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1.
Miguel A. Moreno Maria Jose Pro Angeles Olivares Guillermo Suarez 《Mycopathologia》1988,104(3):149-151
The distribution of aflatoxin producing isolates of the Aspergillus flavus group in feeds was studied. Aflatoxin production was investigated by a sequential method previously reported (fluorescence in Coconut Agar Medium, rapid extraction from a wheat medium, and total extraction from the same wheat medium). Twenty-seven of 32 samples contained A. flavus, and 21 of them had at least one aflatoxicogenic isolate of A. flavus. Of the 115 isolates analysed, 65 produced aflatoxins, mainly B aflatoxins. 相似文献
2.
Pascal Bauduret 《Mycopathologia》1990,109(3):157-164
A survey was carried out in Reunion island to obtain data on the occurrence of fungi, aflatoxigenic strains of Aspergillus flavus, aflatoxins, total aerobic bacteria and salmonellae of 150 samples of mixed poultry feeds and raw materials. These were collected at five farms over a 3-month period during the warm rainy season.White corn and Brazilian soybean meal seemed to present a better microbiological quality than yellow corn and US soybean meal.Mixed poultry feeds presented a high total mold count reflecting the mold flora of raw materials. The most frequent and abundant fungi were Aspergillus flavus, A. glaucus group, Fusarium spp., Penicillium spp., A. candidus, Mucor spp., A. restrictus, Scopulariopsis spp., Cladosporium spp. and A. versicolor.
Of the 118 A. flavus strains screened, 42 (35.6%) were aflatoxigenic. Yellow corn samples were the most frequently contamined with aflatoxigenic strains (54.5%), followed by mixed feeds (44%).Of the 66 samples tested, 24 (36%) contained aflatoxins (traces to 22 ng/g). A good correlation seemed to exist between presence of at least one aflatoxigenic strain per sample and presence of aflatoxins. 相似文献
3.
A total of 126 fungal strains belonging to the Aspergillus flavus group isolated from commercial poultry mixed feeds were studied. One hundred and twenty-five were identified as A. flavus and one as A. parasiticus. Forty nine strains (39%) produced aflatoxins on a crushed moist wheat medium (28 °C/10 days), whereas only sixteen (13%) showed specific fluorescence on Aflatoxin-Producing Ability Medium. In both media, mainly aflatoxins B1 and B2 were detected, the average concentration of aflatoxins being 4294+/–1083 g/kg in crushed moist wheat medium, and 877+/–257 g/kg in Aflatoxin-Producing Ability Medium. 相似文献
4.
The luncheon meat samples analyzed, which were produced locally by the two main luncheon meat producing companies in Egypt
were relatively highly contaminated either by moulds and yeasts in general, aflatoxigenic species and aflatoxin residues in
particular. The most frequently encountered fungi from the samples were yeasts, Aspergillus niger, A. flavus, Penicillium chrysogenum, Rhizopus stolonifer, Mucor circinelloides. Less common were Cladosporium sphaerospermum, Alternaria alternata, Mycosphaerella tassiana, P. aurantiogriseum and P. oxalicum. The most important aflatoxigenic species, A. flavus, was isolated frequently. It was 10% of the total fungal isolates from both samples of the two companies. Seven luncheon
meat samples out of 50 analyzed were positive for aflatoxin B1 or B1 and G1, while all samples were negative for aflatoxins B2, G2, M1 and M2. Aflatoxin B1 was detected only in 4 and 3 samples out of 25 analyzed from each of company A and B, respectively. The highest detectable
level, 11.1 ppb, was recorded in a sample from company B and the least, 0.5 ppb, in a sample from company A. Aflatoxin G1, at concentration of 3.2 ppb, was detected in only one sample of the aflatoxin B1 – contaminated 3 samples of company B: this sample also had the highest level of aflatoxin B1. Some luncheon meat samples had higher numbers of aflatoxigenic A. flavus than others, however these samples were negative for aflatoxins. The hazardous potential of such contamination will be discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Miguel A. Moreno Romo Ma del Carmen Ramos Cartagena Elías F. Rodriguez Ferri Guillermo Suárez Fernández 《Mycopathologia》1986,95(3):145-148
Minimal moisture content for growth and aflatoxin production by Aspergillus parasiticus in mixed feeds was studied. Minimal moisture content for growth is 16.51%+/–0.45. Very low amounts of aflatoxins are accumulated at days 1 or 2 after the growth started when the initial moisture content of the mixed feed was 17% or lower; on the other hand, significant amounts of aflatoxin are detected when it was 18% or higher. 相似文献
6.
A total of 180 samples of poultry feeds were collected during 1996 and 1997 from different factories in the south of the province
of Córdoba-Argentina. They were examined for the occurrence of Penicillium spp. and Aspergillus group species. Likewise, the
capacity to produce aflatoxins by the Aspergillus section flavi group was determined. The predominant species of Aspergillus
were A. flavus and A. parasiticus. For Penicillium spp., P. brevicompactum, P. purpurogenum and P. oxalicum were identified.
Less frequently isolated were A. candidus, A. fumigatus, A. niger, A. orizae, A. parvulus, A. tamarii, A. terreus, and P.
expansum, P. funiculosum, P. minioluteum, P. pinophylum, P. restrictum, P. variabile and others. The mean value counts ranged
from 1 × 103 to 9.5 × 104 CFU/g for the Aspergillus spp. and from 1.2 × 103 to 2.5 × 105 CFU/g for the Penicillium spp. When
cultured on autoclaved rice kernels for 1 week in the dark at 25°C, mycotoxin production by strains of A. flavus was as follows:
21 of the 45 assayed strains (47%) produced aflatoxins. From them, 24% of the isolates produced AFB1 and AFB2 with levels
from 181 to 14 545 and 6 to 3640 μg/kg respectively. Only 10 strains produced AFB1 with levels from 10 to 920 μg/kg. Fifty
percent of the A. parasiticus strain was toxicogenic; six aflatoxicogenic profiles were identified. Only 10% of the strains
produced all of the aflatoxins. These results showed that a potential exists for the production of mycotoxins by the Aspergillus
section flavi and the Penicillium spp. They also suggested an association of mycotoxicosis with poultry feeds in Argentina.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
One hundred and five samples of seven spices (cumin, cinnamon, clove, black pepper, cardamom, ginger, and coriander) were
purchased from five popular companies in the Sultanate of Oman. The spices were surveyed for the mycoflora and aflatoxins.
Twenty fungal species were isolated in which Aspergillus flavus , A. niger . Penicillium , Rhizopus , and Syncephalastrum racemosum were the most dominant. When colony forming units per gm (cfu/gm) of fungi were compared, significant differences were found
among spices and companies. Of the seven spices studied, clove was found to be the least contaminated, while cumin was the
most contaminated. None of the 15 selected samples of the spices contaminated by A. flavus were found to contain aflatoxins. Nevertheless, nine isolates (45%) of the twenty A. flavus strains screened for aflatoxins were aflatoxigenic. The moisture content of most of the spices was below the maximum standard
limit. The results showed that the spices were contaminated by some fungi that might constitute health hazards for humans.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
T. Ueki Y. Noda Y. Teramoto R. Ohba S. Ueda 《World journal of microbiology & biotechnology》1994,10(6):694-696
For improved fermentation of shoyu (soy sauce), a useful koji-making system has been developed using a mixed tane-koji of two shoyu koji moulds, namely Aspergillus oryzae K2 (length of conidiophores about 350 m) and the late-conidiation strain, A. oryzae HG (length of conidiophores about 2500 m). The mixed culture of strains K2 and HG had about twice the glutaminase activity of the single-strain cultures. In addition, the number of conidia in the mixed culture was about 10% of that in a culture of strain K2 alone. 相似文献
9.
Aflatoxins are polyketide-derived, toxic, and carcinogenic secondary metabolites produced primarily by two fungal species,
Aspergillus flavus and A. parasiticus, on crops such as corn, peanuts, cottonseed, and treenuts. Regulatory guidelines issued by the U.S. Food and Drug Administration
(FDA) prevent sale of commodities if contamination by these toxins exceeds certain levels. The biosynthesis of these toxins
has been extensively studied. About 15 stable precursors have been identified. The genes involved in encoding the proteins
required for the oxidative and regulatory steps in the biosynthesis are clustered in a 70 kb portion of chromosome 3 in the
A. flavus genome. With the characterization of the gene cluster, new insights into the cellular processes that govern the genes involved
in aflatoxin biosynthesis have been revealed, but the signaling processes that turn on aflatoxin biosynthesis during fungal
contamination of crops are still not well understood. New molecular technologies, such as gene microarray analyses, quantitative
polymerase chain reaction (PCR), and chromatin immunoprecipitation are being used to understand how physiological stress,
environmental and soil conditions, receptivity of the plant, and fungal virulence lead to episodic outbreaks of aflatoxin
contamination in certain commercially important crops. With this fundamental understanding, we will be better able to design
improved non-aflatoxigenic biocompetitive Aspergillus strains and develop inhibitors of aflatoxin production (native to affected crops or otherwise) amenable to agricultural application
for enhancing host-resistance against fungal invasion or toxin production. Comparisons of aflatoxin-producing species with
other fungal species that retain some of the genes required for aflatoxin formation is expected to provide insight into the
evolution of the aflatoxin gene cluster, and its role in fungal physiology. Therefore, information on how and why the fungus
makes the toxin will be valuable for developing an effective and lasting strategy for control of aflatoxin contamination. 相似文献
10.
Production of aflatoxins by Aspergillus ruber THOM and CHURCH was first reported by KULIK and HOLADAY (1967), although these results have lacked confirmation. In this paper we provide evidence that this fungal strain produces aflatoxins. This finding has implications for food hygiene, especially in countries where such moulds are used in the preparation of foodstuffs. 相似文献
11.
The fungal flora of 6 Asian medicinal plants, Aerva lanata (Linn.) Juss. Alyssicarpus vaginalis D.C., Tribulus terrestris Linn. Adhatoda vasica Nees., Centella asciatica (L.) Urb., Cardiospermum halicacabum Linn. was determined. After surface disinfection Aspergillus spp. were most frequently observed. Aspergillus flavus, isolated from Alyssicarpus vaginalis and Aerva lanata produced aflatoxins in culture. Aflatoxin B1 was also detected in a sample of Aerra lanata at a level of 0.5 g/g. Plant material destined for medicinal use should be stored carefully prior to its use to prevent growth of naturally occurring toxigenic mold fungi. 相似文献
12.
13.
Transformation of sterigmatocystin and O-methylsterigmatocystin (two metabolic aflatoxin precursors) to aflatoxins by aflatoxigenic and nonaflatoxigenic field isolates of Aspergillus flavus was studied. The 24 nonaflatoxigenic isolates investigated failed to transform both precursors. Among the 8 aflatoxin-producing isolates used, 7 transformed both precursors whereas the remaining failed to transform both. According to these results, the usefulness of the measurement of enzymatic activities related to aflatoxin production in understanding the true status of conflictive field isolates is discussed.Abbreviations ST
sterigmatocystin
- OMST
O-methylsterigmatocystin
- AFB1
aflatoxin B1
- AFB2
aflatoxin B2
- AFG1
aflatoxin G1
- AFG2
aflatoxin G2
- GM
growth medium of Adye and Mateles
- RM
replacement medium of Adye and Mateles 相似文献
14.
S. Kachouri S. Halaouli A. Lomascolo M. Asther M. Hamdi 《World journal of microbiology & biotechnology》2005,21(8-9):1465-1470
Summary By contaminating a Tunisian soil with black oxidized and sterilized olive-mill wastewaters (OMW), 30 new indigenous fungal
soil strains able to overcome the OMW toxicity could be directly selected. Ten of the fungal strains previously isolated were
screened for their capability to grow in a liquid culture medium containing oxidized OMW as the only source of carbon and
energy. According to these preliminary tests, strain F2 showed the best capability of removing black colour and COD (chemical
oxygen demand) and was further identified as Aspergillus flavus. After optimization of batch-liquid culture conditions in the presence of oxidized OMW, the time course of biomass and enzyme
production by A. flavus F2 was followed in relation to colour and COD removal. A. flavus F2 could efficiently decolourize and detoxify the black oxidized OMW (58 and 46% of colour and COD removal, respectively,
after 6 days of cultivation), concomitantly with the production of tannase (8000 UI/l on day 3). 相似文献
15.
Secondary metabolism in fungi is frequently associated with asexual and sexual development. Aspergillus parasiticus produces aflatoxins known to contaminate a variety of agricultural commodities. This strictly mitotic fungus, besides producing
conidia asexually, produces sclerotia, structures resistant to harsh conditions and for propagation. Sclerotia are considered
to be derived from the sexual structure, cleistothecia, and may represent a vestige of ascospore production. Introduction
of the aflatoxin pathway-specific regulatory gene, aflR, and aflJ, which encoded a putative co-activator, into an O-methylsterigmatocystin (OMST)-accumulating strain,A. parasiticus SRRC 2043, resulted in elevated levels of accumulation of major aflatoxin precursors, including norsolorinic acid (NOR),
averantin (AVN), versicolorin A (VERA) and OMST. The total amount of these aflatoxin precursors, NOR, VERA, AVN and OMST,
produced by the aflR plus aflJ transformants was two to three-fold that produced by the aflR transformants. This increase indicated a synergisticeffect of aflR and aflJ on the synthesis of aflatoxin precursors. Increased production of the aflatoxin precursors was associated with progressive
decrease in sclerotial size, alteration in sclerotial shape and weakening in the sclerotial structure of the transformants.
The results showed that sclerotial development and aflatoxin biosynthesis are closely related. We proposed that competition
for a common substrate, such as acetate, by the aflatoxin biosynthetic pathway could adversely affect sclerotial development
in A. parasiticus.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
A 2-year study was carried out to determine the effect of applying nontoxigenic strains of Aspergillus flavus and A. parasiticus to soil separately and in combination on preharvest aflatoxin contamination of peanuts. A naturally occurring, nontoxigenic
strain of A. flavus and a UV-induced mutant of A. parasiticus were applied to peanut soils during the middle of each of two growing seasons using a formulation of conidia-coated hulled
barley. In addition to an untreated control, treatments included soil inoculated with nontoxigenic A. flavus only, soil inoculated with nontoxigenic A. parasiticus only, and soil inoculated with a mixture of the two nontoxigenic strains. Plants were exposed to late-season drought conditions
that were optimal for aflatoxin contamination. Results from year one showed that significant displacement (70%) of toxigenic
A. flavus occurred only in peanuts from plots treated with nontoxigenic A. flavus alone; however, displacement did not result in a statistically significant reduction in the mean aflatoxin concentration
in peanuts. In year two, soils were re-inoculated as in year one and all treatments resulted in significant reductions in
aflatoxin, averaging 91.6%. Regression analyses showed strong correlations between the presence of nontoxigenic strains in
peanuts and aflatoxin reduction. It is concluded that treatment with the nontoxigenic A. flavus strain alone is more effective than the A. parasiticus strain alone and equally as effective as the mixture.
The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
17.
The occurrence of Aspergillus flavus in vegetative tissue of cotton plants and its relation to seed infection 总被引:1,自引:0,他引:1
Twenty-seven mature cotton bolls with Aspergillus flavus Link colonies naturally occurring on the surface of the boll or lint were collected in the field in Arizona along with their subtending stems and peduncles. Bolls inoculated through the carpel wall 30 days after anthesis were allowed to mature in the field and were collected in the same manner. The seed and stem and peduncle sections of each boll were surface-sterilized, plated on agar media and observed for A. flavus. Seventy-eight percent of the naturally contaminated bolls with A. flavus in the seed also had the fungus in the stem and peduncle, whereas only 31% of the naturally contaminated bolls with no A. flavus in the seed had the fungus in the stem or peduncle. This difference was significant (P=0.0125), indicating a positive relationship between seed infection and stem and peduncle infection. All of the bolls inoculated through the carpel wall had A. flavus in the seed, but only 11% of the stem and peduncle sections were infected, indicating that the fungus does not readily grow downward from the boll into the supporting stem or peduncle.This unidirectional pattern of movement (upward) was further substantiated in greenhouse experiments where cotton seedlings were inoculated at the cotyledonary leaf scar with A. flavus and plants were sequentially harvested, surface sterilized and plated. Aspergillus flavus was isolated from the cotyledonary leaf scar, flower buds, developing bolls, and stem sections in the upper portion of the plant. It was never isolated from roots or stem sections below the cotyledonary node, again indicating that the fungus does not readily move downward through the plant. 相似文献
18.
Bruce W. Horn Joe W. Dorner Ronald L. Greene Paul D. Blankenship Richard J. Cole 《Mycopathologia》1994,125(3):179-191
Environmental control plots adjusted to late season drought and elevated soil temperatures where inoculated at peanut planting with low and high levels of conidia, sclerotia, and mycelium from a brown conidial mutant ofAspergillus parasiticus. Percentage infection of peanut seeds from undamaged pods was greatest for the subplot containing the high sclerotial inoculum (15/cm2 soil surface). Sclerotia did not germinate sporogenically and may have invaded seeds through mycelium. In contrast, the mycelial inoculum (colonized peanut seed particles) released large numbers of conidia into soil. Soil conidial populations of brownA. parasiticus from treatments with conidia and mycelium were positively correlated with the incidence of seed infection in undamaged pods. The ratio ofA. flavus to wild-typeA. parasiticus in soil shifted from 7:3 to 1:1 in the uninoculated subplot after instigation of drought, whereas in all subplots treated with brownA. parasiticus, the ratio of the two species became approximately 8:2. Despite high levels of brownA. parasiticus populations in soil, nativeA. flavus often dominated peanut seeds, suggesting that it is a more aggressive species. Sclerotia of wild-typeA. parasiticus formed infrequently on preharvest peanut seeds from insect-damaged pods. 相似文献
19.
Paul A. Lemke Norman D. Davis Sriram K. Iyer Gregory W. Creech Urban L. Diener 《Journal of industrial microbiology & biotechnology》1988,3(2):119-125
Summary A convenient miniassay for aflatoxin has been developed for cultures ofAspergillus flavus andA. parasiticus grown for 3–10 days in 10 ml of a coconut extract medium. The sensitivity of the assay, as measured by photofluorometry (365 nm maximum excitation; 445 nm maximum emission), is of the order of 0.01 M (3.12 ng/ml) for aflatoxin B1 dissolved in aqueous iodine (0.26 mM). High performance liquid chromatography, monitored by fluorometric analysis of both an aflatoxin B1 standard and selected culture filtrates, confirmed the sensitivity of the assay and indicated specificity for iodine-enhanced fluorescence of aflatoxin in the coconut extract medium. Thin layer chromatography further confirmed the aflatoxin titers and the specificity for enhancement of aflatoxins B1 and G1 in culture filtrates.Alabama Agricultural Experiment Station Journal No. 6-871297. 相似文献
20.
Dr Peter J. Cotty 《Mycopathologia》1994,126(3):157-162
Four agar media used to isolate aflatoxin producing fungi were compared for utility in isolating fungi in theAspergillus flavus group from agricultural soils collected in 15 fields and four states in the southern United States. The four media wereAspergillus flavus andparasiticus Agar (AFPA, 14), the rose bengal agar described by Bell and Crawford (BCRB; 3), a modified rose bengal agar (M-RB), and Czapek's-Dox Agar supplemented with the antibiotics in BC-RB (CZ-RB). M-RB was the most useful for studying the population biology of this group because it permitted both identification of the greatest number ofA. flavus group strains and growth of the fewest competing fungi. M-RB supported an average of 12% moreA. flavus group colonies than the original rose bengal medium while reducing the number of mucorales colonies and the number of total fungi by 99% and 70%, respectively. M-RB was successfully employed to isolate all three aflatoxin producing species,A. flavus, A. parasiticus andA. nomius, and both the S and L strains ofA. flavus. M-RB is a defined medium without complex nitrogen and carbon sources (e.g. peptone and yeast extract) present in BC-RB. M-RB should be useful for studies on the population biology of theA. flavus group.Abbreviations M-RB
Modified Rose Bengal Agar
- CZ-RB
Czapeks Rose Bengal Agar
- BC-RB
Bell and Crawford's Rose Bengal Agar
- AFPA
Aspergillus flavus andparasiticus agar 相似文献