Mycoflora and Fusarium toxins of three types of corn grains in Egypt with special reference to production of trichothecene-toxins.

Sixty three species and 2 varieties which belong to 21 genera of fungi were isolated from corn grains (53 + 2, 36 + 1 and 34 species belonging to 19, 13, and 12 genera from white, yellow and popcorn, respectively). Aspergillus (15 species), Penicillium (17) and Fusarium (4) were the dominant genera isolated from the three types of corn. Of four species of Fusarium, F. moniliforme was the dominant species. F. oxysporum and F. solani were detected in all the three substrates, whereas F. subglutinans was isolated exclusively from yellow corn. A biological assay (brine shrimp larvae) and chemical analysis (TLC, UV spectrophotometery and NMR spectroscopy) of chloroform extracts proved that 7 out of 78 samples were toxic. Diacetoxyscirpenol (4 samples, 98.4-128.4 micrograms/kg corn), T-2 toxin (4 samples, 72.8 to 130.4 micrograms/kg) and zearalenone (7 samples, 22.6 to 80.4 micrograms/kg) were detected, whereas 90% methanol-water re-extracts revealed that 3 out of 78 samples were toxic due to presence of fusarin C (1 sample, 76.8 micrograms/kg) in addition to an unidentified toxic factor (3 samples). Of 22 Fusarium isolates (F. moniliforme, F. oxysporum, F. solani and F. subglutinans; 10,5,5 and 2 isolates, respectively grown on corn grains, the chloroform extracts of 6,3,3 and 1 isolates were toxic to brine shrimp larvae. Based on chemical analysis, diacetoxyscirpenol (10/22 isolates; 9.8 - 78.6 micrograms/g dry corn grains), T-2 toxin (5/22; 20.8 - 60.4 micrograms/g), HT-2 toxin (3/22; 12.4 - 18.6 micrograms/g) and zearalenone (13/22; 9.8 - 38.4 micrograms/g) were identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Mycoflora and natural occurrence of mycotoxins in tobacco from cigarettes in Egypt.

Forty-two species and 4 varieties belonging to 21 genera were collected from 40 tobacco samples on glucose- and cellulose-Czapek's agar at 28 degrees C and 45 degrees C. The most common mesophiles (at 28 degrees C) in tobacco on the two types of media were: Aspergillus flavus, A. flavus var. columnaris, A. fumigatus, A. niger, Penicillium chrysogenum and P. funiculosum. Two samples were heavily contaminated with members of Fusarium (F. moniliforme, F. oxysporum, F. solani). Some fungi were encountered only on plates of cellulose agar as Chaetomium globosum, Stachybotrys atra var. microspora and S. chartarum. At 45 degrees C the most prevalent fungus was A. fumigatus. Truely thermophiles were also collected: Humicola grisea var. thermoidae, Rhizomucor pusillus and Thermoascus aurantiacus. Based on biological assays (brine shrimp larvae (Artemia salina L.) and Bacillus megatherium test) and chemical analysis of chloroform extraction of tobacco (TLC and UV spectrophotometric), four samples (out of 40) had toxicity and four compounds of mycotoxins were detected namely; aflatoxins B1 & B2 (2 samples; 15.5 and 20.7 micrograms/kg), zearalenone (1 sample, 5.5 micrograms) and T-2 toxin (1 sample, 2.8 micrograms). For studying the tracing of aflatoxins in smoking cigarettes, three doses (10, 20 and 50 micrograms) of aflatoxins B1 and B2 (w/w, 1:1) were injected each in ten cigarettes. All extracts of cigarettes smoke proved to be non-toxic and mycotoxins not detected. However, aflatoxins were detected in topping filter (2.8, 3.5 and 8.8 micrograms/the three doses, respectively).

Macrocyclic trichothecenes produced by Stachybotrys isolated from Egypt and eastern Europe.

Twenty seven isolates of Stachybotrys chartarum, S. albipes, S. kampalensis and S. microspora from Egypt and Eastern Europe were tested for production of macrocyclic trichothecenes. Twenty of the 27 isolates, grown on rice seeds, were toxic to brine shrimp larvae. Based on TLC and HPLC analyses, 5 macrocyclic trichothecenes (verrucarin J, roridin E, satratoxins F, G & H) as well as trichoverrols were identified. When grown in liquid culture on rice extract medium, only 3 isolates were toxic and produced verrucarin J, roridin E and satratoxins G & H. Extracts from mycelial mats were more toxic than culture filterates of two isolates grown on rice extract and both contained the same macrocyclic trichothecenes (285.5 mg/4 L), in addition to trichoverrols A & B (31 mg/4 L) found in mycelial mats only. When grown on 3% sucrose Czapek's medium supplemented with peptone and yeast extract (still cultures), all isolates were non-toxic to brine shrimp and no trichothecenes could be detected in the extracts.

Mycoflora and trichothecene toxins of paddy grains from Egypt.

120 species and 38 genera were collected from 64 samples of paddy grains on glucose- and cellulose-Czapek's agar at 28 degrees C. The total count of glycophilic and cellulose-decomposing fungi fluctuated between 216-29760; and 124-11320 colonies/g paddy grains on the two media, respectively. On glucose agar, the most common species were Aspergillus niger, A. flavus, A. sydowi, A. terreus, A. fumigatus, A. ochraceus, Penicillium chrysogenum, P. corylophilum, Fusarium oxysporum, Alternaria alternata, Cladosporium cladosporioides, Trichoderma viride and Mucor racemosus. On cellulose agar with pH 5.5 & 8.0, the most prevalent fungi were Stachybotrys chartarum, S. bisybi, Aspergillus niger, A. flavus, Fusarium oxysporum, Alternaria alternata, Drechslera sativus and Acremonium strictum. Extracts from 64 paddy samples were tested against brine shrimp larvae (Artemis salina). Of these 9 displayed varying degrees of toxicity. Trichothecene-toxins were detected in the extracts of three paddy samples only. Diacetoxyscirpenol and T-2 toxin were detected in two samples and only T-2 toxin in the other.

Mycoflora and mycotoxins of peanut (Arachis hypogaea L.) seeds in Egypt. 1--Sugar fungi and natural occurrence of mycotoxins.

Sixty-four species and 2 varieties which belong to nineteen genera of fungi were identified from 40 peanut seed samples collected from different places in Egypt by using a dilution-plate method on glucose-Czapek's medium. The most frequent genera were Aspergillus (21 species & 2 varieties), Penicillium (16 species) and Fusarium (6 species). A. flavus, A. fumigatus, A. niger, P. chrysogenum and F. oxysporum were the most common fungal species. Forty seven percent of the samples proved to be toxic to brine shrimp (Artemia salina) larvae. Thin-layer chromatographic analysis revealed that peanuts were contaminated by aflatoxins (11 samples), trichothecene-toxins (10 samples), zearalenone (one sample) and citrinin (one sample). We believe that this is the first report of the natural occurrence of zearalenone and trichothecene-toxins in peanuts.

Mycoflora and mycotoxin-producing fungi of air-dust particles from Egypt.

Using the dilution-plate method, 27 genera and 64 species were collected from 20 air-dust samples on glucose - (24 genera and 57 species) and cellulose - (21 genera and 45 species) Czapek's agar at 28 degrees C. There are basic similarities between the mycoflora of air-dust on the two media and the most prevalent species were Aspergillus niger, A. flavus, A. ochraceus, A. terreus, A. versicolor, Penicillium chrysogenum, P. funiculosum, Alternaria alternata, Cladosporium herbarum, Fusarium oxysporum, Rhizopus stolonifer and Trichoderma viride. Chaetomium globosum, Stachybotrys chartarum, Humicola grisea and Arthrobotrys oligospora were common only on cellulose agar plates. Extracts of mycelium from 25 isolates were tested with brine schrimp (Artemia salina); of these 23 displayed varying degrees of toxicity. Thin layer chromatographic analysis of 12 isolates of Aspergillus flavus revealed that 4 strains were producing detectable aflatoxin. Zearalenone production was noted for 3 out of 5 strains of Fusarium oxysporum and 2 out of 5 strains of F. solani.