels. A 23.7% of the isolates produced 9-116 microg kg(-1) of OTA in vitro. Corn samples (44%) were contaminated with 42-224 microg kg(-1) of OTA. Finished feed (31%) and brewers' grains samples (13%) were contaminated with 36-120 microg kg(-1) and 28-139 microg kg(-1) of OTA, respectively. This is the first scientific report on contamination by OTA-producer molds and OTA in swine feedstuffs from Brazil. The presence of OTA in raw materials and finished feed requires periodic monitoring to prevent mycotoxicoses in animal production, reduce economic losses and minimize hazards to human health.