Mycoflora and mycotoxin of hazelnut (Corylus avellana L.) and walnut (Juglans regia L.) seeds in Egypt

Azole resistance mechanisms and population structure of the human pathogen Aspergillus fumigatus on retail plant products

Aspergillus fumigatus is a ubiquitous saprotroph and human-pathogenic fungus that is life-threatening to the immunocompromised. Triazole-resistant A. fumigatus was found in patients without prior treatment with azoles, leading researchers to conclude that resistance had developed in agricultural environments where azoles are used against plant pathogens. Previous studies have documented azole-resistant A. fumigatus across agricultural environments, but few have looked at retail plant products. Our objectives were to determine if azole-resistant A. fumigatus is prevalent in retail plant products produced in the United States (U.S.), as well as to identify the resistance mechanism(s) and population genetic structure of these isolates. Five hundred twenty-five isolates were collected from retail plant products and screened for azole resistance. Twenty-four isolates collected from compost, soil, flower bulbs, and raw peanuts were pan-azole resistant. These isolates had the TR34/L98H, TR46/Y121F/T289A, G448S, and H147Y cyp51A alleles, all known to underly pan-azole resistance, as well as WT alleles, suggesting that non-cyp51A mechanisms contribute to pan-azole resistance in these isolates. Minimum spanning networks showed two lineages containing isolates with TR alleles or the F46Y/M172V/E427K allele, and discriminant analysis of principle components identified three primary clusters. This is consistent with previous studies detecting three clades of A. fumigatus and identifying pan-azole-resistant isolates with TR alleles in a single clade. We found pan-azole resistance in U.S. retail plant products, particularly compost and flower bulbs, which indicates a risk of exposure to these products for susceptible populations and that highly resistant isolates are likely distributed worldwide on these products.IMPORTANCEAspergillus fumigatus has recently been designated as a critical fungal pathogen by the World Health Organization. It is most deadly to people with compromised immune systems, and with the emergence of antifungal resistance to multiple azole drugs, this disease carries a nearly 100% fatality rate without treatment or if isolates are resistant to the drugs used to treat the disease. It is important to determine the relatedness and origins of resistant A. fumigatus isolates in the environment, including plant-based retail products, so that factors promoting the development and propagation of resistant isolates can be identified.

Mycotoxin Contamination in Hazelnut: Current Status, Analytical Strategies, and Future Prospects

Hazelnuts represent a potential source of mycotoxins that pose a public health issue due to their increasing consumption as food ingredients worldwide. Hazelnuts contamination by mycotoxins may derive from fungal infections occurring during fruit development, or in postharvest. The present review considers the available data on mycotoxins detected in hazelnuts, on fungal species reported as infecting hazelnut fruit, and general analytical approaches adopted for mycotoxin investigation. Prompted by the European safety regulation concerning hazelnuts, many analytical methods have focused on the determination of levels of aflatoxin B1 (AFB1) and total aflatoxins. An overview of the available data shows that a multiplicity of fungal species and further mycotoxins have been detected in hazelnuts, including anthraquinones, cyclodepsipeptides, ochratoxins, sterigmatocystins, trichothecenes, and more. Hence, the importance is highlighted in developing suitable methods for the concurrent detection of a broad spectrum of these mycotoxins. Moreover, control strategies to be employed before and after harvest in the aim of controlling the fungal contamination, and in reducing or inactivating mycotoxins in hazelnuts, are discussed.

Effect of biological treatment used before harvesting and storage methods on the quality, health and microbial characteristics of unripe hazelnut in the husk (Corylus avellana L.)

BACKGROUND

The hazelnut (Corylus avellana) is still one of the most profitable nut crop species. In recent years, however, there has been growing interest in this species in the form of "fresh nuts" that are picked before falling out of the fruit cover. The aim of this study was to evaluate the effect of storage conditions for hazelnuts protected with biological preparations on selected morphological features of the fruits, their health status and the count of bacteria and fungi colonizing the fruits.

RESULTS

The hazelnuts harvested from the trees protected with a preparation containing Pythium oligandrum and stored for 2 months under the controlled atmosphere conditions and in Xtend® bags (MAP) had the greatest weight and the highest percentage of the kernel. After 3 months of storage, the hazelnuts had reduced commercial value. Only a few hazelnuts displayed symptoms of infectious diseases caused by species of Botrytis and Monilia. The protection applied before the hazelnut harvesting contributed to a multiple increase in the bacterial and yeasts count on the husks and shells of the hazelnuts stored for 3 months. The bacterial count on the nuts stored under the controlled atmosphere (CA, 3%O₂:3%CO₂, a temperature of 0-1 °C, humidity of 85-95%) and under the controlled atmosphere conditions and in Xtend® bags (MAP) increased significantly. An analysis of the ITS region sequence revealed the presence of bacteria Arthrobacter luteolus and Pantoea agglomerans. A Koch test proved that both non-pathogenic bacteria and pathogenic fungi can cause the browning of the C. avellana leaf under conditions of high humidity. The application of a controlled atmosphere is recommended for a short-term storage of hazelnuts in the husk.

CONCLUSION

This research showed that 2 months' storage of hazelnuts under controlled atmosphere conditions and Xtend® bags (MAP) prevented a reduction in the weight of hazelnuts in the husk, without the husk, and of the kernel and prevented the nut separation from the husk. In general, the application of biopreparations for the protection of the hazelnut had a positive effect on the kernel weight and size.

Azole-resistant Aspergillus fumigatus in the environment: Identifying key reservoirs and hotspots of antifungal resistance

Aspergillus fumigatus is an opportunistic human pathogen that causes aspergillosis, a spectrum of environmentally acquired respiratory illnesses. It has a cosmopolitan distribution and exists in the environment as a saprotroph on decaying plant matter. Azoles, which target Cyp51A in the ergosterol synthesis pathway, are the primary class of drugs used to treat aspergillosis. Azoles are also used to combat plant pathogenic fungi. Recently, an increasing number of azole-naive patients have presented with pan-azole-resistant strains of A. fumigatus. The TR34/L98H and TR46/Y121F/T289A alleles in the cyp51A gene are the most common ones conferring pan-azole resistance. There is evidence that these mutations arose in agricultural settings; therefore, numerous studies have been conducted to identify azole resistance in environmental A. fumigatus and to determine where resistance is developing in the environment. Here, we summarize the global occurrence of azole-resistant A. fumigatus in the environment based on available literature. Additionally, we have created an interactive world map showing where resistant isolates have been detected and include information on the specific alleles identified, environmental settings, and azole fungicide use. Azole-resistant A. fumigatus has been found on every continent, except for Antarctica, with the highest number of reports from Europe. Developed environments, specifically hospitals and gardens, were the most common settings where azole-resistant A. fumigatus was detected, followed by soils sampled from agricultural settings. The TR34/L98H resistance allele was the most common in all regions except South America where the TR46/Y121F/T289A allele was the most common. A major consideration in interpreting this survey of the literature is sampling bias; regions and environments that have been extensively sampled are more likely to show greater azole resistance even though resistance could be more prevalent in areas that are under-sampled or not sampled at all. Increased surveillance to pinpoint reservoirs, as well as antifungal stewardship, is needed to preserve this class of antifungals for crop protection and human health.

The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans

Human activities have significantly impacted the environment and are changing our climate in ways that will have major consequences for ourselves, and endanger animal, plant and microbial life on Earth. Rising global temperatures and pollution have been highlighted as potential drivers for increases in infectious diseases. Although infrequently highlighted, fungi are amongst the leading causes of infectious disease mortality, resulting in more than 1.5 million deaths every year. In this review we evaluate the evidence linking anthropomorphic impacts with changing epidemiology of fungal disease. We highlight how the geographic footprint of endemic mycosis has expanded, how populations susceptible to fungal infection and fungal allergy may increase and how climate change may select for pathogenic traits and indirectly contribute to the emergence of drug resistance.

HPLC-MS/MS Method for the Detection of Selected Toxic Metabolites Produced by Penicillium spp. in Nuts

Penicillium spp. are emerging as producers of mycotoxins and other toxic metabolites in nuts. A HPLC-MS/MS method was developed to detect 19 metabolites produced by Penicillium spp. on chestnuts, hazelnuts, walnuts and almonds. Two extraction methods were developed, one for chestnuts and one for the other three nuts. The recovery, LOD, LOQ and matrix effect were determined for each analyte and matrix. Correlation coefficients were always >99.99%. In walnuts, a strong signal suppression was observed for most analytes and patulin could not be detected. Six strains: Penicillium bialowiezense, P. brevicompactum, P. crustosum, P. expansum, P. glabrum and P. solitum, isolated from chestnuts, were inoculated on four nuts. Chestnuts favored the production of the largest number of Penicillium toxic metabolites. The method was used for the analysis of 41 commercial samples: 71% showed to be contaminated by Penicillium-toxins. Cyclopenin and cyclopenol were the most frequently detected metabolites, with an incidence of 32% and 68%, respectively. Due to the risk of contamination of nuts with Penicillium-toxins, future studies and legislation should consider a larger number of mycotoxins.

Fungi Associated with and Influence of Moisture on Development of Kernel Mold of Hazelnut

Kernel mold on hazelnuts is defined by the United States Department of Agriculture, U.S.A., as any visible fungal growth either on the outside or inside of the kernel. Only one yeast and one filamentous fungus have been associated with kernel mold of hazelnut in Oregon. In this report, fungi were isolated from kernels with mold and identified using morphological and molecular characters. Penicillium spp. were isolated most often from kernels with mold, but species of Aspergillus and Cladosporium and Diaporthe rudis were also frequently isolated. Additional fungi from three other genera were also isolated. All of the same fungi were also isolated from symptomless kernels. Eremothecium coryli or Ramularia sp. previously associated with kernel defects in Oregon were not found associated with symptoms of kernel mold. Incidence of mold was the highest when nuts were incubated in moist chambers on wet, nonautoclaved orchard soil and was significantly higher than kernel mold found in nuts incubated on either air-dried soil or wet, autoclaved soil. Preventing hazelnuts from coming in contact with wet soil in the field using elevated wire screens resulted in significantly less mold development in two out of three years evaluated. Nuts on screens had a greater chance to dry out between rainstorms as measured by significantly lower nut moisture levels at harvest.

Microbiological Quality and Risk Assessment for Aflatoxins in Groundnuts and Roasted Cashew Nuts Meant for Human Consumption

Nuts are one of the commonly consumed snacks but poor handling and storage practices can make them prone to foodborne infections. The study aimed at assessing the microbiological quality and risk assessment for aflatoxins in groundnuts and cashew nuts consumed in selected locations in Nigeria. The moisture content, colony counts, incidence of pathogenic bacteria, aflatoxin contamination, and risk assessment for aflatoxins were evaluated using standard methods. The moisture content and total viable count ranged from 5.00–8.60% and 5.5–89 × 10³ cfug⁻¹, respectively, while the fungal count was between 4–24 × 10³ and 1.0–4.5 × 10² cfug⁻¹, respectively. Eleven fungal species belonging to 5 genera were isolated from the nuts, with Aspergillus flavus, Rhizopus oryzae, and Fusarium oxysporum having the highest percentage occurrence of 50%. In addition, the aflatoxin concentration ranged 0.1–6.8 and 29–33.78 ng kg⁻¹ for cashew nuts and groundnuts, respectively. The margin of exposure (MOE) to aflatoxin contamination was 6.10 for groundnuts and 1000 for cashew nuts and the nuts consumers were at a risk of exposure to foodborne diseases and aflatoxin contamination with mean exposure values of 27.96 and 0.17 ng kg⁻¹bwday⁻¹, respectively. The risk of primary liver cancer for groundnuts and cashew nuts consumers was also estimated to be 1.38 and 0.01 canceryear⁻¹100,000⁻¹person, respectively. This calls for mitigation measures from appropriate governmental organizations.

Thermophilic Fungi to Dominate Aflatoxigenic/Mycotoxigenic Fungi on Food under Global Warming

Certain filamentous fungi produce mycotoxins that contaminate food. Mycotoxin contamination of crops is highly influenced by environmental conditions and is already affected by global warming, where there is a succession of mycotoxigenic fungi towards those that have higher optimal growth temperatures. Aflatoxigenic fungi are at the highest limit of temperature although predicted increases in temperature are beyond that constraint. The present paper discusses what will succeed these fungi and represents the first such consideration. Aflatoxins are the most important mycotoxins and are common in tropical produce, much of which is exported to temperate regions. Hot countries may produce safer food under climate change because aflatoxigenic fungi will be inhibited. The same situation will occur in previously temperate regions where these fungi have recently appeared, although decades later. Existing thermotolerant and thermophilic fungi (TTF) will dominate, in contrast to the conventional mycotoxigenic fungi adapting or mutating, as it will be quicker. TTF produce a range of secondary metabolites, or potential mycotoxins and patulin which may become a new threat. In addition, Aspergillus fumigatus will appear more frequently, a serious human pathogen, because it is (a) thermotolerant and (b) present on crops: hence this is an even greater problem. An incubation temperature of 41 °C needs employing forthwith to detect TTF. Finally, TTF in crops requires study because of the potential for diseases in humans and animals under climate change.

Final Report on the Safety Assessment of Corylus Avellana (Hazel) Seed Oil, Corylus Americana (Hazel) Seed Oil, Corylus Avellana (Hazel) Seed Extract, Corylus Americana (Hazel) Seed Extract, Corylus Rostrata (Hazel) Seed Extract, Corylus Avellana (Hazel) Leaf Extract, Corylus Americana (Hazel) Leaf Extract, and Corylus Rostrata (Hazel) Leaf Extract

These ingredients are all derived from hazelnut trees. The two seed oils are expressed from the nuts of the hazelnut tree of the particular species identified. Most current reported cosmetic uses are of the seed oils. The seed extracts are the extract of the nuts of the identified species tree. There is one current report of use of seed extract in cosmetics. The leaf extracts are the extract from the leaves of the particular species tree. There are no current reports of use of these extracts in cosmetics. Analysis of seed oil from one species identified Oleic Acid, Palmitoleic Acid, Linoleic Acid, Eicosaenoic Acid, Docosenoic Acid, Eicosanoic Acid, Palmitic Acid, Linolenic Acid, Stearic Acid, and Tetraeicosanoic Acid. Little information is available to characterize the extracts, however. The functions of most of these ingredients in cosmetics are not reported. In studies of hazelnuts from Spain and Egypt, aflatoxin was reported as a possible contaminant. Aflatoxins are considered carcinogenic in humans. Virtually no safety test data are available on these ingredients. Negative results in one comedogenicity study using a seed oil are reported. Cross-sensitivity to proteins in peanuts and those in hazelnuts are reported, but the presence or absence of protein in nut extract and plant extract from hazelnut trees is not known. Additional data were provided regarding concentration of use, method of extraction and contaminants, comedogenicity, and ultraviolet (UV) radiation absorption, but these data related to nut oil from only one species, and were not overall sufficient to resolve questions about irritation, sensitization, and photosensitization. Because of the absence of data, it is concluded that the available data are insufficient to support the safety of these ingredients in cosmetic products. Because of the limited information that characterizes any of these oils or extracts, data are needed on each (except that items 1, 2, and 3 below are not needed for Hazel [Corylus Avellana] Nut Oil). The additonal data needs include: (1) current concentration of use; (2) method of extraction/manufacture and quality control (i.e., chemical analyses); (3) contaminants and methods of extraction (especially pesticides and heavy metals); (4) dermal irritation and sensitization; (5) UV absorption; if there is significant absorption, then a photosensitization study will be needed; (6) 28-day dermal toxicity; (7) reproductive and developmental toxicity; and (8) two genotoxicity assays, one in a mammalian system; if positive, then a 2-year dermal carcinogenesis study using National Toxicology Program (NTP) methods may be needed.

Fungal Presence in Selected Tree Nuts and Dried Fruits

Sixty-four tree nut samples (almonds, pecans, pine nuts, and walnuts) and 50 dried fruit samples (apricots, cranberries, papaya, pineapple, and raisins) were purchased from local supermarkets and analyzed for fungal contamination using conventional culture as well as molecular methods. The results of our study showed that the highest yeast and mold (YM) counts (5.34 log₁₀ CFU g⁻¹) were found in walnuts and the lowest in pecans. The most common mold in nuts was Aspergillus niger, relatively low numbers of A. flavus were found across the board, while Penicillium spp. were very common in pine nuts and walnuts. Low levels (2.00–2.84 log₁₀ CFU g⁻¹) of yeasts were recovered from only two pine nut samples. Fungal contamination in dried fruits was minimal (ranging from <2.00 to 3.86 log₁₀ CFU g⁻¹). The highest fungal levels were present in raisins. All papaya samples and the majority of cranberry, pineapple, and apricot samples were free of live fungi. The most common mold in dried fruits was A. niger followed by Penicillium spp. One apricot sample also contained low levels (2.00 log₁₀ CFU g⁻¹) of yeasts.

Efficacy of Angelica archangelica essential oil, phenyl ethyl alcohol and α- terpineol against isolated molds from walnut and their antiaflatoxigenic and antioxidant activity

Mold association, aflatoxin B1 contamination as well as oxidative deterioration of agri-food items during storage and processing are some global task for food industries. In view of the adverse effects of some synthetic preservatives on treated food items and subsequently on consumers health, recently plant based chemicals are encouraged by food industries as better alternatives of synthetics. The present study recommends the combination (1:1:1) of Angelica archangelica essential oil: Phenyl ethyl alcohol (PEA): α- terpineol as botanical preservative against molds, aflatoxin contamination and oxidative deterioration of walnut samples. Eight mold species were procured from stored walnut samples, including some aflatoxigenic Aspergillus flavus strains. The combination inhibited growth of aflatoxigenic strain Aspergillus flavus NKDW-7 and aflatoxin B1 production at 2.25 and 2.0 μL mL(-1) respectively. The IC50 value of the combination was recorded as 3.89 μL mL(-1), showing strong antioxidant potential. The antifungal action of the combination showed > 90 % decrease in ergosterol content in plasma membrane of A. flavus at 2.0 μL mL(-1). The LD50 of the combination, through oral administration on mice, was 9562.9 μL kg(-1) body weight, indication favourable safety profile as a plant based preservative. The combination may be recommended as safe preservative against molds, aflatoxin contamination and oxidative deterioration of walnut samples.

First report of mycophenolic acid production by Eurotium repens isolated from agricultural and indoor environments

Mycophenolic acid is considered as an immunosuppressive pharmaceutical drug, but also as a mycotoxin due to its undesirable presence in various feedstuffs. Although Penicillium brevicompactum has been historically identified as the major producer of mycophenolic acid, this study reports for the first time the production of mycophenolic acid by isolates of Eurotium repens collected from agricultural and indoor environments. Fungal identification was achieved by scanning electron microscopy and molecular techniques, and mycophenolic acid production was confirmed by two analytical methods (gas and liquid chromatography coupled to mass spectrometry). These findings suggest that mycophenolic acid production and immunosuppressive properties of other closely related Eurotium should be evaluated in future studies.

Incidence of mycoflora and mycotoxins in some edible fruits and seeds of forest origin

Twelve fungi namelyAlternaria alternata, Aspergillus flavus, A niger, A ochraceus, Actinomucor repens, Capnodoium spp., Curvularia lunata, Fusarium pallidoroseum, F solani, F verticillioides, Penicillium citrinum and Rhizopus stolonifer were recorded from samples ofAegle marmelos, Aesculus indica, Buchanania lanzan andPinus gerardiana. In case ofPrunus amygdalus only Rstolonifer was recorded. A significant variation in pattern of mycoflora incidence was observed in terms of source and season. Fungal infestation in most of the substrates was found to be highest during monsoon. Aflatoxins were the most common mycotoxins elaborated by different isolates ofA flavus obtained fromA marmelos, B lanzan andP gerardiana. The amount of aflatoxins produced by the toxigenic isolates ofA flavus was in the range of traces to 0.9-26.0 μg/ml inA marmelos, 0.8-17.5 μg/ml inP gerardiana and 0.65-13.2 μg/ml inB lanzan. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi. Aflatoxins were detected almost in all the samples analyzed for mycotoxin contamination. However, traces of zearalenone were detected inA marmelos. The concentration of aflatoxin B1 was in the range of 0.13-0.75 μg/g inA marmelos, 0.09-0.60 μg/g inP gerardiana and 0.01-0.20 ug/g inB lanzan. Mycotoxins were not detected inAesculus indica andPrunus amygdalus.

Identification of cyclopropyl fatty acids in walnut (Juglans regia L.) oil

AIM

Identification of cyclopropyl fatty acids in walnut oil.

METHOD

GC/MS method was developed for the determination of eight cyclopropyl fatty acids in walnut (Juglans regia) oil.

RESULTS

Monocyclopropane acids: methyl 9-cyclopropyl-nonanoate, 6,7-methylene-, 8,9-methylene-, 9,10-methylene-, 11,12-methylene octadecanoates, and dicyclic acid - methyl 9,10,12,13-dimethylene octadecanoate, tricyclic acid - methyl 9,10,12,13,15,16-trimethylene octadecanoate, and unsaturated - methyl 2-octylcyclopropene-1-octanoate were detected in walnut oil by GC-MS and their mass spectra studied. Four cyclic fatty acids were identified for the fist time in seed oils.

CONCLUSIONS

Eight cyclopropyl fatty acids were detected in the Mediterranean nuts for the first time.

Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: An oestrogenic mycotoxin

Zearalenone (ZEA) is a mycotoxin produced mainly by fungi belonging to the genus Fusarium in foods and feeds. It is frequently implicated in reproductive disorders of farm animals and occasionally in hyperoestrogenic syndromes in humans. There is evidence that ZEA and its metabolites possess oestrogenic activity in pigs, cattle and sheep. However, ZEA is of a relatively low acute toxicity after oral or interperitoneal administration in mice, rat and pig. The biotransformation for ZEA in animals involves the formation of two metabolites alpha-zearalenol (alpha-ZEA) and beta-zearalenol (beta-ZEA) which are subsequently conjugated with glucuronic acid. Moreover, ZEA has also been shown to be hepatotoxic, haematotoxic, immunotoxic and genotoxic. The exact mechanism of ZEA toxicity is not completely established. This paper gives an overview about the acute, subacute and chronic toxicity, reproductive and developmental toxicity, carcinogenicity, genotoxicity and immunotoxicity of ZEA and its metabolites. ZEA is commonly found on several foods and feeds in the temperate regions of Europe, Africa, Asia, America and Oceania. Recent data about the worldwide contamination of foods and feeds by ZEA are considered in this review. Due to economic losses engendered by ZEA and its impact on human and animal health, several strategies for detoxifying contaminated foods and feeds have been described in the literature including physical, chemical and biological process. Dietary intakes of ZEA were reported from few countries from the world. The mean dietary intakes for ZEA have been estimated at 20 ng/kgb.w./day for Canada, Denmark and Norway and at 30 ng/kgb.w./day for the USA. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established a provisional maximum tolerable daily intake (PMTDI) for ZEA of 0.5 microg/kg of body weight.

Human aflatoxicosis in developing countries: a review of toxicology, exposure, potential health consequences, and interventions

Aflatoxins are well recognized as a cause of liver cancer, but they have additional important toxic effects. In farm and laboratory animals, chronic exposure to aflatoxins compromises immunity and interferes with protein metabolism and multiple micronutrients that are critical to health. These effects have not been widely studied in humans, but the available information indicates that at least some of the effects observed in animals also occur in humans. The prevalence and level of human exposure to aflatoxins on a global scale have been reviewed, and the resulting conclusion was that approximately 4.5 billion persons living in developing countries are chronically exposed to largely uncontrolled amounts of the toxin. A limited amount of information shows that, at least in those locations where it has been studied, the existing aflatoxin exposure results in changes in nutrition and immunity. The aflatoxin exposure and the toxic affects of aflatoxins on immunity and nutrition combine to negatively affect health factors (including HIV infection) that account for >40% of the burden of disease in developing countries where a short lifespan is prevalent. Food systems and economics render developed-country approaches to the management of aflatoxins impractical in developing-country settings, but the strategy of using food additives to protect farm animals from the toxin may also provide effective and economical new approaches to protecting human populations.

Deterioration and spoilage of peanuts and desiccated coconuts from two sub-Saharan tropical East African countries due to the associated mycobiota and their degradative enzymes

A broad variety of fungi (84 species belonging to 36 genera) were identified with more taxa infesting peanut seed samples from two tropical countries (29 genera and 61 species) compared to those found in desiccated coconuts (20 genera and 55 species) on both DRBC and DG18 media. This may be due to the higher moisture levels in peanuts (5.07-7.97%) compared with coconuts (1.5-4.17%). More taxa and propagules were recovered on DG18 in both cases. The dominant fungi from both substrates on both isolation media were Aspergillus and Penicillium, with other fungi from only one substrate/medium. The aflatoxigenic species (A. flavus) dominated Kenyan samples more so than Ugandan samples on both substrates. However only 71.5% and 87.5% of the peanut kernels, on DRBC and DG18, respectively, were found to be infested with fungi. The aflatoxigenic species (A. flavus/parasiticus) were found in 75% of the samples, however only 15.75% and 13% of the kernels analyzed were infested. The most frequently isolated species from peanuts were A. niger followed by A. flavus and M. phaseolina. E. repens, E. amstelodami, E. rubrum and E. chevalieri dominated peanut seeds on DG18, and R. stolonifer, A. parasiticus, F. solani, L. theobromae and P. chrysogenum on DRBC. The mean count of fungal propagules in coconut samples were approximately 0.7 x 10(3) and 0.8 x 10(3) on DRBC and DG18, respectively, with a high proportion of those propagules recorded for the aflatoxigenic species (about 0. 17 x 10(3) and 0.25 x 10(3) colonies/g). The mycobiota of desiccated coconut was dominated by A. niger, A. flavus and P. chrysogenum. Also A. ochraceus, P. waksmanii, Paecilomyces variotii, P. islandicum and R. mucilaginosa were more frequent on DRBC, while, species of Cladosporium. Chrysosporium and Eurotium were more frequent on DG18. Enzyme indices (or the activities) for each specific strain, when determined after 5 and 8 days of incubation, proved to be similar. A recommendation is given. The proteolytic and lipolytic potentialities of the most commonly encountered species from both peanuts and coconuts were studied. The most interesting observation is that most of the positive isolates, in both commodities had high enzymic activity compared to those reported earlier for isolates of the same species. Such capabilities suggest that these commodities are expected to deteriorate, since climatic conditions in tropical areas favour fungal proliferation. Emphasis on the proper harvesting, drying, handling, transportation and/or storage; and also education of the populace, especially those are dealing with these foods, should be taken into consideration by the relevant authorities. The contaminated foods constitute a health hazard for human consumption.

Pine nuts: the mycobiota and potential mycotoxins

The mycobiota of pine nuts was investigated. In total, 1832 fungi belonging to 31 species and 15 genera (Ascomycota, 2; Zygomycota, 3; mitosporic fungi, 10) could be isolated. Cladosporium spp. dominated the mycobiota with 685 isolations followed by Phoma macrostoma with 351 isolations. Overall, 16 potentially mycotoxigenic species were present on pine nuts.Key words: pine nuts, mycobiota, potential mycotoxins.

Fungal flora and mycotoxins of six kinds of nut seeds for human consumption in Saudi Arabia

A wide range of moulds representing several genera and species, was recorded in this study from 5 seed samples of each almond, cashew nut, chestnut, hazelnut, pistachio nut and walnut collected from different markets in Ar' Ar, Saudi Arabia. The total counts of fungi were widely fluctuated between 1960-7704 and 1948-7434 colonies/g dry seeds on glucose-Czapek's and glycerol agar media at 28 degrees C, respectively, and represented twenty genera, 53 species and 2 varieties of fungi. The prevalent fungi on the 2 agar media were Aspergillus flavus, A. niger and Penicillium chrysogenum. On glucose-Czapek's agar, Rhizopus stolonifer and Aspergillus flavus var. columnaris were isolated from all 6 kinds of nut, A. parasiticus from 5 kinds and A. fumigatus from 4 kinds with high frequencies. Eurotium species were completely absent on glucose-Czapek's agar but they were isolated in high frequency from all kinds of nut on glycerol agar medium. The different nut samples were analyzed by thin layer chromatography for the presence of aflatoxins B1, B2, G1 & G2, citrinin, ochratoxins, patulin, sterigmatocystin, diacetoxyscirpenol, T-2 toxin and zearalenone. Aflatoxins B1 & G1 were detected in 3 out of the 5 samples tested of chestnut at concentrations ranging between 20 to 60 micrograms/kg. All other samples of almond, cashew nut, hazelnut, pistachio nut, and walnut that were analyzed were mycotoxin free.