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), thrichothecene-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 mycotoxins of peanut (Arachis hypogaea L.) seeds in Egypt. III. Cellulose-decomposing and mycotoxin-producing fungi

From 40 peanut seed samples collected in Egypt, forty-three species and one variety of fungi, belonging to 16 genera, were collected. The most dominant genera were Aspergillus (11 species + one variety), Penicillium (11 species) and Fusarium (4 species). From the preceding genera A. fumigatus, A. flavus, A. niger, P. chrysogenum and F. oxysporum were the most frequent species.Forty-nine isolates belonging to 12 species and one variety were tested for production of mycotoxins, after growth on liquid medium containing two carbon sources (sucrose or cellulose). Thin layer chromatographic analysis revealed that the quality and quantity of mycotoxins was higher on sucrose than cellulose. Mycotoxins identified were aflatoxins B₁, B₂, G₁ & G₂, citrinin; fumagillin; diacetoxyscirpenol T-2 toxin; satratoxin H; and zearalenone.     

Fungal populations and mycotoxins in silage in Assiut and Sohag governorates in Egypt,with a special reference to characteristic Aspergilli toxins

Forty silage samples were collected from Assiut and Sohag governorates in Egypt to measure the presence of fungal population in silage. Forty-three species and 2 species varieties belonging to 17 genera were isolated using glucose Czapeks and Sabourauds dextrose agar media at 28 ^°C. The most prevalent genera were Aspergillus (57.5 and 100 of the samples), Penicillium (100 and 55%) on the two mentioned media, respectively. Also, Fusarium oxysporum and Gibberella fujikurori were recovered in moderate incidences. Mycotoxin profiles were also determined in these samples: Aflatoxins showed the highest incidence rates of occurrence, it occurred in 22.5% of all samples analyzed. Other mycotoxins were detected from all samples (T₂ toxins and sterigmatocystin at incidence of 7.5 and 5%, respectively). The screening of the characteristics mycotoxins of different isolates of Aspergillus isolated from silage samples was tested. The results clarified that some mycotoxins (aflatoxins – aspergillic acid – beta nitro propionic acid – cyclopiazonic acid– kojic acid and sterigmatocystin) were produced by some isolates of A. flavus. Some isolates of A.fumigatus could produce gliotoxin and verrucologen. All of A. niger isolates tested were able to produce kojic acid. One isolate of A. ochraceous formed ochratoxin A and other isolate produced penicillic acid. Concerning A. terreus isolates, the results showed that 5 isolates were able to produce citrinin and 4 isolates had ability to produce patulin. A. versicolor isolates showed the ability to produce ochratoxin A.     

Survey of mycoflora and ochratoxin A in dried vine fruits from Argentina markets

AIMS: The aims of this work were to identify the mycoflora and to evaluate the natural occurrence of OA in dried vine fruits. Likewise, the capacity to produce OA by Aspergillus section Nigri was studied. MATERIALS AND METHODS: Fifty samples of dried vine fruits were obtained from Mendoza and San Juan provinces. The surface disinfection method was used for mycoflora determination using the medium dichloran 18% glycerol agar (DG18) and dichloran Rose Bengal chloramphenicol agar (DRBC). RESULTS: Statistical analysis demonstrated that the species A. niger var. niger and Aspergillus niger var. awamori were isolated in higher frequency from black dried vine fruits from DRBC and DG18 media (P < 0.01). OA was found in 74% of the dried vine fruits samples. Sixty-two strains (28%) of Aspergillus section Nigri, were OA producers. In the species A. carbonarius the highest percentages of ochratoxigenic strains were detected (82.6%). CONCLUSIONS: The presence of ochratoxigenic strains of Nigri section in dried vine fruits suggests that they may be an important source of OA in this substrate. Dried vine fruits can also be an important source of OA people who consume large amounts. SIGNIFICANCE AND IMPACT OF THE STUDY: The dried vine fruits contamination with Aspergillus section Nigri and OA was significant.     

Treatment of lentil (Lens culinaris. L) seeds with various concentrations of salts to check their efficiency against seed-borne mycoflora during storage

Seed sample of lentil collected from the Swabi district were treated with NaCl and KCl at 0.01, 0.1 and 1.0% (w/w). Seed-borne mycoflora was observed at 0, 20, 40, 60 and 80 day intervals. Seed treatment with both the salts was found to be effective against storage fungi; however, KCl was more efficient against storage mycoflora such as Aspergillus species when compared with NaCl. With the passage of time, the incidence of deep-seated fungi was observed in salt-treated seed samples while untreated seed sample showed heavy infestation by the species of Aspergillus. Seed viability also remained unaffected in storage, except in seeds heavily infested with seed-borne mycoflora. Aspergillus spp. were the main cause of seed rot. Surface sterilisation of seeds with 1% Na(OCl)₂ reduced the fungal infestation of seeds. Among various concentrations of salts, 0.1% (w/w) of both salts were better in controlling seed-borne mycoflora.     

Utility of biocontrol agents in the suppression of seed borne pathogenic mycoflora and their effect on seed quality in sorghum (Sorghum bicolor (L.) Moench)

Abstract

The scope of biocontrol agents in the control of sorghum grain molds was investigated both in vitro as well in vivo. Their utility in enhancing the germination and seedling vigor of mold-infected seeds were assessed. The biocontrol agents, Trichoderma viride, T. harzianum, T. hamatum, T. koeningii and Pseudomonas fluorescens (isolates collected from the state of Tamil Nadu, India) were efficient in checking the growth of mold pathogens when grown in Potato Dextrose Agar (PDA) as dual cultures. The bacterial bioagent P. fluorescens was most efficient in checking the growth of all the test pathogens viz., Fusarium moniliforme, Curvularia lunata and Alternaria alternata (66.8, 68.5 and 64.9% inhibition of colony growth respectively) followed by other bioagents for their antagonistic effect. The in vivo effectiveness of the bioagents were enhanced when combined with other components like host-resistance, cultural and chemical control strategies, paving the way for a possible Integrated Disease Management. The percent incidence and severity of molds were lowest (19.44 and 13.5% respectively) with the treatment T₆ (seeds harvested at physiological maturity + propiconazole @ 0.02% + P. fluorescens @ 1 × 10⁸ cfu ml^?1) that recorded maximum 100 seed weight (2.905 g), followed by 2.871 g in T₂ (seeds harvested at physiological maturity + P. fluorescens). The effect of bioagents in enhancing the germination and seedling vigor was most promising. Of all the treatments, P. fluorescens resulted in maximum germination (88%) and seedling vigor (2635.60 vigor index), followed by treatment with T. viride (86.6% and 2478.47 respectively).     

Bacterial blight pathogen concentration in cotton seeds; its role in seed quality parameters of fuzzy and acid delinted seeds

Abstract

The adverse effects of increasing concentration of Xanthomonas axonopodis pv. malvacearum on cotton seed quality parameters, seedling dry weight and on defense-related enzyme, Phenylalanine Ammonia Lyase (PAL) were studied. Different concentrations of pathogen (1×10² to 1×10⁸ CFU/ml) were treated on both fuzzy and acid delinted seeds and subjected to the standard blotter method to study the effect of the pathogen on seed quality parameters. The seedling symptom test following the roll towel method, the modified germination test to study the blight incidence and the field emergence test were carried out to discover the field planting value and disease incidence under laboratory and field conditions. From these experiments, it was found that the decrease in the seed quality parameters like seed germination, seedling vigour, and the dry weight of seedlings when X. axonopodis pv. malvacearum concentration was increased. Whereas the bacterial blight incidence increased with an increase in pathogen concentration, in both greenhouse and field conditions. Phenylalanine ammonia lyase activity was found to increase along with the pathogen concentrations, but total phenol content decreased as pathogen concentration increased. The effect of X. axonopodis pv. malvacearum load on seed quality parameters, PAL enzyme activity of fuzzy and acid delinted cotton seeds are discussed in the present study.     

Empty seeds reduce seed predation by birds in Juniperus osteosperma

Utah juniper (Juniperus osteosperma) is one of many plant species that produce large numbers of fruits containing parthenocarpic or otherwise empty or inviable seeds. We tested the hypothesis that production of empty fruits in this species results in reduced levels of predation on fertile seeds. In a population in west-central Utah, we estimated the proportion of fruits with filled seeds in trees suffering high levels of fruit destruction by the seed-eating bird Parus inornatus and in neighbouring trees similar in crown and fruit-crop size but suffering negligible predation. We found that the heavily attacked trees had higher proportions of filled seeds. Thus, juniper may benefit from producing fruits that contain no offspring. This is the first study to demonstrate that empty seeds may reduce predation by vertebrate seed eaters and the first to demonstrate discrimination based on seed filling at the level of whole plants.     

Survey of the mycoflora of barley grains in Egypt

The fungi of 40 samples of barley grains collected from Upper Egypt were estimated using the dilution- and the grain-plate methods. 33 genera and 109 species, in addition to 2 varieties of Aspergillus nidulans, one variety of Aspergillus flavus and one variety of Penicillium cyclopium were identified. The spectrum of fungal genera and species collected by the grain-plate method (29 genera and 94 species+3 varieties) was broader than by the dilutionplate method (27 genera and 71 species+3 varieties), but the order of frequency of occurrence of fungal genera and species was basically similar in the two methods. The most frequent genera were Aspergillus (25 species+3 varieties), Penicillium (32 species+1 variety), Rhizopus (2 species), Alternaria (2 species), Fusarium (6 species) and Drechslera (5 species) and were represented (as assayed by the grainplate method) in 100 %, 77.5 %, 85 % 62,5 %, 60 % and 52.5 % of the samples constituting 60.4 %, 10.2 %, 7.7 %, 3.7 %, 5 % and 2.3 % of the gross total count of fungi respectively. From the preceding genera A. niger, A. fumigatus, A. flavus, A. sydowii, P. notatum, P. citrinum, F. oxysporum, F. moniliforme, F. solani, R. stolonifer, A. alternata and D. spicifera were the most frequent.     

Effect of cutinase on the degradation of cotton seed coat in bio-scouring

In this paper the effect of cutinase on the degradation of cotton seed coat is analyzed. Fourier transform infrared (FT-IR) microspectroscopy was applied to study the changes of chemical compositions in cotton seed coat epidermal layer and gas chromatography/mass spectrometry (GC/MS) was used to analyse cutinase depolymerization of cotton seed coat. Based on these arguments the ability of cutinase to degrade aliphatic components in cotton seed coat was verified. Positive effect of cutinase on degradation of cotton seed coat was observed with the combination of alkaline pectinase or xylanase. The removal of aliphatic components by cutinase enables other enzymes to penetrate into the inner of cotton seed coat. Cutinase can potentially improve the degradation of cotton seed coat during cotton fabric bio-scouring process.     

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.     

Mycotoxins and mycotoxigenic moulds in nuts and sunflower seeds for human consumption

A survey was carried out to obtain data on the occurrence of mycotoxins and the mycotoxin-producing potential of fungi isolated from nuts (almonds, peanuts, hazelnuts, pistachio nuts) and sunflower seeds in Spain. Thin-layer chromatography was used to separate the toxins. Aflatoxins were detected in one sample of almonds (95 ppb aflatoxin B₁ and 15 ppb aflaxtoxin B₂) and in one sample of peanuts at a level below 10 ppb of aflatoxin B1. 100% of samples showed variable incidence of fungal contamination. The predominant fungi present in samples were Penicillium spp, Aspergillus niger, A. flavus, A. glaucus and Rhizopus spp. The results showed that isolates of different species were able to produce aflatoxins B₁, B₂, G₁, and G₂, sterigmatocystin, ochratoxin A, patulin, citrinin, penicillic acid, zearalenone, and griseofulvin.     

Prevalence and control of wheat (Triticum aestivum L.) seed borne fungi in farmer-saved seeds

High incidence of diseases associated with the use of seeds saved from previous harvests as desire of maintaining local varieties with special attributes is of increased concern in wheat industry worldwide. Prevalent of seed-borne fungi in farmer-saved seeds and seed dressing fungicides to prevent infection from seeds to seedlings was studied in Northern Tanzania. One hundred and thirty five untreated farmer-saved seed lots were collected randomly from farmers. Alternaria alternata, Bipolaris sorokiniana, Drechslera tritici, Fusarium graminearum, Fusarium moniliforme, Aspergillus flavus, Cladosporium sphaerospermum, Epicoccum purpurascens, Pyricularia oryzae and Penicillium corylophilum were fungi isolated in farmer-saved seeds. Mean seed infection was 29% causing average grain yield loss of 1.2 mt/ha^?1. Seed dressing with Metalaxy plus (Methyl carboxaitide), Mancozeb (Manganase-zinc salt) and Baytan (Chlorophenoxy ethanol) increased seed germination by 14, 13 and 17%, respectively, and grain yield by 28, 20 and 18%, respectively. Farmer-saved seeds were heavily infected by fungi with low grain yield performance.     

主要气候因子对麦棉两熟棉花产量的影响

采用灰色关联度分析法和逐步回归分析法,分析了麦棉两熟种植棉花生育期间主要气候因子与籽棉产量的关系.灰色关联度分析法结果表明,黄淮海棉区棉花产量在年度间的差异主要受积温的影响,4-10月份≥20℃积温与籽棉产量的关联系数0.4463;其次为日照时数,关联系数0.4052,第三是降雨量,关联系数0.3133.在棉花生长的4-10月期间,以8月、9月的日照时数和8月份≥20℃的积温对产量的影响最大,关联系数分别达到0.7201、0.7116和0.7042.逐步回归分析法结果同样表明,积温是影响产量的主要因子,且为正效应;而降水量对产量的影响为负效应;得出的回归方程(P=0.0007598,R2 =0.7477)可试用于黄淮棉区两熟籽棉产量的预测和预报.     

Disease forecasting model for newly emerging bacterial seed and boll rot of cotton disease and its vector (Dysdercus cingulatus)

Bacterial seed and boll rot disease is a newly emerging threat to the cotton growers. Disease prediction model was devised to predict the disease progression impacted by the vector (Dysdercus cingulatus) and environmental variables (maximum air temperature, minimum air temperature, relative humidity and rainfall) on four varieties to minimise its losses and disease management cost. Impact of a-biotic environmental variables (maximum and minimum air temperature, relative humidity and rainfall) was assessed on bacterial seed and rot of cotton disease and its vector (D. cingulatus) on FH-941, FH-942, MNH-886 and FH-114 cotton varieties. Maximum red cotton bug population was assessed at 29–31 °C maximum temperature and at 15–17 °C minimum temperature. Disease severity was noticed maximum when maximum and minimum temperature was measured at 28–29 °C and 13–14.5 °C, respectively. Vector population was maximum when relative humidity and rainfall were 63–66% and 1.50–2.5 mm, respectively. Relative humidity at 66–68% and 0.5–1.5 mm rainfall favoured disease development. With increase in number of bugs, increase in disease severity was noted, maximum disease severity 45–48% noticed when 7–8 bugs were recorded. Red cotton bug (Dysdercus cingulatus) population prediction model was devised based on a-biotic factors (maximum and minimum air temperature, relative humidity and rainfall) on four cotton varieties. Disease forecasting model was developed based on biotic (D. cingulatus) and a-biotic factors. A close resemblance between observed and the predicted red cotton bugs and disease severity was seen.     

Fungicidal effect of ultraviolet-C radiations in prevention of mycoflora of castor bean seeds

The effect of ultra violet (UV-C) radiation on germination and fungal flora of castor bean seeds was estimated with different doses stored up to 80?days interval. Results revealed that 20 and 40?min radiated castor bean seeds showed complete reduction in most of the fungi while germination of castor bean seeds were enhanced when UV-C radiations applied for 20?min. Increasing the radiation doses and storage period has been shown decrement in Aspergillus species colonisation.     

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.     

Soil mycoflora from the Dead Sea Oases of Ein Gedi and Einot Zuqim (Israel)

Samples were taken from the top 10 cm of soils from 24 points in the Ein Gedi area. Among 329 isolates, 142 species were identified: 11 genera of ascomycetes, one genus of coelomycetes, 28 genera of hyphomycetes, 7 genera of zygomycetes and one yeast, in addition to some unidentified basidiomycetes. The hyphomycetes were represented by 17 dematiaceous, 9 mucedinaceous and two tuberculariaceous. Melanconiaceous and stilbellaceous genera were not found. Two new varieties of Microascus recently described were reisolated. No strict thermophiles or halophiles were obtained. There is apparently no very characteristic or specific fungal flora of the Dead Sea Oases although it was different from that found in the desert soil surrounding this area.     

豫南茶园树栖真菌群落结构研究

对豫南茶园叶栖及枝栖真菌群落结构进行了初步调查,经分离共得到真菌17属32种。结果表明,茶树不同的器官以及同一器官的不同发育阶段栖居有不同的真菌群落;豫南茶园树栖真菌群落主要由兼性寄生菌和腐生菌构成;茶树不同品种之间树栖真菌群落差别不明显,茶园的生态环境是影响茶园树栖真菌群落结构的主要因素。