I. A. El-Kady

Natural occurrence of mycotoxins in different spices in Egypt

A total of 120 different samples belonging to 24 kinds of spices collected from different places atAssiut Governorate (Egypt) were examined for the natural occurrence of mycotoxins. TLC analysis of spice extracts revealed the presence of aflatoxins (8–35 μg/kg) in 16 samples of anise, black pepper, caraway, black cumin, fennel, peppermint, coriander and marjoram, sterigmatocystin (10–23 μg/kg) in ten samples of red pepper, caraway, cumin and marjoram and citrinin (8–12 ⧎g/kg) in two samples of black cumin, while ochratoxin A and zearalenone could not be detected.

Mycotoxin producing potential of some isolates of Aspergillus flavus and Eurotium groups from meat products

All strains (92) of A. flavus group proved to be positive for production of aflatoxin (45 to 1200 micrograms/50 ml medium) on potato dextrose liquid medium, while 59 strains only proved to be positive (35-310 micrograms/50 ml) on 15% NaCl potato-dextrose liquid medium. Most of the strains tested of A. flavus, A. flavus var. columnaris and A. oryzae produced aflatoxins B1, B2, G1 & G2. All positive strains of A. tamarii produced aflatoxins G1 & G2 while the tested isolate of A. zonatus produced aflatoxins B1 & G1. Of 95 strains tested of Eurotium, aflatoxins B1 & G1 were produced by one strain of each of E. chevalieri var. intermedium, E. repens and E. rubrum. Gliotoxin was detected in the extract of two strains of E. chevalieri and one strain of each of E. chevalieri var. intermedium and E. pseudoglaucum on the salt-free medium, and two strains of each of E. chevalieri, E. chevalieri var. intermedium and one of E. pseudoglaucum on 15% NaCl medium. Sterigmatocystin was produced by some strains of E. chevalieri, E. chevalieri var. intermedium, E. amstelodami, E. pseudoglaucum and E. rubrum on the two experimental media. One strain only of E. repens produced ochratoxin A while citrinin was detected in the extract of one strain of E. pseudoglaucum.

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)

Contribution to the fungal flora of cereal grains in Egypt

Abstract30 genera and 77 species, in addition to 4 varieties were isolated from 25 samples of each of barley, wheat, maize and sorghum grains collected from different places in Egypt. The broadest spectrum of genera and species was recorded in wheat (25 genera and 59 species + 4 varieties) followed by barley (21 genera and 52 species + 2 varieties), sorghum (14 genera and 33 species + 2 varieties) and maize grains (11 genera and 29 species + 2 varieties). Aspergillus, Fusarium, Penicillium and Rhizopus were the most common genera in the four grains, except maize where Penicillium emerged in low frequency. Aspergillus was the main component of the fungal flora of the four grains and contributed 79–94.4% of the gross total count of fungi. From the preceding genera A. niger, A. flavus, A. fumigatus, F. oxysporum, P. chrysogenum, P. corylophilum, P. notatum and R. stolonifer were the most frequent.

Mycoflora and trichothecene toxins of paddy grains from Egypt

Abstract120 species and 38 genera were collected from 64 samples of paddy grains on glucose- and cellulose-Czapeks agar at 28 °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.

Toxigenic fungi isolated from Roquefort cheese.

To evaluate the potential for mycotoxin production by fungi contaminating blue-veined cheese, as well as by the ripening fungus,Penicillium roqueforti, the fungal flora of six of local and imported brands was determined. A total of 19 fungi were isolated from the six brands tested. Fourteen of the isolates were toxic to chicken embryos. The toxigenic fungi produced the following mycotoxins:Aspergillus fumigatus, kojic acid;A. versicolor, sterigmatocystin;Penicillium roqueforti, penicillic acid and unidentified toxic metabolites.

Screening of zearalenone-producing Fusarium species in Egypt and chemically defined medium for production of the toxin.

Abstract296 isolates of Fusarium spp. from 100 samples of cereale grains were examined for their ability to produce zearalenone on liquid culture medium. Thin layer Chromatographic analysis revealed that the mycotoxin was detected from 45 isolates, (F. oxysporum, 36; F. moniliforme, 8; and F. equiseti, one isolate). A suitable liquid medium and some optimal conditions for the biosynthesis of zearalenone were reported. Glutamine and riboflavin stimulated the production of the toxin. The maximum amount of zearalenone appeared at pH 7, after 12 days of incubation at 20 °C.

Toxigenicity and toxins of Stachybotrys isolates from wheat straw samples in Egypt

One hundred and sixty-six isolates ofStachybotrys (164 ofS. chartarum and one isolate of each ofS. microspora andS. kampalensis), isolated from 50 samples of wheat straw collected from different localities in Egypt, were screened for toxicity and toxin production, using the rabbit skin test and thin-layer chromatographic analysis. Sixty-six isolates proved to be toxic, and 55 of the toxic isolates (54 ofS. chartarum and the single isolate ofS. microspora) produced at least one of the following toxins: verrucarol, verrucarin J, roridin E and satratoxin H. No regular correlation between any morphological features ofStachybotrys isolates with toxicity or toxin production was drawn, and no regular correlation between a positive resorcinol test and toxicity or toxin production was observed. This is the first report on toxin production byS. microspora.

Contribution of the mesophilic fungi of different spices in Egypt

Thirty-eight genera and 81 species of fungi were isolated and identified from 120 samples of 24 kinds of spices collected from different places at Assiut Governorate, Egypt. Predominant genera wereAspergillus (25 species) andPenicillium (7 species) of whichA. flavus, A. niger, A. ochraceus, A. fumigatus, A. flavus var.columnaris, A. terreus, P. chrysogenum andP. corylophilum were the most commonly occurring.

Glycerol production by two filamentous fungi grown at different ionic and nonionic osmotics and cheese whey

Glycerol production by a highly glycerol-producing local isolate (Eurotium amstelodami) and a standard reference isolate (Aspergillus wentii) was markedly enhanced by high saline media. Glycerol concentration depended on the external osmotic. Thus, the highest glycerol concentration was found in the presence of NaCl, followed by KCl, with considerably lower values for MgCl2 and CaCl2 saline media. With glucose (5–50%) used as a nonionic osmotic, low levels of glycerol were obtained and the main pool of polyols was mannitol. Glycerol production was gradually increased with the increase of NaCl concentration of cheese whey, reaching maxima by both organisms when whey was supplemented with 8% NaCl (total of 16% NaCl). The quantity of glycerol produced byA. wentii was twice higher than that obtained byE. amstelodami on whey treated with 8% NaCl.