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Sample records for aflatoxigenic aspergillus flavus

  1. Characterization of aflatoxigenic and non-aflatoxigenic Aspergillus flavus isolates from pistachio.

    PubMed

    Hua, Sui Sheng T; McAlpin, Cesaria E; Chang, Perng-Kuang; Sarreal, Siov Bouy L

    2012-02-01

    Pistachio is a popular snack food. Aflatoxin contamination of pistachio nuts is a serious problem for many producing countries. The development of biological control methods based on ecological parameters is an environmentally friendly approach. Thirty-eight Aspergillus flavus isolates collected from a pistachio orchard in California (CA) were analyzed for production of aflatoxin (AF), cyclopiazonic acid (CPA), vegetative compatibility groups (VCGs), and mating types. All aflatoxigenic isolates produced both AFB1 and CPA. The most toxigenic one was CA28 which produced 164 μg AFB1 per 5 ml PDA fungal culture and small sclerotia (S strain, sclertoium size less than 400 μm). The other aflatoxigenic strains produce AFB1 ranging from 1.2 μg to 80 μg per 5 ml fungal culture. Twenty-one percent of the CA isolates produced AFB1, 84% produced CPA and half formed sclerotia on at least one of three tested media. The 38 CA isolates formed 26 VCGs, 6 of which had two or more isolates and 20 contained single isolates. The S strain isolates belong to 4 different VCGs. Genomic profiling by a retrotransposon DNA probe revealed fingerprint patterns that were highly polymorphic. The predicted VCGs (Pred-VCGs) based on a similarity coefficient >80% matched the VCGs of multiple isolates determined by complementation. All isolates within a VCG had the same mating-type gene of either MAT1-1 or MAT1-2. Uncorrected and VCG-corrected MAT1-1 and MAT1-2 among the isolates were equally distributed.

  2. Use of a Granular Bioplastic Formulation for Carrying Conidia of a Non-aflatoxigenic Strain of Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous research demonstrated that aflatoxin contamination in corn grown in Mississippi is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillus flavus strain NRRL 30797. To facilitate field applications of the biocontrol isolate, a series of laboratory ...

  3. Cryptic Sexuality Influences Aflatoxigenicity in Aspergillus parasiticus and A. flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascomycetous fungi of the genus Aspergillus comprise a wide variety of species of biotechnological importance as well as pathogens and toxin producers. Recent studies report A. fumigatus to be heterothallic and possibly undergoing sexual reproduction. We therefore investigated whether compatible mat...

  4. Expression of Genes by Aflatoxigenic and Nonaflatoxigenic Strains of Aspergillus flavus Isolated from Brazil Nuts.

    PubMed

    Baquião, Arianne Costa; Rodriges, Aline Guedes; Lopes, Evandro Luiz; Tralamazza, Sabina Moser; Zorzete, Patricia; Correa, Benedito

    2016-08-01

    The aims of the present study were to monitor the production of aflatoxin B1 (AFB1) and mycelial growth, and to evaluate the expression of genes directly and indirectly involved in the biosynthesis of aflatoxins by Aspergillus flavus isolated from Brazil nuts. Six previously identified A. flavus strains were grown on coconut agar at 25°C for up to 10 days. Mycotoxins were separated by high-performance liquid chromatography and fungal growth was measured daily using the diametric mycelial growth rate. Transcriptional analysis was performed by real-time polymerase chain reaction (PCR) after 2 and 7 d of incubation using specific primers (aflR, aflD, aflP, lipase, metalloprotease, and LaeA). Three (50%) of the six A. flavus isolates produced AFB1 (ICB-1, ICB-12, and ICB-54) and three (50%) were not aflatoxigenic (ICB-141, ICB-161, and ICB-198). Aflatoxin production was observed from d 2 of incubation (1.5 ng/g for ICB-54) and increased gradually with time of incubation until d 10 (15,803.6 ng/g for ICB-54). Almost all A. flavus isolates exhibited a similar gene expression pattern after 2 d of incubation (p > 0.10). After 7 d of incubation, the LaeA (p < 0.05) and metalloprotease (p < 0.05) genes were the most expressed by nonaflatoxigenic strains, whereas aflatoxigenic isolates exhibited higher expression of the aflR (p < 0.05) and aflD genes (p < 0.05). Our results suggest that the expression of aflR and aflD is correlated with aflatoxin production in A. flavus and that overexpression of aflR could affect the transcriptional and aflatoxigenic pattern (ICB-54). Elucidation of the molecular mechanisms that regulate the secondary metabolism of toxigenic fungi may permit the rational silencing of the genes involved and consequently the programmed inhibition of aflatoxin production. Knowledge of the conditions, under which aflatoxin genes are expressed, should contribute to the development of innovative and more cost-effective strategies to

  5. Expression of Genes by Aflatoxigenic and Nonaflatoxigenic Strains of Aspergillus flavus Isolated from Brazil Nuts.

    PubMed

    Baquião, Arianne Costa; Rodriges, Aline Guedes; Lopes, Evandro Luiz; Tralamazza, Sabina Moser; Zorzete, Patricia; Correa, Benedito

    2016-08-01

    The aims of the present study were to monitor the production of aflatoxin B1 (AFB1) and mycelial growth, and to evaluate the expression of genes directly and indirectly involved in the biosynthesis of aflatoxins by Aspergillus flavus isolated from Brazil nuts. Six previously identified A. flavus strains were grown on coconut agar at 25°C for up to 10 days. Mycotoxins were separated by high-performance liquid chromatography and fungal growth was measured daily using the diametric mycelial growth rate. Transcriptional analysis was performed by real-time polymerase chain reaction (PCR) after 2 and 7 d of incubation using specific primers (aflR, aflD, aflP, lipase, metalloprotease, and LaeA). Three (50%) of the six A. flavus isolates produced AFB1 (ICB-1, ICB-12, and ICB-54) and three (50%) were not aflatoxigenic (ICB-141, ICB-161, and ICB-198). Aflatoxin production was observed from d 2 of incubation (1.5 ng/g for ICB-54) and increased gradually with time of incubation until d 10 (15,803.6 ng/g for ICB-54). Almost all A. flavus isolates exhibited a similar gene expression pattern after 2 d of incubation (p > 0.10). After 7 d of incubation, the LaeA (p < 0.05) and metalloprotease (p < 0.05) genes were the most expressed by nonaflatoxigenic strains, whereas aflatoxigenic isolates exhibited higher expression of the aflR (p < 0.05) and aflD genes (p < 0.05). Our results suggest that the expression of aflR and aflD is correlated with aflatoxin production in A. flavus and that overexpression of aflR could affect the transcriptional and aflatoxigenic pattern (ICB-54). Elucidation of the molecular mechanisms that regulate the secondary metabolism of toxigenic fungi may permit the rational silencing of the genes involved and consequently the programmed inhibition of aflatoxin production. Knowledge of the conditions, under which aflatoxin genes are expressed, should contribute to the development of innovative and more cost-effective strategies to

  6. Enhanced diversity and aflatoxigenicity in interspecific hybrids of Aspergillus flavus and Aspergillus parasiticus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus and A. parasiticus are two of the most important aflatoxin-producing species that contaminate agricultural commodities worldwide. Both species are heterothallic and undergo sexual reproduction in laboratory crosses. Here, we examine the possibility of interspecific matings betwe...

  7. Comparison of major biocontrol strains of non-aflatoxigenic Aspergillus flavus for the reduction of aflatoxins and cyclopiazonic acid in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biological control of toxigenic Aspergillus flavus in maize through competitive displacement by non-aflatoxigenic strains was evaluated in a series of field studies. Four sets of experiments were conducted between 2007 to 2009 to assess the competitiveness of non-aflatoxigenic strains when challen...

  8. Co-inoculation of aflatoxigenic and non-aflatoxigenic strains of Aspergillus flavus to study fungal invasion, colonization, and competition in maize kernels

    PubMed Central

    Hruska, Zuzana; Rajasekaran, Kanniah; Yao, Haibo; Kincaid, Russell; Darlington, Dawn; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

    2014-01-01

    A currently utilized pre-harvest biocontrol method involves field inoculations with non-aflatoxigenic Aspergillus flavus strains, a tactic shown to strategically suppress native aflatoxin-producing strains and effectively decrease aflatoxin contamination in corn. The present in situ study focuses on tracking the invasion and colonization of an aflatoxigenic A. flavus strain (AF70), labeled with green fluorescent protein (GFP), in the presence of a non-aflatoxigenic A. flavus biocontrol strain (AF36), to better understand the competitive interaction between these two strains in seed tissue of corn (Zea mays). Corn kernels that had been co-inoculated with GFP-labeled AF70 and wild-type AF36 were cross-sectioned and observed under UV and blue light to determine the outcome of competition between these strains. After imaging, all kernels were analyzed for aflatoxin levels. There appeared to be a population difference between the co-inoculated AF70-GFP+AF36 and the individual AF70-GFP tests, both visually and with pixel count analysis. The GFP allowed us to observe that AF70-GFP inside the kernels was suppressed up to 82% when co-inoculated with AF36 indicating that AF36 inhibited progression of AF70-GFP. This was in agreement with images taken of whole kernels where AF36 exhibited a more robust external growth compared to AF70-GFP. The suppressed growth of AF70-GFP was reflected in a corresponding (upto 73%) suppression in aflatoxin levels. Our results indicate that the decrease in aflatoxin production correlated with population depression of the aflatoxigenic fungus by the biocontrol strain supporting the theory of competitive exclusion through robust propagation and fast colonization by the non-aflatoxigenic fungus. PMID:24734028

  9. Enhanced diversity and aflatoxigenicity in interspecific hybrids of Aspergillus flavus and Aspergillus parasiticus.

    PubMed

    Olarte, Rodrigo A; Worthington, Carolyn J; Horn, Bruce W; Moore, Geromy G; Singh, Rakhi; Monacell, James T; Dorner, Joe W; Stone, Eric A; Xie, De-Yu; Carbone, Ignazio

    2015-04-01

    Aspergillus flavus and A. parasiticus are the two most important aflatoxin-producing fungi responsible for the contamination of agricultural commodities worldwide. Both species are heterothallic and undergo sexual reproduction in laboratory crosses. Here we examine the possibility of interspecific matings between A. flavus and A. parasiticus. These species can be distinguished morphologically and genetically, as well as by their mycotoxin profiles. Aspergillus flavus produces both B aflatoxins and cyclopiazonic acid (CPA), B aflatoxins or CPA alone, or neither mycotoxin; Aspergillus parasiticus produces B and G aflatoxins or the aflatoxin precursor O-methylsterigmatocystin, but not CPA. Only four of forty-five attempted interspecific crosses between opposite mating types of A. flavus and A. parasiticus were fertile and produced viable ascospores. Single ascospore strains from each cross were shown to be recombinant hybrids using multilocus genotyping and array comparative genome hybridization. Conidia of parents and their hybrid progeny were haploid and predominantly monokaryons and dikaryons based on flow cytometry. Multilocus phylogenetic inference showed that experimental hybrid progeny were grouped with naturally occurring A. flavus L strain and A. parasiticus. Higher total aflatoxin concentrations in some F1 progeny strains compared to midpoint parent aflatoxin levels indicate synergism in aflatoxin production; moreover, three progeny strains synthesized G aflatoxins that were not produced by the parents, and there was evidence of allopolyploidization in one strain. These results suggest that hybridization is an important diversifying force resulting in the genesis of novel toxin profiles in these agriculturally important fungi.

  10. Use of a granular bioplastic formulation for carrying conidia of a non-aflatoxigenic strain of Aspergillus flavus.

    PubMed

    Accinelli, Cesare; Saccà, M Ludovica; Abbas, Hamed K; Zablotowicz, Robert M; Wilkinson, Jeffery R

    2009-09-01

    Previous research demonstrated that aflatoxin contamination in corn is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillus flavus strain NRRL 30797. To facilitate field applications of this biocontrol isolate, a series of laboratory studies were conducted on the reliability and efficiency of replacing wheat grains with the novel bioplastic formulation Mater-Bi to serve as a carrier matrix to formulate this fungus. Mater-Bi granules were inoculated with a conidial suspension of NRRL 30797 to achieve a final cell density of approximately log 7 conidia/granule. Incubation of 20-g soil samples receiving a single Mater-Bi granule for 60-days resulted in log 4.2-5.3 propagules of A. flavus/g soil in microbiologically active and sterilized soil, respectively. Increasing the number of granules had no effect on the degree of soil colonization by the biocontrol fungus. In addition to the maintenance of rapid vegetative growth and colonization of soil samples, the bioplastic formulation was highly stable, indicating that Mater-Bi is a suitable substitute for biocontrol applications of A. flavus NRRL 30797.

  11. RNA-Seq-Based Transcriptome Analysis of Aflatoxigenic Aspergillus flavus in Response to Water Activity

    PubMed Central

    Zhang, Feng; Guo, Zhenni; Zhong, Hong; Wang, Sen; Yang, Weiqiang; Liu, Yongfeng; Wang, Shihua

    2014-01-01

    Aspergillus flavus is one of the most important producers of carcinogenic aflatoxins in crops, and the effect of water activity (aw) on growth and aflatoxin production of A. flavus has been previously studied. Here we found the strains under 0.93 aw exhibited decreased conidiation and aflatoxin biosynthesis compared to that under 0.99 aw. When RNA-Seq was used to delineate gene expression profile under different water activities, 23,320 non-redundant unigenes, with an average length of 1297 bp, were yielded. By database comparisons, 19,838 unigenes were matched well (e-value < 10−5) with known gene sequences, and another 6767 novel unigenes were obtained by comparison to the current genome annotation of A. flavus. Based on the RPKM equation, 5362 differentially expressed unigenes (with |log2Ratio| ≥ 1) were identified between 0.99 aw and 0.93 aw treatments, including 3156 up-regulated and 2206 down-regulated unigenes, suggesting that A. flavus underwent an extensive transcriptome response during water activity variation. Furthermore, we found that the expression of 16 aflatoxin producing-related genes decreased obviously when water activity decreased, and the expression of 11 development-related genes increased after 0.99 aw treatment. Our data corroborate a model where water activity affects aflatoxin biosynthesis through increasing the expression of aflatoxin producing-related genes and regulating development-related genes. PMID:25421810

  12. Non-aflatoxigenic Aspergillus flavus to prevent aflatoxin contamination in crops: advantages and limitations

    PubMed Central

    Ehrlich, Kenneth C.

    2014-01-01

    Aspergillus flavus is a diverse assemblage of strains that include aflatoxin-producing and non-toxigenic strains with cosmopolitan distribution. The most promising strategy currently being used to reduce preharvest contamination of crops with aflatoxin is to introduce non-aflatoxin (biocontrol) A. flavus into the crop environment. Whether or not introduction of biocontrol strains into agricultural fields is enough to reduce aflatoxin contamination to levels required for acceptance of the contaminated food as fit for consumption is still unknown. There is no question that biocontrol strains are able to reduce the size of the populations of aflatoxin-producing strains but the available data suggests that at most only a four- to five-fold reduction in aflatoxin contamination is achieved. There are many challenges facing this strategy that are both short term and long term. First, the population biology of A. flavus is not well understood due in part to A. flavus’s diversity, its ability to form heterokaryotic reproductive forms, and its unknown ability to survive for prolonged periods after application. Second, biocontrol strains must be selected that are suitable for the environment, the type of crop, and the soil into which they will be introduced. Third, there is a need to guard against inadvertent introduction of A. flavus strains that could impose an additional burden on food safety and food quality, and fourth, with global warming and resultant changes in the soil nutrients and concomitant microbiome populations, the biocontrol strategy must be sufficiently flexible to adapt to such changes. Understanding genetic variation within strains of A. flavus is important for developing a robust biocontrol strategy and it is unlikely that a “one size fits all” strategy will work for preharvest aflatoxin reduction. PMID:24575088

  13. Heritability study of eGFP-transformed Aspergillus flavus strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pre-harvest prevention of aflatoxin contamination of corn, cottonseed, and peanut through field inoculation with non-aflatoxigenic Aspergillus flavus appears to be the only method for biocontrol currently being used. Until recently, evidence for out-crossing in A. flavus was observed in agar slants...

  14. Degeneration of aflatoxin gene clusters in Aspergillus flavus from Africa and North America.

    PubMed

    Adhikari, Bishwo N; Bandyopadhyay, Ranajit; Cotty, Peter J

    2016-12-01

    Aspergillus flavus is the most common causal agent of aflatoxin contamination of food and feed. However, aflatoxin-producing potential varies widely among A. flavus genotypes with many producing no aflatoxins. Some non-aflatoxigenic genotypes are used as biocontrol agents to prevent contamination. Aflatoxin biosynthesis genes are tightly clustered in a highly conserved order. Gene deletions and presence of single nucleotide polymorphisms (SNPs) in aflatoxin biosynthesis genes are often associated with A. flavus inability to produce aflatoxins. In order to identify mechanisms of non-aflatoxigenicity in non-aflatoxigenic genotypes of value in aflatoxin biocontrol, complete cluster sequences of 35 A. flavus genotypes from Africa and North America were analyzed. Inability of some genotypes to produce aflatoxin resulted from deletion of biosynthesis genes. In other genotypes, non-aflatoxigenicity originated from SNP formation. The process of degeneration differed across the gene cluster; genes involved in early biosynthesis stages were more likely to be deleted while genes involved in later stages displayed high frequencies of SNPs. Comparative analyses of aflatoxin gene clusters provides insight into the diversity of mechanisms of non-aflatoxigenicity in A. flavus genotypes used as biological control agents. The sequences provide resources for both diagnosis of non-aflatoxigenicity and monitoring of biocontrol genotypes during biopesticide manufacture and in the environment. PMID:27576895

  15. Managing and Monitoring of Aspergillus flavus in Corn Using Bioplastic-based Formulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, we evaluated the feasibility of bioplastic-based formulations for delivering a non-aflatoxigenic strain of Aspergillus flavus and for monitoring Aspergilli with the final objective of controlling aflatoxin contamination in corn. Field application of inoculated bioplastic granules show...

  16. Testing the efficacy of eGFP-transformed Aspergillus flavus as biocontrol strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current biological control methods to prevent pre-harvest aflatoxin contamination of corn, cottonseed, and ground and tree nuts involve field inoculation of non-aflatoxigenic Aspergillus flavus. To date, the efficacy of this approach requires annual reapplication of the biocontrol agent. The reason ...

  17. Distribution of aflatoxigenic Aspergillus section Flavi in commercial poultry feed in Nigeria.

    PubMed

    Ezekiel, C N; Atehnkeng, J; Odebode, A C; Bandyopadhyay, R

    2014-10-17

    The distribution and aflatoxigenicity of Aspergillus section Flavi isolates in 58 commercial poultry feed samples obtained from 17 states in five agro-ecological zones (AEZs) in Nigeria were determined in order to assess the safety of the feeds with respect to aflatoxin-producing fungi. Correlation was also performed for incidence of species, aflatoxin-producing ability of isolates in vitro, and aflatoxin (AFB1) concentrations in the feed. A total of 1006 Aspergillus section Flavi isolates were obtained from 87.9% of the feed samples and identified as Aspergillus flavus, unnamed taxon SBG, Aspergillus parasiticus and Aspergillus tamarii. A. flavus was the most prevalent (91.8%) of the isolates obtained from the feed in the AEZs while A. parasiticus had the lowest incidence (0.1%) and was isolated only from a layer mash sample collected from the DS zone. About 29% of the Aspergillus isolates produced aflatoxins in maize grains at concentrations up to 440,500μg/kg B and 341,000μg/kgG aflatoxins. The incidence of toxigenic isolates was highest (44.4%) in chick mash and lowest (19.9%) in grower mash. The population of A. flavus in the feed had positive (r=0.50) but non significant (p>0.05) correlations with proportion of toxigenic isolates obtained from the feed while SBG had significant (p<0.001) positive (r=0.99) influence on AFB1 concentrations in the feed. Poultry feed in Nigerian markets are therefore highly contaminated with aflatoxigenic Aspergillus species and consequently, aflatoxins. This is a potential threat to the poultry industry and requires urgent intervention.

  18. Assessment of aflatoxigenic Aspergillus and other fungi in millet and sesame from Plateau State, Nigeria

    PubMed Central

    Ezekiel, C.N.; Udom, I.E.; Frisvad, J.C.; Adetunji, M.C.; Houbraken, J.; Fapohunda, S.O.; Samson, R.A.; Atanda, O.O.; Agi-Otto, M.C.; Onashile, O.A.

    2014-01-01

    Sixteen fonio millet and 17 sesame samples were analysed for incidence of moulds, especially aflatoxigenic Aspergillus species, in order to determine the safety of both crops to consumers, and to correlate aflatoxin levels in the crops with levels produced by toxigenic isolates on laboratory medium. Diverse moulds including Alternaria, Aspergillus, Cercospora, Fusarium, Mucor, Penicillium, Rhizopus and Trichoderma were isolated. Aspergillus was predominantly present in both crops (46–48%), and amongst the potentially aflatoxigenic Aspergillus species, A. flavus recorded the highest incidence (68% in fonio millet; 86% in sesame kernels). All A. parvisclerotigenus isolates produced B and G aflatoxins in culture while B aflatoxins were produced by only 39% and 20% of A. flavus strains isolated from the fonio millet and sesame kernels, respectively. Aflatoxin concentrations in fonio millet correlated inversely (r = −0.55; p = 0.02) with aflatoxin levels produced by toxigenic isolates on laboratory medium, but no correlation was observed in the case of the sesame samples. Both crops, especially sesame, may not be suitable substrates for aflatoxin biosynthesis. This is the first report on A. parvisclerotigenus in sesame. PMID:24772370

  19. Assessment of aflatoxigenic Aspergillus and other fungi in millet and sesame from Plateau State, Nigeria.

    PubMed

    Ezekiel, C N; Udom, I E; Frisvad, J C; Adetunji, M C; Houbraken, J; Fapohunda, S O; Samson, R A; Atanda, O O; Agi-Otto, M C; Onashile, O A

    2014-03-01

    Sixteen fonio millet and 17 sesame samples were analysed for incidence of moulds, especially aflatoxigenic Aspergillus species, in order to determine the safety of both crops to consumers, and to correlate aflatoxin levels in the crops with levels produced by toxigenic isolates on laboratory medium. Diverse moulds including Alternaria, Aspergillus, Cercospora, Fusarium, Mucor, Penicillium, Rhizopus and Trichoderma were isolated. Aspergillus was predominantly present in both crops (46-48%), and amongst the potentially aflatoxigenic Aspergillus species, A. flavus recorded the highest incidence (68% in fonio millet; 86% in sesame kernels). All A. parvisclerotigenus isolates produced B and G aflatoxins in culture while B aflatoxins were produced by only 39% and 20% of A. flavus strains isolated from the fonio millet and sesame kernels, respectively. Aflatoxin concentrations in fonio millet correlated inversely (r = -0.55; p = 0.02) with aflatoxin levels produced by toxigenic isolates on laboratory medium, but no correlation was observed in the case of the sesame samples. Both crops, especially sesame, may not be suitable substrates for aflatoxin biosynthesis. This is the first report on A. parvisclerotigenus in sesame. PMID:24772370

  20. 76 FR 16297 - Aspergillus flavus

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-23

    ... Findings In the Federal Register of March 3, 2010 (75 FR 9596) (FRL-8811-2), EPA issued a notice pursuant..., 2003 (68 FR 41541) (FRL-7311-6). Those health effects data were the basis for establishing the... exemptions for experimental use of Aspergillus flavus AF36 on pistachio (72 FR 28871, May 23, 2007)...

  1. Decontamination of Aspergillus flavus and Aspergillus parasiticus spores on hazelnuts via atmospheric pressure fluidized bed plasma reactor.

    PubMed

    Dasan, Beyhan Gunaydin; Mutlu, Mehmet; Boyaci, Ismail Hakki

    2016-01-01

    In this study, an atmospheric pressure fluidized bed plasma (APFBP) system was designed and its decontamination effect on aflatoxigenic fungi (Aspergillus flavus and Aspergillus parasiticus) on the surface of hazelnuts was investigated. Hazelnuts were artificially contaminated with A. flavus and A. parasiticus and then were treated with dry air plasma for up to 5min in the APFBP system at various plasma parameters. Significant reductions of 4.50 log (cfu/g) in A. flavus and 4.19 log (cfu/g) in A. parasiticus were achieved after 5min treatments at 100% V - 25kHz (655W) by using dry air as the plasma forming gas. The decontamination effect of APFBP on A. flavus and A. parasiticus spores inoculated on hazelnuts was increased with the applied reference voltage and the frequency. No change or slight reductions were observed in A. flavus and A. parasiticus load during the storage of plasma treated hazelnuts whereas on the control samples fungi continued to grow under storage conditions (30days at 25°C). Temperature change on hazelnut surfaces in the range between 35 and 90°C was monitored with a thermal camera, and it was demonstrated that the temperature increase taking place during plasma treatment did not have a lethal effect on A. flavus and A. parasiticus spores. The damage caused by APFBP treatment on Aspergillus spp. spores was also observed by scanning electron microscopy.

  2. Decontamination of Aspergillus flavus and Aspergillus parasiticus spores on hazelnuts via atmospheric pressure fluidized bed plasma reactor.

    PubMed

    Dasan, Beyhan Gunaydin; Mutlu, Mehmet; Boyaci, Ismail Hakki

    2016-01-01

    In this study, an atmospheric pressure fluidized bed plasma (APFBP) system was designed and its decontamination effect on aflatoxigenic fungi (Aspergillus flavus and Aspergillus parasiticus) on the surface of hazelnuts was investigated. Hazelnuts were artificially contaminated with A. flavus and A. parasiticus and then were treated with dry air plasma for up to 5min in the APFBP system at various plasma parameters. Significant reductions of 4.50 log (cfu/g) in A. flavus and 4.19 log (cfu/g) in A. parasiticus were achieved after 5min treatments at 100% V - 25kHz (655W) by using dry air as the plasma forming gas. The decontamination effect of APFBP on A. flavus and A. parasiticus spores inoculated on hazelnuts was increased with the applied reference voltage and the frequency. No change or slight reductions were observed in A. flavus and A. parasiticus load during the storage of plasma treated hazelnuts whereas on the control samples fungi continued to grow under storage conditions (30days at 25°C). Temperature change on hazelnut surfaces in the range between 35 and 90°C was monitored with a thermal camera, and it was demonstrated that the temperature increase taking place during plasma treatment did not have a lethal effect on A. flavus and A. parasiticus spores. The damage caused by APFBP treatment on Aspergillus spp. spores was also observed by scanning electron microscopy. PMID:26398284

  3. Interaction between maize seed and Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is an opportunistic fungal pathogen that colonizes maize seeds and contaminates them with aflatoxin. The fungus is localized in the endosperm and aleurone. To investigate the plant microbe interaction, we conducted histological and molecular studies to characterize the internal co...

  4. Cyclopiazonic Acid Biosynthesis of Aspergillus flavus and Aspergillus oryzae

    PubMed Central

    Chang, Perng-Kuang; Ehrlich, Kenneth C.; Fujii, Isao

    2009-01-01

    Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by some of the same strains of A. flavus that produce aflatoxins and by some Aspergillus oryzae strains. Despite its discovery 40 years ago, few reviews of its toxicity and biosynthesis have been reported. This review examines what is currently known about the toxicity of CPA to animals and humans, both by itself or in combination with other mycotoxins. The review also discusses CPA biosynthesis and the genetic diversity of CPA production in A. flavus/oryzae populations. PMID:22069533

  5. Nuclear heterogeneity in conidial populations of Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a major producer of aflatoxin and an opportunistic pathogen for a wide range of hosts. Understanding genotypic and phenotypic variations within strains of A. flavus is important for controlling disease and reducing aflatoxin contamination. A. flavus is multinucleate and predomi...

  6. Inhibition of aflatoxin metabolism and growth of Aspergillus flavus in liquid culture by a DNA methylation inhibitor.

    PubMed

    Yang, Kunlong; Zhuang, Zhenhong; Zhang, Feng; Song, Fengqin; Zhong, Hong; Ran, Fanlei; Yu, Song; Xu, Gaopo; Lan, Faxiu; Wang, Shihua

    2015-01-01

    Aflatoxins (AFs) are a group of highly oxygenated polyketidese-derived toxins mainly produced by Aspergillus flavus and A. parasiticus, whose biosynthesis mechanisms are extremely sophisticated. Methylation is known as the major form of epigenetic regulation, which is correlated with gene expression. As the DNA methylation inhibitor 5-azacytidine (5-AC) blocks AF production, we studied AFB1 metabolism and morphological changes of A. flavus by treatment with 5-AC in liquid culture. The results show that 5-AC caused a decrease in AF production and concurrent changes in morphology. In addition, we isolated a non-aflatoxigenic mutant of A. flavus, showing a significant reduction in pigment production, after 5-AC treatment. This mutant showed significant reduction in the expression of genes in the AF biosynthesis pathway, and conidia formation. Furthermore, as AF biosynthesis and oxidative stress are intimately related events, we assessed the viability of A. flavus to oxidative stress after treatment with 5-AC, which showed that the mutant was more sensitive to the strong oxidant hydrogen peroxide. We found that the non-aflatoxigenic mutant showed a decrease in reactive oxygen species (ROS) and metabolites indicative of oxidative stress, which may be caused by the disruption of the defence system against excessive ROS formation after 5-AC treatment. These data indicate that 5-AC, as an inactivator of DNA methyltransferase, plays a very important role in AFB1 metabolism and the development of A. flavus, which might provide an effective strategy to pre- or post-harvest control of AFs. PMID:25312249

  7. Comparative mapping of aflatoxin pathway gene clusters in Aspergillus parasiticus and Aspergillus flavus.

    PubMed Central

    Yu, J; Chang, P K; Cary, J W; Wright, M; Bhatnagar, D; Cleveland, T E; Payne, G A; Linz, J E

    1995-01-01

    Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. Aflatoxins are synthesized by condensation of acetate units; their synthesis is estimated to involve at least 16 different enzymes. In this study we have shown that at least nine genes involved in the aflatoxin biosynthetic pathway are located within a 60-kb DNA fragment. Four of these genes, nor-1, aflR, ver-1, and omtA (previously named omt-1), have been cloned in A. flavus and A. parasiticus. In addition, five other genes, pksA, uvm8, aad, ord-1, and ord-2 have been recently cloned in A. parasiticus. The pksA, aad, and uvm8 genes exhibit sequence homologies to polyketide synthase, aryl-alcohol dehydrogenase, and fatty acid synthase genes, respectively. The cDNA sequences of ord-1 and ord-2 genes, which may be involved in later steps of aflatoxin biosynthesis, have been determined; the ord-1 gene product exhibits homology to cytochrome P-450-type enzymes. By characterizing the overlapping regions of the DNA inserts in different cosmid and lambda DNA clones, we have determined the order of these aflatoxin pathway genes within this 60-kb DNA region to be pksA, nor-1, uvm8, aflR, aad, ver-1, ord-1, ord-2, and omtA in A. parasiticus and nor-1, aflR, ver-1, ord-1, ord-2, and omtA in A. flavus. The order is related to the order in enzymatic steps required for aflatoxin biosynthesis. The physical distances (in kilobase pairs) and the directions of transcription of these genes have been determined for both aflatoxigenic species. PMID:7793957

  8. Characterization of Natural Antisense Transcript, Sclerotia Development and Secondary Metabolism by Strand-Specific RNA Sequencing of Aspergillus flavus

    PubMed Central

    Yin, Chao; Guo, Yong; Lin, Ying; Pan, Li; Wang, Bin

    2014-01-01

    Aspergillus flavus has received much attention owing to its severe impact on agriculture and fermented products induced by aflatoxin. Sclerotia morphogenesis is an important process related to A. flavus reproduction and aflatoxin biosynthesis. In order to obtain an extensive transcriptome profile of A. flavus and provide a comprehensive understanding of these physiological processes, the isolated mRNA of A. flavus CA43 cultures was subjected to high-throughput strand-specific RNA sequencing (ssRNA-seq). Our ssRNA-seq data profiled widespread transcription across the A. flavus genome, quantified vast transcripts (73% of total genes) and annotated precise transcript structures, including untranslated regions, upstream open reading frames (ORFs), alternative splicing variants and novel transcripts. We propose natural antisense transcripts in A. flavus might regulate gene expression mainly on the post-transcriptional level. This regulation might be relevant to tune biological processes such as aflatoxin biosynthesis and sclerotia development. Gene Ontology annotation of differentially expressed genes between the mycelia and sclerotia cultures indicated sclerotia development was related closely to A. flavus reproduction. Additionally, we have established the transcriptional profile of aflatoxin biosynthesis and its regulation model. We identified potential genes linking sclerotia development and aflatoxin biosynthesis. These genes could be used as targets for controlled regulation of aflatoxigenic strains of A. flavus. PMID:24849659

  9. Polymerase chain reaction-mediated characterization of molds belonging to the Aspergillus flavus group and detection of Aspergillus parasiticus in peanut kernels by a multiplex polymerase chain reaction.

    PubMed

    Chen, Ruey-Shyang; Tsay, Jwu-Guh; Huang, Yu-Fen; Chiou, Robin Y Y

    2002-05-01

    The Aspergillus flavus group covers species of A. flavus and Aspergillus parasiticus as aflatoxin producers and Aspergillus oryzae and Aspergillus sojae as koji molds. Genetic similarity among these species is high, and aflatoxin production of a culture may be affected by cultivation conditions and substrate composition. Therefore, a polymerase chain reaction (PCR)-mediated method of detecting the aflatoxin-synthesizing genes to indicate the degree of risk a genotype has of being a phenotypic producer was demonstrated. In this study, 19 strains of the A. flavus group, including A. flavus, A. parasiticus, A. oryzae, A. sojae, and one Aspergillus niger, were subjected to PCR testing in an attempt to detect four genes, encoding for norsolorinic acid reductase (nor-1), versicolorin A dehydrogenase (ver-1), sterigmatocystin O-methyltransferase (omt-1), and a regulatory protein (apa-2), involved in aflatoxin biosynthesis. Concurrently, the strains were cultivated in yeast-malt (YM) broth for aflatoxin detection. Fifteen strains were shown to possess the four target DNA fragments. With regard to aflatoxigenicity, all seven aflatoxigenic strains possessed the four DNA fragments, and five strains bearing less than the four DNA fragments did not produce aflatoxin. When peanut kernels were artificially contaminated with A. parasiticus and A. niger for 7 days, the contaminant DNA was extractable from a piece of cotyledon (ca. 100 mg), and when subjected to multiplex PCR testing using the four pairs of primers coding for the above genes, they were successfully detected. The target DNA fragments were detected in the kernels infected with A. parasiticus, and none was detected in the sound (uninoculated) kernels or in the kernels infected with A. niger.

  10. Draft genome sequence of an aflatoxigenic Aspergillus species, A. bombycis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genome of the A. bombycis Type strain was sequenced using a Personal Genome Machine, followed by annotation of its predicted genes. The genome size for A. bombycis was found to be approximately 37 Mb and contained 12,266 genes. This announcement introduces a sequenced genome for an aflatoxigenic...

  11. Molecular characterisation of Aspergillus flavus isolates from peanut fields in India using AFLP.

    PubMed

    Singh, Diwakar; Radhakrishnan, T; Kumar, Vinod; Bagwan, N B; Basu, M S; Dobaria, J R; Mishra, Gyan P; Chanda, S V

    2015-01-01

    Aflatoxin contamination of peanut, due to infection by Aspergillus flavus, is a major problem of rain-fed agriculture in India. In the present study, molecular characterisation of 187 Aspergillus flavus isolates, which were sampled from the peanut fields of Gujarat state in India, was performed using AFLP markers. On a pooled cluster analysis, the markers could successfully discriminate among the 'A', 'B' and 'G' group A. flavus isolates. PCoA analysis also showed equivalent results to the cluster analysis. Most of the isolates from one district could be clustered together, which indicated genetic similarity among the isolates. Further, a lot of genetic variability was observed within a district and within a group. The results of AMOVA test revealed that the variance within a population (84%) was more than that between two populations (16%). The isolates, when tested by indirect competitive ELISA, showed about 68.5% of them to be atoxigenic. Composite analysis between the aflatoxin production and AFLP data was found to be ineffective in separating the isolate types by aflatoxigenicity. Certain unique fragments, with respect to individual isolates, were also identified that may be used for development of SCAR marker to aid in rapid and precise identification of isolates.

  12. Aspergillus flavus contamination in two Portuguese wastewater treatment plants.

    PubMed

    Viegas, C; Dias, R; Gomes, A Quintal; Meneses, M; Sabino, R; Viegas, S

    2014-01-01

    Filamentous fungi from genus Aspergillus were previously detected in wastewater treatment plants (WWTP) as being Aspergillus flavus (A. flavus), an important toxigenic fungus producing aflatoxins. This study aimed to determine occupational exposure adverse effects due to fungal contamination produced by A. flavus complex in two Portuguese WWTP using conventional and molecular methodologies. Air samples from two WWTP were collected at 1 m height through impaction method. Surface samples were collected by swabbing surfaces of the same indoor sites. After counting A. flavus and identification, detection of aflatoxin production was ensured through inoculation of seven inoculates in coconut-milk agar. Plates were examined under long-wave ultraviolet (UV; 365 nm) illumination to search for the presence of fluorescence in the growing colonies. To apply molecular methods, air samples were also collected using the impinger method. Samples were collected and collection liquid was subsequently used for DNA extraction. Molecular identification of A. flavus was achieved by real-time polymerase chain reaction (RT-PCR) using the Rotor-Gene 6000 qPCR detection system (Corbett). Among the Aspergillus genus, the species that were more abundant in air samples from both WWTP were Aspergillus versicolor (38%), Aspergillus candidus (29.1%), and Aspergillus sydowii (12.7%). However, the most commonly species found on surfaces were A. flavus (47.3%), Aspergillus fumigatus (34.4%), and Aspergillus sydowii (10.8%). Aspergillus flavus isolates that were inoculated in coconut agar medium were not identified as toxigenic strains and were not detected by RT-PCR in any of the analyzed samples from both plants. Data in this study indicate the need for monitoring fungal contamination in this setting. Although toxigenic strains were not detected from A. flavus complex, one cannot disregard the eventual presence and potential toxicity of aflatoxins. PMID:25072712

  13. Nutrient environment influences competition among Aspergillus flavus genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Structures of Aspergillus flavus populations, shaped by intraspecific competition, influence the incidences and severities of crop aflatoxin contamination. Competition for nutrients may be one factor modulating intraspecific interactions, but influences of specific types and concentrations of nutrie...

  14. Potential of Aspergillus flavus Genomics for Applications in Biotechnology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a common saprophyte and opportunistic pathogen that survives in the natural environment by extracting nutrition from plant debris, insect carcasses and a variety of other carbon sources. A. flavus produces numerous secondary metabolites and hydrolytic enzymes. The primary obj...

  15. The maize rachis affects Aspergillus flavus movement during ear development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus expressing green fluorescent protein (GFP) was used to follow infection in ears of maize hybrids resistant and susceptible to the fungus. Developing ears were needle-inoculated with GFP-transformed A. flavus 20 days after silk emergence, and GFP fluorescence in the pith was evalu...

  16. Population dynamics of Aspergillus flavus following biocontrol treatment of corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a fungal pathogen of many agronomically important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, North Carolina, over a period of two years. The field was planted in 2010 and plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Af...

  17. Population structure of Aspergillus flavus before and after biocontrol treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a fungal pathogen of many important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, North Carolina, over a period of two years. Plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Afla-Guard) biocontrol strains, both of which are ...

  18. 40 CFR 180.1206 - Aspergillus flavus AF36; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Aspergillus flavus AF36; exemption... FOOD Exemptions From Tolerances § 180.1206 Aspergillus flavus AF36; exemption from the requirement of a... pesticide Aspergillus flavus AF36 in or on cotton, gin byproducts; cotton, hulls; cotton, meal;...

  19. Effect of sexual recombination on population diversity in aflatoxin production by Aspergillus flavus and evidence for cryptic heterokaryosis.

    PubMed

    Olarte, Rodrigo A; Horn, Bruce W; Dorner, Joe W; Monacell, James T; Singh, Rakhi; Stone, Eric A; Carbone, Ignazio

    2012-03-01

    Aspergillus flavus is the major producer of carcinogenic aflatoxins (AFs) in crops worldwide. Natural populations of A. flavus show tremendous variation in AF production, some of which can be attributed to environmental conditions, differential regulation of the AF biosynthetic pathway and deletions or loss-of-function mutations in the AF gene cluster. Understanding the evolutionary processes that generate genetic diversity in A. flavus may also explain quantitative differences in aflatoxigenicity. Several population studies using multilocus genealogical approaches provide indirect evidence of recombination in the genome and specifically in the AF gene cluster. More recently, A. flavus has been shown to be functionally heterothallic and capable of sexual reproduction in laboratory crosses. In the present study, we characterize the progeny from nine A. flavus crosses using toxin phenotype assays, DNA sequence-based markers and array comparative genome hybridization. We show high AF heritability linked to genetic variation in the AF gene cluster, as well as recombination through the independent assortment of chromosomes and through crossing over within the AF cluster that coincides with inferred recombination blocks and hotspots in natural populations. Moreover, the vertical transmission of cryptic alleles indicates that while an A. flavus deletion strain is predominantly homokaryotic, it may harbour AF cluster genes at a low copy number. Results from experimental matings indicate that sexual recombination is driving genetic and functional hyperdiversity in A. flavus. The results of this study have significant implications for managing AF contamination of crops and for improving biocontrol strategies using nonaflatoxigenic strains of A. flavus.

  20. Genomic sequence for the aflatoxigenic filamentous fungus Aspergillus nomius

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genome of the A. nomius type strain was sequenced using a personal genome machine. Annotation of the genes was undertaken, followed by gene ontology and an investigation into the number of secondary metabolite clusters. Comparative studies with other Aspergillus species involved shared/unique ge...

  1. Genetic Response to Seed Colonizatin by Aspergillus flavus in Peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies to evaluate peanut genotypes for in vitro resistance to seed colonization by Aspergillus flavus have not resulted in the development of cultivars with resistance to aflatoxin contamination in the field. New breeding lines showing pre-harvest field resistance to aflatoxin contaminat...

  2. Aflatoxin production and oxidative stress in Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The colonization of crops by Aspergillus flavus results in the production of aflatoxins. Aflatoxin production is also exacerbated by abiotic stresses in the field. Here, we investigated the role of reactive oxygen species (ROS), which accumulate in plant tissues in response to drought and heat stres...

  3. Cryptic Sexuality in Aspergillus parasiticus and A. flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascomycetous fungi of the genus Aspergillus comprise a wide variety of species of biotechnological importance (e.g. A. sojae, A. oryzae, A. niger) as well as pathogens and toxin producers (e.g. A. flavus, A. parasiticus, A. fumigatus, A. nidulans). With the exception of A. nidulans, which is a homot...

  4. Aspergillus flavus SUMO Contributes to Fungal Virulence and Toxin Attributes.

    PubMed

    Nie, Xinyi; Yu, Song; Qiu, Mengguang; Wang, Xiuna; Wang, Yu; Bai, Youhuang; Zhang, Feng; Wang, Shihua

    2016-09-01

    Small ubiquitin-like modifiers (SUMOs) can be reversibly attached to target proteins in a process known as SUMOylation, and this process influences several important eukaryotic cell events. However, little is known regarding SUMO or SUMOylation in Aspergillus flavus. Here, we identified a novel member of the SUMO family in A. flavus, AfSumO, and validated the existence of SUMOylation in this pathogenic filamentous fungus. We investigated the roles of AfsumO in A. flavus by determining the effects of AfsumO mutations on the growth phenotype, stress response, conidia and sclerotia production, aflatoxin biosynthesis, and pathogenicity to seeds, and we found that SUMOylation plays a role in fungal virulence and toxin attributes. Taken together, these results not only reveal potential mechanisms of fungal virulence and toxin attributes in A. flavus but also provide a novel approach for promising new control strategies of this fungal pathogen. PMID:27532332

  5. Understanding the genetics of regulation of aflatoxin production and Aspergillus flavus development.

    PubMed

    Bhatnagar, Deepak; Cary, Jeffrey W; Ehrlich, Kenneth; Yu, Jiujiang; Cleveland, Thomas E

    2006-09-01

    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

  6. Lipids in Aspergillus flavus-maize interaction

    PubMed Central

    Scarpari, Marzia; Punelli, Marta; Scala, Valeria; Zaccaria, Marco; Nobili, Chiara; Ludovici, Matteo; Camera, Emanuela; Fabbri, Anna A.; Reverberi, Massimo; Fanelli, Corrado

    2014-01-01

    In some filamentous fungi, the pathways related to the oxidative stress and oxylipins production are involved both in the process of host-recognition and in the pathogenic phase. In fact, recent studies have shown that the production of oxylipins in filamentous fungi, yeasts and chromists is also related to the development of the organism itself and to mechanisms of communication with the host at the cellular level. The oxylipins, also produced by the host during defense reactions, are able to induce sporulation and to regulate the biosynthesis of mycotoxins in several pathogenic fungi. In A. flavus, the oxylipins play a crucial role as signals for regulating the biosynthesis of aflatoxins, the conidiogenesis and the formation of sclerotia. To investigate the involvement of an oxylipins based cross-talk into Z. mays and A. flavus interaction, we analyzed the oxylipins profile of the wild type strain and of three mutants of A. flavus that are deleted at the Aflox1 gene level also during maize kernel invasion. A lipidomic approach has been addressed through the use of LC-ToF-MS, followed by a statistical analysis of the principal components (PCA). The results showed the existence of a difference between the oxylipins profile generated by the WT and the mutants onto challenged maize. In relation to this, aflatoxin synthesis which is largely hampered in vitro, is intriguingly restored. These results highlight the important role of maize oxylipin in driving secondary metabolism in A. flavus. PMID:24578700

  7. Potential involvement of Aspergillus flavus laccases in peanut invasion at low water potential

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus (Link) accumulates aflatoxins in peanuts, mainly affecting immature kernels during drought. Peanut invasion by A. flavus induces synthesis of phytoalexins, mostly stilbenoids, as a plant defense mechanism. Fungal laccases are often related to pathogenicity, and among other subst...

  8. Genotypic and Phenotypic Versatility of Aspergillus flavus during Maize Exploitation

    PubMed Central

    Reverberi, Massimo; Punelli, Marta; Scala, Valeria; Scarpari, Marzia; Uva, Paolo; Mentzen, Wieslawa I.; Dolezal, Andrea L.; Woloshuk, Charles; Pinzari, Flavia; Fabbri, Anna A.; Fanelli, Corrado; Payne, Gary A.

    2013-01-01

    Aspergillus flavus is a cosmopolitan fungus able to respond to external stimuli and to shift both its trophic behaviour and the production of secondary metabolites, including that of the carcinogen aflatoxin (AF). To better understand the adaptability of this fungus, we examined genetic and phenotypic responses within the fungus when grown under four conditions that mimic different ecological niches ranging from saprophytic growth to parasitism. Global transcription changes were observed in both primary and secondary metabolism in response to these conditions, particularly in secondary metabolism where transcription of nearly half of the predicted secondary metabolite clusters changed in response to the trophic states of the fungus. The greatest transcriptional change was found between saprophytic and parasitic growth, which resulted in expression changes in over 800 genes in A. flavus. The fungus also responded to growth conditions, putatively by adaptive changes in conidia, resulting in differences in their ability to utilize carbon sources. We also examined tolerance of A. flavus to oxidative stress and found that growth and secondary metabolism were altered in a superoxide dismutase (sod) mutant and an alkyl-hydroperoxide reductase (ahp) mutant of A. flavus. Data presented in this study show a multifaceted response of A. flavus to its environment and suggest that oxidative stress and secondary metabolism are important in the ecology of this fungus, notably in its interaction with host plant and in relation to changes in its lifestyle (i.e. saprobic to pathogenic). PMID:23894339

  9. Draft Genome Sequences of Two Closely Related Aflatoxigenic Aspergillus Species Obtained from the Ivory Coast.

    PubMed

    Moore, Geromy G; Mack, Brian M; Beltz, Shannon B

    2015-12-03

    Aspergillus ochraceoroseus and Aspergillus rambellii were isolated from soil detritus in Taï National Park, Ivory Coast, Africa. The Type strain for each species happens to be the only representative ever sampled. Both species secrete copious amounts of aflatoxin B1 and sterigmatocystin, because each of their genomes contains clustered genes for biosynthesis of these mycotoxins. We sequenced their genomes using a personal genome machine and found them to be smaller in size (A. ochraceoroseus = 23.9 Mb and A. rambellii = 26.1 Mb), as well as in numbers of predicted genes (7,837 and 7,807, respectively), compared to other sequenced Aspergilli. Our findings also showed that the A. ochraceoroseus Type strain contains a single MAT1-1 gene, while the Type strain of A. rambellii contains a single MAT1-2 gene, indicating that these species are heterothallic (self-infertile). These draft genomes will be useful for understanding the genes and pathways necessary for the cosynthesis of these two toxic secondary metabolites as well as the evolution of these pathways in aflatoxigenic fungi.

  10. Draft Genome Sequences of Two Closely Related Aflatoxigenic Aspergillus Species Obtained from the Ivory Coast.

    PubMed

    Moore, Geromy G; Mack, Brian M; Beltz, Shannon B

    2016-03-01

    Aspergillus ochraceoroseus and Aspergillus rambellii were isolated from soil detritus in Taï National Park, Ivory Coast, Africa. The Type strain for each species happens to be the only representative ever sampled. Both species secrete copious amounts of aflatoxin B1 and sterigmatocystin, because each of their genomes contains clustered genes for biosynthesis of these mycotoxins. We sequenced their genomes using a personal genome machine and found them to be smaller in size (A. ochraceoroseus = 23.9 Mb and A. rambellii = 26.1 Mb), as well as in numbers of predicted genes (7,837 and 7,807, respectively), compared to other sequenced Aspergilli. Our findings also showed that the A. ochraceoroseus Type strain contains a single MAT1-1 gene, while the Type strain of A. rambellii contains a single MAT1-2 gene, indicating that these species are heterothallic (self-infertile). These draft genomes will be useful for understanding the genes and pathways necessary for the cosynthesis of these two toxic secondary metabolites as well as the evolution of these pathways in aflatoxigenic fungi. PMID:26637470

  11. Atoxigenic Aspergillus flavus endemic to Italy for biocontrol of aflatoxins in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effective biological control of aflatoxin­producing Aspergillus flavus with atoxigenic members of that species requires suitable A. flavus well adapted to and resident in target agroecosystems. Eighteen atoxigenic isolates of A. flavus endemic in Italy were compared for ability to reduce aflatoxin c...

  12. Effect of gamma radiation on Aspergillus flavus and Aspergillus ochraceus ultrastructure and mycotoxin production

    NASA Astrophysics Data System (ADS)

    Ribeiro, J.; Cavaglieri, L.; Vital, H.; Cristofolini, A.; Merkis, C.; Astoreca, A.; Orlando, J.; Carú, M.; Dalcero, A.; Rosa, C. A. R.

    2011-05-01

    The aim of this work was to study the effect of gamma radiation (2 kGy) on Aspergillus flavus and Aspergillus ochraceus ultrastructure. Moreover, the influence on aflatoxin B 1 and ochratoxin A production was also observed. Irradiated A. flavus strain showed a dull orangish colony while control strain showed the typical green color. Minor differences were observed on stipes, metulae and conidia size between control and irradiated A. flavus and A. ochraceus strains. Irradiated fungi showed ultrastructural changes on cell wall, plasmalema and cytoplasm levels. The levels of mycotoxins produced by irradiated strains were two times greater than those produced by control strains. Successive transferences of irradiated strains on malt extract agar allowed the fungus to recuperate morphological characteristics. Although minor changes in the fungal morphology were observed, ultrastructural changes at cell wall level and the increase of mycotoxin production ability were observed. Inappropriate storage of irradiated food and feed would allow the development of potentially more toxicogenic fungal propagules.

  13. Aspergillus flavus impairs antioxidative enzymes of Sternochetus mangiferae during mycosis.

    PubMed

    Jayanthi, Kamala P D; Ayyasamy, Arthikirubha; Kempraj, Vivek; Aurade, Ravindra M; Govindan, Selvakumar; Verghese, Abraham

    2015-01-01

    Insects depend upon cuticular, humoral and cellular defenses to resist mycosis. However, entomopathogenic fungi through co-evolution have developed mechanisms to counter such defenses. Although a plethora of mechanisms of mycosis by entomopathogenic fungi are well-established, studies on the impairment of insects' antioxidative enzymes during mycosis remain elusive. Here, we used the interaction of Sternochetus mangiferae and its associated entomopathogenic fungus, Aspergillus flavus, as a model to validate our hypothesis. Uninfected insects were exposed to fungal spores for infection to occur. We observed symptoms of mycosis within 48 h of incubation period. Biochemical studies on antioxidative enzymes namely catalase, peroxidase and phenoloxidase, in infected and uninfected insects revealed decreased activity of these enzymes. It appears that A. flavus disables the host's antioxidative enzyme system that plays a crucial role in elimination of oxidative toxins produced during mycosis. PMID:25446036

  14. How Peroxisomes Affect Aflatoxin Biosynthesis in Aspergillus Flavus

    PubMed Central

    Reverberi, Massimo; Punelli, Marta; Smith, Carrie A.; Zjalic, Slaven; Scarpari, Marzia; Scala, Valeria; Cardinali, Giorgia; Aspite, Nicaela; Pinzari, Flavia; Payne, Gary A.; Fabbri, Anna A.; Fanelli, Corrado

    2012-01-01

    In filamentous fungi, peroxisomes are crucial for the primary metabolism and play a pivotal role in the formation of some secondary metabolites. Further, peroxisomes are important site for fatty acids β-oxidation, the formation of reactive oxygen species and for their scavenging through a complex of antioxidant activities. Oxidative stress is involved in different metabolic events in all organisms and it occurs during oxidative processes within the cell, including peroxisomal β-oxidation of fatty acids. In Aspergillus flavus, an unbalance towards an hyper-oxidant status into the cell is a prerequisite for the onset of aflatoxin biosynthesis. In our preliminary results, the use of bezafibrate, inducer of both peroxisomal β-oxidation and peroxisome proliferation in mammals, significantly enhanced the expression of pex11 and foxA and stimulated aflatoxin synthesis in A. flavus. This suggests the existence of a correlation among peroxisome proliferation, fatty acids β-oxidation and aflatoxin biosynthesis. To investigate this correlation, A. flavus was transformed with a vector containing P33, a gene from Cymbidium ringspot virus able to induce peroxisome proliferation, under the control of the promoter of the Cu,Zn-sod gene of A. flavus. This transcriptional control closely relates the onset of the antioxidant response to ROS increase, with the proliferation of peroxisomes in A. flavus. The AfP33 transformant strain show an up-regulation of lipid metabolism and an higher content of both intracellular ROS and some oxylipins. The combined presence of a higher amount of substrates (fatty acids-derived), an hyper-oxidant cell environment and of hormone-like signals (oxylipins) enhances the synthesis of aflatoxins in the AfP33 strain. The results obtained demonstrated a close link between peroxisome metabolism and aflatoxin synthesis. PMID:23094106

  15. Aqueous extracts of Tulbaghia violacea inhibit germination of Aspergillus flavus and Aspergillus parasiticus conidia.

    PubMed

    Somai, Benesh Munilal; Belewa, Vuyokazi

    2011-06-01

    Aspergillus flavus and Aspergillus parasiticus are important plant pathogens and causal agents of pre- and postharvest rots of corn, peanuts, and tree nuts. These fungal pathogens cause significant crop losses and produce aflatoxins, which contaminate many food products and contribute to liver cancer worldwide. Aqueous preparations of Tulbaghia violacea (wild garlic) were antifungal and at 10 mg/ml resulted in sustained growth inhibition of greater than 50% for both A. flavus and A. parasiticus. Light microscopy revealed that the plant extract inhibited conidial germination in a dose-dependent manner. When exposed to T. violacea extract concentrations of 10 mg/ml and above, A. parasiticus conidia began germinating earlier and germination was completed before that of A. flavus, indicating that A. parasiticus conidia were more resistant to the antifungal effects of T. violacea than were A. flavus conidia. At a subinhibitory extract dose of 15 mg/ml, hyphae of both fungal species exhibited increased granulation and vesicle formation, possibly due to increased reactivity between hyphal cellular components and T. violacea extract. These hyphal changes were not seen when hyphae were formed in the absence of the extract. Transmission electron microscopy revealed thickening of conidial cell walls in both fungal species when grown in the presence of the plant extract. Cell walls of A. flavus also became considerably thicker than those of A. parasiticus, indicating differential response to the extract. Aqueous preparations of T. violacea can be used as antifungal treatments for the control of A. flavus and A. parasiticus. Because the extract exhibited a more pronounced effect on A. flavus than on A. parasiticus, higher doses may be needed for control of A. parasiticus infections. PMID:21669082

  16. Copper induction and differential expression of laccase in Aspergillus flavus

    PubMed Central

    Gomaa, Ola M.; Momtaz, Osama A.

    2015-01-01

    Aspergillus flavus was isolated from soil and exhibited laccase activity under both constitutive and copper induced conditions. Spiking the medium with 1 mM copper sulfate resulted in an increase in the activity which reached 51.84 U/mL, a distinctive protein band was detected at 60 kDa. The extracellular enzyme was purified 81 fold using gel filtration chromatography and resulted in two different laccase fractions L1 and L2, the latter had a higher enzymatic activity which reached 79.57 U/mL and specific activity of 64.17 U/μg protein. The analysis of the spectrum of the L2 fraction showed a shoulder at 330 nm which is characteristic for T2/T3 copper centers; both copper and zinc were detected suggesting that this is an unconventional white laccase. Primers of laccase gene were designed and synthesized to recover specific gene from A. flavus . Sequence analysis indicated putative laccase (Genbank ID: JF683612) at the amino acid level suggesting a close identity to laccases from other genera containing the copper binding site. Decolorization of textile waste water under different conditions showed possible application in bioremediation within a short period of time. The effect of copper on A. flavus was concentration dependent. PMID:26221119

  17. Chemoprevention by essential oil of turmeric leaves (Curcuma longa L.) on the growth of Aspergillus flavus and aflatoxin production.

    PubMed

    Sindhu, S; Chempakam, B; Leela, N K; Suseela Bhai, R

    2011-05-01

    Turmeric is well known for a wide range of medicinal properties. Essential oil of turmeric leaves (Curcuma longa L.) were evaluated at varying concentrations of 0.01, 0.05, 0.1, 0.5, 0.75, 1.0 and 1.5% (v/v) in Yeast Extract Sucrose (YES) broth inoculated with spore suspension of Aspergillus flavus of 10(6)conidia/ml. These were evaluated for their potential in the control of aflatoxigenic fungus A. flavus and aflatoxin production. Turmeric leaf oil exhibited 95.3% and 100% inhibition of toxin production respectively at 1.0% and 1.5%. The extent of inhibition of fungal growth and aflatoxin production was dependent on the concentration of essential oil used. The oil exhibited significant inhibition of fungal growth as well as aflatoxins B(1) and G(1) production. The LD(50) and LD(90) were also determined. GC-MS analysis of the oil showed α-phellandrene, p-cymene and terpinolene as the major components in turmeric leaf oil. The possibility of using these phytochemical components as bio-preservatives for storage of spices is discussed.

  18. Reduction of aflatoxin production by Aspergillus flavus and Aspergillus parasiticus in interaction with Streptomyces.

    PubMed

    Verheecke, C; Liboz, T; Anson, P; Diaz, R; Mathieu, F

    2015-05-01

    The aim of this study is to investigate aflatoxin gene expression during Streptomyces-Aspergillus interaction. Aflatoxins are carcinogenic compounds produced mainly by Aspergillus flavus and Aspergillus parasiticus. A previous study has shown that Streptomyces-A. flavus interaction can reduce aflatoxin content in vitro. Here, we first validated this same effect in the interaction with A. parasiticus. Moreover, we showed that growth reduction and aflatoxin content were correlated in A. parasiticus but not in A. flavus. Secondly, we investigated the mechanisms of action by reverse-transcriptase quantitative PCR. As microbial interaction can lead to variations in expression of household genes, the most stable [act1, βtub (and cox5 for A. parasiticus)] were chosen using geNorm software. To shed light on the mechanisms involved, we studied during the interaction the expression of five genes (aflD, aflM, aflP, aflR and aflS). Overall, the results of aflatoxin gene expression showed that Streptomyces repressed gene expression to a greater level in A. parasiticus than in A. flavus. Expression of aflR and aflS was generally repressed in both Aspergillus species. Expression of aflM was repressed and was correlated with aflatoxin B1 content. The results suggest that aflM expression could be a potential aflatoxin indicator in Streptomyces species interactions. Therefore, we demonstrate that Streptomyces can reduce aflatoxin production by both Aspergillus species and that this effect can be correlated with the repression of aflM expression.

  19. Characterization of the Far Transcription Factor Family in Aspergillus flavus

    PubMed Central

    Luo, Xingyu; Affeldt, Katharyn J.; Keller, Nancy P.

    2016-01-01

    Metabolism of fatty acids is a critical requirement for the pathogenesis of oil seed pathogens including the fungus Aspergillus flavus. Previous studies have correlated decreased ability to grow on fatty acids with reduced virulence of this fungus on host seed. Two fatty acid metabolism regulatory transcription factors, FarA and FarB, have been described in other filamentous fungi. Unexpectedly, we find A. flavus possesses three Far homologs, FarA, FarB, and FarC, with FarA and FarC showing a greater protein similarity to each other than FarB. farA and farB are located in regions of colinearity in all Aspergillus spp. sequenced to date, whereas farC is limited to a subset of species where it is inserted in an otherwise colinear region in Aspergillus genomes. Deletion and overexpression (OE) of farA and farB, but not farC, yielded mutants with aberrant growth patterns on specific fatty acids as well as altered expression of genes involved in fatty acid metabolism. Marked differences included significant growth defects of both ∆farA and ∆farB on medium-chain fatty acids and decreased growth of OE::farA on unsaturated fatty acids. Loss of farA diminished expression of mitochondrial β-oxidation genes whereas OE::farA inhibited expression of genes involved in unsaturated fatty acid catabolism. FarA also positively regulated the desaturase genes required to generate polyunsaturated fatty acids. Aflatoxin production on toxin-inducing media was significantly decreased in the ∆farB mutant and increased in the OE::farB mutant, with gene expression data supporting a role for FarB in tying β-oxidation processes with aflatoxin accumulation. PMID:27534569

  20. Antibiotic Extraction as a Recent Biocontrol Method for Aspergillus Niger andAspergillus Flavus Fungi in Ancient Egyptian mural paintings

    NASA Astrophysics Data System (ADS)

    Hemdan, R. Elmitwalli; Fatma, Helmi M.; Rizk, Mohammed A.; Hagrassy, Abeer F.

    Biodeterioration of mural paintings by Aspergillus niger and Aspergillus flavus Fungi has been proved in different mural paintings in Egypt nowadays. Several researches have studied the effect of fungi on mural paintings, the mechanism of interaction and methods of control. But none of these researches gives us the solution without causing a side effect. In this paper, for the first time, a recent treatment by antibiotic "6 penthyl α pyrone phenol" was applied as a successful technique for elimination of Aspergillus niger and Aspergillus flavus. On the other hand, it is favorable for cleaning Surfaces of Murals executed by tembera technique from the fungi metabolism which caused a black pigments on surfaces.

  1. Flocculation behavior and mechanism of bioflocculant produced by Aspergillus flavus.

    PubMed

    Aljuboori, Ahmad H Rajab; Idris, Azni; Al-joubory, Hamid Hussain Rijab; Uemura, Yoshimitsu; Ibn Abubakar, B S U

    2015-03-01

    In this study, the flocculation behavior and mechanism of a cation-independent bioflocculant IH-7 produced by Aspergillus flavus were investigated. Results showed 91.6% was the lowest flocculating rate recorded by IH-7 (0.5 mg L(-1)) at pH range 4-8. Moreover, IH-7 showed better flocculation performance than polyaluminum chloride (PAC) at a wide range of flocculant concentration (0.06-25 mg L(-1)), temperature (5-45 °C) and salinity (10-60% w/w). The current study found that cation addition did not significantly enhance the flocculating rate and IH-7 is a positively charged bioflocculant. These findings suggest that charge neutralization is the main flocculation mechanism of IH-7 bioflocculant. IH-7 was significantly used to flocculate different types of suspended solids such as activated carbons, kaolin clays, soil solids and yeast cells.

  2. Transformation of Aspergillus flavus to study aflatoxin biosynthesis.

    PubMed

    Payne, G A; Woloshuk, C P

    1989-09-01

    Aflatoxin contamination of agricultural commodities continues to be a serious problem in the United States. Breeding for resistant genotypes has been unsuccessful and detoxification of food sources is not economically feasible. New strategies for control may become apparent once more is known about the biosynthesis and regulation of aflatoxin. Although the biosynthetic pathway of aflatoxin has been extensively studied, little is known about the regulation of the individual steps in the pathway. We have developed a genetic transformation system for Aspergillus flavus that provides a new and expedient approach to studying the biosynthesis of aflatoxin and its regulation. Through the use of this genetic transformation system, genes for aflatoxin biosynthesis can be identified and isolated by the complementation of aflatoxin negative mutants. In this paper we discuss molecular strategies for studying the regulation and biosynthesis of aflatoxin. PMID:2515438

  3. Proteomic profile of Aspergillus flavus in response to water activity.

    PubMed

    Zhang, Feng; Zhong, Hong; Han, Xiaoyun; Guo, Zhenni; Yang, Weiqiang; Liu, Yongfeng; Yang, Kunlong; Zhuang, Zhenhong; Wang, Shihua

    2015-03-01

    Aspergillus flavus, a common contaminant of crops and stored grains, can produce aflatoxins that are harmful to humans and other animals. Water activity (aw) is one of the key factors influencing both fungal growth and mycotoxin production. In this study, we used the isobaric tagging for relative and absolute quantitation (iTRAQ) technique to investigate the effect of aw on the proteomic profile of A. flavus. A total of 3566 proteins were identified, of which 837 were differentially expressed in response to variations in aw. Among these 837 proteins, 403 were over-expressed at 0.99 aw, whereas 434 proteins were over-expressed at 0.93 aw. According to Gene Ontology (GO) analysis, the secretion of extracellular hydrolases increased as aw was raised, suggesting that extracellular hydrolases may play a critical role in induction of aflatoxin biosynthesis. On the basis of Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) categorizations, we identified an exportin protein, KapK, that may down-regulate aflatoxin biosynthesis by changing the location of NirA. Finally, we considered the role of two osmotic stress-related proteins (Sln1 and Glo1) in the Hog1 pathway and investigated the expression patterns of proteins related to aflatoxin biosynthesis. The data uncovered in this study are critical for understanding the effect of water stress on toxin production and for the development of strategies to control toxin contamination of agricultural products.

  4. Formation of Aspergillus flavus sclerotia on corn grown under different drought stress conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a major producer of carcinogenic aflatoxins worldwide in corn, peanuts, tree nuts, cottonseed, spices and other crops. Many countries have strict limits on the amount of aflatoxins permitted in human commodities and animal feed. Sclerotia produced by A. flavus serve several f...

  5. Identification of hydrolytic activities expressed by Aspergillus flavus grown on cotton carpel tissue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus secreted at least two endoxylanase activities, two esterase activities and a pectolytic activity when grown on a medium containing cotton carpel tissue as a sole carbon source. A concentrated sample of A. flavus growth medium (6-day) was subjected to gel filtration chromatography...

  6. Degeneration of aflatoxin gene cluster in Aspergillus flavus from Africa and North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is the primary causal agent of food and feed contamination with the toxic fungal metabolites aflatoxins. Aflatoxin-producing potential of A. flavus is known to vary among isolates. The genes involved in aflatoxin biosynthesis are clustered together and the order of genes within th...

  7. The potential role of oxidative stress in Aspergillus flavus survivability and aflatoxin biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxin contamination of food and feed occurs due to growth of Aspergillus flavus. This poses a serious health risk because of aflatoxin’s toxic and carcinogenic properties which negatively impact human and livestock health. Colonization and subsequent aflatoxin production by A. flavus is typicall...

  8. Spread of Aspergillus flavus by navel orangeworm (Amyelois transitella) on almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Navel orangeworm (NOW) damage to almonds is correlated with increased incidence of aflatoxin contamination caused by Aspergillus flavus. However, no reports demonstrate a causative relationship between NOW feeding and A. flavus infection. To demonstrate the potential of NOW to act as a vector of A. ...

  9. Transcriptomic profiling of decanal effects on Aspergillus flavus gene expression in development and secondary metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a saprophyte and an opportunistic plant pathogen. It is capable of producing carcinogenic aflatoxins. We treated A. flavus CA42 with the volatile decanal and analyzed changes in the transcriptomic profiles at different stages of growth and development. Paired-end RNA-Seq reads ...

  10. Aspergillus flavus Genomic Data Mining Provides Clues for Its Use in Producing Biobased Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is notorious for its ability to produce aflatoxins. It is also an opportunistic pathogen that infects plants, animals and human beings. The ability to survive in the natural environment, living on plant tissues (leaves or stalks), live or dead insects make A. flavus a ubiquitous...

  11. Aspergillus flavus Blast2GO gene ontology database: elevated growth temperature alters amino acid metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The availability of a representative gene ontology (GO) database is a prerequisite for a successful functional genomics study. Using online Blast2GO resources we constructed a GO database of Aspergillus flavus. Of the predicted total 13,485 A. flavus genes 8,987 were annotated with GO terms. The mea...

  12. Sexual reproduction in Aspergillus flavus sclerotia: acquisition of novel alleles from soil populations and uniparental mitochondrial inheritance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus colonizes agricultural commodities worldwide and contaminates them with carcinogenic aflatoxins. The high genetic diversity of A. flavus populations is largely due to sexual reproduction characterized by the formation of ascospore-bearing ascocarps embedded within sclerotia. A. ...

  13. Detection of toxigenic isolates of Aspergillus flavus and related species on coconut cream agar.

    PubMed

    Dyer, S K; McCammon, S

    1994-01-01

    A new readily-prepared medium, coconut cream agar, was developed for the detection of aflatoxin production by isolates of Aspergillus flavus and related species. Coconut cream agar, which comprised coconut cream (50%) and agar (1.5%), detected isolates of A. flavus more effectively than the synthetic media tested and was as effective as media containing desiccated coconut. Fluorescence colouring of colonies grown on coconut cream agar could be used to differentiate A. flavus from A. parasiticus and A. nomius. In addition, conidial colour of A. flavus and A. nomius was quite distinct from that of A. parasiticus.

  14. Modelling Aspergillus flavus growth and aflatoxins production in pistachio nuts.

    PubMed

    Marín, Sonia; Ramos, Antonio J; Sanchis, V

    2012-12-01

    Aflatoxins (AFs) are the main contaminants in pistachio nuts. AFs production in pistachio has been attributed to Aspergillus flavus. The aim of this study was to apply existing models to predict growth and AFs production by an A. flavus isolated from pistachios as a function of moisture content and storage temperature of pistachios in order to test their usefulness and complementarities. A full factorial design was used: the moisture content levels assayed were 10, 15, 20, 25 and 30% and incubation temperatures were 10, 15, 20, 25, 30, 37 and 42 °C. Both kinetic and probability models were built to predict growth of the strain under the assayed conditions. Among the assayed models, cardinal ones gave a good quality fit for radial growth rate data. Moreover, the progressive approach, which was developed based on a reduced number of experimental points led to an improved prediction in the validation step. This is quite significant as may allow for improved experimental designs, less costly than full factorial ones. Probability model proved to be concordant in 91% of the calibration set observations. Even though the validation set included conditions around the growth/no-growth interface, there was a 100% agreement in the predictions from the data set (n = 16, cut off = 0.5) after 60 days. Similarly, the probability for AF presence was rightly predicted in 89% of the cases. According to our results EC maximum aflatoxin levels would be surpassed in a period as short as 1 month if pistachio nuts reach 20 °C, unless %mc is ≤10%.

  15. An attempt to model the probability of growth and aflatoxin B1 production of Aspergillus flavus under non-isothermal conditions in pistachio nuts.

    PubMed

    Aldars-García, Laila; Ramos, Antonio J; Sanchis, Vicente; Marín, Sonia

    2015-10-01

    Human exposure to aflatoxins in foods is of great concern. The aim of this work was to use predictive mycology as a strategy to mitigate the aflatoxin burden in pistachio nuts postharvest. The probability of growth and aflatoxin B1 (AFB1) production of aflatoxigenic Aspergillus flavus, isolated from pistachio nuts, under static and non-isothermal conditions was studied. Four theoretical temperature scenarios, including temperature levels observed in pistachio nuts during shipping and storage, were used. Two types of inoculum were included: a cocktail of 25 A. flavus isolates and a single isolate inoculum. Initial water activity was adjusted to 0.87. Logistic models, with temperature and time as explanatory variables, were fitted to the probability of growth and AFB1 production under a constant temperature. Subsequently, they were used to predict probabilities under non-isothermal scenarios, with levels of concordance from 90 to 100% in most of the cases. Furthermore, the presence of AFB1 in pistachio nuts could be correctly predicted in 70-81 % of the cases from a growth model developed in pistachio nuts, and in 67-81% of the cases from an AFB1 model developed in pistachio agar. The information obtained in the present work could be used by producers and processors to predict the time for AFB1 production by A. flavus on pistachio nuts during transport and storage.

  16. RNA interference reduces aflatoxin accumulation by Aspergillus flavus in peanut seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are among the most powerful carcinogens in nature. They are produced by the fungal pathogen Aspergillus flavus Link and other Aspergillus species. Aflatoxins accumulate in many crops, including rice, wheat, oats, pecans, pistachios, soybean, cassava, almonds, peanuts, beans, corn and cot...

  17. rmtA, encoding a putative anginine methyltransferase, regulates secondary metabolism and development in Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is found colonizing numerous oil seed crops such as corn, peanuts, sorghum, treenuts and cotton worldwide, contaminating them with aflatoxin and other harmful potent toxins. In the phylogenetically related model fungus Aspergillus nidulans, the methyltransferase, RmtA, has been de...

  18. Production of chitin deacetylase by Aspergillus flavus in submerged conditions.

    PubMed

    Narayanan, Karthik; Parameswaran, Binod; Pandey, Ashok

    2016-07-01

    Chitosan is a biopolymer obtained by deacetylation of chitin and has been proven to have various applications in industry and biomedicine. Deacetylation of chitin using the enzyme chitin deacetylase (CDA) is favorable in comparison to the hazardous chemical method involving strong alkali and high temperature. A fungal strain producing CDA was isolated from environmental samples collected from coastal regions of South Kerala, India. It was identified as Aspergillus flavus by morphological characteristics and ITS DNA analysis. Nutritional requirement for maximum production of CDA under submerged condition was optimized using statistical methods including Plackett-Burman and response surface methodology central composite design. A 5.98-fold enhancement in CDA production was attained in shake flasks when the fermentation process parameters were used at their optimum levels. The highest CDA activity was 57.69 ± 1.68 U under optimized bioprocess conditions that included 30 g L(-1) glucose, 40 g L(-1) yeast extract, 15 g L(-1) peptone, and 7 g L(-1) MgCl2 at initial media pH of 7 and incubation temperature of 32°C after 48 hr of incubation, while the unoptimized basal medium yielded 9.64 ± 2.04 U. PMID:26474347

  19. Identification of the Predominant Volatile Compounds Produced by Aspergillus flavus

    PubMed Central

    Kaminśki, E.; Libbey, L. M.; Stawicki, S.; Wasowicz, E.

    1972-01-01

    A culture of Aspergillus flavus grown on moistened wheat meal was homogenized with a blendor, and the resulting slurry was vacuum-distilled at 5 mm of Hg and 35 C. The aqueous distillate was collected in traps cooled to -10 to -80 C. The culture volatiles were extracted from the distillate with CH2Cl2, and, after removal of the bulk of the solvent, the concentrated volatiles were examined by packed-column gas chromatography. Nineteen peaks were observed, and coupled gas chromatography-mass spectrometry was employed to identify the larger components. The compounds identified were: 3-methyl-butanol, 3-octanone, 3-octanol, 1-octen-3-ol, 1-octanol, and cis-2-octen-1-ol. The two octenols were the predominant compounds, and sufficient sample was trapped from the gas chromatograph for infrared analyses; this confirmed the mass spectral identifications and permitted the assignment of the cis designation to 2-octen-1-ol. Both oct-1-en-3-ol and cis-2-octen-1-ol are thought to be responsible for the characteristic musty-fungal odor of certain fungi; the latter compound may be a useful chemical index of fungal growth. PMID:4629700

  20. RNA sequencing of an nsdC mutant reveals global regulation of secondary metabolic gene clusters in Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The zinc finger transcription factor nsdC is required for both sexual development and aflatoxin production in the saprophytic fungus Aspergillus flavus. While previous work with an nsdC knockout mutant was conducted in Aspergillus nidulans and A. flavus strain 3357, here we demonstrate perturbations...

  1. Genetic diversity analysis of Aspergillus flavus isolates from plants and air by ISSR markers.

    PubMed

    Mahmoud1, M A; El-Samawaty, A M A; Yassin, M A; Abd El-Aziz, A R M

    2016-04-28

    Aspergillus flavus is one of the most abundant and widely distributed fungi on earth. A. flavus produces aflatoxins (AFs), which are toxic secondary metabolites. AFs have harmful effects on public health (humans and animals) and agricultural crops. Inter-simple sequence repeat (ISSR) markers were used to analyze the genetic diversity of 30 A. flavus isolates from five agricultural crops and air. Genetic similarity coefficients (GSC) ranged from 0.51 to 0.10 based on three ISSR markers for the isolates tested. A. flavus isolates grouped into 6, 5, and 3 clusters using the unweighted pair-group method with arithmetic average of three ISSR markers. This study suggests that ISSR biotechnology is a highly useful tool for characterizing genetic diversity of A. flavus isolated from different sources.

  2. Polyamines as modulators of microcycle conidiation in Aspergillus flavus.

    PubMed

    Khurana, N; Saxena, R K; Gupta, R; Rajam, M V

    1996-03-01

    Since polyamines (PAs) play a potential role in the regulation of growth and developmental processes in a wide variety of organisms, we have examined the influence of the PAs putrescine (Put) and spermidine (Spd) and the PA biosynthetic inhibitors alpha-difluoromethylornithine (DFMO), alpha-difluoromethylarginine (DFMA), methylglyoxal bis-(guanylhydrazone) (MGBG) and cyclohexylamine (CHA), singly and in combinations on microcycle conidiation (MC) in Aspergillus flavus. The exogenous application of the diamine Put (concentrations ranging from 0.1 to 5 mM) caused a sharp decline of MC in a dose-dependent fashion, but induced vegetative growth. However, the triamine Spd (0.1-5 mM) had a minimal effect on MC and induced a shift from MC to normal condition. PA inhibitors, especially DFMO, MGBG and CHA, produced greater inhibition of MC and complete inhibition of MC was observed at 5 mM of these inhibitors. DFMA even at 5 mM had only a weak inhibitory effect on MC. DFMO also inhibited conidial germination and germ tube growth. MGBG and CHA, while having an inhibitory effect on MC, induced vegetative growth. The inhibitory effect of PA inhibitors was partially reversed by exogenous Put or Spd, with Spd being more effective than Put. The analysis of free PA levels during various phases of MC revealed that undifferentiated spores contained a high Put/Spd ratio and there was a dramatic decrease in Put/Spd ratio before and during microcycle conidiophore maturity. The change in spermine titres could not be detected. These observations imply that Put is essential for vegetative growth, while Spd is involved in MC, and that a low Put/Spd ratio seems to be important for spore differentiation to MC.

  3. The effect of 2-phenylethanol treatment on Aspergillus flavus transcriptome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pichia anomalais, which produces the antimicrobial volatile 2-phenylethanol (2-PE), is effective in reducing A. flavus growth and aflatoxin production. We treated A. flavus NRRL3357 with 2-PE and analyzed changes in the transcriptomic profiles at different stages of fungal growth. RNA-Seq reads from...

  4. Hyperspectral imagery for observing spectral signature change in Aspergillus flavus

    NASA Astrophysics Data System (ADS)

    DiCrispino, Kevin; Yao, Haibo; Hruska, Zuzana; Brabham, Kori; Lewis, David; Beach, Jim; Brown, Robert L.; Cleveland, Thomas E.

    2005-11-01

    Aflatoxin contaminated corn is dangerous for domestic animals when used as feed and cause liver cancer when consumed by human beings. Therefore, the ability to detect A. flavus and its toxic metabolite, aflatoxin, is important. The objective of this study is to measure A. flavus growth using hyperspectral technology and develop spectral signatures for A. flavus. Based on the research group's previous experiments using hyperspectral imaging techniques, it has been confirmed that the spectral signature of A. flavus is unique and readily identifiable against any background or surrounding surface and among other fungal strains. This study focused on observing changes in the A. flavus spectral signature over an eight-day growth period. The study used a visible-near-infrared hyperspectral image system for data acquisition. This image system uses focal plane pushbroom scanning for high spatial and high spectral resolution imaging. Procedures previously developed by the research group were used for image calibration and image processing. The results showed that while A. flavus gradually progressed along the experiment timeline, the day-to-day surface reflectance of A. flavus displayed significant difference in discreet regions of the wavelength spectrum. External disturbance due to environmental changes also altered the growth and subsequently changed the reflectance patterns of A. flavus.

  5. Functional Genomic Analysis of Aspergillus flavus Interacting with Resistant and Susceptible Peanut

    PubMed Central

    Wang, Houmiao; Lei, Yong; Yan, Liying; Wan, Liyun; Ren, Xiaoping; Chen, Silong; Dai, Xiaofeng; Guo, Wei; Jiang, Huifang; Liao, Boshou

    2016-01-01

    In the Aspergillus flavus (A. flavus)–peanut pathosystem, development and metabolism of the fungus directly influence aflatoxin contamination. To comprehensively understand the molecular mechanism of A. flavus interaction with peanut, RNA-seq was used for global transcriptome profiling of A. flavus during interaction with resistant and susceptible peanut genotypes. In total, 67.46 Gb of high-quality bases were generated for A. flavus-resistant (af_R) and -susceptible peanut (af_S) at one (T1), three (T2) and seven (T3) days post-inoculation. The uniquely mapped reads to A. flavus reference genome in the libraries of af_R and af_S at T2 and T3 were subjected to further analysis, with more than 72% of all obtained genes expressed in the eight libraries. Comparison of expression levels both af_R vs. af_S and T2 vs. T3 uncovered 1926 differentially expressed genes (DEGs). DEGs associated with mycelial growth, conidial development and aflatoxin biosynthesis were up-regulated in af_S compared with af_R, implying that A. flavus mycelia more easily penetrate and produce much more aflatoxin in susceptible than in resistant peanut. Our results serve as a foundation for understanding the molecular mechanisms of aflatoxin production differences between A. flavus-R and -S peanut, and offer new clues to manage aflatoxin contamination in crops. PMID:26891328

  6. Xerophilic aflatoxigenic black tea fungi and their inhibition by Elettaria cardamomum and Syzygium aromaticum extracts.

    PubMed

    Al-Sohaibani, Saleh; Murugan, K; Lakshimi, G; Anandraj, K

    2011-10-01

    Black tea is consumed worldwide and is believed to play a role in cancer prevention. Xerophilic aflatoxigenic fungi are highly hazardous contaminants of tea since they are associated with tea quality impairment and human health risk. The present study reports isolation of such xerophilic and aflatoxigenic fungi associated with marketed tea. Twenty different tea samples collected from the local markets of Tamilnadu, India were investigated for fungal contamination. The results indicated contamination by 0.38% Aspergillus flavus. Other common contaminant fungi including Penicillium spp. (0.30%), Pacelomyces spp. (0.14%), and Mucor spp. (0.19%) were also isolated. Amongst the fungi isolated Aspergillus niger ML01 and A. flavus ML02 were found to be xerophilic aflatoxigenic mycoflora. Phylogenetic analysis based on 28S rRNA revealed their close ancestry. The chloroform and acetone extracts of spices Elettaria cardamomum and Syzygium aromaticum exhibited antifungal inhibitory activity on growth and toxin elaboration of both these xerophilic tea contaminants A. niger ML01 and A. flavus ML02. The results advocate the use of these spices plant or their extracts as novel antimicrobials which may add preservation and flavour in marketed tea. PMID:23961151

  7. Xerophilic aflatoxigenic black tea fungi and their inhibition by Elettaria cardamomum and Syzygium aromaticum extracts.

    PubMed

    Al-Sohaibani, Saleh; Murugan, K; Lakshimi, G; Anandraj, K

    2011-10-01

    Black tea is consumed worldwide and is believed to play a role in cancer prevention. Xerophilic aflatoxigenic fungi are highly hazardous contaminants of tea since they are associated with tea quality impairment and human health risk. The present study reports isolation of such xerophilic and aflatoxigenic fungi associated with marketed tea. Twenty different tea samples collected from the local markets of Tamilnadu, India were investigated for fungal contamination. The results indicated contamination by 0.38% Aspergillus flavus. Other common contaminant fungi including Penicillium spp. (0.30%), Pacelomyces spp. (0.14%), and Mucor spp. (0.19%) were also isolated. Amongst the fungi isolated Aspergillus niger ML01 and A. flavus ML02 were found to be xerophilic aflatoxigenic mycoflora. Phylogenetic analysis based on 28S rRNA revealed their close ancestry. The chloroform and acetone extracts of spices Elettaria cardamomum and Syzygium aromaticum exhibited antifungal inhibitory activity on growth and toxin elaboration of both these xerophilic tea contaminants A. niger ML01 and A. flavus ML02. The results advocate the use of these spices plant or their extracts as novel antimicrobials which may add preservation and flavour in marketed tea.

  8. Genetic isolation among sympatric vegetative compatibility groups of the aflatoxin-producing fungus Aspergillus flavus.

    PubMed

    Grubisha, L C; Cotty, P J

    2010-01-01

    Aspergillus flavus, a fungal pathogen of animals and both wild and economically important plants, is most recognized for producing aflatoxin, a cancer-causing secondary metabolite that contaminates food and animal feed globally. Aspergillus flavus has two self/nonself recognition systems, a sexual compatibility system and a vegetative incompatibility system, and both play a role in directing gene flow in populations. Aspergillus flavus reproduces clonally in wild and agricultural settings, but whether a cryptic sexual stage exists in nature is currently unknown. We investigated the distribution of genetic variation in 243 samples collected over 4 years from three common vegetative compatibility groups (VCGs) in Arizona and Texas from cotton using 24 microsatellite loci and the mating type locus (MAT) to assess population structure and potential gene flow among A. flavus VCGs in sympatric populations. All isolates within a VCG had the same mating type with OD02 having MAT1-2 and both CG136 and MR17 having MAT1-1. Our results support the hypothesis that these three A. flavus VCGs are genetically isolated. We found high levels of genetic differentiation and no evidence of gene flow between VCGs, including VCGs of opposite mating-type. Our results suggest that these VCGs diverged before domestication of agricultural hosts (>10,000 yr bp).

  9. Detection of aflatoxigenic aspergillus flavus contamination of coconut (cocos nucifera) nutmeat (copra) using ammonia treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For many crops government regulations define mycotoxin contamination levels that represent the primary determinants of quality, value and possible uses of crops. Quality can be raised in some crops by lowering the mycotoxin level through removal of infected products. In the case of copra, the drie...

  10. Visualization of aflatoxigenic Aspergillus flavus contamination of coconut (Cocos nucifera) nutmeat (Copra) using ammonia treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For many crops government regulations define mycotoxin contamination levels that reflect the primary determinants of quality, value and possible uses of crops. Quality can be raised by lowering the mycotoxin level through a remediation process. In the case of copra, the dried nutmeat of the coconu...

  11. Evaluation of the atoxigenic Aspergillus flavus strain AF36 in pistachio orchards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The atoxigenic strain Aspergillus flavus AF36, which has been extensively used as a biocontrol agent in commercial corn and cotton fields to reduce aflatoxin contamination, was applied in research pistachio orchards from 2002 to 2005 and in commercial pistachio orchards from 2008 to 2011. AF36 was a...

  12. Intraspecific competition during infection by Aspergillus flavus is influenced by plant host species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Communities of Aspergillus flavus are composed of diverse genotypes that collectively influence incidence and severity of crop aflatoxin contamination. Isolates vary in competitive ability on maize, but empirical data on the extent to which host-specific influences determine outcomes of competition ...

  13. 40 CFR 180.1206 - Aspergillus flavus AF36; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... tolerance is established for residues of Aspergillus flavus AF36 in or on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover,...

  14. 40 CFR 180.1206 - Aspergillus flavus AF36; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... tolerance is established for residues of Aspergillus flavus AF36 in or on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover,...

  15. 40 CFR 180.1206 - Aspergillus flavus AF36; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... tolerance is established for residues of Aspergillus flavus AF36 in or on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover,...

  16. Hyperspectral image classification and development of fluorescence index for single corn kernels infected with Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are toxic secondary metabolites predominantly produced by the fungi Aspergillus flavus and A. parasiticus. Aflatoxin contaminated corn is toxic to domestic animals when ingested in feed and is a known carcinogen associated with liver and lung cancer in humans. Consequently, aflatoxin leve...

  17. Aspergillus flavus whole genome and EST sequence releases and construction of homologous gene search blast server

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are toxic and carcinogenic secondary metabolites. These compounds, produced by Aspergillus flavus and A. parasiticus, contaminate pre-harvest agricultural crops in the field and post-harvest grains during storage. In order to reduce and eliminate aflatoxin contamination of food and feed...

  18. Is rachis lignification a deterrent to Aspergillus flavus movement through the developing maize ear?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In previous research, the proteomes of the immature rachis of Aspergillus flavus resistant and susceptible maize inbreds were compared using differential-in-gel electrophoresis (DIGE). One of the proteins that was 66-fold more abundant in the resistant inbred MP313E than in the susceptible inbred S...

  19. Identification of atoxigenic Aspergillus flavus isolates to reduce aflatoxin contamination of maize in Kenya

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acute aflatoxin poisonings (aflatoxicosis) in Kenya have led to the deaths of several hundred people between 2004 and 2006. Etiology of contamination in the outbreak districts (Eastern Province) identified an unusual fungal community structure dominated by the highly toxigenic Aspergillus flavus S s...

  20. Transcriptomic analysis reveal diverse responses to environmental oxidative stress in Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought stress predisposes oilseed crops such as maize and peanut to infection by Aspergillus flavus resulting in their contamination with aflatoxins. Drought stress in plants results in the accumulation of reactive oxygen species (ROS) in their tissues, and these ROS have been shown to stimulate af...

  1. Efficacy of water dispersible formulations of biocontrol strains of Aspergillus flavus for aflatoxin management in corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field experiments were conducted in 2011 and 2012 to evaluate the efficacy of water dispersible granule (WDG) formulations of biocontrol strains of Aspergillus flavus in controlling aflatoxin contamination of corn. In 2011, when aflatoxin was present at very high levels, no WDG treatment provided s...

  2. Comparative transcriptome analysis of Aspergillus flavus isolates under different oxidative stresses and culture media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus and aflatoxin contamination in the field are known to be influenced by numerous stress factors, particularly drought and heat stress. However, the purpose of aflatoxin production is unknown. Here, we report transcriptome analyses comprised of 282.6 Gb of sequencing data describing...

  3. New Monomeric Stilbenoids from Peanut (Arachis hypogaea) Seeds Challenged by an Aspergillus flavus Strain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two new stilbene derivatives have been isolated from peanut seeds challenged by an Aspergillus flavus strain, along with chiricanine B that has not been reported from peanuts, as well as a stilbenoid that has been known as a synthetic product. The structures of these new putative phytoalexins were d...

  4. Application of biotechnology towards the enhancement of maize resistance to aflatoxin contamination by Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contamination of maize with aflatoxins by the fungi Aspergillus flavus and A. parasiticus poses serious health hazards to humans and animals worldwide. This important fact and the regulations instituted in many countries to control the occurrence of aflatoxins in foods and feed have stimulated rese...

  5. A maize lectin-like protein with antifungal activity against Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The filamentous fungus, Aspergillus flavus, causes an ear rot on maize and produces a mycotoxin, aflatoxin, in colonized maize kernels. Aflatoxins are carcinogenic to humans and animals upon ingestion. The presence of aflatoxins in food and feed is strictly regulated by several governmental agenci...

  6. Resistance to Aspergillus flavus in maize and peanut: Molecular biology, breeding, environmental stress and future perspectives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The colonization of maize (Zea mays L.) and peanut (Arachis hypogaea L.) by the fungal pathogen Aspergillus flavus and A. parasiticus results in the contamination with carcinogenic mycotoxins known as aflatoxins leading to economic losses as well as a potential health threat to human. The interactio...

  7. Expression Profiling of Non-Aflatoxigenic Aspergillus parasiticus Mutants Obtained by 5-Azacytosine Treatment or Serial Mycelial Transfer

    PubMed Central

    Wilkinson, Jeffrey R.; Kale, Shubha P.; Bhatnagar, Deepak; Yu, Jiujiang; Ehrlich, Kenneth C.

    2011-01-01

    Aflatoxins are carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and Aspergillus parasiticus. Previous studies found that repeated serial mycelial transfer or treatment of A. parasiticus with 5-azacytidine produced colonies with a fluffy phenotype and inability to produce aflatoxins. To understand how these treatments affect expression of genes involved in aflatoxin production and development, we carried out expressed sequence tag (EST)-based microarray assays to identify genes in treated clones that are differentially expressed compared to the wild-type. Expression of 183 genes was significantly dysregulated. Of these, 38 had at least two-fold or lower expression compared to the untreated control and only two had two-fold or higher expression. The most frequent change was downregulation of genes predicted to encode membrane-bound proteins. Based on this result we hypothesize that the treatments cause changes in the structure of cellular and organelle membranes that prevent normal development and aflatoxin biosynthesis. PMID:22069749

  8. Application of loop-mediated isothermal amplification assays for direct identification of pure cultures of Aspergillus flavus, A. nomius, and A. caelatus and for their rapid detection in shelled Brazil nuts.

    PubMed

    Luo, Jie; Taniwaki, Marta H; Iamanaka, Beatriz T; Vogel, Rudi F; Niessen, Ludwig

    2014-02-17

    Brazil nuts have a high nutritional content and are a very important trade commodity for some Latin American countries. Aflatoxins are carcinogenic fungal secondary metabolites. In Brazil nuts they are produced predominantly by Aspergillus (A.) nomius and A. flavus. In the present study we applied and evaluated two sets of primers previously published for the specific detection of the two species using loop-mediated isothermal amplification (LAMP) technology. Moreover, a primer set specific for A. caelatus as a frequently occurring non-aflatoxigenic member of Aspergillus section Flavi in Brazil nuts was newly developed. LAMP assays were combined with a simplified DNA release method and used for rapid identification of pure cultures and rapid detection of A. nomius and A. flavus from samples of shelled Brazil nuts. An analysis of pure cultures of 68 isolates representing the major Aspergillus species occurring on Brazil nuts showed that the three LAMP assays had individual accuracies of 61.5%, 84.4%, and 93.3% for A. flavus, A. nomius, and A. caelatus, respectively when morphological identification was used as a reference. The detection limits for conidia added directly to the individual LAMP reactions were found to be 10⁵ conidia per reaction with the primer set ID9 for A. nomius and 10⁴ conidia per reaction with the primer set ID58 for A. flavus. Sensitivity was increased to 10¹ and 10² conidia per reaction for A. nomius and A. flavus, respectively, when sample preparation included a spore disruption step. The results of LAMP assays obtained during the analysis of 32 Brazil nut samples from different regions of Brazil and from different steps in the production process of the commodity were compared with results obtained from mycological analysis and aflatoxin analysis of corresponding samples. Compared with mycological analysis of the samples, the Negative Predictive Values of LAMP assays were 42.1% and 12.5% while the Positive Predictive Values were 61

  9. Application of loop-mediated isothermal amplification assays for direct identification of pure cultures of Aspergillus flavus, A. nomius, and A. caelatus and for their rapid detection in shelled Brazil nuts.

    PubMed

    Luo, Jie; Taniwaki, Marta H; Iamanaka, Beatriz T; Vogel, Rudi F; Niessen, Ludwig

    2014-02-17

    Brazil nuts have a high nutritional content and are a very important trade commodity for some Latin American countries. Aflatoxins are carcinogenic fungal secondary metabolites. In Brazil nuts they are produced predominantly by Aspergillus (A.) nomius and A. flavus. In the present study we applied and evaluated two sets of primers previously published for the specific detection of the two species using loop-mediated isothermal amplification (LAMP) technology. Moreover, a primer set specific for A. caelatus as a frequently occurring non-aflatoxigenic member of Aspergillus section Flavi in Brazil nuts was newly developed. LAMP assays were combined with a simplified DNA release method and used for rapid identification of pure cultures and rapid detection of A. nomius and A. flavus from samples of shelled Brazil nuts. An analysis of pure cultures of 68 isolates representing the major Aspergillus species occurring on Brazil nuts showed that the three LAMP assays had individual accuracies of 61.5%, 84.4%, and 93.3% for A. flavus, A. nomius, and A. caelatus, respectively when morphological identification was used as a reference. The detection limits for conidia added directly to the individual LAMP reactions were found to be 10⁵ conidia per reaction with the primer set ID9 for A. nomius and 10⁴ conidia per reaction with the primer set ID58 for A. flavus. Sensitivity was increased to 10¹ and 10² conidia per reaction for A. nomius and A. flavus, respectively, when sample preparation included a spore disruption step. The results of LAMP assays obtained during the analysis of 32 Brazil nut samples from different regions of Brazil and from different steps in the production process of the commodity were compared with results obtained from mycological analysis and aflatoxin analysis of corresponding samples. Compared with mycological analysis of the samples, the Negative Predictive Values of LAMP assays were 42.1% and 12.5% while the Positive Predictive Values were 61

  10. Sequence of host contact influences the outcome of competition among Aspergillus flavus isolates during host tissue invasion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biological control of aflatoxin contamination by Aspergillus flavus is achieved by competitive exclusion of aflatoxin producers by atoxigenic strains. However, factors dictating the extent to which competitive displacement occurs during host infection are unknown. The role of preemptive exclusion in...

  11. Aspergillus flavus diversity on crops and in the environment can be exploited to reduce aflatoxin exposure and improve health

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Humans and animals are exposed to aflatoxins, toxic carcinogenic fungal metabolites, through consumption of contaminated food and feed. Aspergillus flavus, the primary causal agent of crop aflatoxin contamination, is composed of phenotypically and genotypically diverse vegetative compatibility group...

  12. Characterization of AFLAV, a Tf1/Sushi retrotransposon from Aspergillus flavus.

    PubMed

    Hua, Sui-Sheng T; Tarun, Alice S; Pandey, Sonal N; Chang, Leo; Chang, Perng-Kuang

    2007-02-01

    The plasmid, pAF28, a genomic clone from Aspergillus flavus NRRL 6541, has been used as a hybridization probe to fingerprint A. flavus strains isolated in corn and peanut fields. The insert of pAF28 contains a 4.5 kb region which encodes a truncated retrotransposon (AfRTL-1). In search for a full-length and intact copy of retrotransposon, we exploited a novel PCR cloning strategy by amplifying a 3.4 kb region from the genomic DNA of A. flavus NRRL 6541. The fragment was cloned into pCR 4-TOPO. Sequence analysis confirmed that this region encoded putative domains of partial reverse transcriptase, RNase H, and integrase of the predicted retrotransposon. The two flanking long terminal repeats (LTRs) and the sequence between them comprise a putative full-length LTR retrotransposon of 7799 bp in length. This intact retrotransposon sequence is named AFLAV (A. flavus Retrotransposon). The order of the predicted catalytic domains in the polyprotein (Pol) placed AFLAV in the Tf1/sushi subgroup of the Ty3/gypsy retrotransposon family. Primers derived from AFLAV sequence were used to screen this retrotransposon in other strains of A. flavus. More than fifty strains of A. flavus isolated from different geological origins were surveyed and the results show that many strains have extensive deletions in the regions encoding the capsid (Gag) and Pol.

  13. Comparison of soil and corn kernel Aspergillus flavus populations: evidence for niche specialization.

    PubMed

    Sweany, Rebecca Ruth; Damann, Kenneth Eugene; Kaller, Michael Douglas

    2011-08-01

    Aspergillus flavus is considered a generalist-opportunistic pathogen, but studies are beginning to show that A. flavus populations have strains specific to various hosts. The research objective was to determine whether A. flavus soil populations consist of solely saprophytic strains and strains which can be facultatively parasitic on corn. A. flavus was isolated from both corn kernels and soil within 11 Louisiana fields. Sixteen vegetative compatibility groups (VCGs) were identified among 255 soil isolates. Only 6 of the 16 VCGs were identified in the 612 corn isolates and 88% of corn isolates were in two VCGs, whereas only 5% of soil isolates belonged to the same two VCGs. Isolates were characterized for aflatoxin B1 production and sclerotial size. A random subset of the isolates (99 from corn and 91 from soil) were further characterized for simple-sequence repeat (SSR) haplotype and mating type. SSR polymorphisms revealed 26 haplotypes in the corn isolates and 78 in the soil isolates, and only 1 haplotype was shared between soil and corn isolates. Corn and soil populations were highly significantly different for all variables. Differences between corn and soil populations indicate that some soil isolates are not found in corn and some isolates have become specialized to infect corn. Further understanding of A. flavus virulence is important for development of resistant hybrids and for better biological control against toxigenic A. flavus. PMID:21405994

  14. The master transcription factor MtfA governs aflatoxin production, morphological development, and pathogenicity in the fungus Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus produces a variety of toxic secondary metabolites, among them the aflatoxins (AFs) are the most well-known. These compounds are highly mutagenic and carcinogenic, particularly AFB1. A. flavus is capable of colonizing economically important crops contaminating them with AFs. Molecu...

  15. The role of Aspergillus flavus veA in the production of extracellular proteins during growth on starch substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aflatoxin-producer and opportunistic plant pathogenic, filamentous fungus Aspergillus flavus is responsible for the contamination of corn and other important agricultural commodities. In order to obtain nutrients from the host A. flavus produces a variety of extracellular hydrolytic enzymes. Int...

  16. Effect of sexual recombination on population diversity in aflatoxin production by Aspergillus flavus and evidence for cryptic heterokaryosis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is the major producer of carcinogenic aflatoxins (AFs) in crops worldwide. Natural populations of A. flavus show tremendous variation in AF production, some of which can be attributed to environmental conditions, differential regulation of the AF biosynthetic pathway, and deletio...

  17. Toxigenic Aspergillus flavus and other fungi of public health concern in food and organic matter in southwest Nigeria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Six Aspergillus flavus isolates out of 17 fungal isolates were sampled from diverse food and organic matter in southwest Nigeria. All the A. flavus samples produced aflatoxin and cyclopiazonic acid. These six isolates constitute a ready mycobank of toxigenic species for analytical research involving...

  18. Evaluation of resistance to aflatoxin contamination in kernels of maize genotypes using a GFP-expressing Aspergillus flavus strain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of resistance or susceptibility of corn inbreds to infection by Aspergillus flavus was evaluated by a kernel screening assay. A GFP-expressing strain of A. flavus was used to accomplish this study to measure fungal spread and aflatoxin levels in real time. Among the four inbreds tested, ...

  19. Transcriptomic profiles of Aspergillus flavus CA42, a strain that produces small sclerotia, by decanal treatment and after recovery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a ubiquitous saprophyte and is capable of producing many secondary metabolites including the carcinogenic aflatoxins. The A. flavus population that produces small sclerotia (S strain) has been implicated as the culprit for persistent aflatoxin contamination of crops in fields. ...

  20. Antifungal activity of extracts of Rosmarinus officinalis and Thymus vulgaris against Aspergillus flavus and A. ochraceus.

    PubMed

    Centeno, S; Calvo, M A; Adelantado, C; Figueroa, S

    2010-05-01

    The antifungal activity of ethanolic extracts of Rosmarinus officinalis and Thymus vulgaris were tested against strains of Aspergillus flavus and A. ochraceus, since these two species are common contaminants of cereals and grains and are able to produce and accumulate mycotoxins. The methodology used is based on measuring the inhibition halos produced by discs impregnated with the extracts and establishing their Minimum Inhibitory Concentration (MIC) as well as the Minimum Fungicide Concentration (MFC). The results obtained suggest that the assayed extracts affect the proper development of A. flavus and A. ochraceus; leading to a lower MIC (1200 ppm) and MFC (2400 ppm) for T. vulgaris extract against A. ochraceus than against A. flavus. The results show, that the extracts of Rosmarinus officinalis and Thymus vulgaris used at low concentrations could have significant potential for the biological control of fungi in foodstuffs. PMID:20973400

  1. Workflow to study genetic biodiversity of aflatoxigenic Aspergillus spp. in Georgia, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peanut seeds were sampled from the entire state of Georgia in 2014. More than 600 isolates of Aspergillus spp. were collected using modified-dichloran rose Bengal (MDRB) medium, 240 of those isolates were fingerprinted with 25 InDel markers within the aflatoxin-biosynthesis gene cluster (ABC). Clust...

  2. Investigations on the Antifungal Effect of Nerol against Aspergillus flavus Causing Food Spoilage

    PubMed Central

    Tian, Jun; Zeng, Xiaobin; Zeng, Hong; Feng, Zhaozhong; Miao, Xiangmin; Peng, Xue

    2013-01-01

    The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μL/mL and 0.1 μL/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1) by A. flavus, totally restraining AFB1 production at 0.6 μL/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μL/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage. PMID:24453813

  3. Investigations on the antifungal effect of nerol against Aspergillus flavus causing food spoilage.

    PubMed

    Tian, Jun; Zeng, Xiaobin; Zeng, Hong; Feng, Zhaozhong; Miao, Xiangmin; Peng, Xue

    2013-01-01

    The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μ L/mL and 0.1 μ L/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1) by A. flavus, totally restraining AFB1 production at 0.6 μ L/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μ L/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage. PMID:24453813

  4. Investigations on the antifungal effect of nerol against Aspergillus flavus causing food spoilage.

    PubMed

    Tian, Jun; Zeng, Xiaobin; Zeng, Hong; Feng, Zhaozhong; Miao, Xiangmin; Peng, Xue

    2013-01-01

    The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μ L/mL and 0.1 μ L/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1) by A. flavus, totally restraining AFB1 production at 0.6 μ L/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μ L/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage.

  5. Aspergillus flavus genomics: gateway to human and animal health, food safety, and crop resistance to diseases.

    PubMed

    Yu, Jiujiang; Cleveland, Thomas E; Nierman, William C; Bennett, Joan W

    2005-12-01

    Aspergillus flavus is an imperfect filamentous fungus that is an opportunistic pathogen causing invasive and non-invasive aspergillosis in humans, animals, and insects. It also causes allergic reactions in humans. A. flavus infects agricultural crops and stored grains and produces the most toxic and potent carcinogic metabolites such as aflatoxins and other mycotoxins. Breakthroughs in A. flavus genomics may lead to improvement in human health, food safety, and agricultural economy. The availability of A. flavus genomic data marks a new era in research for fungal biology, medical mycology, agricultural ecology, pathogenicity, mycotoxin biosynthesis, and evolution. The availability of whole genome microarrays has equipped scientists with a new powerful tool for studying gene expression under specific conditions. They can be used to identify genes responsible for mycotoxin biosynthesis and for fungal infection in humans, animals and plants. A. flavus genomics is expected to advance the development of therapeutic drugs and to provide information for devising strategies in controlling diseases of humans and other animals. Further, it will provide vital clues for engineering commercial crops resistant to fungal infection by incorporating antifungal genes that may prevent aflatoxin contamination of agricultural harvest. PMID:16499411

  6. Isolation of maize soil and rhizosphere bacteria with antagonistic activity against Aspergillus flavus and Fusarium verticillioides.

    PubMed

    Palumbo, Jeffrey D; O'Keeffe, Teresa L; Abbas, Hamed K

    2007-07-01

    Bacterial isolates from Mississippi maize field soil and maize rhizosphere samples were evaluated for their potential as biological control agents against Aspergillus flavus and Fusarium verticillioides. Isolated strains were screened for antagonistic activities in liquid coculture against A. flavus and on agar media against A. flavus and F. verticillioides. We identified 221 strains that inhibited growth of both fungi. These bacteria were further differentiated by their production of extracellular enzymes that hydrolyzed chitin and yeast cell walls and by production of antifungal metabolites. Based on molecular and nutritional identification of the bacterial strains, the most prevalent genera isolated from rhizosphere samples were Burkholderia and Pseudomonas, and the most prevalent genera isolated from nonrhizosphere soil were Pseudomonas and Bacillus. Less prevalent genera included Stenotrophomonas, Agrobacterium, Variovorax, Wautersia, and several genera of coryneform and enteric bacteria. In quantitative coculture assays, strains of P. chlororaphis and P. fluorescens consistently inhibited growth of A. flavus and F. verticillioides in different media. These results demonstrate the potential for developing individual biocontrol agents for simultaneous control of the mycotoxigenic A. flavus and F. verticillioides. PMID:17685333

  7. Streptomyces-Aspergillus flavus interactions: impact on aflatoxin B accumulation.

    PubMed

    Verheecke, C; Liboz, T; Anson, P; Zhu, Y; Mathieu, F

    2015-01-01

    The aim of this work was to investigate the potential of Streptomyces sp. as biocontrol agents against aflatoxins in maize. As such, we assumed that Streptomyces sp. could provide a complementary approach to current biocontrol systems such as Afla-guard(®) and we focused on biocontrol that was able to have an antagonistic contact with A. flavus. A previous study showed that 27 (out of 38) Streptomyces sp. had mutual antagonism in contact with A. flavus. Among these, 16 Streptomyces sp. were able to reduce aflatoxin content to below 17% of the residual concentration. We selected six strains to understand the mechanisms involved in the prevention of aflatoxin accumulation. Thus, in interaction with A. flavus, we monitored by RT-qPCR the gene expression of aflD, aflM, aflP, aflR and aflS. All the Streptomyces sp. were able to reduce aflatoxin concentration (24.0-0.2% residual aflatoxin B1). They all impacted on gene expression, but only S35 and S38 were able to repress expression significantly. Indeed, S35 significantly repressed aflM expression and S38 significantly repressed aflR, aflM and aflP. S6 reduced aflatoxin concentrations (2.3% residual aflatoxin B1) and repressed aflS, aflM and enhanced aflR expression. In addition, the S6 strain (previously identified as the most reducing pure aflatoxin B1) was further tested to determine a potential adsorption mechanism. We did not observe any adsorption phenomenon. In conclusion, this study showed that Streptomyces sp. prevent the production of (aflatoxin gene expression) and decontamination of (aflatoxin B1 reduction) aflatoxins in vitro. PMID:25632796

  8. Genome Sequences of Eight Aspergillus flavus spp. and One A. parasiticus sp., Isolated From Peanut Seeds in Georgia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus and A. parasiticus fungi, carcinogen-mycotoxins producers, infect peanut seeds, causing considerable impact on both human health and the economy. Here we report 9 genome sequences of Aspergillus spp. isolated from peanut seeds. The information obtained will allow conducting biodiv...

  9. Sex and recombination in aflatoxigenic Aspergilli: global implications

    PubMed Central

    Moore, Geromy G.

    2014-01-01

    For most of the half century that aflatoxigenic species have been intensively studied, these molds were known only to reproduce asexually, with parasexuality found only in the laboratory between certain mutant strains. Therefore, the fairly recent discovery of their sexual (teleomorphic) states creates a new wrinkle in our understanding of the field behavior of these agriculturally significant fungi. Sex within populations of these fungi, and attendant genetic recombination, eventually may create difficulties for their control; and subsequently for the protection of important human and animal food supplies. Moreover, if fungal sex is a form of response to ecological and environmental stressors, then perhaps human influence and climate change could accelerate this phenomenon. This article will explore scientific research into sexuality and recombination in aflatoxigenic Aspergillus species; the potential impacts these phenomena could have on a popular method of pre-harvest prevention of aflatoxin contamination (i.e., use of non-aflatoxigenic A. flavus for biocontrol); and the outlook for maintaining control of aflatoxin contamination in an era of changing global climate. PMID:24550903

  10. Loss of msnA, a putative stress regulatory gene, in Aspergillus parasiticus and Aspergillus flavus increased production of conidia, aflatoxins and kojic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillus flavus has been postulated to be a mechanism to relieve oxidative stress. The msnA gene, the ortholog of Saccharomyces cerevisiae MSN2 associated with multi-stress response, of the two species was disrupted....

  11. The Aspergillus flavus fluP-associated metabolite promotes sclerotial production.

    PubMed

    Chang, Perng-Kuang; Scharfenstein, Leslie L; Ehrlich, Kenneth C; Diana Di Mavungu, José

    2016-10-01

    Aspergillus flavus is able to synthesize a variety of polyketide-derived secondary metabolites including the hepatocarcinogen, aflatoxin B1. The fungus reproduces and disseminates predominantly by production of conidia. It also produces hardened mycelial aggregates called sclerotia that are used to cope with unfavourable growth environments. In the present study, we examined the role of A. flavus fluP, the backbone polyketide synthase gene of secondary metabolite gene cluster 41, on fungal development. The A. flavus CA14 fluP deletion mutant (AfΔfluP) grew and accumulated aflatoxin normally but produced a lower amount of sclerotia than the parental strain. This was also true for the Aspergillus parasiticus BN9 fluP deletion mutant (ApΔfluP). The A. flavus fluP gene was positively regulated by developmental regulators of VeA and VelB but not by the global regulator of secondary metabolism, LaeA. Overexpression of fluP in AfΔfluP (OEfluP) elevated its ability to produce sclerotia compared to that of the parental strain. Coculture of OEfluP with CA14, AfΔfluP, ApΔfluP, or an A. flavus pptA deletion mutant incapable of producing functional polyketide synthases also allowed increased sclerotial production of the respective strains at edges where colonies made contact. Acetone extracts of OEfluP but not of AfΔfluP exhibited the same effect in promoting sclerotial production of AfΔfluP. These results suggest that FluP polyketide synthase is involved in the synthesis of a diffusible metabolite that could serve as a signal molecule to regulate sclerotiogenesis. PMID:27647242

  12. Aspergillus Flavus Endocarditis of the Native Mitral Valve in a Bone Marrow Transplant Patient

    PubMed Central

    Demir, Tolga; Ergenoglu, Mehmet Umit; Ekinci, Abdurrahman; Tanrikulu, Nursen; Sahin, Mazlum; Demirsoy, Ergun

    2015-01-01

    Patient: Male, 36 Final Diagnosis: Aspergillus flavus endocarditis Symptoms: Malaise • fatigue and dyspnea Medication: — Clinical Procedure: Mitral vale replacemnet Specialty: Cardiology Objective: Rare disease Background: Infective endocarditis due to Aspergillus species is an uncommon infection with a high mortality rate. It mostly occurs after the implantation of prosthetic heart valves. Parenteral nutrition, immunosuppression, broad-spectrum antibiotic regimens, and illegal intravenous drug use are the risk factors for developing infection. Case Report: We report a case of Aspergillus flavus native mitral valve endocarditis in a patient who had allogeneic stem cell transplantation in the past due to myelodysplastic syndrome. Conclusions: Although it is rare and there is limited experience available with the diagnosis and treatment, early recognition and therapeutic intervention with systemic antifungal therapy and aggressive surgical intervention are critical to prevent further complications that may eventually lead to death. In addition, better novel diagnostic tools are needed to facilitate more accurate identification of patients with invasive Aspergillus and to permit earlier initiation of antifungal treatment. PMID:25603977

  13. The Aspergillus flavus Histone Acetyltransferase AflGcnE Regulates Morphogenesis, Aflatoxin Biosynthesis, and Pathogenicity.

    PubMed

    Lan, Huahui; Sun, Ruilin; Fan, Kun; Yang, Kunlong; Zhang, Feng; Nie, Xin Y; Wang, Xiunai; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops. PMID:27625637

  14. Role of Oxidative Stress in Sclerotial Differentiation and Aflatoxin B1 Biosynthesis in Aspergillus flavus

    PubMed Central

    Grintzalis, Konstantinos; Vernardis, Spyros I.; Klapa, Maria I.

    2014-01-01

    We show here that oxidative stress is involved in both sclerotial differentiation (SD) and aflatoxin B1 biosynthesis in Aspergillus flavus. Specifically, we observed that (i) oxidative stress regulates SD, as implied by its inhibition by antioxidant modulators of reactive oxygen species and thiol redox state, and that (ii) aflatoxin B1 biosynthesis and SD are comodulated by oxidative stress. However, aflatoxin B1 biosynthesis is inhibited by lower stress levels compared to SD, as shown by comparison to undifferentiated A. flavus. These same oxidative stress levels also characterize a mutant A. flavus strain, lacking the global regulatory gene veA. This mutant is unable to produce sclerotia and aflatoxin B1. (iii) Further, we show that hydrogen peroxide is the main modulator of A. flavus SD, as shown by its inhibition by both an irreversible inhibitor of catalase activity and a mimetic of superoxide dismutase activity. On the other hand, aflatoxin B1 biosynthesis is controlled by a wider array of oxidative stress factors, such as lipid hydroperoxide, superoxide, and hydroxyl and thiyl radicals. PMID:25002424

  15. Effects of Nutrients in Substrates of Different Grains on Aflatoxin B1 Production by Aspergillus flavus.

    PubMed

    Liu, Jie; Sun, Lvhui; Zhang, Niya; Zhang, Jiacai; Guo, Jiao; Li, Chong; Rajput, Shahid Ali; Qi, Desheng

    2016-01-01

    The current study was to better understand the potential factors affecting aflatoxin B1 (AFB1) accumulation varies between different grains. The nutrient composition and contents of defatted substrates were determined; additionally, according to the nutrient content of the substrates, the effects of starch, soluble sugars, amino acids, and trace elements on AFB1 production and mycelial growth in Czapek-Dox medium were examined. These results verified that removal of lipids from ground substrates significantly reduced the substrate's potential for AFB1 production by Aspergillus flavus. Maltose, glucose, sucrose, arginine, glutamic acid, aspartic acid, and zinc significantly induced AFB1 production up to 1.7- to 26.6-fold. And stachyose more significantly promoted A. flavus growth than the other nutrients. Thus, this study demonstrated that, combined with the nutrients content of grains, in addition to lipids, sucrose, stachyose, glutamic acid, and zinc might play key roles in various grains that are differentially infected by A. flavus. Particularly, two new nutrients (arginine and stachyose) of the grains we found significantly stimulate AFB1 production and A. flavus growth, respectively. The results provide new concepts for antifungal methods to protect food and animal feed from AFB1 contamination. PMID:27294129

  16. Aflatoxins in Rice Artificially Contaminated with Aflatoxin-producing Aspergillus flavus under Natural Storage in Japan.

    PubMed

    Sugihara, Satoshi; Doi, Hiroyuki; Kato, Masahiko; Mitoh, Yoshihiro; Tsuda, Toshihide; Ikeda, Satoru

    2016-06-01

    Aflatoxin (AFT) contamination is frequent in foods grown in tropical regions, including rice. Although AFTs are generally not found in temperate-region foods, global warming has affected typical temperate-region climates, potentially permitting the contamination of foods with AFT-producing Aspergillus flavus (A. flavus). Here we investigated the AFT production in rice during storage under natural climate conditions in Japan. We examined AFTs in brown rice and rough rice artificially contaminated with A. flavus for 1 year in Japan, and we subjected AFTs in white rice to the same treatment in airtight containers and examined the samples in warm and cold seasons, simulating the storage of white rice in general households. In the brown rice, AFTs increased after 2 months (March) and peaked after 9 months (October). The AFT contamination in the rough rice was minimal. After the polishing and cooking of the brown rice, AFTs were undetectable. In the white rice stored in airtight containers, AFTs increased after 1 month (August) and peaked after 2 months (September). Minimal AFTs were detected in the cold season. Thus, AFT contamination in rice may occur in temperate regions following A. flavus contamination. The storage of rice as rough rice could provide be useful for avoiding AFT contamination.

  17. The DmtA methyltransferase contributes to Aspergillus flavus conidiation, sclerotial production, aflatoxin biosynthesis and virulence

    PubMed Central

    Yang, Kunlong; Liang, Linlin; Ran, Fanlei; Liu, Yinghang; Li, Zhenguo; Lan, Huahui; Gao, Peili; Zhuang, Zhenhong; Zhang, Feng; Nie, Xinyi; Kalayu Yirga, Shimuye; Wang, Shihua

    2016-01-01

    DNA methylation is essential for epigenetic regulation of gene transcription and development in many animals, plants and fungi. We investigated whether DNA methylation plays a role in the development and secondary metabolism of Aspergillus flavus, identified the DmtA methyltransferase from A. flavus, and produced a dmtA knock-out mutant by replacing the dmtA coding sequence with the pyrG selectable marker. The A. flavus dmtA null mutant lines produced white fluffy mycelium in liquid medium, and displayed a slightly flavescent conidial pigmentation compared with the normal yellow of the wild-type strain when grown on agar. The ΔdmtA lines exhibited decreased conidiation and aflatoxin (AF) biosynthesis, compared with the wild-type line, suggesting that the DmtA knock-out affected the transcriptional level of genes in the AF cluster. In particular, sclerotia development and host colonization were altered in the dmtA null mutants. Green fluorescent protein tagging at the C-terminus of DmtA showed that DmtA localized to the nucleus and cytoplasm. DNA methylation content measurements in the dmtA mutants revealed no widespread DNA methylation in the mutants or wild-type lines. Thus, our findings suggest that DmtA, apart from being a C-5 cytosine methyltransferase in A. flavus, contributes to asexual development, aflatoxin biosynthesis, sclerotial production and virulence. PMID:26979781

  18. The Aspergillus flavus Histone Acetyltransferase AflGcnE Regulates Morphogenesis, Aflatoxin Biosynthesis, and Pathogenicity

    PubMed Central

    Lan, Huahui; Sun, Ruilin; Fan, Kun; Yang, Kunlong; Zhang, Feng; Nie, Xin Y.; Wang, Xiunai; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops. PMID:27625637

  19. Effects of Nutrients in Substrates of Different Grains on Aflatoxin B1 Production by Aspergillus flavus

    PubMed Central

    Liu, Jie; Sun, Lvhui; Zhang, Niya; Zhang, Jiacai; Guo, Jiao; Li, Chong; Rajput, Shahid Ali; Qi, Desheng

    2016-01-01

    The current study was to better understand the potential factors affecting aflatoxin B1 (AFB1) accumulation varies between different grains. The nutrient composition and contents of defatted substrates were determined; additionally, according to the nutrient content of the substrates, the effects of starch, soluble sugars, amino acids, and trace elements on AFB1 production and mycelial growth in Czapek-Dox medium were examined. These results verified that removal of lipids from ground substrates significantly reduced the substrate's potential for AFB1 production by Aspergillus flavus. Maltose, glucose, sucrose, arginine, glutamic acid, aspartic acid, and zinc significantly induced AFB1 production up to 1.7- to 26.6-fold. And stachyose more significantly promoted A. flavus growth than the other nutrients. Thus, this study demonstrated that, combined with the nutrients content of grains, in addition to lipids, sucrose, stachyose, glutamic acid, and zinc might play key roles in various grains that are differentially infected by A. flavus. Particularly, two new nutrients (arginine and stachyose) of the grains we found significantly stimulate AFB1 production and A. flavus growth, respectively. The results provide new concepts for antifungal methods to protect food and animal feed from AFB1 contamination. PMID:27294129

  20. Comparative Chemistry of Aspergillus oryzae (RIB40) and A. flavus (NRRL 3357)

    PubMed Central

    Rank, Christian; Klejnstrup, Marie Louise; Petersen, Lene Maj; Kildgaard, Sara; Frisvad, Jens Christian; Gotfredsen, Charlotte Held; Larsen, Thomas Ostenfeld

    2012-01-01

    Aspergillus oryzae and A. flavus are important species in industrial biotechnology and food safety and have been some of the first aspergilli to be fully genome sequenced. Bioinformatic analysis has revealed 99.5% gene homology between the two species pointing towards a large coherence in the secondary metabolite production. In this study we report on the first comparison of secondary metabolite production between the full genome sequenced strains of A. oryzae (RIB40) and A. flavus (NRRL 3357). Surprisingly, the overall chemical profiles of the two strains were mostly very different across 15 growth conditions. Contrary to previous studies we found the aflatrem precursor 13-desoxypaxilline to be a major metabolite from A. oryzae under certain growth conditions. For the first time, we additionally report A. oryzae to produce parasiticolide A and two new analogues hereof, along with four new alkaloids related to the A. flavus metabolites ditryptophenalines and miyakamides. Generally the secondary metabolite capability of A. oryzae presents several novel end products likely to result from the domestication process from A. flavus. PMID:24957367

  1. The Aspergillus flavus Histone Acetyltransferase AflGcnE Regulates Morphogenesis, Aflatoxin Biosynthesis, and Pathogenicity

    PubMed Central

    Lan, Huahui; Sun, Ruilin; Fan, Kun; Yang, Kunlong; Zhang, Feng; Nie, Xin Y.; Wang, Xiunai; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    Histone acetyltransferases (HATs) help regulate fungal development and the production of secondary metabolites. In this study, we determined that the HAT AflGcnE influenced morphogenesis and aflatoxin biosynthesis in Aspergillus flavus. We observed that AflGcnE localized to the nucleus and cytoplasm during the conidial production and germination stages, while it was located mainly in the nucleus during the hyphal development stage. Deletion of AflgcnE inhibited the growth of A. flavus and decreased the hydrophobicity of the cell surface. The ΔAflgcnE mutant exhibited a lack of asexual sporulation and was unable to generate sclerotia. Additionally, AflgcnE was required to maintain cell wall integrity and genotoxic stress responses. Importantly, the ΔAflgcnE mutant did not produce aflatoxins, which was consistent with a significant down-regulation of aflatoxin gene expression levels. Furthermore, our data revealed that AflgcnE is a pathogenicity factor required for colonizing maize seeds. In summary, we revealed that A. flavus AflGcnE is crucial for morphological development, aflatoxin biosynthesis, stress responses, and pathogenicity. Our findings help clarify the functional divergence of GcnE orthologs, and may provide a possible target for controlling A. flavus infections of agriculturally important crops.

  2. Inactivation of Aspergillus flavus in drinking water after treatment with UV irradiation followed by chlorination.

    PubMed

    Al-Gabr, Hamid Mohammad; Zheng, Tianling; Yu, Xin

    2013-10-01

    The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety of drinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination, ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followed by chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UV irradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log10 control of A. flavus was achieved after 30 s of irradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3 mg/l, in contact time of 60, 5, 1 and 1 min, respectively. However, combined use (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5 s UV irradiation followed by chlorination produced 4 log10 reduction of A. flavus at chlorine concentrations of 2 and 3 mg/l under a contact time of 15 min. The results indicated that efficiency of UV irradiation improves when followed by chlorination at low concentrations.

  3. Aspergillus flavus infection induces transcriptional and physical changes in developing maize kernels

    PubMed Central

    Dolezal, Andrea L.; Shu, Xiaomei; OBrian, Gregory R.; Nielsen, Dahlia M.; Woloshuk, Charles P.; Boston, Rebecca S.; Payne, Gary A.

    2014-01-01

    Maize kernels are susceptible to infection by the opportunistic pathogen Aspergillus flavus. Infection results in reduction of grain quality and contamination of kernels with the highly carcinogenic mycotoxin, aflatoxin. To understanding host response to infection by the fungus, transcription of approximately 9000 maize genes were monitored during the host-pathogen interaction with a custom designed Affymetrix GeneChip® DNA array. More than 4000 maize genes were found differentially expressed at a FDR of 0.05. This included the up regulation of defense related genes and signaling pathways. Transcriptional changes also were observed in primary metabolism genes. Starch biosynthetic genes were down regulated during infection, while genes encoding maize hydrolytic enzymes, presumably involved in the degradation of host reserves, were up regulated. These data indicate that infection of the maize kernel by A. flavus induced metabolic changes in the kernel, including the production of a defense response, as well as a disruption in kernel development. PMID:25132833

  4. Antimicrobial effects of ionizing radiation on artificially and naturally contaminated cacao beans. [Aspergillus flavus; Penicillium citrinum

    SciTech Connect

    Restaino, L.; Myron, J.J.J.; Lenovich, L.M.; Bills, S.; Tscherneff, K.

    1984-04-01

    With an initial microbial level of ca. 10/sup 7/ microorganisms per g of Ivory Coast cacao beans, 5 kGy of gamma radiation from a Co/sup 60/ source under an atmosphere of air reduced the microflora per g by 2.49 and 3.03 logs at temperatures of 35 and 50/sup 0/C, respectively. Bahia cacao beans were artificially contaminated with dried spores of Aspergillus flavus and Penicillium citrinum, giving initial fungal levels of 1.9 x 10/sup 4/ and 1.4 x 10/sup 3/ spores per g of whole Bahia cacao beans, respectively. The average D/sub 10/ values for A. flavus and P. citrinum spores on Bahia cacao beans were 0.66 and 0.88 kGy, respectively. 12 references.

  5. Recombinant expression and inhibition mechanism analysis of pectin methylesterase from Aspergillus flavus.

    PubMed

    Jiang, Xiuping; Jia, Qiulei; Chen, Lei; Chen, Qi; Yang, Qing

    2014-06-01

    Phytopathogenic microorganisms can produce pectin methylesterase (PME) to degrade plant cell walls during plant invasion. This enzyme is thought to be a virulence factor of phytopathogens. In this work, PME from Aspergillus flavus (AFPME) was expressed in Pichia pastoris and an in vitro inhibitor study was performed. The purified AFPME with a yield of 52.2% was resolved as one band with a molecular mass of c. 40 kDa by SDS-PAGE. Optimal activity of the enzyme occurred at a temperature of 55 °C and a pH of 4.8. Epigallocatechin gallate (EGCG) strongly inhibited the activity of recombinant AFPME. The molecular docking analysis indicated that EGCG could form hydrogen bonds and π-π interactions with some amino acid residues in the active site of AFPME. Our studies provide a novel strategy for the control of the plant invasion of A. flavus. PMID:24766423

  6. Degradation of polyurethane by Aspergillus flavus (ITCC 6051) isolated from soil.

    PubMed

    Mathur, Garima; Prasad, Ramasare

    2012-07-01

    The present study deals with the isolation of fungi from soil with the ability to degrade polyurethane (PU). A pure fungal isolate was analyzed for its ability to utilize PU as a sole carbon source in shaking culture for 30 days. Incubation of PU with Aspergillus flavus resulted in 60.6% reduction in weight of PU. The scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) results showed certain changes on the surface of PU film and formation of some new intermediate products after polymer breakdown. Thermogravimetric curves showed changes between the thermal behavior of the samples that were inoculated with A. flavus and control. FTIR spectra showed detectable changes in control and incubated samples, suggesting that degradation occurs, with the decreased intensity of band at 1,715 cm(-1), corresponding to ester linkages. We have identified an extracellular esterase activity which might be responsible for the polyurethanolytic activity. PMID:22367637

  7. Conidial movement of nontoxigenic Aspergillus flavus and A. parasiticus in peanut fields following application to soil.

    PubMed

    Horn, B W; Greene, R L; Sorensen, R B; Blankenship, P D; Dorner, J W

    2001-01-01

    The use of nontoxigenic strains of Aspergillus flavus and A. parasiticus in biological control effectively reduces aflatoxin in peanuts when conidium- producing inoculum is applied to the soil surface. In this study, the movement of conidia in soil was examined following natural rainfall and controlled precipitation from a sprinkler irrigation system. Conidia of nontoxigenic A. flavus and A. parasiticus remained near the soil surface despite repeated rainfall and varying amounts of applied water from irrigation. In addition, rainfall washed the conidia along the peanut furrows for up to 100 meters downstream from the experimental plot boundary. The dispersal gradient was otherwise very steep upstream along the furrows and in directions perpendicular to the peanut rows. The retention of biocontrol conidia in the upper soil layers is likely important in reducing aflatoxin contamination of peanuts and aerial crops such as corn and cottonseed. PMID:11554582

  8. Proteomic analysis of rutin-induced secreted proteins from Aspergillus flavus.

    PubMed

    Medina, Martha L; Kiernan, Urban A; Francisco, Wilson A

    2004-03-01

    Few studies have been conducted to identify the extracellular proteins and enzymes secreted by filamentous fungi, particularly with respect to dispensable metabolic pathways. Proteomic analysis has proven to be the most powerful method for identification of proteins in complex mixtures and is suitable for the study of the alteration of protein expression under different environmental conditions. The filamentous fungus Aspergillus flavus can degrade the flavonoid rutin as the only source of carbon via an extracellular enzyme system. In this study, a proteomic analysis was used to differentiate and identify the extracellular rutin-induced and non-induced proteins secreted by A. flavus. The secreted proteins were analyzed by two-dimensional electrophoresis and MALDI-TOF mass spectrometry. While 15 rutin-induced proteins and 7 non-induced proteins were identified, more than 90 protein spots remain unidentified, indicating that these proteins are either novel proteins or proteins that have not yet been sequenced.

  9. Controlling Aspergillus flavus and Aspergillus parasiticus growth and aflatoxin production in poultry feed using carvacrol and trans-cinnamaldehyde.

    PubMed

    Yin, Hsin-Bai; Chen, Chi-Hung; Kollanoor-Johny, Anup; Darre, Michael J; Venkitanarayanan, Kumar

    2015-09-01

    Aflatoxins (AF) are toxic metabolites primarily produced by molds, Aspergillus flavus and Aspergillus parasiticus. Contamination of poultry feed with AF is a major concern to the poultry industry due to severe economic losses stemming from poor performance, reduced egg production, and diminished egg hatchability. This study investigated the inhibitory effect of 2 generally regarded as safe (GRAS), natural plant compounds, namely carvacrol (CR) and trans-cinnamaldehyde (TC), on A. flavus and A. parasiticus growth and AF production in potato dextrose broth (PDB) and in poultry feed. In broth culture, PDB supplemented with CR (0%, 0.02%, 0.04% and 0.08%) or TC (0%, 0.005%, 0.01% and 0.02%) was inoculated with A. flavus or A. parasiticus (6 log CFU/mL), and mold counts and AF production were determined on days 0, 1, 3, and 5. Similarly, 200 g portions of poultry feed supplemented with CR or TC (0%, 0.4%, 0.8%, and 1.0%) were inoculated with each mold, and their counts and AF concentrations in the feed were determined at 0, 1, 2, 3, 4, 8, and 12 weeks of storage. Moreover, the effect of CR and TC on the expression of AF synthesis genes in A. flavus and A. parasiticus (aflC, nor1, norA, and ver1) was determined using real-time quantitative PCR (RT-qPCR). All experiments had duplicate samples and were replicated 3 times. Results indicated that CR and TC reduced A. flavus and A. parasiticus growth and AF production in broth culture and chicken feed (P<0.05). All tested concentrations of CR and TC decreased AF production in broth culture and chicken feed by at least 60% when compared to controls (P<0.05). In addition, CR and TC down-regulated the expression of major genes associated with AF synthesis in the molds (P<0.05). Results suggest the potential use of CR and TC as feed additives to control AF contamination in poultry feed.

  10. A maize lectin-like protein with antifungal activity against Aspergillus flavus.

    PubMed

    Baker, R L; Brown, R L; Chen, Z-Y; Cleveland, T E; Fakhoury, A M

    2009-01-01

    The filamentous fungus Aspergillus flavus causes an ear rot on maize and produces a mycotoxin (aflatoxin) in colonized maize kernels. Aflatoxins are carcinogenic to humans and animals upon ingestion. Aflatoxin contamination results in a large loss of profits and marketable yields for farmers each year. Several research groups have worked to pinpoint sources of resistance to A. flavus and the resulting aflatoxin contamination in maize. Some maize genotypes exhibit greater resistance than others. A proteomics approach has recently been used to identify endogenous maize proteins that may be associated with resistance to the fungus. Research has been conducted on cloning, expression, and partial characterization of one such protein, which has a sequence similar to that of cold-regulated proteins. The expressed protein, ZmCORp, exhibited lectin-like hemagglutination activity against fungal conidia and sheep erythrocytes. Quantitative real-time PCR assays revealed that ZmCOR is expressed 50% more in maize kernels from the Mp420 line, a type of maize resistant to A. flavus, compared with the expression level of the gene in the susceptible B73 line. ZmCORp exhibited fungistatic activity when conidia from A. flavus were exposed to the protein at a final concentration of 18 mM. ZmCORp inhibited the germination of conidia by 80%. A 50% decrease in mycelial growth resulted when germinated conidia were incubated with the protein. The partial characterization of ZmCORp suggests that this protein may play an important role in enhancing kernel resistance to A. flavus infection and aflatoxin accumulation. PMID:19205472

  11. Potential of essential oils for protection of grains contaminated by aflatoxin produced by Aspergillus flavus

    PubMed Central

    Esper, Renata H.; Gonçalez, Edlayne; Marques, Marcia O. M.; Felicio, Roberto C.; Felicio, Joana D.

    2014-01-01

    Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oils of Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) on the mycelial growth and aflatoxin B1 production by Aspergillus flavus have been studied previously in culture medium. The aim of this study was to evaluate aflatoxin B1 production by Aspergillus flavus in real food systems (corn and soybean) treated with Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) essential oils. Samples with 60 g of the grains were treated with different volumes of essential oils, 200, 100, 50, and 10 μL for oregano and 50, 30, 15, and 10 μL for mentrasto. Fungal growth was evaluated by disk diffusion method. Aflatoxin B1 production was evaluated inoculating suspensions of A. flavus containing 1.3 × 105 spores/mL in 60 g of grains (corn and soybeans) after adjusting the water activity at 0.94. Aflatoxin was quantified by photodensitometry. Fungal growth and aflatoxin production were inhibited by essential oils, but the mentrasto oil was more effective in soybeans than that of oregano. On the other hand, in corn samples, the oregano essential oil was more effective than that of mentrasto. Chemical compositions of the essential oils were also investigated. The GC/MS oils analysis showed that the main component of mentrasto essential oil is precocene I and of the main component of oregano essential oil is 4-terpineol. The results indicate that both essential oils can become an alternative for the control of aflatoxins in corn and soybeans. PMID:24926289

  12. Identification of novel metabolites from Aspergillus flavus by high resolution and multiple stage mass spectrometry.

    PubMed

    Malysheva, Svetlana V; Arroyo-Manzanares, Natalia; Cary, Jeffrey W; Ehrlich, Kenneth C; Vanden Bussche, Julie; Vanhaecke, Lynn; Bhatnagar, Deepak; Di Mavungu, José Diana; De Saeger, Sarah

    2014-01-01

    The filamentous fungus Aspergillus flavus is one of the most important species in the Aspergillus genus and is distributed worldwide as a prevalent aflatoxin-producing food and feed contaminant. A. flavus contains more than 55 gene clusters that are predicted to encode proteins involved in secondary metabolite production. One of these, cluster 27, contains a polyketide synthase (pks27) gene that encodes a protein that is highly homologous to the aflatoxin cluster PKS. Comparative metabolomics, using ultra-high performance liquid chromatography (UHPLC) coupled to high resolution Orbitrap mass spectrometry (MS) was used to detect metabolites differentially expressed in the A. flavus wild-type and ∆pks27 mutant strains. Metabolite profiling was aided by a statistical differential analysis of MS data using SIEVE software. This differential analysis combined with accurate mass data from the Orbitrap and ion trap multiple stage MS allowed four metabolites to be identified that were produced only by the wild-type culture. These included asparasone A (358 Da), an anthraquinone pigment, and related anthraquinones with masses of 316, 340 and 374 Da. These latter three compounds had similar fragmentation patterns to that of asparasone A. The 316 Da anthraquinone is particularly interesting because it is most likely formed by incorporation of seven malonyl-CoA units rather than the eight units required for the formation of asparasone A. The 340 and 374 Da metabolites are the dehydration and an oxy-derivative of asparasone A, respectively. Asparasone A was also identified in extracts from several other Aspergillus species. PMID:24405210

  13. Identification of novel metabolites from Aspergillus flavus by high resolution and multiple stage mass spectrometry.

    PubMed

    Malysheva, Svetlana V; Arroyo-Manzanares, Natalia; Cary, Jeffrey W; Ehrlich, Kenneth C; Vanden Bussche, Julie; Vanhaecke, Lynn; Bhatnagar, Deepak; Di Mavungu, José Diana; De Saeger, Sarah

    2014-01-01

    The filamentous fungus Aspergillus flavus is one of the most important species in the Aspergillus genus and is distributed worldwide as a prevalent aflatoxin-producing food and feed contaminant. A. flavus contains more than 55 gene clusters that are predicted to encode proteins involved in secondary metabolite production. One of these, cluster 27, contains a polyketide synthase (pks27) gene that encodes a protein that is highly homologous to the aflatoxin cluster PKS. Comparative metabolomics, using ultra-high performance liquid chromatography (UHPLC) coupled to high resolution Orbitrap mass spectrometry (MS) was used to detect metabolites differentially expressed in the A. flavus wild-type and ∆pks27 mutant strains. Metabolite profiling was aided by a statistical differential analysis of MS data using SIEVE software. This differential analysis combined with accurate mass data from the Orbitrap and ion trap multiple stage MS allowed four metabolites to be identified that were produced only by the wild-type culture. These included asparasone A (358 Da), an anthraquinone pigment, and related anthraquinones with masses of 316, 340 and 374 Da. These latter three compounds had similar fragmentation patterns to that of asparasone A. The 316 Da anthraquinone is particularly interesting because it is most likely formed by incorporation of seven malonyl-CoA units rather than the eight units required for the formation of asparasone A. The 340 and 374 Da metabolites are the dehydration and an oxy-derivative of asparasone A, respectively. Asparasone A was also identified in extracts from several other Aspergillus species.

  14. An opportunistic human pathogen on the fly: strains of Aspergillus flavus vary in virulence in Drosophila melanogaster.

    PubMed

    Ramírez-Camejo, Luis A; Torres-Ocampo, Ana P; Agosto-Rivera, José L; Bayman, Paul

    2014-02-01

    Aspergilloses are fungal diseases in humans and animals that is caused by members of the genus Aspergillus. Aspergillus flavus is an important opportunistic pathogen, second only to A. fumigatus as a cause of human aspergillosis. Differences in virulence among A. flavus isolates from clinical and other substrates and mating types are not well known. The fruit fly Drosophila melanogaster has become a model organism for investigating virulence of human pathogens due to similarities between its immune system and that of mammals. In this study we used D. melanogaster as a model host to compare virulence among A. flavus strains obtained from clinical sources as compared with other substrates, between isolates of different mating types, and between isolates of A. flavus and A. fumigatus. Anesthetized flies were infected with A. flavus; mortality ranged from 15% to >90%. All strains were virulent, but some were significantly more so than others, which in turn led to the wide mortality range. Clinical strains were significantly less virulent than environmental strains, probably because the clinical strains were from culture collections and the environmental strains were recent isolates. Mean virulence did not differ between MAT1-1 and MAT1-2 mating types and the phylogeny of A. flavus isolates did not predict virulence. A. flavus was on average significantly more virulent than A. fumigatus on two lines of wild-type flies, Canton-S and Oregon-R. D. melanogaster is an attractive model to test pathogenicity and could be useful for identifying genes involved in virulence.

  15. Loss of msnA, a Putative Stress Regulatory Gene, in Aspergillus parasiticus and Aspergillus flavus Increased Production of Conidia, Aflatoxins and Kojic Acid

    PubMed Central

    Chang, Perng-Kuang; Scharfenstein, Leslie L.; Luo, Meng; Mahoney, Noreen; Molyneux, Russell J.; Yu, Jiujiang; Brown, Robert L.; Campbell, Bruce C.

    2011-01-01

    Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillus flavus has been postulated to be a mechanism to relieve oxidative stress. The msnA gene of A. parasiticus and A. flavus is the ortholog of Saccharomyces cerevisiae MSN2 that is associated with multi-stress response. Compared to wild type strains, the msnA deletion (∆msnA) strains of A. parasiticus and A. flavus exhibited retarded colony growth with increased conidiation. The ∆msnA strains also produced slightly higher amounts of aflatoxins and elevated amounts of kojic acid on mixed cereal medium. Microarray assays showed that expression of genes encoding oxidative stress defense enzymes, i.e., superoxide dismutase, catalase, and cytochrome c peroxidase in A. parasiticus ∆msnA, and the catalase A gene in A. flavus ∆msnA, was up-regulated. Both A. parasiticus and A. flavus ∆msnA strains produced higher levels of reactive oxygen species (ROS), and ROS production of A. flavus msnA addback strains was decreased to levels comparable to that of the wild type A. flavus. The msnA gene appears to be required for the maintenance of the normal oxidative state. The impairment of msnA resulted in the aforementioned changes, which might be used to combat the increased oxidative stress in the cells. PMID:22069691

  16. Loss of msnA, a putative stress regulatory gene, in Aspergillus parasiticus and Aspergillus flavus increased production of conidia, aflatoxins and kojic acid.

    PubMed

    Chang, Perng-Kuang; Scharfenstein, Leslie L; Luo, Meng; Mahoney, Noreen; Molyneux, Russell J; Yu, Jiujiang; Brown, Robert L; Campbell, Bruce C

    2011-01-01

    Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillus flavus has been postulated to be a mechanism to relieve oxidative stress. The msnA gene of A. parasiticus and A. flavus is the ortholog of Saccharomyces cerevisiae MSN2 that is associated with multi-stress response. Compared to wild type strains, the msnA deletion (∆msnA) strains of A. parasiticus and A. flavus exhibited retarded colony growth with increased conidiation. The ∆msnA strains also produced slightly higher amounts of aflatoxins and elevated amounts of kojic acid on mixed cereal medium. Microarray assays showed that expression of genes encoding oxidative stress defense enzymes, i.e., superoxide dismutase, catalase, and cytochrome c peroxidase in A. parasiticus ∆msnA, and the catalase A gene in A. flavus ∆msnA, was up-regulated. Both A. parasiticus and A. flavus ∆msnA strains produced higher levels of reactive oxygen species (ROS), and ROS production of A. flavus msnA addback strains was decreased to levels comparable to that of the wild type A. flavus. The msnA gene appears to be required for the maintenance of the normal oxidative state. The impairment of msnA resulted in the aforementioned changes, which might be used to combat the increased oxidative stress in the cells. PMID:22069691

  17. Thanatin confers partial resistance against aflatoxigenic fungi in maize (Zea mays).

    PubMed

    Schubert, Max; Houdelet, Marcel; Kogel, Karl-Heinz; Fischer, Rainer; Schillberg, Stefan; Nölke, Greta

    2015-10-01

    Aflatoxin-producing fungi can contaminate plants and plant-derived products with carcinogenic secondary metabolites that present a risk to human and animal health. In this study, we investigated the effect of antimicrobial peptides on the major aflatoxigenic fungi Aspergillus flavus and A. parasiticus. In vitro assays with different chemically-synthesized peptides demonstrated that the broad-spectrum peptide thanatin from the spined soldier bug (Podisus maculiventris) had the greatest potential to eliminate aflatoxigenic fungi. The minimal inhibitory concentrations of thanatin against A. flavus and A. parasiticus were 3.13 and 12.5 µM, respectively. A thanatin cDNA was subsequently cloned in a plant expression vector under the control of the ubiquitin-1 promoter allowing the recombinant peptide to be directed to the apoplast in transgenic maize plants. Successful integration of the thanatin expression cassette was confirmed by PCR and expression was demonstrated by semi-quantitative RT-PCR in transgenic maize kernels. Infection assays with maize kernels from T1 transgenic plants showed up to three-fold greater resistance against Aspergillus spp. infections compared to non-transgenic kernels. We demonstrated for the first time that heterologous expression of the antimicrobial peptide thanatin inhibits the growth of Aspergillus spp. in transgenic maize plants offering a solution to protect crops from aflatoxin-producing fungi and the resulting aflatoxin contamination in the field and under storage conditions.

  18. New Monomeric Stilbenoids from Peanut (Arachis hypogaea) Seeds Challenged by an Aspergillus flavus Strain.

    PubMed

    Sobolev, Victor S; Krausert, Nicole M; Gloer, James B

    2016-01-27

    Two new stilbene derivatives have been isolated from peanut seeds challenged by an Aspergillus flavus strain, along with chiricanine B, which has not been previously reported from peanuts, as well as a stilbenoid reported previously only as a synthetic product. The structures of these new putative phytoalexins were determined by analysis of (1)H and (13)C NMR, HRESIMS, MS(n), and UV data. The new stilbenoids were named arahypin-13 (21), arahypin-14 (22), and arahypin-15 (23). Together with other known bioactive peanut stilbenoids that were also produced in the challenged seeds, these new compounds may play a defensive role against invasive fungi. PMID:26672388

  19. New Monomeric Stilbenoids from Peanut (Arachis hypogaea) Seeds Challenged by an Aspergillus flavus Strain.

    PubMed

    Sobolev, Victor S; Krausert, Nicole M; Gloer, James B

    2016-01-27

    Two new stilbene derivatives have been isolated from peanut seeds challenged by an Aspergillus flavus strain, along with chiricanine B, which has not been previously reported from peanuts, as well as a stilbenoid reported previously only as a synthetic product. The structures of these new putative phytoalexins were determined by analysis of (1)H and (13)C NMR, HRESIMS, MS(n), and UV data. The new stilbenoids were named arahypin-13 (21), arahypin-14 (22), and arahypin-15 (23). Together with other known bioactive peanut stilbenoids that were also produced in the challenged seeds, these new compounds may play a defensive role against invasive fungi.

  20. Antifungal properties and inhibitory effects upon aflatoxin production of Thymus vulgaris L. by Aspergillus flavus Link.

    PubMed

    Kohiyama, Cássia Yumie; Yamamoto Ribeiro, Milene Mayumi; Mossini, Simone Aparecida Galerani; Bando, Erika; Bomfim, Natália da Silva; Nerilo, Samuel Botião; Rocha, Gustavo Henrique Oliveira; Grespan, Renata; Mikcha, Jane Martha Graton; Machinski, Miguel

    2015-04-15

    The antifungal and antiaflatoxigenic properties of Thymus vulgaris essential oil (TEO) were evaluated upon Aspergillus flavus "in vitro". Suspension containing 10(6) of A. flavus were cultivated with TEO in concentrations ranging from 50 to 500 μg/mL. TEO reached minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) at 250 μg/mL. Inhibition of ergosterol biosynthesis was detected at a concentration of 100 μg/mL of TEO. Morphological evaluation performed by both light microscopy and scanning electron microscopy showed that antifungal activity of TEO could be detected starting at a concentration of 50 μg/mL and the fungicide effect at a concentration of 250 μg/mL. TEO completely inhibited production of both B1 and B2 aflatoxins (AFB1 and AFB2) at a concentration of 150 μg/mL. This way, fungal biomass development and aflatoxin production were dependent on TEO concentration. Therefore, TEO was capable of controlling the growth of A. flavus and its production of aflatoxins.

  1. Self-sufficient redox biotransformation of lignin-related benzoic acids with Aspergillus flavus.

    PubMed

    Palazzolo, Martín A; Mascotti, María L; Lewkowicz, Elizabeth S; Kurina-Sanz, Marcela

    2015-12-01

    Aromatic carboxylic acids are readily obtained from lignin in biomass processing facilities. However, efficient technologies for lignin valorization are missing. In this work, a microbial screening was conducted to find versatile biocatalysts capable of transforming several benzoic acids structurally related to lignin, employing vanillic acid as model substrate. The wild-type Aspergillus flavus growing cells exhibited exquisite selectivity towards the oxidative decarboxylation product, 2-methoxybenzene-1,4-diol. Interestingly, when assaying a set of structurally related substrates, the biocatalyst displayed the oxidative removal of the carboxyl moiety or its reduction to the primary alcohol whether electron withdrawing or donating groups were present in the aromatic ring, respectively. Additionally, A. flavus proved to be highly tolerant to vanillic acid increasing concentrations (up to 8 g/L), demonstrating its potential application in chemical synthesis. A. flavus growing cells were found to be efficient biotechnological tools to perform self-sufficient, structure-dependent redox reactions. To the best of our knowledge, this is the first report of a biocatalyst exhibiting opposite redox transformations of the carboxylic acid moiety in benzoic acid derivatives, namely oxidative decarboxylation and carboxyl reduction, in a structure-dependent fashion.

  2. Time course study of substrate utilization by Aspergillus flavus in medium simulating corn (Zea mays) kernels.

    PubMed

    Mellon, Jay E; Dowd, Michael K; Cotty, Peter J

    2002-01-30

    Utilization of the three major corn reserve materials, starch, triglycerides (refined corn oil), and zein (storage protein), by Aspergillus flavus was monitored in vitro over a 7-day fermentation. Medium composition in which proportions of reserve materials initially approximated proportions in mature corn kernels changed little over the first 18 h. Subsequently, hydrolysis of both starch and triglycerides occurred simultaneously, with peak concentrations of glucose and free fatty acids on day 2 of the fermentation period. Fatty acid concentrations dropped relatively rapidly after day 2 but increased again after day 6. Aflatoxin B(1) production increased after 36 h, with a peak at day 4. Aflatoxin B(1) production paralleled fungal biomass production during the exponential growth phase. A. flavus did not appear to preferentially utilize any of the released fatty acids. A number of fungus-specific metabolites were detected, including arabitol, erythritol, mannitol, trehalose, and kojic acid. Mannitol exceeded the other metabolites in concentration, and the timing of mannitol production closely paralleled that of aflatoxin B(1). Kojic acid concentrations peaked at day 6. In contrast to previously described selective use of simple carbohydrates by A. flavus, less discrimination was displayed when faced with utilization of complex substrates such as starch or triglycerides.

  3. Substrate utilization by Aspergillus flavus in inoculated whole corn kernels and isolated tissues.

    PubMed

    Mellon, Jay E; Dowd, Michael K; Cotty, Peter J

    2005-03-23

    Utilization of the major corn (Zea mays) reserve materials (free saccharides, starch, triglycerides, and zein) was monitored during infection of detached kernels by Aspergillus flavus (A. flavus) over a 12-day period. Inoculated whole kernels were compared to noninoculated kernels. Concentrations of sucrose and raffinose in inoculated seed decreased to nearly zero at 6 days, whereas concentrations of these saccharides in noninoculated seed dropped at a considerably slower rate, and significant levels remained at the end of the incubation period. Triglyceride concentrations remained unchanged in the noninoculated seed but dropped continuously after 2 days in the inoculated seed. Starch and zein concentrations did not change during the 12-day incubation period. Aflatoxin B1 was first detected after 2 days and increased to about 20 microg/g (20,000 ppb) after 12 days. Very low aflatoxin concentrations were detected in the noninoculated seed. Significant concentrations of erythritol, arabitol, and mannitol were produced during infection, with peak concentrations occurring at 8 days. Whole seed and germ tissue appeared to support good fungal growth and aflatoxin production, whereas ground tissues and endosperm did not. A. flavus preferentially utilized saccharides as initial carbon substrates followed by triglycerides. When invading nonwounded corn kernels, the fungus selectively targets the germ tissue where these materials are localized in the highest concentrations.

  4. Environmental influences on maize-Aspergillus flavus interactions and aflatoxin production.

    PubMed

    Fountain, Jake C; Scully, Brian T; Ni, Xinzhi; Kemerait, Robert C; Lee, Robert D; Chen, Zhi-Yuan; Guo, Baozhu

    2014-01-01

    Since the early 1960s, the fungal pathogen Aspergillus flavus (Link ex Fr.) has been the focus of intensive research due to the production of carcinogenic and highly toxic secondary metabolites collectively known as aflatoxins following pre-harvest colonization of crops. Given this recurrent problem and the occurrence of a severe aflatoxin outbreak in maize (Zea mays L.), particularly in the Southeast U.S. in the 1977 growing season, a significant research effort has been put forth to determine the nature of the interaction occurring between aflatoxin production, A. flavus, environment and its various hosts before harvest. Many studies have investigated this interaction at the genetic, transcript, and protein levels, and in terms of fungal biology at either pre- or post-harvest time points. Later experiments have indicated that the interaction and overall resistance phenotype of the host is a quantitative trait with a relatively low heritability. In addition, a high degree of environmental interaction has been noted, particularly with sources of abiotic stress for either the host or the fungus such as drought or heat stresses. Here, we review the history of research into this complex interaction and propose future directions for elucidating the relationship between resistance and susceptibility to A. flavus colonization, abiotic stress, and its relationship to oxidative stress in which aflatoxin production may function as a form of antioxidant protection to the producing fungus. PMID:24550905

  5. Antifungal properties and inhibitory effects upon aflatoxin production of Thymus vulgaris L. by Aspergillus flavus Link.

    PubMed

    Kohiyama, Cássia Yumie; Yamamoto Ribeiro, Milene Mayumi; Mossini, Simone Aparecida Galerani; Bando, Erika; Bomfim, Natália da Silva; Nerilo, Samuel Botião; Rocha, Gustavo Henrique Oliveira; Grespan, Renata; Mikcha, Jane Martha Graton; Machinski, Miguel

    2015-04-15

    The antifungal and antiaflatoxigenic properties of Thymus vulgaris essential oil (TEO) were evaluated upon Aspergillus flavus "in vitro". Suspension containing 10(6) of A. flavus were cultivated with TEO in concentrations ranging from 50 to 500 μg/mL. TEO reached minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) at 250 μg/mL. Inhibition of ergosterol biosynthesis was detected at a concentration of 100 μg/mL of TEO. Morphological evaluation performed by both light microscopy and scanning electron microscopy showed that antifungal activity of TEO could be detected starting at a concentration of 50 μg/mL and the fungicide effect at a concentration of 250 μg/mL. TEO completely inhibited production of both B1 and B2 aflatoxins (AFB1 and AFB2) at a concentration of 150 μg/mL. This way, fungal biomass development and aflatoxin production were dependent on TEO concentration. Therefore, TEO was capable of controlling the growth of A. flavus and its production of aflatoxins. PMID:25466118

  6. A beta-glucuronidase reporter gene construct for monitoring aflatoxin biosynthesis in Aspergillus flavus.

    PubMed Central

    Flaherty, J E; Weaver, M A; Payne, G A; Woloshuk, C P

    1995-01-01

    Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. Current research is directed at the elimination of these compounds in important food sources. The objective of this research was to develop a method to study the induction and regulation of aflatoxin biosynthesis by examining the expression of one aflatoxin pathway gene, ver1. The promoter region of ver1 was fused to the beta-glucuronidase (GUS) gene (uidA) from Escherichia coli to form the reporter construct, GAP13. A. flavus 656-2 was transformed with this construct. Aflatoxin production, GUS activity, and transcript accumulation were determined in transformants after shifting the cultures from a nonconducive medium to a medium conducive to aflatoxin biosynthesis. Transformants harboring GAP13 displayed GUS expression only when aflatoxin was detected in culture. Further, the transcription of the uidA gene driven by the ver1 promoter followed the same profile as for the ver1 genes. The results show that the GAP13 construct may be useful as a genetic tool to study the induction of aflatoxin in situ and to identify substances that affect the expression of genes involved in aflatoxin biosynthesis. The utility of this construct to detect inducers of aflatoxin biosynthesis in maize kernels was tested in a bioassay. A heat-stable inducer of aflatoxin with a molecular size of less than 10 kDa was detected in extracts from maize kernels colonized by A. flavus. PMID:7618859

  7. Environmental influences on maize-Aspergillus flavus interactions and aflatoxin production

    PubMed Central

    Fountain, Jake C.; Scully, Brian T.; Ni, Xinzhi; Kemerait, Robert C.; Lee, Robert D.; Chen, Zhi-Yuan; Guo, Baozhu

    2014-01-01

    Since the early 1960s, the fungal pathogen Aspergillus flavus (Link ex Fr.) has been the focus of intensive research due to the production of carcinogenic and highly toxic secondary metabolites collectively known as aflatoxins following pre-harvest colonization of crops. Given this recurrent problem and the occurrence of a severe aflatoxin outbreak in maize (Zea mays L.), particularly in the Southeast U.S. in the 1977 growing season, a significant research effort has been put forth to determine the nature of the interaction occurring between aflatoxin production, A. flavus, environment and its various hosts before harvest. Many studies have investigated this interaction at the genetic, transcript, and protein levels, and in terms of fungal biology at either pre- or post-harvest time points. Later experiments have indicated that the interaction and overall resistance phenotype of the host is a quantitative trait with a relatively low heritability. In addition, a high degree of environmental interaction has been noted, particularly with sources of abiotic stress for either the host or the fungus such as drought or heat stresses. Here, we review the history of research into this complex interaction and propose future directions for elucidating the relationship between resistance and susceptibility to A. flavus colonization, abiotic stress, and its relationship to oxidative stress in which aflatoxin production may function as a form of antioxidant protection to the producing fungus. PMID:24550905

  8. Heterologous, Expression, and Characterization of Thermostable Glucoamylase Derived from Aspergillus flavus NSH9 in Pichia pastoris

    PubMed Central

    Karim, Kazi Muhammad Rezaul; Hossain, Md. Anowar; Sing, Ngieng Ngui; Mohd Sinang, Fazia; Hussain, Mohd Hasnain Md.; Roslan, Hairul Azman

    2016-01-01

    A novel thermostable glucoamylase cDNA without starch binding domain (SBD) of Aspergillus flavus NSH9 was successfully identified, isolated, and overexpressed in Pichia pastoris GS115. The complete open reading frame of glucoamylase from Aspergillus flavus NSH9 was identified by employing PCR that encodes 493 amino acids lacking in the SBD. The first 17 amino acids were presumed to be a signal peptide. The cDNA was cloned into Pichia pastoris and the highest expression of recombinant glucoamylase (rGA) was observed after 8 days of incubation period with 1% methanol. The molecular weight of the purified rGA was about 78 kDa and exhibited optimum catalytic activity at pH 5.0 and temperature of 70°C. The enzyme was stable at higher temperature with 50% of residual activity observed after 20 min at 90°C and 100°C. Low concentration of metal (Mg++, Fe++, Zn++, Cu++, and Pb++) had positive effect on rGA activity. This rGA has the potential for use and application in the saccharification steps, due to its thermostability, in the starch processing industries. PMID:27504454

  9. Heterologous, Expression, and Characterization of Thermostable Glucoamylase Derived from Aspergillus flavus NSH9 in Pichia pastoris.

    PubMed

    Karim, Kazi Muhammad Rezaul; Husaini, Ahmad; Hossain, Md Anowar; Sing, Ngieng Ngui; Mohd Sinang, Fazia; Hussain, Mohd Hasnain Md; Roslan, Hairul Azman

    2016-01-01

    A novel thermostable glucoamylase cDNA without starch binding domain (SBD) of Aspergillus flavus NSH9 was successfully identified, isolated, and overexpressed in Pichia pastoris GS115. The complete open reading frame of glucoamylase from Aspergillus flavus NSH9 was identified by employing PCR that encodes 493 amino acids lacking in the SBD. The first 17 amino acids were presumed to be a signal peptide. The cDNA was cloned into Pichia pastoris and the highest expression of recombinant glucoamylase (rGA) was observed after 8 days of incubation period with 1% methanol. The molecular weight of the purified rGA was about 78 kDa and exhibited optimum catalytic activity at pH 5.0 and temperature of 70°C. The enzyme was stable at higher temperature with 50% of residual activity observed after 20 min at 90°C and 100°C. Low concentration of metal (Mg(++), Fe(++), Zn(++), Cu(++), and Pb(++)) had positive effect on rGA activity. This rGA has the potential for use and application in the saccharification steps, due to its thermostability, in the starch processing industries. PMID:27504454

  10. Heterologous, Expression, and Characterization of Thermostable Glucoamylase Derived from Aspergillus flavus NSH9 in Pichia pastoris.

    PubMed

    Karim, Kazi Muhammad Rezaul; Husaini, Ahmad; Hossain, Md Anowar; Sing, Ngieng Ngui; Mohd Sinang, Fazia; Hussain, Mohd Hasnain Md; Roslan, Hairul Azman

    2016-01-01

    A novel thermostable glucoamylase cDNA without starch binding domain (SBD) of Aspergillus flavus NSH9 was successfully identified, isolated, and overexpressed in Pichia pastoris GS115. The complete open reading frame of glucoamylase from Aspergillus flavus NSH9 was identified by employing PCR that encodes 493 amino acids lacking in the SBD. The first 17 amino acids were presumed to be a signal peptide. The cDNA was cloned into Pichia pastoris and the highest expression of recombinant glucoamylase (rGA) was observed after 8 days of incubation period with 1% methanol. The molecular weight of the purified rGA was about 78 kDa and exhibited optimum catalytic activity at pH 5.0 and temperature of 70°C. The enzyme was stable at higher temperature with 50% of residual activity observed after 20 min at 90°C and 100°C. Low concentration of metal (Mg(++), Fe(++), Zn(++), Cu(++), and Pb(++)) had positive effect on rGA activity. This rGA has the potential for use and application in the saccharification steps, due to its thermostability, in the starch processing industries.

  11. RmtA, a Putative Arginine Methyltransferase, Regulates Secondary Metabolism and Development in Aspergillus flavus.

    PubMed

    Satterlee, Timothy; Cary, Jeffrey W; Calvo, Ana M

    2016-01-01

    Aspergillus flavus colonizes numerous oil seed crops such as corn, peanuts, treenuts and cotton worldwide, contaminating them with aflatoxin and other harmful potent toxins. In the phylogenetically related model fungus Aspergillus nidulans, the methyltransferase, RmtA, has been described to be involved in epigenetics regulation through histone modification. Epigenetics regulation affects a variety of cellular processes, including morphogenesis and secondary metabolism. Our study shows that deletion of rmtA in A. flavus results in hyperconidiating colonies, indicating that rmtA is a repressor of asexual development in this fungus. The increase in conidiation in the absence of rmtA coincides with greater expression of brlA, abaA, and wetA compared to that in the wild type. Additionally, the rmtA deletion mutant presents a drastic reduction or loss of sclerotial production, while forced expression of this gene increased the ability of this fungus to generate these resistant structures, revealing rmtA as a positive regulator of sclerotial formation. Importantly, rmtA is also required for the production of aflatoxin B1 in A. flavus, affecting the expression of aflJ. Furthermore, biosynthesis of additional metabolites is also controlled by rmtA, indicating a broad regulatory output in the control of secondary metabolism. This study also revealed that rmtA positively regulates the expression of the global regulatory gene veA, which could contribute to mediate the effects of rmtA on development and secondary metabolism in this relevant opportunistic plant pathogen. PMID:27213959

  12. RmtA, a Putative Arginine Methyltransferase, Regulates Secondary Metabolism and Development in Aspergillus flavus

    PubMed Central

    Satterlee, Timothy; Cary, Jeffrey W.; Calvo, Ana M.

    2016-01-01

    Aspergillus flavus colonizes numerous oil seed crops such as corn, peanuts, treenuts and cotton worldwide, contaminating them with aflatoxin and other harmful potent toxins. In the phylogenetically related model fungus Aspergillus nidulans, the methyltransferase, RmtA, has been described to be involved in epigenetics regulation through histone modification. Epigenetics regulation affects a variety of cellular processes, including morphogenesis and secondary metabolism. Our study shows that deletion of rmtA in A. flavus results in hyperconidiating colonies, indicating that rmtA is a repressor of asexual development in this fungus. The increase in conidiation in the absence of rmtA coincides with greater expression of brlA, abaA, and wetA compared to that in the wild type. Additionally, the rmtA deletion mutant presents a drastic reduction or loss of sclerotial production, while forced expression of this gene increased the ability of this fungus to generate these resistant structures, revealing rmtA as a positive regulator of sclerotial formation. Importantly, rmtA is also required for the production of aflatoxin B1 in A. flavus, affecting the expression of aflJ. Furthermore, biosynthesis of additional metabolites is also controlled by rmtA, indicating a broad regulatory output in the control of secondary metabolism. This study also revealed that rmtA positively regulates the expression of the global regulatory gene veA, which could contribute to mediate the effects of rmtA on development and secondary metabolism in this relevant opportunistic plant pathogen. PMID:27213959

  13. Morphological and molecular identification of filamentous Aspergillus flavus and Aspergillus parasiticus isolated from compound feeds in South Africa.

    PubMed

    Iheanacho, Henry E; Njobeh, Patrick B; Dutton, Francis M; Steenkamp, Paul A; Steenkamp, Lucia; Mthombeni, Julian Q; Daru, Barnabas H; Makun, Anthony H

    2014-12-01

    Isolation of filamentous species of two Aspergillum genera from compound feeds produced in South Africa, and subsequent extraction of their individual DNA in this study, presents a simple but rapid molecular procedure for high through-put analysis of the individual morphological forms. DNA was successfully isolated from the Aspergillus spp. from agar cultures by use of a commercial kit. Agarose gel electrophoresis fractionation of the fungi DNA, showed distinct bands. The DNA extracted by this procedure appears to be relatively pure with a ratio absorbance at 260 and 280 nm. However, the overall morphological and molecular data indicated that 67.5 and 51.1% of feed samples were found to be contaminated with Aspergillus flavus and Aspergillus parasiticus, respectively, with poultry feed having the highest contamination mean level of 5.7 × 105 CFU/g when compared to cattle (mean: 4.0 × 106 CFU/g), pig (mean: 2.7 × 104 CFU/g) and horse (1.0 × 102 CFU) feed. This technique presents a readily achievable, easy to use method in the extraction of filamentous fungal DNA and it's identification. Hence serves as an important tool towards molecular study of these organisms for routine analysis check in monitoring and improving compound feed quality against fungal contamination.

  14. Effects of Gamma and Electron Beam Radiation on Brazil Nuts Artificially Inoculated with Aspergillus flavus.

    PubMed

    Assunção, Ednei; Reis, Tatiana Alves; Baquião, Arianne Costa; Corrêa, Benedito

    2015-07-01

    The aim of this study was to evaluate the effects of gamma radiation (GR) and electron beam (EB) on Brazil nut samples contaminated with Aspergillus flavus. Fifty samples were spread with an A. flavus suspension and incubated at 30°C and a relative humidity of 93%. After 15 days of incubation, mycobiota and aflatoxin analysis were performed. The samples were divided into three groups (control, group 1, and group 2) that received radiation doses of 0 kGy (control) and 5 and 10 kGy each of GR and EB (groups 1 and 2). Noninoculated samples were irradiated with the same doses for sensory evaluation. The results showed that after 15 days of incubation, the average water activity of the samples was 0.80. The irradiation with GR and EB at doses of 5 and 10 kGy was able to eliminate A. flavus in Brazil nut samples. Aflatoxin analysis showed that EB doses of 5 and 10 kGy reduced aflatoxin B1 levels by 53.32 and 65.66%, respectively, whereas the same doses of GR reduced the levels of this toxin by 70.61 and 84.15% compared with the level in the control groups. Sensory evaluation demonstrated that the texture and odor of irradiated Brazil nut samples were acceptable. The taste evaluation indicated that 5 kGy of GR was judged acceptable. The results highlight that both irradiation processes (5- and 10-kGy doses) showed efficiency in A. flavus and aflatoxin elimination. GR and EB treatments resulted in some alterations in the sensory attributes of samples with the doses used in this study; however, Brazil nut samples irradiated with 5-kGy GR doses were considered acceptable. PMID:26197295

  15. Buckwheat achenes antioxidant profile modulates Aspergillus flavus growth and aflatoxin production.

    PubMed

    Chitarrini, G; Nobili, C; Pinzari, F; Antonini, A; De Rossi, P; Del Fiore, A; Procacci, S; Tolaini, V; Scala, V; Scarpari, M; Reverberi, M

    2014-10-17

    Buckwheat (Fagopyrum spp.) is a "pseudo-cereal" of great interest in the production of healthy foods since its flour, derived from achenes, is enriched with bioactive compounds and, due to the absence of gluten, may be used in composition of celiac diets. Amongst buckwheat species, F. tataricum achenes possess a larger amount of the antioxidant flavenol rutin than the common buckwheat F. esculentum. Ongoing climate change may favor plant susceptibility to the attack by pathogenic, often mycotoxigenic, fungi with consequent increase of mycotoxins in previously unexploited feeds and foodstuffs. In particular, Aspergillus flavus, under suitable environmental conditions such as those currently occurring in Italy, may produce aflatoxin B1 (AFB1), the most carcinogenic compound of fungal origin which is classified by IARC as Category 1. In this study, the viable achenes of two buckwheat species, F. tataricum (var. Golden) and F. esculentum (var. Aelita) were inoculated with an AFB1-producing A. flavus NRRL 3357 to analyze their relative performances against fungal invasion and toxin contamination. Notably, we sought the existence of a correlation between the amount of tocols/flavonols in the achenes of buckwheat, infected and non-infected with A. flavus, and to analyze the ability of the pathogen to grow and produce toxin during achene infection. Results suggest that achenes of F. tataricum, the best producer of antioxidant compounds in this study, are less susceptible to A. flavus infection and consequently, but not proportionally, to mycotoxin contamination compared with F. esculentum. Moreover, rutin-derived quercetin appears to be more efficient in inhibiting aflatoxin biosynthesis than the parent compound.

  16. Effects of Gamma and Electron Beam Radiation on Brazil Nuts Artificially Inoculated with Aspergillus flavus.

    PubMed

    Assunção, Ednei; Reis, Tatiana Alves; Baquião, Arianne Costa; Corrêa, Benedito

    2015-07-01

    The aim of this study was to evaluate the effects of gamma radiation (GR) and electron beam (EB) on Brazil nut samples contaminated with Aspergillus flavus. Fifty samples were spread with an A. flavus suspension and incubated at 30°C and a relative humidity of 93%. After 15 days of incubation, mycobiota and aflatoxin analysis were performed. The samples were divided into three groups (control, group 1, and group 2) that received radiation doses of 0 kGy (control) and 5 and 10 kGy each of GR and EB (groups 1 and 2). Noninoculated samples were irradiated with the same doses for sensory evaluation. The results showed that after 15 days of incubation, the average water activity of the samples was 0.80. The irradiation with GR and EB at doses of 5 and 10 kGy was able to eliminate A. flavus in Brazil nut samples. Aflatoxin analysis showed that EB doses of 5 and 10 kGy reduced aflatoxin B1 levels by 53.32 and 65.66%, respectively, whereas the same doses of GR reduced the levels of this toxin by 70.61 and 84.15% compared with the level in the control groups. Sensory evaluation demonstrated that the texture and odor of irradiated Brazil nut samples were acceptable. The taste evaluation indicated that 5 kGy of GR was judged acceptable. The results highlight that both irradiation processes (5- and 10-kGy doses) showed efficiency in A. flavus and aflatoxin elimination. GR and EB treatments resulted in some alterations in the sensory attributes of samples with the doses used in this study; however, Brazil nut samples irradiated with 5-kGy GR doses were considered acceptable.

  17. Multilocus variable-number tandem-repeat analysis of clinical isolates of Aspergillus flavus from Iran reveals the first cases of Aspergillus minisclerotigenes associated with human infection

    PubMed Central

    2014-01-01

    Background Aspergillus flavus is intensively studied for its role in infecting crop plants and contaminating produce with aflatoxin, but its role as a human pathogen is less well understood. In parts of the Middle East and India, A. flavus surpasses A. fumigatus as a cause of invasive aspergillosis and is a significant cause of cutaneous, sinus, nasal and nail infections. Methods A collection of 45 clinical and 10 environmental A. flavus isolates from Iran were analysed using Variable-Number Tandem-Repeat (VNTR) markers with MICROSAT and goeBURST to determine their genetic diversity and their relatedness to clinical and environmental A. flavus isolates from Australia. Phylogeny was assessed using partial β-tubulin and calmodulin gene sequencing, and mating type was determined by PCR. Antifungal susceptibility testing was performed on selected isolates using a reference microbroth dilution method. Results There was considerable diversity in the A. flavus collection, with no segregation on goeBURST networks according to source or geographic location. Three Iranian isolates, two from sinus infections and one from a paranasal infection grouped with Aspergillus minisclerotigenes, and all produced B and G aflatoxin. Phylogenic analysis using partial β-tubulin and calmodulin sequencing confirmed two of these as A. minisclerotigenes, while the third could not be differentiated from A. flavus and related species within Aspergillus section flavi. Based on epidemiological cut-off values, the A. minisclerotigens and A. flavus isolates tested were susceptible to commonly used antifungal drugs. Conclusions This is the first report of human infection due to A. minisclerotigenes, and it raises the possiblity that other species within Aspergillus section flavi may also cause clinical disease. Clinical isolates of A. flavus from Iran are not distinct from Australian isolates, indicating local environmental, climatic or host features, rather than fungal features, govern the high

  18. Community structure of Aspergillus flavus and A. parasiticus in major almond producing areas of California, United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several nut crops including almonds, pistachios, and walnuts can become contaminated with mycotoxins. Of greatest economic significance are aflatoxins, which are mainly produced by members of Aspergillus section Flavi. The distribution of the two sclerotial-size morphotypes of A. flavus (i.e. S and ...

  19. Gene expression profiling and identification of resistance genes to aspergillus flavus infection in peanut through EST and microarray strategies.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus and A. parasiticus infect peanut seeds and produce aflatoxins, which are associated with various diseases in domestic animals and humans throughout the world. The most cost-effective strategy to minimize aflatoxin contamination involves the development of peanut cultivars that are...

  20. Effects of laeA deletion on Aspergillus flavus conidial development and hydrophobicity may contribute to loss of aflatoxin production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The laeA gene encodes a nuclear protein that governs production of multiple fungal secondary metabolites. We examined the effects of laeA deletion in an Aspergillus flavus strain. Compared to wild type, expression of genes involved in secondary metabolism, conidiation and hydrophobicity was drastica...

  1. The effect of water activity and storage temperature on the growth of Aspergillus flavus in medicinal herbs.

    PubMed

    Kulshrestha, Rashmi; Gupta, Chandra Prakash; Shukla, Gyanesh; Kundu, Madan Gopal; Bhatnagar, Satyendra Prasad; Katiyar, Chandra Kant

    2008-08-01

    The quality control of medicinal herbs post harvesting or after collection becomes very critical because of susceptibility to fungal invasion during storage depending on the temperature and humidity of the storage area. The information on moisture equilibrium is important on the process and storage of foods which can be extended to medicinal herbs. In the present study, the growth of Aspergillus flavus was observed on selected ten medicinal herbs with water activity aw above 0.81 when stored at 25 +/- 2 degrees C, 30 +/- 2 degrees C and 40 +/- 2 degrees C except for Picrorhiza kurrooa and Alpinia galanga which were found to have anti-fungal properties. Aspergillus flavus did not grow in any samples of medicinal herbs with water activity aw below 0.81 at temperatures of 25 +/- 2 degrees C, 30 +/- 2 degrees C and 40 +/- 2 degrees C. Also Aspergillus flavus did not grow in any samples of medicinal herbs with water activity aw above 0.81 when stored below 10 +/- 2 degrees C. Therefore it can be concluded that the contamination of medicinal herbs with aflatoxins can be minimized by controlling water activity and storage temperature. Sorption isotherms (desorption) can be interpreted to determine the optimum drying which can lower the water activity to the level required for preventing growth of Aspergillus flavus and also for ensuring quality of medicinal herbs which may get destroyed upon over drying. Furthermore, it also saves incremental cost in prolonged drying over the optimum drying. PMID:18553273

  2. Variation in Competitive ability among Isolates of Aspergillus flavus from Different Vegetative Compatibility Groups during Maize Infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus, the primary causal agent of aflatoxin contamination, includes many genetically diverse vegetative compatibility groups (VCGs). Competitive ability during infection of living maize kernels varied among isolates from 38 VCGs. Kernels were inoculated with both a common VCG, CG136, a...

  3. Use of functional genomics to assess the impact of climate change on Aspergillus flavus and aflatoxin production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is an opportunistic pathogenic fungus that infects several crops of agricultural importance, among them, corn, cotton, and peanuts. Once established as a pathogen the fungus may secrete secondary metabolites commonly known as mycotoxins, that if consumed by humans or animals may r...

  4. Influence of tricarboxylic acid cycle intermediates and related metabolites on the biosynthesis of aflatoxin by resting cells of Aspergillus flavus.

    PubMed

    Shantha, T; Murthy, V S

    1981-11-01

    Resting cells of Aspergillus flavus synthesized aflatoxin from acetate as the sole carbon source after 36 h of incubation. Addition of pyruvate (5.5 mg/m) as cosubstrate to [1-14C]acetate and unlabeled acetate considerably reduced toxin production but increased the radioactivity on the tricarboxylic acid intermediates. This suggests that high tricarboxylic acid activity drastically affected toxin synthesis.

  5. Evaluation of recycled bioplastic pellets and a sprayable formulation for application of an Aspergillus flavus biocontrol strain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biocontrol of Aspergillus flavus using inoculated bioplastic granules has been proven to be effective under laboratory and field conditions. In the present study, the use of low-density pellets from recycled bioplastic as a biocontrol strain carrier was evaluated. Applying recycled bioplastic pell...

  6. The Stress Response Regulator AflSkn7 Influences Morphological Development, Stress Response, and Pathogenicity in the Fungus Aspergillus flavus.

    PubMed

    Zhang, Feng; Xu, Gaopo; Geng, Longpo; Lu, Xiaoyan; Yang, Kunlong; Yuan, Jun; Nie, Xinyi; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    This study focused on AflSkn7, which is a stress response regulator in the aflatoxin-producing Aspergillus flavus. The ΔAflSkn7 mutants exhibited partially defective conidial formation and a complete inability to generate sclerotia, indicating AflSkn7 affects A. flavus asexual and sexual development. The mutants tolerated osmotic stress but were partially susceptible to the effects of cell wall stress. Additionally, the ΔAflSkn7 mutants were especially sensitive to oxidative stress. These observations confirmed that AflSkn7 influences oxidative stress responses rather than osmotic stress responses. Additionally, AflSkn7 was observed to increase aflatoxin biosynthesis and seed infection rates. These results indicate AflSkn7 affects A. flavus morphological development, stress response, aflatoxin production, and pathogenicity. The results of this study may facilitate the development of new methods to manage A. flavus infections. PMID:27399770

  7. Menadione-Induced Oxidative Stress Re-Shapes the Oxylipin Profile of Aspergillus flavus and Its Lifestyle

    PubMed Central

    Zaccaria, Marco; Ludovici, Matteo; Sanzani, Simona Marianna; Ippolito, Antonio; Aiese Cigliano, Riccardo; Sanseverino, Walter; Scarpari, Marzia; Scala, Valeria; Fanelli, Corrado; Reverberi, Massimo

    2015-01-01

    Aspergillus flavus is an efficient producer of mycotoxins, particularly aflatoxin B1, probably the most hepatocarcinogenic naturally-occurring compound. Although the inducing agents of toxin synthesis are not unanimously identified, there is evidence that oxidative stress is one of the main actors in play. In our study, we use menadione, a quinone extensively implemented in studies on ROS response in animal cells, for causing stress to A. flavus. For uncovering the molecular determinants that drive A. flavus in challenging oxidative stress conditions, we have evaluated a wide spectrum of several different parameters, ranging from metabolic (ROS and oxylipin profile) to transcriptional analysis (RNA-seq). There emerges a scenario in which A. flavus activates several metabolic processes under oxidative stress conditions for limiting the ROS-associated detrimental effects, as well as for triggering adaptive and escape strategies. PMID:26512693

  8. Inhibition of Aspergillus flavus on agar media and brown rice cereal bars using cold atmospheric plasma treatment.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Nisoa, Mudtorlep; Matan, Nirundorn

    2013-02-01

    This study aimed to optimize the operating parameters of cold atmospheric plasma treatment to inhibit the growth of Aspergillus flavus on agar media and brown rice cereal bars. The effects of argon plasma jet treatment on the growth of A. flavus on malt extract agar (MEA) at powers of 20 W and 40 W with exposure times at 5, 15 and 25 min were studied using response surface methodology (RSM) with a central composite face-centered (CCF) design. Multiple regression analysis indicated that plasma treatment at 40 W for 25 min is most effective for inhibiting growth of A. flavus on the agar medium. On brown rice cereal bars, plasma powered at 40 W for 20 min was capable of giving protection against A. flavus growth for up to 20 days under storage conditions of 25°C and 100% RH. These results demonstrated the potential of cold atmospheric plasma jet treatment to control mold growth on various food products.

  9. The Stress Response Regulator AflSkn7 Influences Morphological Development, Stress Response, and Pathogenicity in the Fungus Aspergillus flavus

    PubMed Central

    Zhang, Feng; Xu, Gaopo; Geng, Longpo; Lu, Xiaoyan; Yang, Kunlong; Yuan, Jun; Nie, Xinyi; Zhuang, Zhenhong; Wang, Shihua

    2016-01-01

    This study focused on AflSkn7, which is a stress response regulator in the aflatoxin-producing Aspergillus flavus. The ΔAflSkn7 mutants exhibited partially defective conidial formation and a complete inability to generate sclerotia, indicating AflSkn7 affects A. flavus asexual and sexual development. The mutants tolerated osmotic stress but were partially susceptible to the effects of cell wall stress. Additionally, the ΔAflSkn7 mutants were especially sensitive to oxidative stress. These observations confirmed that AflSkn7 influences oxidative stress responses rather than osmotic stress responses. Additionally, AflSkn7 was observed to increase aflatoxin biosynthesis and seed infection rates. These results indicate AflSkn7 affects A. flavus morphological development, stress response, aflatoxin production, and pathogenicity. The results of this study may facilitate the development of new methods to manage A. flavus infections. PMID:27399770

  10. Antifungal metabolites (monorden, monocillin IV, and cerebrosides) from Humicola fuscoatra traaen NRRL 22980, a mycoparasite of Aspergillus flavus sclerotia.

    PubMed

    Wicklow, D T; Joshi, B K; Gamble, W R; Gloer, J B; Dowd, P F

    1998-11-01

    The mycoparasite Humicola fuscoatra NRRL 22980 was isolated from a sclerotium of Aspergillus flavus that had been buried in a cornfield near Tifton, Ga. When grown on autoclaved rice, this fungus produced the antifungal metabolites monorden, monocillin IV, and a new monorden analog. Each metabolite produced a clear zone of inhibition surrounding paper assay disks on agar plates seeded with conidia of A. flavus. Monorden was twice as inhibitory to A. flavus mycelium extension (MIC > 28 microg/ml) as monocillin IV (MIC > 56 microg/ml). Cerebrosides C and D, metabolites known to potentiate the activity of cell wall-active antibiotics, were separated from the ethyl acetate extract but were not inhibitory to A. flavus when tested as pure compounds. This is the first report of natural products from H. fuscoatra. PMID:9797310

  11. Larval Preference and Performance of Amyelois transitella (Navel Orangeworm, Lepidoptera: Pyralidae) in Relation to the Fungus Aspergillus flavus.

    PubMed

    Ampt, Eline A; Bush, Daniel S; Siegel, Joel P; Berenbaum, May R

    2016-02-01

    The navel orangeworm, Amyelois transitella (Walker), is a polyphagous pest of California nut crops and is responsible for extensive losses in the United States. It directly damages crops by feeding and contaminating nuts with frass and webbing and vectors saprophytic fungi that infect crops. The navel orangeworm is commonly associated with Aspergillus species, including the toxigenic Aspergillus flavus, which causes crop loss by producing carcinogens, including aflatoxin B1. This lepidopteran-fungus association is the most economically serious pest complex in Central Valley orchards, and evidence indicates that this relationship is mutualistic. We assessed preference and performance of navel orangeworm larvae associated with A. flavus in behavioral bioassays in which neonates were allowed to orient within arenas to media with or without fungal tissue, and performance bioassays in which larvae were reared with and without A. flavus on potato dextrose agar (PDA) and a semidefined almond PDA diet to evaluate effects on development and pupal weight. Navel orangeworm larvae were attracted to A. flavus and developed faster in its presence, indicating a nutritional benefit to the caterpillars. Larvae reached pupation ∼33% faster on diet containing A. flavus, and pupal weights were ∼18% higher for males and ∼13% higher for females on this diet. Our findings indicate that A. flavus plays an important role in larval orientation and development on infected hosts. The preference-performance relationship between navel orangeworms and Aspergillus flavus is consistent with a facultative mutualism that has broad implications for pest management efforts and basic understanding of Lepidoptera-plant interactions. PMID:26491042

  12. Terpenoid composition and antifungal activity of three commercially important essential oils against Aspergillus flavus and Aspergillus niger.

    PubMed

    Bisht, Deepa; Pal, Anirban; Chanotiya, C S; Mishra, Dhirendra; Pandey, K N

    2011-12-01

    Hydro-distilled essential oils extracted from three commercially important aromatic plants were analysed by capillary gas chromatography-flame ionization detector and gas chromatography/quadrupole mass spectrometry and subjected to antifungal activity. Fifteen compounds, which accounted for 97.8% of Acorus calamus root oil composition have been identified. Besides the major constituent (Z)-asarone (81.1-92.4%), (Z)-methyl isoeugenol (1.8-2.1%), (Z)-isoelemicin (1.2-1.3%), (E)-asarone (1.0-2.6%), (E)-methyl isoeugenol (0.2-0.4%), (Z)-β-ocimene (0.2-0.4%), elemicin (0.2-0.3%), linalool (0.1-0.9%) and kessane (t-0.2%) were identified. Monoterpenes constituted the main fraction of Origanum vulgare essential oil attaining 90.5% of the total oil composition. p-Cymene (10.3%) was the major component of the monoterpene hydrocarbon fraction while thymol (53.2%) and carvacrol (3.9%) were the most abundant oxygenated monoterpenes among the 33 identified constituents. Cinnamomum tamala leaf oil contained (E)-cinnamaldehyde as the principal component. Quantitative variations in (Z)-cinnamaldehyde (5.8-7.1%), linalool (6.4-8.5%) and (E)-cinnamyl acetate (4.7-5.2%) were significant. The antifungal activity of the hydro-distilled essential oils of A. calamus, O. vulgare and C. tamala were evaluated against Aspergillus flavus and Aspergillus niger. Disc diffusion method was used for the determination of the inhibitory effect. O. vulgare essential oil exhibited the highest activity. Moreover, all three essential oils inhibit the growth of A. flavus and A. niger. PMID:21707253

  13. The inhibitory effects of Curcuma longa L. essential oil and curcumin on Aspergillus flavus link growth and morphology.

    PubMed

    Dias Ferreira, Flávio; Mossini, Simone Aparecida Galerani; Dias Ferreira, Francine Maery; Arrotéia, Carla Cristina; da Costa, Christiane Luciana; Nakamura, Celso Vataru; Machinski, Miguel

    2013-01-01

    The essential oil from Curcuma longa L. was analysed by GC/MS. The major components of the oil were ar-turmerone (33.2%), α -turmerone (23.5%) and β -turmerone (22.7%). The antifungal activities of the oil were studied with regard to Aspergillus flavus growth inhibition and altered morphology, as preliminary studies indicated that the essential oil from C. longa inhibited Aspergillus flavus Link aflatoxin production. The concentration of essential oil in the culture media ranged from 0.01% to 5.0% v/v, and the concentration of curcumin was 0.01-0.5% v/v. The effects on sporulation, spore viability, and fungal morphology were determined. The essential oil exhibited stronger antifungal activity than curcumin on A. flavus. The essential oil reduced the fungal growth in a concentration-dependent manner. A. flavus growth rate was reduced by C. longa essential oil at 0.10%, and this inhibition effect was more efficient in concentrations above 0.50%. Germination and sporulation were 100% inhibited in 0.5% oil. Scanning electron microscopy (SEM) of A. flavus exposed to oil showed damage to hyphae membranes and conidiophores. Because the fungus is a plant pathogen and aflatoxin producer, C. longa essential oil may be used in the management of host plants.

  14. Aflatoxin Production and Degradation by Aspergillus flavus in 20-Liter Fermentors

    PubMed Central

    Ciegler, A.; Peterson, R. E.; Lagoda, A. A.; Hall, H. H.

    1966-01-01

    Yields of from 200 to 300 mg per liter of aflatoxins B1 and G1 were produced by two strains of Aspergillus flavus in 20-liter fermentors under proper conditions of inoculum (well-dispersed growth) and aeration (0.5 volume per volume per min of air, 300 rev/min, 30 psi back pressure, baffles). Peak yields were usually attained in 72 hr, after which the aflatoxin concentration declined rapidly. Degradation of aflatoxin depended primarily on mycelial lysis and high-aeration conditions. Cultures previously reported not to degrade aflatoxin could be induced to do so under these conditions. The percentage and rate of toxin degradation were independent of toxin concentration, and appeared to be nonenzymatic and nonspecific. Degradation simulating that occurring in the fermentor was achieved by reacting aflatoxin with peroxidized methyl esters of vegetable oil; initial degradation was rapid and appeared to involve a complex series of reactions. PMID:5970470

  15. Biosynthesis of fat in surface culture of a local strain of Aspergillus flavus.

    PubMed

    Selim, M S; Attah, N K

    1979-01-01

    An Aspergillus flavus strain isolated from Egyptian soil produced fat in appreciable amounts. General evidence for the operation of the tricarboxylic acid cycle in this organism has been ascertained by the detection of citric, malic and fumaric acids in the metabolized culture solution. Maximum fat yield was attained after seven days of incubation. The lower intial pH value of the media favoured the fat obtained from the felts and raised its acid value. When the felts were sterilized in their acidic metabolism solutions increased the acid values of the fats over those of fats extracted from felts sterilized in distilled water. The felts autoclaved for the longest time produced the highest yields of fat with the highest free acidity. The employment of calcium carbonate in the nutrient solutions raised appreciably the acid values of the fats and suppressed the other metabolic activities.

  16. Control of Aspergillus flavus in maize with plant essential oils and their components.

    PubMed

    Montes-Belmont, R; Carvajal, M

    1998-05-01

    The effects of 11 plant essential oils for maize kernel protection against Aspergillus flavus were studied. Tests were conducted to determine optimal levels of dosages for maize protection, effects of combinations of essential oils, and residual effects and toxicity of essential oils to maize plants. Principal constituents of eight essential oils were tested for ability to protect maize kernels. Essential oils of Cinnamomum zeylanicum (cinnamon), Mentha piperita (peppermint), Ocimum basilicum (basil), Origanum vulgare (origanum), Teloxys ambrosioides (the flavoring herb epazote), Syzygium aromaticum (clove), and Thymus vulgaris (thyme) caused a total inhibition of fungal development on maize kernels. Thymol and o-methoxycinnamaldehyde significantly reduced maize grain contamination. The optimal dosage for protection of maize varied from 3 to 8%. Combinations of C. zeylanicum with the remaining oils gave efficient control. A residual effect of C. zeylanicum was detected after 4 weeks of kernel treatment. No phytotoxic effect on germination and corn growth was detected with any of these oils.

  17. Extracellular biosynthesis and characterization of silver nanoparticles using Aspergillus flavus NJP08: A mechanism perspective

    NASA Astrophysics Data System (ADS)

    Jain, Navin; Bhargava, Arpit; Majumdar, Sonali; Tarafdar, J. C.; Panwar, Jitendra

    2011-02-01

    The present study demonstrates an eco-friendly and low cost protocol for synthesis of silver nanoparticles using the cell-free filtrate of Aspergillus flavus NJP08 when supplied with aqueous silver (Ag+) ions. Identification of the fungal isolate was based on nuclear ribosomal DNA internal transcribed spacer (ITS) identities. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) revealed the formation of spherical metallic silver nanoparticles. The average particle size calculated using Dynamic Light Scattering measurements (DLS) was found to be 17 +/- 5.9 nm. UV-Visible and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of extracellular proteins. SDS-PAGE profiles of the extracellular proteins showed the presence of two intense bands of 32 and 35 kDa, responsible for the synthesis and stability of silver nanoparticles, respectively. A probable mechanism behind the biosynthesis is discussed, which leads to the possibility of using the present protocol in future ``nano-factories''.

  18. Relating significance and relations of differentially expressed genes in response to Aspergillus flavus infection in maize.

    PubMed

    Asters, Matthew C; Williams, W Paul; Perkins, Andy D; Mylroie, J Erik; Windham, Gary L; Shan, Xueyan

    2014-01-01

    Aspergillus flavus is a pathogenic fungus infecting maize and producing aflatoxins that are health hazards to humans and animals. Characterizing host defense mechanism and prioritizing candidate resistance genes are important to the development of resistant maize germplasm. We investigated methods amenable for the analysis of the significance and relations among maize candidate genes based on the empirical gene expression data obtained by RT-qPCR technique from maize inbred lines. We optimized a pipeline of analysis tools chosen from various programs to provide rigorous statistical analysis and state of the art data visualization. A network-based method was also explored to construct the empirical gene expression relational structures. Maize genes at the centers in the network were considered as important candidate genes for maize DNA marker studies. The methods in this research can be used to analyze large RT-qPCR datasets and establish complex empirical gene relational structures across multiple experimental conditions. PMID:24770700

  19. Relating significance and relations of differentially expressed genes in response to Aspergillus flavus infection in maize

    PubMed Central

    Asters, Matthew C.; Williams, W. Paul; Perkins, Andy D.; Mylroie, J. Erik; Windham, Gary L.; Shan, Xueyan

    2014-01-01

    Aspergillus flavus is a pathogenic fungus infecting maize and producing aflatoxins that are health hazards to humans and animals. Characterizing host defense mechanism and prioritizing candidate resistance genes are important to the development of resistant maize germplasm. We investigated methods amenable for the analysis of the significance and relations among maize candidate genes based on the empirical gene expression data obtained by RT-qPCR technique from maize inbred lines. We optimized a pipeline of analysis tools chosen from various programs to provide rigorous statistical analysis and state of the art data visualization. A network-based method was also explored to construct the empirical gene expression relational structures. Maize genes at the centers in the network were considered as important candidate genes for maize DNA marker studies. The methods in this research can be used to analyze large RT-qPCR datasets and establish complex empirical gene relational structures across multiple experimental conditions. PMID:24770700

  20. Inactivation of Aspergillus flavus spores in a sealed package by cold plasma streamers

    NASA Astrophysics Data System (ADS)

    Sohbatzadeh, F.; Mirzanejhad, S.; Shokri, H.; Nikpour, M.

    2016-06-01

    The main objective of this study is to investigate the inactivation efficacy of cold streamers in a sealed package on pathogenic fungi Aspergillus flavus ( A. flavus) spores that artificially contaminated pistachio surface. To produce penetrating cold streamers, electric power supply was adapted to deposit adequate power into the package. The plasma streamers were generated by an alternating high voltage with carrier frequency of 12.5 kHz which was suppressed by a modulated pulsed signal at frequency of 110 Hz. The plasma exposition time was varied from 8 to 18 min to show the effect of the plasma treatment on fungal clearance while the electrode and sample remained at room temperature. This proved a positive effect of the cold streamers treatment on fungal clearance. Benefits of deactivation of fungal spores by streamers inside the package include no heating, short treatment time and adaptability to existing processes. Given its ability to ensure the safety and longevity of food products, this technology has great potential for utilization in food packaging and processing industry. In this study, moisture and pH changes of pistachio samples after plasma streamers treatment were also investigated.

  1. Optimization of L-malic acid production by Aspergillus flavus in a stirred fermentor.

    PubMed

    Battat, E; Peleg, Y; Bercovitz, A; Rokem, J S; Goldberg, I

    1991-05-01

    Effects of various nutritional and environmental factors on the accumulation of organic acids (mainly L-malic acid) by the filamentous fungus Aspergillus flavus were studied in a 16-L stirred fermentor. Improvement of the molar yield (moles acid produced per moles glucose consumed) of L-malic acid was obtained mainly by increasing the agitation rate (to 350 rpm) and the Fe(z+) ion concentration (to 12 mg/L) and by lowering the nitrogen (to 271 mg/L) and phosphate concentrations (to 1.5 mM) in the medium. These changes resulted in molar yields for L-malic acid and total C(4) acids (L-malic, succinic, and fumaric acids) of 128 and 155%, respectively. The high molar yields obtained (above 100%) are additional evidence for the operation of part of the reductive branch of the tricarboxylic acid cycle in L-malic acid accumulation by A. flavus. The fermentation conditions developed using the above mentioned factors and 9% CaCO(3) in the medium resulted in a high concentration (113 g/L L-malic acid from 120 g/L glucose utilized) and a high overall productivity (0.59 g/L h) of L-malic acid. These changes in acid accumulation coincide with increases in the activities of NAD(+)-malate dehydrogenase, fumarase, and citrate synthase.

  2. Global Survey of Canonical Aspergillus flavus G Protein-Coupled Receptors

    PubMed Central

    Affeldt, Katharyn J.; Carrig, Joseph; Amare, Meareg

    2014-01-01

    ABSTRACT G protein-coupled receptors (GPCRs) are transmembrane receptors that relay signals from the external environment inside the cell, allowing an organism to adapt to its surroundings. They are known to detect a vast array of ligands, including sugars, amino acids, pheromone peptides, nitrogen sources, oxylipins, and light. Despite their prevalence in fungal genomes, very little is known about the functions of filamentous fungal GPCRs. Here we present the first full-genome assessment of fungal GPCRs through characterization of null mutants of all 15 GPCRs encoded by the aflatoxin-producing fungus Aspergillus flavus. All strains were assessed for growth, development, ability to produce aflatoxin, and response to carbon sources, nitrogen sources, stress agents, and lipids. Most GPCR mutants were aberrant in one or more response processes, possibly indicative of cross talk in downstream signaling pathways. Interestingly, the biological defects of the mutants did not correspond with assignment to established GPCR classes; this is likely due to the paucity of data for characterized fungal GPCRs. Many of the GPCR transcripts were differentially regulated under various conditions as well. The data presented here provide an extensive overview of the full set of GPCRs encoded by A. flavus and provide a framework for analysis in other fungal species. PMID:25316696

  3. Genome-wide transcriptome analysis of cotton (Gossypium hirsutum L.) identifies candidate gene signatures in response to aflatoxin producing fungus Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are toxic metabolites and potent carcinogen produced from asexual fungi Aspergillus flavus and A. parasiticus. Aflatoxins can contaminate cottonseed under conducive preharvest and postharvest conditions. U.S. federal regulations restrict the use of aflatoxin contaminated cottonseed at >20...

  4. Global Phosphoproteomic Analysis Reveals the Involvement of Phosphorylation in Aflatoxins Biosynthesis in the Pathogenic Fungus Aspergillus flavus

    PubMed Central

    Ren, Silin; Yang, Mingkun; Li, Yu; Zhang, Feng; Chen, Zhuo; Zhang, Jia; Yang, Guang; Yue, Yuewei; Li, Siting; Ge, Feng; Wang, Shihua

    2016-01-01

    Aspergillus flavus is a pathogenic fungus that produces toxic and carcinogenic aflatoxins and is the causative agent of aflatoxicosis. A growing body of evidence indicates that reversible phosphorylation plays important roles in regulating diverse functions in this pathogen. However, only a few phosphoproteins of this fungus have been identified, which hampers our understanding of the roles of phosphorylation in A. flavus. So we performed a global and site-specific phosphoproteomic analysis of A. flavus. A total of 598 high-confidence phosphorylation sites were identified in 283 phosphoproteins. The identified phosphoproteins were involved in various biological processes, including signal transduction and aflatoxins biosynthesis. Five identified phosphoproteins associated with MAPK signal transduction and aflatoxins biosynthesis were validated by immunoblotting using phospho-specific antibodies. Further functional studies revealed that phosphorylation of the MAP kinase kinase kinase Ste11 affected aflatoxins biosynthesis in A. flavus. Our data represent the results of the first global survey of protein phosphorylation in A. flavus and reveal previously unappreciated roles for phosphorylation in the regulation of aflatoxins production. The generated dataset can serve as an important resource for the functional analysis of protein phosphorylation in A. flavus and facilitate the elucidation of phosphorylated signaling networks in this pathogen. PMID:27667718

  5. Development of a GFP-expressing Aspergillus flavus strain to study fungal invasion, colonization, and resistance in cottonseed.

    PubMed

    Rajasekaran, Kanniah; Cary, Jeffrey W; Cotty, Peter J; Cleveland, Thomas E

    2008-02-01

    Cotton bolls were inoculated with a green fluorescent protein (GFP)-expressing Aspergillus flavus (strain 70) to monitor fungal growth, mode of entry, colonization of cottonseeds, and production of aflatoxins. The GFP strain and the wild-type did not differ significantly in pathogen aggressiveness as indicated by similar reductions in inoculated locule weight. GFP fluorescence was at least 10 times higher than the blue green yellow fluorescence (BGYF) produced in response to infection by A. flavus. The GFP produced by the strain made it possible to identify and monitor specific plant tissues colonized by the fungus. For example, the inner seed coat and cotyledon were colonized by the fungus within 72 h of inoculation and the mode of entry was invariably through the porous chalazal cap in intact seeds. The amount of GFP fluorescence was shown to be an indicator of fungal growth, colonization and, to some extent, aflatoxin production. The A. flavus strain expressing GFP should be very useful for rapidly identifying cotton lines with enhanced resistance to A. flavus colonization developed through genetic engineering or traditional plant breeding. In addition, development of GFP expressing A. flavus strain provides an easy and rapid assay procedure for studying the ecology, etiology, and epidemiology of cotton boll rot caused by A. flavus resulting in aflatoxin contamination.

  6. Aspergillus flavus genetic diversity of corn fields treated with non-toxigenic strain afla-guard in the southern U.S

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus genetic diversity of corn fields treated with the non-toxigenic strain Afla-Guard (NRRL 21882) was determined for 384 A. flavus isolates from 14 locations within 6 states in the southern U.S. ELISA test has determined low levels of toxigenic strains (only 91 positive). Nearly hal...

  7. Use of UHPLC high resolution Orbitrap mass spectrometry to investigate genes involved in the production of secondary metabolites in Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Aspergillus flavus is known for its ability to produce the toxic and carcinogenic aflatoxins in food and feed. While aflatoxins are of most concern, A. flavus is predicted to be capable of producing many more metabolites based on a study of its complete genome sequence. Some of these meta...

  8. rtfA, a putative RNA-Pol II transcription elongation factor, is necessary for normal morphological and chemical development in Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The filamentous fungus Aspergillus flavus is an agriculturally important opportunistic plant pathogen that produces potent carcinogenic compounds called aflatoxins. We identified the A. flavus rtfA gene, the ortholog of rtf1 in S. cerevisiae and rtfA in A. nidulans. Interestingly, rtfA has multiple ...

  9. Environmental distribution and genetic diversity of vegetative compatibility groups determine biocontrol strategies to mitigate aflatoxin contamination of maize by Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize infected by aflatoxin-producing Aspergillus flavus may become contaminated with aflatoxins and as a result, threaten human health, food security, and farmers’ income in developing countries where maize is a staple. Environmental distribution and genetic diversity of A. flavus can influence the...

  10. Transcriptome analysis of Aspergillus flavus reveals veA-dependent regulation of secondary metabolite gene clusters, including the novel aflavarin cluster

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The global regulatory veA gene governs development and secondary metabolism in numerous fungal species, including Aspergillus flavus. This is especially relevant since A. flavus infects crops of agricultural importance worldwide, contaminating them with potent mycotoxins. The most well-known are afl...

  11. Functional characterization of a veA-dependent polyketide synthase gene in Aspergillus flavus necessary for the synthesis of asparasone, a sclerotium-specific pigment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The filamentous fungus, Aspergillus flavus, produces the toxic and carcinogenic, polyketide synthase (PKS)-derived family of secondary metabolites termed aflatoxins. While analysis of the A. flavus genome has identified many other PKSs capable of producing secondary metabolites, to date, only a few ...

  12. Biosynthesis of extracellular and intracellular gold nanoparticles by Aspergillus fumigatus and A. flavus.

    PubMed

    Gupta, Saurabh; Bector, Shruti

    2013-05-01

    Green chemistry is a boon for the development of safe, stable and ecofriendly nanostructures using biological tools. The present study was carried out to explore the potential of selected fungal strains for biosynthesis of intra- and extracellular gold nanostructures. Out of the seven cultures, two fungal strains (SBS-3 and SBS-7) were selected on the basis of development of dark pink colour in cell free supernatant and fungal beads, respectively indicative of extra- and intracellular gold nanoparticles production. Both biomass associated and cell free gold nanoparticles were characterized using X-ray diffractogram (XRD) analysis and transmission electron microscopy (TEM). XRD analysis confirmed crystalline, face-centered cubic lattice of metallic gold nanoparticles along with average crystallite size. A marginal difference in average crystallite size of extracellular (17.76 nm) and intracellular (26 and 22 nm) Au-nanostructures was observed using Scherrer equation. In TEM, a variety of shapes (triangles, spherical, hexagonal) were observed in both extra- and intracellular nanoparticles. 18S rRNA gene sequence analysis by multiple sequence alignment (BLAST) indicated 99 % homology of SBS-3 to Aspergillus fumigatus with 99 % alignment coverage and 98 % homology of SBS-7 to Aspergillus flavus with 98 % alignment coverage respectively. Native-PAGE and activity staining further confirmed enzyme linked synthesis of gold nanoparticles. PMID:23400423

  13. Comparison of expression of secondary metabolite biosynthesis cluster genes in Aspergillus flavus, A. parasiticus, and A. oryzae.

    PubMed

    Ehrlich, Kenneth C; Mack, Brian M

    2014-06-01

    Fifty six secondary metabolite biosynthesis gene clusters are predicted to be in the Aspergillus flavus genome. In spite of this, the biosyntheses of only seven metabolites, including the aflatoxins, kojic acid, cyclopiazonic acid and aflatrem, have been assigned to a particular gene cluster. We used RNA-seq to compare expression of secondary metabolite genes in gene clusters for the closely related fungi A. parasiticus, A. oryzae, and A. flavus S and L sclerotial morphotypes. The data help to refine the identification of probable functional gene clusters within these species. Our results suggest that A. flavus, a prevalent contaminant of maize, cottonseed, peanuts and tree nuts, is capable of producing metabolites which, besides aflatoxin, could be an underappreciated contributor to its toxicity. PMID:24960201

  14. Comparison of Expression of Secondary Metabolite Biosynthesis Cluster Genes in Aspergillus flavus, A. parasiticus, and A. oryzae

    PubMed Central

    Ehrlich, Kenneth C.; Mack, Brian M.

    2014-01-01

    Fifty six secondary metabolite biosynthesis gene clusters are predicted to be in the Aspergillus flavus genome. In spite of this, the biosyntheses of only seven metabolites, including the aflatoxins, kojic acid, cyclopiazonic acid and aflatrem, have been assigned to a particular gene cluster. We used RNA-seq to compare expression of secondary metabolite genes in gene clusters for the closely related fungi A. parasiticus, A. oryzae, and A. flavus S and L sclerotial morphotypes. The data help to refine the identification of probable functional gene clusters within these species. Our results suggest that A. flavus, a prevalent contaminant of maize, cottonseed, peanuts and tree nuts, is capable of producing metabolites which, besides aflatoxin, could be an underappreciated contributor to its toxicity. PMID:24960201

  15. Comparison of expression of secondary metabolite biosynthesis cluster genes in Aspergillus flavus, A. parasiticus, and A. oryzae.

    PubMed

    Ehrlich, Kenneth C; Mack, Brian M

    2014-06-23

    Fifty six secondary metabolite biosynthesis gene clusters are predicted to be in the Aspergillus flavus genome. In spite of this, the biosyntheses of only seven metabolites, including the aflatoxins, kojic acid, cyclopiazonic acid and aflatrem, have been assigned to a particular gene cluster. We used RNA-seq to compare expression of secondary metabolite genes in gene clusters for the closely related fungi A. parasiticus, A. oryzae, and A. flavus S and L sclerotial morphotypes. The data help to refine the identification of probable functional gene clusters within these species. Our results suggest that A. flavus, a prevalent contaminant of maize, cottonseed, peanuts and tree nuts, is capable of producing metabolites which, besides aflatoxin, could be an underappreciated contributor to its toxicity.

  16. Identification of Aspergillus (A. flavus and A. niger) Allergens and Heterogeneity of Allergic Patients' IgE Response.

    PubMed

    Vermani, Maansi; Vijayan, Vannan Kandi; Agarwal, Mahendra Kumar

    2015-08-01

    Aspergillus species (A. flavus and A. niger) are important sources of inhalant allergens. Current diagnostic modalities employ crude Aspergillus extracts which only indicate the source to which the patient has been sensitized, without identifying the number and type of allergens in crude extracts. We report a study on the identification of major and minor allergens of the two common airborne Aspergillus species and heterogeneity of patients' IgE response to them. Skin prick tests were performed on 300 patients of bronchial asthma and/or allergic rhinitis and 20 healthy volunteers. Allergen specific IgE in patients' sera was estimated by enzyme allergosorbent test (EAST). Immunoblots were performed to identify major/minor allergens of Aspergillus extracts and to study heterogeneity of patients'IgE response to them. Positive cutaneous responses were observed in 17% and 14.7% of patients with A. flavus and A. niger extracts, respectively. Corresponding EAST positivity was 69.2% and 68.7%. In immunoblots, 5 allergenic proteins were identified in A. niger extract, major allergens being 49, 55.4 and 81.5 kDa. Twelve proteins bound patients' IgE in A. flavus extract, three being major allergens (13.3, 34 and 37 kDa). The position and slopes of EAST binding and inhibition curves obtained with individual sera varied from patient to patient. The number and molecular weight of IgE-binding proteins in both the Aspergillus extracts varied among patients. These results gave evidence of heterogeneity of patients' IgE response to major/minor Aspergillus allergens. This approach will be helpful to identify disease eliciting molecules in the individual patients (component resolved diagnosis) and may improve allergen-specific immunotherapy.

  17. Toward elucidation of genetic and functional genetic mechanisms in corn host resistance to Aspergillus flavus infection and aflatoxin contamination.

    PubMed

    Shan, Xueyan; Williams, W Paul

    2014-01-01

    Aflatoxins are carcinogenic mycotoxins produced by some species in the Aspergillus genus, such as A. flavus and A. parasiticus. Contamination of aflatoxins in corn profusely happens at pre-harvest stage when heat and drought field conditions favor A. flavus colonization. Commercial corn hybrids are generally susceptible to A. flavus infection. An ideal strategy for preventing aflatoxin contamination is through the enhancement of corn host resistance to Aspergillus infection and aflatoxin production. Constant efforts have been made by corn breeders to develop resistant corn genotypes. Significantly low levels of aflatoxin accumulation have been determined in certain resistant corn inbred lines. A number of reports of quantitative trait loci have provided compelling evidence supporting the quantitative trait genetic basis of corn host resistance to aflatoxin accumulation. Important findings have also been obtained from the investigation on candidate resistance genes through transcriptomics approach. Elucidation of molecular mechanisms will provide in-depth understanding of the host-pathogen interactions and hence facilitate the breeding of corn with resistance to A. flavus infection and aflatoxin accumulation. PMID:25101068

  18. Toward elucidation of genetic and functional genetic mechanisms in corn host resistance to Aspergillus flavus infection and aflatoxin contamination

    PubMed Central

    Shan, Xueyan; Williams, W. Paul

    2014-01-01

    Aflatoxins are carcinogenic mycotoxins produced by some species in the Aspergillus genus, such as A. flavus and A. parasiticus. Contamination of aflatoxins in corn profusely happens at pre-harvest stage when heat and drought field conditions favor A. flavus colonization. Commercial corn hybrids are generally susceptible to A. flavus infection. An ideal strategy for preventing aflatoxin contamination is through the enhancement of corn host resistance to Aspergillus infection and aflatoxin production. Constant efforts have been made by corn breeders to develop resistant corn genotypes. Significantly low levels of aflatoxin accumulation have been determined in certain resistant corn inbred lines. A number of reports of quantitative trait loci have provided compelling evidence supporting the quantitative trait genetic basis of corn host resistance to aflatoxin accumulation. Important findings have also been obtained from the investigation on candidate resistance genes through transcriptomics approach. Elucidation of molecular mechanisms will provide in-depth understanding of the host–pathogen interactions and hence facilitate the breeding of corn with resistance to A. flavus infection and aflatoxin accumulation. PMID:25101068

  19. Effect of temperature and water activity on growth and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus on cured meat model systems.

    PubMed

    Peromingo, Belén; Rodríguez, Alicia; Bernáldez, Victoria; Delgado, Josué; Rodríguez, Mar

    2016-12-01

    Dry-cured hams may be colonised by aflatoxin-producing Aspergillus flavus and Aspergillus parasiticus during the ripening process. The objective of this study was to evaluate the interaction between non-ionic water stress and temperatures may have on lag phases prior to growth, growth rates and aflatoxin production by two strains of each A. parasiticus and A. flavus on meat matrices over a period of 12days. Results showed that A. flavus CBS 573.65 had shorter lag phases than A. parasiticus CECT 2688, however the growth rates were quite similar. For both species, no growth occurred at 10°C and all aw tested and optimum growth happened at 25°C and 0.95 aw. Similar aflatoxin B1 production profiles between both species were found, however A. flavus produced much higher concentration of such toxin than A. parasiticus. Both species produced aflatoxins when the temperature and the aw were ≥15°C and ≥0.90. PMID:27498402

  20. Effect of corn and peanut cultivation on soil populations of Aspergillus flavus and A. parasiticus in southwestern Georgia.

    PubMed Central

    Horn, B W; Greene, R L; Dorner, J W

    1995-01-01

    The effect of corn and peanut cultivation on the proportion of Aspergillus flavus to A. parasiticus in soil was examined. Soil populations were monitored in three fields during three different years in southwestern Georgia. Each field was planted in both peanuts and corn, and soil was sampled within plots for each crop. A. flavus and A. parasiticus were present in similar proportions in plots from all fields at the beginning of the growing season. A. terreus, A. niger, and A. fumigatus were the other dominant aspergilli in soil. Fields A and B did not show drought stress in peanut or corn plants, and soil populations of A. flavus and A. parasiticus remained stable during the course of the year. In field C, drought stress in corn plants with associated A. flavus infection and aflatoxin contamination greatly increased soil populations of A. flavus relative to A. parasiticus upon dispersal of corn debris to the soil surface by a combine harvester. Colonization of organic debris after it has been added to the soil may maintain soil populations of A. parasiticus despite lower crop infection. PMID:7618858

  1. RNA sequencing of an nsdC mutant reveals global regulation of secondary metabolic gene clusters in Aspergillus flavus.

    PubMed

    Gilbert, Matthew K; Mack, Brian M; Wei, Qijian; Bland, John M; Bhatnagar, Deepak; Cary, Jeffrey W

    2016-01-01

    The filamentous fungus, Aspergillus flavus (A. flavus) is an opportunistic pathogen capable of invading a number of crops and contaminating them with toxic secondary metabolites such as aflatoxins. Characterizing the molecular mechanisms governing growth and development of this organism is vital for developing safe and effective strategies for reducing crop contamination. The transcription factor nsdC has been identified as being required for normal asexual development and aflatoxin production in A. flavus. Building on a previous study using a large (L)-sclerotial morphotype A. flavus nsdC mutant we observed alterations in conidiophore development and loss of sclerotial and aflatoxin production using a nsdC mutant of a small (S)-sclerotial morphotype, that normally produces aflatoxin and sclerotia in quantities much higher than the L-morphotype. RNA sequencing analysis of the nsdC knockout mutant and isogenic control strain identified a number of differentially expressed genes related to development and production of secondary metabolites, including aflatoxin, penicillin and aflatrem. Further, RNA-seq data indicating down regulation of aflatrem biosynthetic gene expression in the nsdC mutant correlated with HPLC analyses showing a decrease in aflatrem levels. The current study expands the role of nsdC as a globally acting transcription factor that is a critical regulator of both asexual reproduction and secondary metabolism in A. flavus. PMID:26686623

  2. ROS Involves the Fungicidal Actions of Thymol against Spores of Aspergillus flavus via the Induction of Nitric Oxide

    PubMed Central

    Shen, Qingshan; Zhou, Wei; Li, Hongbo; Hu, Liangbin; Mo, Haizhen

    2016-01-01

    Aspergillus flavus is a well-known pathogenic fungus for both crops and human beings. The acquisition of resistance to azoles by A. flavus is leading to more failures occurring in the prevention of infection by A. flavus. In this study, we found that thymol, one of the major chemical constituents of the essential oil of Monarda punctate, had efficient fungicidal activity against A. flavus and led to sporular lysis. Further studies indicated that thymol treatment induced the generation of both ROS and NO in spores, whereas NO accumulation was far later than ROS accumulation in response to thymol. By blocking ROS production with the inhibitors of NADPH oxidase, NO generation was also significantly inhibited in the presence of thymol, which indicated that ROS induced NO generation in A. flavus in response to thymol treatment. Moreover, the removal of either ROS or NO attenuated lysis and death of spores exposed to thymol. The addition of SNP (exogenous NO donor) eliminated the protective effects of the inhibitors of NADPH oxidase on thymol-induced lysis and death of spores. Taken together, it could be concluded that ROS is involved in spore death induced by thymol via the induction of NO. PMID:27196096

  3. ROS Involves the Fungicidal Actions of Thymol against Spores of Aspergillus flavus via the Induction of Nitric Oxide.

    PubMed

    Shen, Qingshan; Zhou, Wei; Li, Hongbo; Hu, Liangbin; Mo, Haizhen

    2016-01-01

    Aspergillus flavus is a well-known pathogenic fungus for both crops and human beings. The acquisition of resistance to azoles by A. flavus is leading to more failures occurring in the prevention of infection by A. flavus. In this study, we found that thymol, one of the major chemical constituents of the essential oil of Monarda punctate, had efficient fungicidal activity against A. flavus and led to sporular lysis. Further studies indicated that thymol treatment induced the generation of both ROS and NO in spores, whereas NO accumulation was far later than ROS accumulation in response to thymol. By blocking ROS production with the inhibitors of NADPH oxidase, NO generation was also significantly inhibited in the presence of thymol, which indicated that ROS induced NO generation in A. flavus in response to thymol treatment. Moreover, the removal of either ROS or NO attenuated lysis and death of spores exposed to thymol. The addition of SNP (exogenous NO donor) eliminated the protective effects of the inhibitors of NADPH oxidase on thymol-induced lysis and death of spores. Taken together, it could be concluded that ROS is involved in spore death induced by thymol via the induction of NO. PMID:27196096

  4. Tissue-specific gene expression in maize seeds during colonization by Aspergillus flavus and Fusarium verticillioides.

    PubMed

    Shu, Xiaomei; Livingston, David P; Franks, Robert G; Boston, Rebecca S; Woloshuk, Charles P; Payne, Gary A

    2015-09-01

    Aspergillus flavus and Fusarium verticillioides are fungal pathogens that colonize maize kernels and produce the harmful mycotoxins aflatoxin and fumonisin, respectively. Management practice based on potential host resistance to reduce contamination by these mycotoxins has proven difficult, resulting in the need for a better understanding of the infection process by these fungi and the response of maize seeds to infection. In this study, we followed the colonization of seeds by histological methods and the transcriptional changes of two maize defence-related genes in specific seed tissues by RNA in situ hybridization. Maize kernels were inoculated with either A. flavus or F. verticillioides 21-22 days after pollination, and harvested at 4, 12, 24, 48, 72, 96 and 120 h post-inoculation. The fungi colonized all tissues of maize seed, but differed in their interactions with aleurone and germ tissues. RNA in situ hybridization showed the induction of the maize pathogenesis-related protein, maize seed (PRms) gene in the aleurone and scutellum on infection by either fungus. Transcripts of the maize sucrose synthase-encoding gene, shrunken-1 (Sh1), were observed in the embryo of non-infected kernels, but were induced on infection by each fungus in the aleurone and scutellum. By comparing histological and RNA in situ hybridization results from adjacent serial sections, we found that the transcripts of these two genes accumulated in tissue prior to the arrival of the advancing pathogens in the seeds. A knowledge of the patterns of colonization and tissue-specific gene expression in response to these fungi will be helpful in the development of resistance.

  5. Biocontrol of Aspergillus flavus on peanut kernels by use of a strain of marine Bacillus megaterium.

    PubMed

    Kong, Qing; Shan, Shihua; Liu, Qizheng; Wang, Xiudan; Yu, Fangtang

    2010-04-30

    A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its activity in reducing postharvest decay of peanut kernels caused by Aspergillus flavus in in vitro and in vivo tests. The results showed that the concentrations of antagonist had a significant effect on biocontrol effectiveness in vivo: when the concentration of the washed bacteria cell suspension was used at 1x10(9)CFU/ml, the percentage rate of rot of peanut kernels was 31.67%+/-2.89%, which was markedly lower than that treated with water (the control) after 7days of incubation at 28 degrees C. The results also showed that unwashed cell culture of B. megaterium was as effective as the washed cell suspension, and better biocontrol was obtained when longer incubation time of B. megaterium was applied. When the incubation time of B. megaterium was 60-h, the rate of decay declined to 41.67%+/-2.89%. Furthermore, relative to the expression of 18S rRNA, the mRNA abundances of aflR gene and aflS gene in the experiment group were 0.28+/-0.03 and 0.024+/-0.005 respectively, indicating that this strain of B. megaterium could significantly reduce the biosynthesis of aflatoxins and expression of aflR gene and aflS gene (p<0.01). To the best of our knowledge, this is a first report demonstrating that the marine bacterium B. megaterium could be used as a biocontrol agent against postharvest fungal disease caused by A. flavus. PMID:20156660

  6. The bZIP Protein MeaB Mediates Virulence Attributes in Aspergillus flavus

    PubMed Central

    Yin, Wen-Bing; Franke, Stephen; Choithani, Anjali; Keller, Nancy P.

    2013-01-01

    LaeA is a fungal specific virulence factor of both plant and human pathogenic fungi. Transcriptional profiles of laeA mutants have been successfully exploited to identify regulatory mechanisms of secondary metabolism in fungi; here we use laeA mutants as tools to elucidate virulence attributes in Aspergillus flavus. Microarray expression profiles of ΔlaeA and over-expression laeA (OE::laeA) were compared to wild type A. flavus. Strikingly, several nitrogen metabolism genes are oppositely mis-regulated in the ΔlaeA and OE::laeA mutants. One of the nitrogen regulatory genes, the bZIP encoding meaB, is up-regulated in ΔlaeA. Significantly, over-expression of meaB (OE::meaB) phenocopies the decreased virulence attributes of a ΔlaeA phenotype including decreased colonization of host seed, reduced lipase activity and loss of aflatoxin B1 production in seed. However, a double knock-down of laeA and meaB (KD::laeA,meaB) demonstrated that KD::laeA,meaB closely resembled ΔlaeA rather than wild type or ΔmeaB in growth, aflatoxin biosynthesis and sclerotia production thus suggesting that meaB does not contribute to the ΔlaeA phenotype. MeaB and LaeA appear to be part of regulatory networks that allow them to have both shared and distinct roles in fungal biology. PMID:24040154

  7. Prevalence of airborne Aspergillus flavus in Khartoum (Sudan) airspora with reference to dusty weather and inoculum survival in simulated summer conditions.

    PubMed

    Abdalla, M H

    1988-12-01

    Khartoum air was scanned for airborne Aspergillus flavus for 12 months using the horizontal gravitational settling method. Frequency of occurrence was related to total fungal catch and dusty weather. The Aspergilli were prevalent (68% of total isolated/plate/month) and A. flavus constituted 31% of the total Aspergilli. In June (hot, dry & dusty) Aspergilli constituted 79% of the total isolates, whilst A. flavus represented 30% from amongst the other Aspergilli. A. flavus, A. niger, A. nidulans (conidial & ascosporic states), A. terreus, Eurotium amstelodami and A. fumigatus, in descending order of prevalence were isolated in June. Other pathogenic or potentially pathogenic forms, isolated, were Cladosporium, Curvularia and Penicillium. Amongst winter isolations A. flavus was sporadic to absent in occurrence. A. flavus spore inocula that underwent hourly intermitted exposure to 45 degrees C, showed a decrease in spore germinability as well as reduced germ length. PMID:3148861

  8. Rapid detection of aflatoxigenic Aspergillus sp. in herbal specimens by a simple, bendable, paper-based lab-on-a-chip.

    PubMed

    Chaumpluk, Piyasak; Plubcharoensook, Pattra; Prasongsuk, Sehanat

    2016-06-01

    Postharvest herbal product contamination with mycotoxins and mycotoxin-producing fungi represents a potentially carcinogenic hazard. Aspergillus flavus is a major cause of this issue. Available mold detection methods are PCR-based and rely heavily on laboratories; thus, they are unsuitable for on-site monitoring. In this study, a bendable, paper-based lab-on-a-chip platform was developed to rapidly detect toxigenic Aspergillus spp. DNA. The 3.0-4.0 cm(2) chip is fabricated using Whatman™ filter paper, fishing line and a simple plastic lamination process and has nucleic acid amplification and signal detection components. The Aspergillus assay specifically amplifies the aflatoxin biosynthesis gene, aflR, using loop-mediated isothermal amplification (LAMP); hybridization between target DNA and probes on blue silvernanoplates (AgNPls) yields colorimetric results. Positive results are indicated by the detection pad appearing blue due to dispersed blue AgNPls; negative results are indicated by the detection pad appearing colorless or pale yellow due to probe/target DNA hybridization and AgNPls aggregation. Assay completion requires less than 40 min, has a limit of detection (LOD) of 100 aflR copies, and has high specificity (94.47%)and sensitivity (100%). Contamination was identified in 14 of 32 herbal samples tested (43.75%). This work demonstrates the fabrication of a simple, low-cost, paper-based lab-on-a-chip platform suitable for rapid-detection applications. PMID:27168276

  9. Misidentification of Aspergillus nomius and Aspergillus tamarii as Aspergillus flavus: characterization by internal transcribed spacer, β-Tubulin, and calmodulin gene sequencing, metabolic fingerprinting, and matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    PubMed

    Tam, Emily W T; Chen, Jonathan H K; Lau, Eunice C L; Ngan, Antonio H Y; Fung, Kitty S C; Lee, Kim-Chung; Lam, Ching-Wan; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

    2014-04-01

    Aspergillus nomius and Aspergillus tamarii are Aspergillus species that phenotypically resemble Aspergillus flavus. In the last decade, a number of case reports have identified A. nomius and A. tamarii as causes of human infections. In this study, using an internal transcribed spacer, β-tubulin, and calmodulin gene sequencing, only 8 of 11 clinical isolates reported as A. flavus in our clinical microbiology laboratory by phenotypic methods were identified as A. flavus. The other three isolates were A. nomius (n = 2) or A. tamarii (n = 1). The results corresponded with those of metabolic fingerprinting, in which the A. flavus, A. nomius, and A. tamarii strains were separated into three clusters based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC MS) analysis. The first two patients with A. nomius infections had invasive aspergillosis and chronic cavitary and fibrosing pulmonary and pleural aspergillosis, respectively, whereas the third patient had A. tamarii colonization of the airway. Identification of the 11 clinical isolates and three reference strains by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) showed that only six of the nine strains of A. flavus were identified correctly. None of the strains of A. nomius and A. tamarii was correctly identified. β-Tubulin or the calmodulin gene should be the gene target of choice for identifying A. flavus, A. nomius, and A. tamarii. To improve the usefulness of MALDI-TOF MS, the number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability.

  10. Misidentification of Aspergillus nomius and Aspergillus tamarii as Aspergillus flavus: Characterization by Internal Transcribed Spacer, β-Tubulin, and Calmodulin Gene Sequencing, Metabolic Fingerprinting, and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    PubMed Central

    Tam, Emily W. T.; Chen, Jonathan H. K.; Lau, Eunice C. L.; Ngan, Antonio H. Y.; Fung, Kitty S. C.; Lee, Kim-Chung; Lam, Ching-Wan; Yuen, Kwok-Yung

    2014-01-01

    Aspergillus nomius and Aspergillus tamarii are Aspergillus species that phenotypically resemble Aspergillus flavus. In the last decade, a number of case reports have identified A. nomius and A. tamarii as causes of human infections. In this study, using an internal transcribed spacer, β-tubulin, and calmodulin gene sequencing, only 8 of 11 clinical isolates reported as A. flavus in our clinical microbiology laboratory by phenotypic methods were identified as A. flavus. The other three isolates were A. nomius (n = 2) or A. tamarii (n = 1). The results corresponded with those of metabolic fingerprinting, in which the A. flavus, A. nomius, and A. tamarii strains were separated into three clusters based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC MS) analysis. The first two patients with A. nomius infections had invasive aspergillosis and chronic cavitary and fibrosing pulmonary and pleural aspergillosis, respectively, whereas the third patient had A. tamarii colonization of the airway. Identification of the 11 clinical isolates and three reference strains by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) showed that only six of the nine strains of A. flavus were identified correctly. None of the strains of A. nomius and A. tamarii was correctly identified. β-Tubulin or the calmodulin gene should be the gene target of choice for identifying A. flavus, A. nomius, and A. tamarii. To improve the usefulness of MALDI-TOF MS, the number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability. PMID:24452174

  11. Nutritional changes in powdered red pepper upon in vitro infection of Aspergillus flavus

    PubMed Central

    Tripathi, Smita; Mishra, H.N.

    2009-01-01

    Quantitative losses in various biochemical constituents like capsaicin, carotenes, ascorbic acid, polyphenols, mineral matter, sugars (soluble and insoluble), protein and fat were estimated after the successful growth of Aspergillus flavus for 30 days on powdered red pepper. The fungal biomass was measured by ergosterol content and Aflatoxin B1 by HPLC. Amongst the various nutritional constituents evaluated for nutritional losses and changes the highest nutritional loss was reported in total carotenoids (88.55%) followed by total sugars (85.5%). The protein content of the infected sample increased from 18.01% to 23%. The nutritional profile of chilli powder (Capsicum annum var. sannam L.) shows highest share of total soluble sugars (32.89%) and fiber content (21.05%), followed by protein (18.01%) and fat (13.32%) making it an ideal solid- substrate for mould growth. At the end of incubation the fungal biomass was 192. 25 mg / 100 gram powder, total plate count 17.5 X 10 4 CFU/g and Aflatoxin B1 content was 30.06 μg / kg. PMID:24031333

  12. Characterization of the Maize Chitinase Genes and Their Effect on Aspergillus flavus and Aflatoxin Accumulation Resistance

    PubMed Central

    Hawkins, Leigh K.; Mylroie, J. Erik; Oliveira, Dafne A.; Smith, J. Spencer; Ozkan, Seval; Windham, Gary L.; Williams, W. Paul; Warburton, Marilyn L.

    2015-01-01

    Maize (Zea mays L.) is a crop of global importance, but prone to contamination by aflatoxins produced by fungi in the genus Aspergillus. The development of resistant germplasm and the identification of genes contributing to resistance would aid in the reduction of the problem with a minimal need for intervention by farmers. Chitinolytic enzymes respond to attack by potential pathogens and have been demonstrated to increase insect and fungal resistance in plants. Here, all chitinase genes in the maize genome were characterized via sequence diversity and expression patterns. Recent evolution within this gene family was noted. Markers from within each gene were developed and used to map the phenotypic effect on resistance of each gene in up to four QTL mapping populations and one association panel. Seven chitinase genes were identified that had alleles associated with increased resistance to aflatoxin accumulation and A. flavus infection in field grown maize. The chitinase in bin 1.05 identified a new and highly significant QTL, while chitinase genes in bins 2.04 and 5.03 fell directly beneath the peaks of previously published QTL. The expression patterns of these genes corroborate possible grain resistance mechanisms. Markers from within the gene sequences or very closely linked to them are presented to aid in the use of marker assisted selection to improve this trait. PMID:26090679

  13. Effect of climate change on Aspergillus flavus and aflatoxin B1 production

    PubMed Central

    Medina, Angel; Rodriguez, Alicia; Magan, Naresh

    2014-01-01

    This review considers the available information on the potential impact of key environmental factors and their interactions on the molecular ecology, growth and aflatoxin production by Aspergillus flavus in vitro and in maize grain. The recent studies which have been carried out to examine the impact of water activity × temperature on aflatoxin biosynthesis and phenotypic aflatoxin production are examined. These have shown that there is a direct relationship between the relative expression of key regulatory and structural genes under different environmental conditions which correlate directly with aflatoxin B1 production. A model has been developed to integrate the relative expression of 10 biosynthetic genes in the pathway, growth and aflatoxin B1 (AFB1) production which was validated under elevated temperature and water stress conditions. The effect of interacting conditions of aw × temperature × elevated CO2 (2 × and 3 × existing levels) are detailed for the first time. This suggests that while such interacting environmental conditions have little effect on growth they do have a significant impact on aflatoxin biosynthetic gene expression (structural aflD and regulatory aflR genes) and can significantly stimulate the production of AFB1. While the individual factors alone have an impact, it is the combined effect of these three abiotic factors which have an impact on mycotoxin production. This approach provides data which is necessary to help predict the real impacts of climate change on mycotoxigenic fungi. PMID:25101060

  14. Characterization of the Maize Chitinase Genes and Their Effect on Aspergillus flavus and Aflatoxin Accumulation Resistance.

    PubMed

    Hawkins, Leigh K; Mylroie, J Erik; Oliveira, Dafne A; Smith, J Spencer; Ozkan, Seval; Windham, Gary L; Williams, W Paul; Warburton, Marilyn L

    2015-01-01

    Maize (Zea mays L.) is a crop of global importance, but prone to contamination by aflatoxins produced by fungi in the genus Aspergillus. The development of resistant germplasm and the identification of genes contributing to resistance would aid in the reduction of the problem with a minimal need for intervention by farmers. Chitinolytic enzymes respond to attack by potential pathogens and have been demonstrated to increase insect and fungal resistance in plants. Here, all chitinase genes in the maize genome were characterized via sequence diversity and expression patterns. Recent evolution within this gene family was noted. Markers from within each gene were developed and used to map the phenotypic effect on resistance of each gene in up to four QTL mapping populations and one association panel. Seven chitinase genes were identified that had alleles associated with increased resistance to aflatoxin accumulation and A. flavus infection in field grown maize. The chitinase in bin 1.05 identified a new and highly significant QTL, while chitinase genes in bins 2.04 and 5.03 fell directly beneath the peaks of previously published QTL. The expression patterns of these genes corroborate possible grain resistance mechanisms. Markers from within the gene sequences or very closely linked to them are presented to aid in the use of marker assisted selection to improve this trait. PMID:26090679

  15. Cyclopiazonic acid production by Aspergillus flavus and its effects on broiler chickens.

    PubMed Central

    Dorner, J W; Cole, R J; Lomax, L G; Gosser, H S; Diener, U L

    1983-01-01

    Cyclopiazonic acid (CPA) was purified from cultures of Aspergillus flavus, and ca. 14 g of the toxin was collected for use in feeding studies. Chicken rations were artificially contaminated with purified CPA at concentrations of 10, 50, and 100 ppm (microgram/g) and fed ad libitum to eight groups of chickens for 7 weeks. Chickens receiving feed with 100 ppm of CPA had high mortality, decreased weight gain, and poor feed conversion when compared with birds receiving other doses. Postmortem examination showed that chickens fed the two greatest doses of CPA had proventricular lesions characterized by mucosal erosion and hyperemia (100 ppm) and by thick mucosa and dilated proventricular lumens (50 ppm). Birds given 100 ppm of CPA in feed also had numerous yellow foci in their livers and spleens. Microscopic examination of tissues of birds that received 100 ppm of CPA revealed ulcerative proventriculitis, mucosal necrosis in the gizzard, and hepatic and splenic necrosis and inflammation. Birds given 50 ppm of CPA had hyperplasia of the proventricular mucosal epithelium. Birds given 10 ppm of CPA and control birds had no significant treatment-related lesions. PMID:6416167

  16. Modeling kinetics of aflatoxin production by Aspergillus flavus in maize-based medium and maize grain.

    PubMed

    Garcia, Daiana; Ramos, Antonio J; Sanchis, Vicente; Marín, Sonia

    2013-03-15

    Predictive mycology has dealt mainly with germination, growth and inactivation of fungi while the issue of mycotoxin production remains relatively unexplored. Very few studies provide biomass dry weight/colony size data along with mycotoxin data for the same sample times, thus the ratio mycotoxin accumulation per fungal biomass dry weight/colony size has rarely been reported. For this reason, the objective of the present study was to model the kinetics of mycotoxin production under the assumption of existing both no-growth-associated and growth-associated production. Aspergillus flavus was chosen as a model mycotoxigenic microorganism, and it was grown in maize agar medium and maize grain at 0.90 and 0.99 aw at 25°C. A significant positive correlation (p<0.05) was observed among the biomass responses (colony radius and biomass dry weight) in agar medium and colony radius in maize at both aw levels assayed. The Luedeking-Piret model was used to model AFB1 production and reasonable percentages of variability were explained. Moreover, AFB1 production was in general slightly better predicted through colony area. As conclusion, aflatoxin production may follow a mixed-growth associated trend, confirming that toxin formation does not present a clear delay in relation to growth under certain conditions. PMID:23422844

  17. Sexual Reproduction in Aspergillus flavus Sclerotia: Acquisition of Novel Alleles from Soil Populations and Uniparental Mitochondrial Inheritance

    PubMed Central

    Horn, Bruce W.; Gell, Richard M.; Singh, Rakhi; Sorensen, Ronald B.; Carbone, Ignazio

    2016-01-01

    Aspergillus flavus colonizes agricultural commodities worldwide and contaminates them with carcinogenic aflatoxins. The high genetic diversity of A. flavus populations is largely due to sexual reproduction characterized by the formation of ascospore-bearing ascocarps embedded within sclerotia. A. flavus is heterothallic and laboratory crosses between strains of the opposite mating type produce progeny showing genetic recombination. Sclerotia formed in crops are dispersed onto the soil surface at harvest and are predominantly produced by single strains of one mating type. Less commonly, sclerotia may be fertilized during co-infection of crops with sexually compatible strains. In this study, laboratory and field experiments were performed to examine sexual reproduction in single-strain and fertilized sclerotia following exposure of sclerotia to natural fungal populations in soil. Female and male roles and mitochondrial inheritance in A. flavus were also examined through reciprocal crosses between sclerotia and conidia. Single-strain sclerotia produced ascospores on soil and progeny showed biparental inheritance that included novel alleles originating from fertilization by native soil strains. Sclerotia fertilized in the laboratory and applied to soil before ascocarp formation also produced ascospores with evidence of recombination in progeny, but only known parental alleles were detected. In reciprocal crosses, sclerotia and conidia from both strains functioned as female and male, respectively, indicating A. flavus is hermaphroditic, although the degree of fertility depended upon the parental sources of sclerotia and conidia. All progeny showed maternal inheritance of mitochondria from the sclerotia. Compared to A. flavus populations in crops, soil populations would provide a higher likelihood of exposure of sclerotia to sexually compatible strains and a more diverse source of genetic material for outcrossing. PMID:26731416

  18. Sexual Reproduction in Aspergillus flavus Sclerotia: Acquisition of Novel Alleles from Soil Populations and Uniparental Mitochondrial Inheritance.

    PubMed

    Horn, Bruce W; Gell, Richard M; Singh, Rakhi; Sorensen, Ronald B; Carbone, Ignazio

    2016-01-01

    Aspergillus flavus colonizes agricultural commodities worldwide and contaminates them with carcinogenic aflatoxins. The high genetic diversity of A. flavus populations is largely due to sexual reproduction characterized by the formation of ascospore-bearing ascocarps embedded within sclerotia. A. flavus is heterothallic and laboratory crosses between strains of the opposite mating type produce progeny showing genetic recombination. Sclerotia formed in crops are dispersed onto the soil surface at harvest and are predominantly produced by single strains of one mating type. Less commonly, sclerotia may be fertilized during co-infection of crops with sexually compatible strains. In this study, laboratory and field experiments were performed to examine sexual reproduction in single-strain and fertilized sclerotia following exposure of sclerotia to natural fungal populations in soil. Female and male roles and mitochondrial inheritance in A. flavus were also examined through reciprocal crosses between sclerotia and conidia. Single-strain sclerotia produced ascospores on soil and progeny showed biparental inheritance that included novel alleles originating from fertilization by native soil strains. Sclerotia fertilized in the laboratory and applied to soil before ascocarp formation also produced ascospores with evidence of recombination in progeny, but only known parental alleles were detected. In reciprocal crosses, sclerotia and conidia from both strains functioned as female and male, respectively, indicating A. flavus is hermaphroditic, although the degree of fertility depended upon the parental sources of sclerotia and conidia. All progeny showed maternal inheritance of mitochondria from the sclerotia. Compared to A. flavus populations in crops, soil populations would provide a higher likelihood of exposure of sclerotia to sexually compatible strains and a more diverse source of genetic material for outcrossing.

  19. Efficacy of two chemical coagulants and three different filtration media on removal of Aspergillus flavus from surface water.

    PubMed

    Al-Gabr, Hamid Mohammad; Zheng, Tianling; Yu, Xin

    2014-02-01

    Aquatic fungi are common in various aqueous environments and play potentially crucial roles in nutrient and carbon cycling as well as interacting with other organisms. Species of Aspergillus are the most common fungi that occur in water. The present study was undertaken to elucidate the efficacy of two coagulants, aluminum sulfate and ferric chloride, used at different concentrations to treat drinking water, in removing Aspergillus flavus, as well as testing three different filtration media: sand, activated carbon, and ceramic granules, for their removal of fungi from water. The results revealed that both coagulants were effective in removing fungi and decreasing the turbidity of drinking water, and turbidity decreased with increasing coagulant concentration. Also, at the highest concentration of the coagulants, A. flavus was decreased by 99.6% in the treated water. Among ceramic granules, activated carbon, and sand used as media for water filtration, the sand and activated carbon filters were more effective in removing A. flavus than ceramic granules while simultaneously decreasing the turbidity levels in the test water samples. Post-treatment total organic carbon (TOC) and total nitrogen (TN) concentrations in the experimental water did not decrease; on the contrary, TN concentrations increased with the increasing dosage of coagulants. The filtration process had no effect in reducing TOC and TN in tested water.

  20. Inhibition of Aspergillus flavus on agar media and brown rice cereal bars using cold atmospheric plasma treatment.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Nisoa, Mudtorlep; Matan, Nirundorn

    2013-02-01

    This study aimed to optimize the operating parameters of cold atmospheric plasma treatment to inhibit the growth of Aspergillus flavus on agar media and brown rice cereal bars. The effects of argon plasma jet treatment on the growth of A. flavus on malt extract agar (MEA) at powers of 20 W and 40 W with exposure times at 5, 15 and 25 min were studied using response surface methodology (RSM) with a central composite face-centered (CCF) design. Multiple regression analysis indicated that plasma treatment at 40 W for 25 min is most effective for inhibiting growth of A. flavus on the agar medium. On brown rice cereal bars, plasma powered at 40 W for 20 min was capable of giving protection against A. flavus growth for up to 20 days under storage conditions of 25°C and 100% RH. These results demonstrated the potential of cold atmospheric plasma jet treatment to control mold growth on various food products. PMID:23279819

  1. Effects of soil moisture and temperature on preharvest invasion of peanuts by the Aspergillus flavus group and subsequent aflatoxin development.

    PubMed Central

    Hill, R A; Blankenship, P D; Cole, R J; Sanders, T H

    1983-01-01

    Four soil temperature and moisture treatment regimens were imposed on Florunner peanuts 94 days after planting in experimental plots in 1980. At harvest (145 days after planting), the incidence of the Aspergillus flavus group and the aflatoxin concentration were greatest in damaged kernels. Extensive colonization of sound mature kernels (SMK) by the A. flavus group occurred with the drought stress treatment (56% kernels colonized); colonization was less in the irrigated plot (7%) and the drought stress plot with cooled soil (11%) and was intermediate in the irrigated plot with heated soil (26%). Aflatoxin was virtually absent from SMK with the last three treatments, but it was found at an average concentration of 244 ppb (ng/g) in drought-stressed SMK. Colonization of SMK by the A. flavus group and aflatoxin production were greater with hot dry conditions. Neither elevated temperature alone nor drought stress alone caused aflatoxin contamination in SMK. When the ratio of SMK colonized by A. flavus compared with A. niger was greater than 19:1, there was aflatoxin contamination, but there was none if this ratio was less than 9:1. Irrigation caused a higher incidence of A. niger than drought did. This may have prevented the aflatoxin contamination of undamaged peanuts. PMID:6402980

  2. Gene expression profiling and identification of resistance genes to Aspergillus flavus infection in peanut through EST and microarray strategies.

    PubMed

    Guo, Baozhu; Fedorova, Natalie D; Chen, Xiaoping; Wan, Chun-Hua; Wang, Wei; Nierman, William C; Bhatnagar, Deepak; Yu, Jiujiang

    2011-07-01

    Aspergillus flavus and A. parasiticus infect peanut seeds and produce aflatoxins, which are associated with various diseases in domestic animals and humans throughout the world. The most cost-effective strategy to minimize aflatoxin contamination involves the development of peanut cultivars that are resistant to fungal infection and/or aflatoxin production. To identify peanut Aspergillus-interactive and peanut Aspergillus-resistance genes, we carried out a large scale peanut Expressed Sequence Tag (EST) project which we used to construct a peanut glass slide oligonucleotide microarray. The fabricated microarray represents over 40% of the protein coding genes in the peanut genome. For expression profiling, resistant and susceptible peanut cultivars were infected with a mixture of Aspergillusflavus and parasiticus spores. The subsequent microarray analysis identified 62 genes in resistant cultivars that were up-expressed in response to Aspergillus infection. In addition, we identified 22 putative Aspergillus-resistance genes that were constitutively up-expressed in the resistant cultivar in comparison to the susceptible cultivar. Some of these genes were homologous to peanut, corn, and soybean genes that were previously shown to confer resistance to fungal infection. This study is a first step towards a comprehensive genome-scale platform for developing Aspergillus-resistant peanut cultivars through targeted marker-assisted breeding and genetic engineering. PMID:22069737

  3. Identification of alternative splice variants in Aspergillus flavus through comparison of multiple tandem MS search algorithms

    PubMed Central

    2011-01-01

    Background Database searching is the most frequently used approach for automated peptide assignment and protein inference of tandem mass spectra. The results, however, depend on the sequences in target databases and on search algorithms. Recently by using an alternative splicing database, we identified more proteins than with the annotated proteins in Aspergillus flavus. In this study, we aimed at finding a greater number of eligible splice variants based on newly available transcript sequences and the latest genome annotation. The improved database was then used to compare four search algorithms: Mascot, OMSSA, X! Tandem, and InsPecT. Results The updated alternative splicing database predicted 15833 putative protein variants, 61% more than the previous results. There was transcript evidence for 50% of the updated genes compared to the previous 35% coverage. Database searches were conducted using the same set of spectral data, search parameters, and protein database but with different algorithms. The false discovery rates of the peptide-spectrum matches were estimated < 2%. The numbers of the total identified proteins varied from 765 to 867 between algorithms. Whereas 42% (1651/3891) of peptide assignments were unanimous, the comparison showed that 51% (568/1114) of the RefSeq proteins and 15% (11/72) of the putative splice variants were inferred by all algorithms. 12 plausible isoforms were discovered by focusing on the consensus peptides which were detected by at least three different algorithms. The analysis found different conserved domains in two putative isoforms of UDP-galactose 4-epimerase. Conclusions We were able to detect dozens of new peptides using the improved alternative splicing database with the recently updated annotation of the A. flavus genome. Unlike the identifications of the peptides and the RefSeq proteins, large variations existed between the putative splice variants identified by different algorithms. 12 candidates of putative isoforms

  4. Efficacy of water-dispersible formulations of biological control strains of Aspergillus flavus for aflatoxin management in corn.

    PubMed

    Weaver, Mark A; Abbas, Hamed K; Jin, Xixuan; Elliott, Brad

    2016-01-01

    Field experiments were conducted in 2011 and 2012 to evaluate the efficacy of water-dispersible granule (WDG) formulations of biocontrol strains of Aspergillus flavus in controlling aflatoxin contamination of corn. In 2011, when aflatoxin was present at very high levels, there was no WDG treatment that could provide significant protection against aflatoxin contamination. The following year a new WDG formulation was tested that resulted in 100% reduction in aflatoxin in one field experiment and ≥ 49% reduction in all five WDG treatments with biocontrol strain 21882. Large sampling error, however, limited the resolution of various treatment effects. Corn samples were also subjected to microbial analysis to understand better the mechanisms of successful biocontrol. In the samples examined here, the size of the A. flavus population on the grain was associated with the amount of aflatoxin, but the toxigenic status of that population was a poor predictor of aflatoxin concentration.

  5. Absence of the aflatoxin biosynthesis gene, norA, allows accumulation of deoxyaflatoxin B1 in Aspergillus flavus cultures

    PubMed Central

    Ehrlich, Kenneth C.; Chang, Perng-Kuang; Scharfenstein, Lester L.; Cary, Jeffrey W.; Crawford, Jason M.; Townsend, Craig A.

    2010-01-01

    Biosynthesis of the highly toxic and carcinogenic aflatoxins in select Aspergillus species from the common intermediate O-methylsterigmatocystin (OMST) has been postulated to require only the cytochrome P450 monooxygenase, OrdA (AflQ). We now provide evidence that the aryl alcohol dehydrogenase NorA (AflE) encoded by the aflatoxin biosynthetic gene cluster in A. flavus affects the accumulation of aflatoxins in the final steps of aflatoxin biosynthesis. Mutants with inactive norA produced reduced quantities of aflatoxin B1 (AFB1), but elevated quantities of a new metabolite, deoxyAFB1. To explain this result, we suggest that, in the absence of NorA, the AFB1 reduction product, aflatoxicol, is produced and is readily dehydrated to deoxyAFB1 in the acidic medium, enabling us to observe this otherwise minor toxin produced in wild-type A. flavus. PMID:20158523

  6. Identification of Maize Genes Associated with Host Plant Resistance or Susceptibility to Aspergillus flavus Infection and Aflatoxin Accumulation

    PubMed Central

    Kelley, Rowena Y.; Williams, W. Paul; Mylroie, J. Erik; Boykin, Deborah L.; Harper, Jonathan W.; Windham, Gary L.; Ankala, Arunkanth; Shan, Xueyan

    2012-01-01

    Background Aspergillus flavus infection and aflatoxin contamination of maize pose negative impacts in agriculture and health. Commercial maize hybrids are generally susceptible to this fungus. Significant levels of host plant resistance have been observed in certain maize inbred lines. This study was conducted to identify maize genes associated with host plant resistance or susceptibility to A. flavus infection and aflatoxin accumulation. Results Genome wide gene expression levels with or without A. flavus inoculation were compared in two resistant maize inbred lines (Mp313E and Mp04∶86) in contrast to two susceptible maize inbred lines (Va35 and B73) by microarray analysis. Principal component analysis (PCA) was used to find genes contributing to the larger variances associated with the resistant or susceptible maize inbred lines. The significance levels of gene expression were determined by using SAS and LIMMA programs. Fifty candidate genes were selected and further investigated by quantitative RT-PCR (qRT-PCR) in a time-course study on Mp313E and Va35. Sixteen of the candidate genes were found to be highly expressed in Mp313E and fifteen in Va35. Out of the 31 highly expressed genes, eight were mapped to seven previously identified quantitative trait locus (QTL) regions. A gene encoding glycine-rich RNA binding protein 2 was found to be associated with the host hypersensitivity and susceptibility in Va35. A nuclear pore complex protein YUP85-like gene was found to be involved in the host resistance in Mp313E. Conclusion Maize genes associated with host plant resistance or susceptibility were identified by a combination of microarray analysis, qRT-PCR analysis, and QTL mapping methods. Our findings suggest that multiple mechanisms are involved in maize host plant defense systems in response to Aspergillus flavus infection and aflatoxin accumulation. These findings will be important in identification of DNA markers for breeding maize lines resistant to

  7. Toxigenic potentiality of Aspergillus flavus and Aspergillus parasiticus strains isolated from black pepper assessed by an LC-MS/MS based multi-mycotoxin method.

    PubMed

    Yogendrarajah, Pratheeba; Devlieghere, Frank; Njumbe Ediage, Emmanuel; Jacxsens, Liesbeth; De Meulenaer, Bruno; De Saeger, Sarah

    2015-12-01

    A liquid chromatography triple quadrupole tandem mass spectrometry method was developed and validated to determine mycotoxins, produced by fungal isolates grown on malt extract agar (MEA). All twenty metabolites produced by different fungal species were extracted using acetonitrile/1% formic acid. The developed method was applied to assess the toxigenic potentiality of Aspergillus flavus (n = 11) and Aspergillus parasiticus (n = 6) strains isolated from black peppers (Piper nigrum L.) following their growth at 22, 30 and 37 °C. Highest mean radial colony growth rates were observed at 30 °C for A. flavus (5.21 ± 0.68 mm/day) and A. parasiticus (4.97 ± 0.33 mm/day). All of the A. flavus isolates produced aflatoxin B1 and O-methyl sterigmatocystin (OMST) while 91% produced aflatoxin B2 (AFB2) and 82% of them produced sterigmatocystin (STERIG) at 30 °C. Except one, all the A. parasiticus isolates produced all the four aflatoxins, STERIG and OMST at 30 °C. Remarkably high AFB1 was produced by some A. flavus isolates at 22 °C (max 16-40 mg/kg). Production of mycotoxins followed a different trend than that of growth rate of both species. Notable correlations were found between different secondary metabolites of both species; R(2) 0.87 between AFB1 and AFB2 production. Occurrence of OMST could be used as a predictor for AFB1 production. PMID:26338134

  8. Toxigenic potentiality of Aspergillus flavus and Aspergillus parasiticus strains isolated from black pepper assessed by an LC-MS/MS based multi-mycotoxin method.

    PubMed

    Yogendrarajah, Pratheeba; Devlieghere, Frank; Njumbe Ediage, Emmanuel; Jacxsens, Liesbeth; De Meulenaer, Bruno; De Saeger, Sarah

    2015-12-01

    A liquid chromatography triple quadrupole tandem mass spectrometry method was developed and validated to determine mycotoxins, produced by fungal isolates grown on malt extract agar (MEA). All twenty metabolites produced by different fungal species were extracted using acetonitrile/1% formic acid. The developed method was applied to assess the toxigenic potentiality of Aspergillus flavus (n = 11) and Aspergillus parasiticus (n = 6) strains isolated from black peppers (Piper nigrum L.) following their growth at 22, 30 and 37 °C. Highest mean radial colony growth rates were observed at 30 °C for A. flavus (5.21 ± 0.68 mm/day) and A. parasiticus (4.97 ± 0.33 mm/day). All of the A. flavus isolates produced aflatoxin B1 and O-methyl sterigmatocystin (OMST) while 91% produced aflatoxin B2 (AFB2) and 82% of them produced sterigmatocystin (STERIG) at 30 °C. Except one, all the A. parasiticus isolates produced all the four aflatoxins, STERIG and OMST at 30 °C. Remarkably high AFB1 was produced by some A. flavus isolates at 22 °C (max 16-40 mg/kg). Production of mycotoxins followed a different trend than that of growth rate of both species. Notable correlations were found between different secondary metabolites of both species; R(2) 0.87 between AFB1 and AFB2 production. Occurrence of OMST could be used as a predictor for AFB1 production.

  9. The Master Transcription Factor mtfA Governs Aflatoxin Production, Morphological Development and Pathogenicity in the Fungus Aspergillus flavus

    PubMed Central

    Zhuang, Zhenhong; Lohmar, Jessica M.; Satterlee, Timothy; Cary, Jeffrey W.; Calvo, Ana M.

    2016-01-01

    Aspergillus flavus produces a variety of toxic secondary metabolites; among them, the aflatoxins (AFs) are the most well known. These compounds are highly mutagenic and carcinogenic, particularly AFB1. A. flavus is capable of colonizing a number of economically-important crops, such as corn, cotton, peanut and tree nuts, and contaminating them with AFs. Molecular genetic studies in A. flavus could identify novel gene targets for use in strategies to reduce AF contamination and its adverse impact on food and feed supplies worldwide. In the current study, we investigated the role of the master transcription factor gene mtfA in A. flavus. Our results revealed that forced overexpression of mtfA results in a drastic decrease or elimination of several secondary metabolites, among them AFB1. The reduction in AFB1 was accompanied by a decrease in aflR expression. Furthermore, mtfA also regulates development; conidiation was influenced differently by this gene depending on the type of colonized substrate. In addition to its effect on conidiation, mtfA is necessary for the normal maturation of sclerotia. Importantly, mtfA positively affects the pathogenicity of A. flavus when colonizing peanut seeds. AF production in colonized seeds was decreased in the deletion mtfA strain and particularly in the overexpression strain, where only trace amounts were detected. Interestingly, a more rapid colonization of the seed tissue occurred when mtfA was overexpressed, coinciding with an increase in lipase activity and faster maceration of the oily part of the seed. PMID:26805883

  10. A Caleosin-Like Protein with Peroxygenase Activity Mediates Aspergillus flavus Development, Aflatoxin Accumulation, and Seed Infection

    PubMed Central

    Almousally, Ibrahem; Shaban, Mouhnad; Blee, Elizabeth

    2015-01-01

    Caleosins are a small family of calcium-binding proteins endowed with peroxygenase activity in plants. Caleosin-like genes are present in fungi; however, their functions have not been reported yet. In this work, we identify a plant caleosin-like protein in Aspergillus flavus that is highly expressed during the early stages of spore germination. A recombinant purified 32-kDa caleosin-like protein supported peroxygenase activities, including co-oxidation reactions and reduction of polyunsaturated fatty acid hydroperoxides. Deletion of the caleosin gene prevented fungal development. Alternatively, silencing of the gene led to the increased accumulation of endogenous polyunsaturated fatty acid hydroperoxides and antioxidant activities but to a reduction of fungal growth and conidium formation. Two key genes of the aflatoxin biosynthesis pathway, aflR and aflD, were downregulated in the strains in which A. flavus PXG (AfPXG) was silenced, leading to reduced aflatoxin B1 production in vitro. Application of caleosin/peroxygenase-derived oxylipins restored the wild-type phenotype in the strains in which AfPXG was silenced. PXG-deficient A. flavus strains were severely compromised in their capacity to infect maize seeds and to produce aflatoxin. Our results uncover a new branch of the fungal oxylipin pathway and may lead to the development of novel targets for controlling fungal disease. PMID:26116672

  11. A Caleosin-Like Protein with Peroxygenase Activity Mediates Aspergillus flavus Development, Aflatoxin Accumulation, and Seed Infection.

    PubMed

    Hanano, Abdulsamie; Almousally, Ibrahem; Shaban, Mouhnad; Blee, Elizabeth

    2015-09-01

    Caleosins are a small family of calcium-binding proteins endowed with peroxygenase activity in plants. Caleosin-like genes are present in fungi; however, their functions have not been reported yet. In this work, we identify a plant caleosin-like protein in Aspergillus flavus that is highly expressed during the early stages of spore germination. A recombinant purified 32-kDa caleosin-like protein supported peroxygenase activities, including co-oxidation reactions and reduction of polyunsaturated fatty acid hydroperoxides. Deletion of the caleosin gene prevented fungal development. Alternatively, silencing of the gene led to the increased accumulation of endogenous polyunsaturated fatty acid hydroperoxides and antioxidant activities but to a reduction of fungal growth and conidium formation. Two key genes of the aflatoxin biosynthesis pathway, aflR and aflD, were downregulated in the strains in which A. flavus PXG (AfPXG) was silenced, leading to reduced aflatoxin B1 production in vitro. Application of caleosin/peroxygenase-derived oxylipins restored the wild-type phenotype in the strains in which AfPXG was silenced. PXG-deficient A. flavus strains were severely compromised in their capacity to infect maize seeds and to produce aflatoxin. Our results uncover a new branch of the fungal oxylipin pathway and may lead to the development of novel targets for controlling fungal disease. PMID:26116672

  12. The alcohol dehydrogenase gene adh1 is induced in Aspergillus flavus grown on medium conducive to aflatoxin biosynthesis.

    PubMed Central

    Woloshuk, C P; Payne, G A

    1994-01-01

    An Aspergillus flavus cDNA library was screened by differential hybridization to isolate clones corresponding to genes that are actively transcribed under culture conditions conducive to aflatoxin biosynthesis. One clone with a 1.28-kb insert was isolated, and its nucleotide sequence was determined. The nucleotide sequence of this clone had 75% DNA identity to those of the alcohol dehydrogenase genes from Aspergillus nidulans, and the putative polypeptide translated from the cDNA sequence had 82% similarity with the amino acid sequences of the A. nidulans proteins. Thus, this gene has been designated adh1. Southern hybridization analysis of genomic DNA from A. flavus indicated that there was one copy of the adh1 gene. Northern (RNA) hybridization analysis indicated that the adh1 transcript accumulated in culture medium conducive to aflatoxin production and the timing of accumulation of adh1 transcripts was similar to that for aflatoxin. Fusion of the promoter region of adh1 to a beta-glucuronidase reporter gene indicated that accumulation of the adh1 transcript was the result of transcriptional activation. These molecular data support previous physiological evidence that showed the importance of carbohydrate metabolism during aflatoxin biosynthesis. Images PMID:8135521

  13. Morphological and toxigenic variability in the Aspergillus flavus isolates from peanut (Arachis hypogaea L.) production system in Gujarat (India).

    PubMed

    Singh, Diwakar; Thankappan, Radhakrishnan; Kumar, Vinod; Bagwan, Naimoddin B; Basu, Mukti S; Dobaria, Jentilal R; Mishra, Gyan P; Chanda, Sumitra

    2015-03-01

    Morphological and toxigenic variability in 187 Aspergillus flavus isolates, collected from a major Indian peanut production system, from 10 districts of Gujarat was studied. On the basis of colony characteristics, the isolates were grouped as group A (83%), B (11%) and G (6%). Of all the isolates, 21%, 47% and 32% were found to be fast-growing, moderately-fast and slow-growing respectively, and nosclerotia and sclerotia production was recorded in 32.1% and 67% isolates respectively. Large, medium and small number of sclerotia production was observed in 55, 38 and 34 isolates respectively. Toxigenic potential based on ammonia vapour test was not found reliable, while ELISA test identified 68.5%, 18.7% and 12.8% isolates as atoxigenic, moderately-toxigenic and highly-toxigenic, respectively. On clustering, the isolates were grouped into 15 distinct clusters, 'A' group of isolates was grouped distinctly in different clusters, while 'B' and 'G' groups of isolates were clustered together. No association was observed between morphological-diversity and toxigenic potential of the isolates. From the present investigation, most virulent isolates were pooled to form a consortium for sick-plot screening of germplasm, against Aspergillus flavus. In future, atoxigenic isolates may be evaluated for their potential to be used as bio-control agent against toxigenicisolates.

  14. Optimization of process parameters influencing the submerged fermentation of extracellular lipases from Pseudomonas aeruginosa, candida albicans and Aspergillus flavus.

    PubMed

    Padhiar, Jigita; Das, Arijit; Bhattacharya, Sourav

    2011-11-15

    The present study was aimed at optimization, production and partial purification of lipases from Pseudomonas aeruginosa, Candida albicans and Aspergillus flavus. Various nutritional and physical parameters affecting lipase production such as carbon and nitrogen supplements, pH, temperature, agitation speed and incubation time were studied. Refined sunflower oil (1% v/v) and tryptone at a pH of 6.2 favored maximum lipase production in Pseudomonas at 30 degrees C and 150 rpm, when incubated for 5 days. In C. albicans refined sunflower oil (3% v/v) and peptone resulted in maximum lipase production at pH 5.2, 30 degrees C and 150 rpm, when incubated for 5 days. In A. flavus coconut oil (3% v/v) and peptone yielded maximum lipase at pH 6.2, 37 degrees C, 200 rpm after an incubation period of 5 days. The lipases were partially purified by ammonium sulphate precipitation and dialysis. In P. aeruginosa enzyme activity of the dialyzed fraction was found to be 400 U mL-' and for C. albicans 410 U mL(-1). The dialysed lipase fraction from A. flavus demonstrated an activity of 460 U mL(-1). The apparent molecular weights of the dialyzed lipases were determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The dialyzed lipase fraction obtained from P. aeruginosa revealed molecular weights of 47, 49 and 51 kDa, whereas, lipases from C. albicans and A. flavus demonstrated 3 bands (16.5, 27 and 51 kDa) and one band (47 kDa), respectively. These extracellular lipases may find wide industrial applications.

  15. Optimization of process parameters influencing the submerged fermentation of extracellular lipases from Pseudomonas aeruginosa, candida albicans and Aspergillus flavus.

    PubMed

    Padhiar, Jigita; Das, Arijit; Bhattacharya, Sourav

    2011-11-15

    The present study was aimed at optimization, production and partial purification of lipases from Pseudomonas aeruginosa, Candida albicans and Aspergillus flavus. Various nutritional and physical parameters affecting lipase production such as carbon and nitrogen supplements, pH, temperature, agitation speed and incubation time were studied. Refined sunflower oil (1% v/v) and tryptone at a pH of 6.2 favored maximum lipase production in Pseudomonas at 30 degrees C and 150 rpm, when incubated for 5 days. In C. albicans refined sunflower oil (3% v/v) and peptone resulted in maximum lipase production at pH 5.2, 30 degrees C and 150 rpm, when incubated for 5 days. In A. flavus coconut oil (3% v/v) and peptone yielded maximum lipase at pH 6.2, 37 degrees C, 200 rpm after an incubation period of 5 days. The lipases were partially purified by ammonium sulphate precipitation and dialysis. In P. aeruginosa enzyme activity of the dialyzed fraction was found to be 400 U mL-' and for C. albicans 410 U mL(-1). The dialysed lipase fraction from A. flavus demonstrated an activity of 460 U mL(-1). The apparent molecular weights of the dialyzed lipases were determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The dialyzed lipase fraction obtained from P. aeruginosa revealed molecular weights of 47, 49 and 51 kDa, whereas, lipases from C. albicans and A. flavus demonstrated 3 bands (16.5, 27 and 51 kDa) and one band (47 kDa), respectively. These extracellular lipases may find wide industrial applications. PMID:22514878

  16. Effects of Hydrogen Peroxide on Different Toxigenic and Atoxigenic Isolates of Aspergillus flavus

    PubMed Central

    Fountain, Jake C.; Scully, Brian T.; Chen, Zhi-Yuan; Gold, Scott E.; Glenn, Anthony E.; Abbas, Hamed K.; Lee, R. Dewey; Kemerait, Robert C.; Guo, Baozhu

    2015-01-01

    Drought stress in the field has been shown to exacerbate aflatoxin contamination of maize and peanut. Drought and heat stress also produce reactive oxygen species (ROS) in plant tissues. Given the potential correlation between ROS and exacerbated aflatoxin production under drought and heat stress, the objectives of this study were to examine the effects of hydrogen peroxide (H2O2)-induced oxidative stress on the growth of different toxigenic (+) and atoxigenic (−) isolates of Aspergillus flavus and to test whether aflatoxin production affects the H2O2 concentrations that the isolates could survive. Ten isolates were tested: NRRL3357 (+), A9 (+), AF13 (+), Tox4 (+), A1 (−), K49 (−), K54A (−), AF36 (−), and Aflaguard (−); and one A. parasiticus isolate, NRRL2999 (+). These isolates were cultured under a H2O2 gradient ranging from 0 to 50 mM in two different media, aflatoxin-conducive yeast extract-sucrose (YES) and non-conducive yeast extract-peptone (YEP). Fungal growth was inhibited at a high H2O2 concentration, but specific isolates grew well at different H2O2 concentrations. Generally the toxigenic isolates tolerated higher concentrations than did atoxigenic isolates. Increasing H2O2 concentrations in the media resulted in elevated aflatoxin production in toxigenic isolates. In YEP media, the higher concentration of peptone (15%) partially inactivated the H2O2 in the media. In the 1% peptone media, YEP did not affect the H2O2 concentrations that the isolates could survive in comparison with YES media, without aflatoxin production. It is interesting to note that the commercial biocontrol isolates, AF36 (−), and Aflaguard (−), survived at higher levels of stress than other atoxigenic isolates, suggesting that this testing method could potentially be of use in the selection of biocontrol isolates. Further studies will be needed to investigate the mechanisms behind the variability among isolates with regard to their degree of oxidative stress

  17. 75 FR 9596 - Notice of Filing of a Pesticide Petition for Residues of a Aspergillus flavus AF36 on Corn Food...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-03

    ... potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to... enforcement of environmental laws, regulations, and policies. To help address potential environmental justice... residues of the antifungal ] agent, Aspergillus flavus AF36, in or on corn food and feed commodities....

  18. The major volatile compound 2-phenylethanol from the biocontrol yeast Pichia anomala inhibits growth and expression of aflatoxin biosynthetic genes of Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus is a globally distributed fungus and an important food contaminant because it produces the most potent natural carcinogenic compound known as aflatoxin (AF) B1. The major volatile from a yeast strain, Pichia anomala WRL-076 was identified by SPEM-GC/MS analysis to be 2-phenylethan...

  19. Effect of inoculum concentrations of Aspergillus flavus and A. parasiticus on aflatoxin accumulation and kernel infection in resistant and susceptible maize hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over a three year period, we compared aflatoxin accumulation and kernel infection in maize hybrids inoculated with six inoculum concentrations of Aspergillus flavus isolate NRRL 3357 or A. parasiticus isolate NRRL 6111 which is a norsolorinic acid producer. Aflatoxin resistant and susceptible mai...

  20. The two genome sequence release and blast server construction for aflatoxin-producing L and S strains Aspergillus parasiticus and A. flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are toxic and carcinogenic secondary metabolites. These compounds, produced by Aspergillus flavus and A. parasiticus, contaminate pre-harvest agricultural crops in the field and post-harvest grains during storage. In order to reduce and eliminate aflatoxin contamination of food and feed...

  1. Identification and quantification of a toxigenic and non-toxigenic Aspergillus flavus strain in contaminated maize using quantitative real-time PCR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins, which are produced by the fungus Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin. Plant resistance and biological control using non-toxin producing strains are considered effective st...

  2. Transcriptome analysis of Aspergillus flavus reveals isolate specific gene profiles in the response to oxidative stresses and carbon sources in vitro

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxin contamination of peanut and maize is exacerbated by drought stress. Reactive oxygen species (ROS) are produced in host plants during drought/heat stress, and are hypothesized to stimulate aflatoxin production. In order to better understand why Aspergillus flavus produces aflatoxin and the ...

  3. An Aspergillus flavus secondary metabolic gene cluster containing a hybrid PKS-NRPS is necessary for synthesis of the 2-pyridones, leporins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genome of the filamentous fungus, Aspergillus flavus, has been shown to harbor as many as 55 putative secondary metabolic gene clusters including the one responsible for production of the toxic and carcinogenic, polyketide synthase (PKS)-derived family of secondary metabolites termed aflatoxins....

  4. A public platform for the verification of the phenotypic effect of candidate genes for resistance to aflatoxin accumulation and Aspergillus flavus infection in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A public candidate gene testing pipeline for resistance to aflatoxin accumulation or Aspergillus flavus infection in maize is presented here. The pipeline consists of steps for identifying, testing, and verifying the association of any maize gene sequence with resistance under field conditions. Reso...

  5. Could biorational insecticides be used in the management of aflatoxigenic Aspergillus parasiticus and its insect vectors in stored wheat?

    PubMed

    Khan, Tiyyabah; Shahid, Ahmad Ali; Khan, Hafiz Azhar Ali

    2016-01-01

    Insect pests in stored wheat cause significant losses and play an important role in the dispersal of viable fungal spores of various species including aflatoxin producing Aspergillus parasiticus. The problem of insecticide resistance in stored insects and environmental hazards associated with fumigants and conventional grain protectants underscore the need to explore reduced risk insecticides to control stored insects with the ultimate effect on aflatoxin production. The purpose of this study was to investigate the insecticidal potential of four biorational insecticides: spinosad, thiamethoxam, imidacloprid and indoxacarb, on wheat grains artificially infested with Rhyzopertha dominica/Sitophilus oryzae and/or A. parasiticus spores, and the subsequent effect on aflatoxin production. Spinosad and thiamethoxam were the most effective insecticides against R. dominica compared to S. oryzae followed by imidacloprid. Spinosad applied at 0.25-1 ppm and thiamethoxam at 2 and 4 ppm concentrations resulted in complete mortality of R. dominica. However, indoxacarb was more toxic against S. oryzae compared to R. dominica. Wheat grains inoculated with R. dominica/S. oryzae +spores elicited higher aflatoxin levels than wheat grains inoculated with or without insecticide+spores. In all the treatment combinations containing insects, aflatoxin production was dependent on insects' survival rate. In addition, thiamethoxam and imidacloprid had also a significant direct effect on reducing aflatoxin production. Aflatoxin levels were lower in the treatment combinations with any concentration of thiamethoxam/imidacloprid+spores as compared to wheat grains inoculated with spores only. Correlation analyses revealed highly significant and positive association between moisture contents/insect survival rate and production of aflatoxin levels, and insect survival rate and moisture contents of the wheat grains. In conclusion, the results of the present study provide baseline data on the use of

  6. Could biorational insecticides be used in the management of aflatoxigenic Aspergillus parasiticus and its insect vectors in stored wheat?

    PubMed Central

    Khan, Tiyyabah; Shahid, Ahmad Ali

    2016-01-01

    Insect pests in stored wheat cause significant losses and play an important role in the dispersal of viable fungal spores of various species including aflatoxin producing Aspergillus parasiticus. The problem of insecticide resistance in stored insects and environmental hazards associated with fumigants and conventional grain protectants underscore the need to explore reduced risk insecticides to control stored insects with the ultimate effect on aflatoxin production. The purpose of this study was to investigate the insecticidal potential of four biorational insecticides: spinosad, thiamethoxam, imidacloprid and indoxacarb, on wheat grains artificially infested with Rhyzopertha dominica/Sitophilus oryzae and/or A. parasiticus spores, and the subsequent effect on aflatoxin production. Spinosad and thiamethoxam were the most effective insecticides against R. dominica compared to S. oryzae followed by imidacloprid. Spinosad applied at 0.25–1 ppm and thiamethoxam at 2 and 4 ppm concentrations resulted in complete mortality of R. dominica. However, indoxacarb was more toxic against S. oryzae compared to R. dominica. Wheat grains inoculated with R. dominica/S. oryzae +spores elicited higher aflatoxin levels than wheat grains inoculated with or without insecticide+spores. In all the treatment combinations containing insects, aflatoxin production was dependent on insects’ survival rate. In addition, thiamethoxam and imidacloprid had also a significant direct effect on reducing aflatoxin production. Aflatoxin levels were lower in the treatment combinations with any concentration of thiamethoxam/imidacloprid+spores as compared to wheat grains inoculated with spores only. Correlation analyses revealed highly significant and positive association between moisture contents/insect survival rate and production of aflatoxin levels, and insect survival rate and moisture contents of the wheat grains. In conclusion, the results of the present study provide baseline data on the use

  7. Nanocapsular dispersion of cinnamaldehyde for enhanced inhibitory activity against aflatoxin production by Aspergillus flavus.

    PubMed

    Li, Hongbo; Shen, Qingshan; Zhou, Wei; Mo, Haizhen; Pan, Daodong; Hu, Liangbin

    2015-01-01

    Cinnamaldehyde (CA) is marginally soluble in water, making it challenging to evenly disperse it in foods, and resulting in lowered anti-A. flavus efficacy. In the present study, nano-dispersed CA (nano-CA) was prepared to increase its aqueous solubility. Free and nano-dispersed CA were compared in terms of their inhibitory activity against fungal growth and aflatoxin production of A. flavus both in Sabouraud Dextrose (SD) culture and in peanut butter. Our results indicated that free CA inhibited the mycelia growth and aflatoxin production of A. flavus with a minimal inhibitory concentration (MIC) value of 1.0 mM, but promoted the aflatoxin production at some concentrations lower than the MIC. Nano-CA had a lower MIC value of 0.8 mM against A. flavus, and also showed improved activity against aflatoxin production without the promotion at lower dose. The solidity of peanut butter had an adverse impact on the antifungal activity of free CA, whereas nano-dispersed CA showed more than 2-fold improved activity against the growth of A. flavus. Free CA still promoted AFB1 production at the concentration of 0.25 mM, whereas nano-CA showed more efficient inhibition of AFB1 production in the butter. PMID:25853318

  8. PR10 expression in maize and its effect on host resistance against Aspergillus flavus infection and aflatoxin production.

    PubMed

    Chen, Zhi-Yuan; Brown, Robert L; Damann, Kenneth E; Cleveland, Thomas E

    2010-01-01

    Maize (Zea mays L.) is a major crop susceptible to Aspergillus flavus infection and subsequent contamination with aflatoxins, the potent carcinogenic secondary metabolites of the fungus. Protein profiles of maize genotypes resistant and susceptible to A. flavus infection and/or aflatoxin contamination have been compared, and several resistance-associated proteins have been found, including a pathogenesis-related protein 10 (PR10). In this study, RNA interference (RNAi) gene silencing technology was employed to further investigate the importance of PR10. An RNAi gene silencing vector was constructed and introduced into immature Hi II maize embryos through both bombardment and Agrobacterium infection procedures. PR10 expression was reduced by 65% to more than 99% in transgenic callus lines from bombardment. The RNAi-silenced callus lines also showed increased sensitivity to heat stress treatment. A similar reduction in PR10 transcript levels was observed in seedling leaf and root tissues developed from transgenic kernels. When inoculated with A. flavus, RNAi-silenced mature kernels produced from Agrobacterium-mediated transformation showed a significant increase in fungal colonization and aflatoxin production in 10 and six, respectively, of 11 RNAi lines compared with the non-silenced control. Further proteomic analysis of RNAi-silenced kernels revealed a significant reduction in PR10 production in eight of 11 RNAi lines that showed positive for transformation. A significant negative correlation between PR10 expression at either transcript or protein level and kernel aflatoxin production was observed. The results indicate a major role for PR10 expression in maize aflatoxin resistance. PMID:20078777

  9. Antifungal activity evaluation of Mexican oregano (Lippia berlandieri Schauer) essential oil on the growth of Aspergillus flavus by gaseous contact.

    PubMed

    Gómez-Sánchez, Aída; Palou, Enrique; López-Malo, Aurelio

    2011-12-01

    The antifungal activity of Mexican oregano (Lippia berlandieri Schauer) essential oil by gaseous contact on the growth of Aspergillus flavus at selected essential oil concentrations (14.7, 29.4, 58.8, or 117.6 μl of essential oil per liter of air) and temperatures (25, 30, or 35°C) was evaluated in potato dextrose agar formulated at water activity of 0.98 and pH 4.0. Mold growth curves were adequately fitted (0.984 < R(2) < 0.999) by the modified Gompertz model. The effect of the independent variables (concentration of essential oil and temperature) on the estimated model parameters (reciprocal of growth rate [1/ν(m)] and lag time [λ]) were evaluated through polynomial equations. Both ν(m) and λ were significantly (P < 0.05) affected by the independent variables; ν(m) decreased and λ increased as essential oil concentration increased and temperature decreased, which suggests that Mexican oregano essential oil retards or inhibits mold germination stage. Further, minimum fungistatic and fungicide essential oil concentrations at 30 and 35°C were determined. Mexican oregano essential oil applied in gas phase exerts important antifungal activity on the growth of A. flavus, suggesting its potential to inhibit other food spoilage molds. PMID:22186064

  10. In silico analysis of β-mannanases and β-mannosidase from Aspergillus flavus and Trichoderma virens UKM1

    NASA Astrophysics Data System (ADS)

    Yee, Chai Sin; Murad, Abdul Munir Abdul; Bakar, Farah Diba Abu

    2013-11-01

    A gene encoding an endo-β-1,4-mannanase from Trichoderma virens UKM1 (manTV) and Aspergillus flavus UKM1 (manAF) was analysed with bioinformatic tools. In addition, A. flavus NRRL 3357 genome database was screened for a β-mannosidase gene and analysed (mndA-AF). These three genes were analysed to understand their gene properties. manTV and manAF both consists of 1,332-bp and 1,386-bp nucleotides encoding 443 and 461 amino acid residues, respectively. Both the endo-β-1,4-mannanases belong to the glycosyl hydrolase family 5 and contain a carbohydrate-binding module family 1 (CBM1). On the other hand, mndA-AF which is a 2,745-bp gene encodes a protein sequence of 914 amino acid residues. This β-mannosidase belongs to the glycosyl hydrolase family 2. Predicted molecular weight of manTV, manAF and mndA-AF are 47.74 kDa, 49.71 kDa and 103 kDa, respectively. All three predicted protein sequences possessed signal peptide sequence and are highly conserved among other fungal β-mannanases and β-mannosidases.

  11. The inhibitory effect of Bacillus megaterium on aflatoxin and cyclopiazonic acid biosynthetic pathway gene expression in Aspergillus flavus.

    PubMed

    Kong, Qing; Chi, Chen; Yu, Jiujiang; Shan, Shihua; Li, Qiyu; Li, Qianting; Guan, Bin; Nierman, William C; Bennett, Joan W

    2014-06-01

    Aspergillus flavus is one of the major moulds that colonize peanut in the field and during storage. The impact to human and animal health, and to the economy in agriculture and commerce, is significant since this mold produces the most potent known natural toxins, aflatoxins, which are carcinogenic, mutagenic, immunosuppressive, and teratogenic. A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its effect in inhibiting aflatoxin formation in A. flavus through down-regulating aflatoxin pathway gene expression as demonstrated by gene chip analysis. Aflatoxin accumulation in potato dextrose broth liquid medium and liquid minimal medium was almost totally (more than 98 %) inhibited by co-cultivation with B. megaterium. Growth was also reduced. Using expression studies, we identified the fungal genes down-regulated by co-cultivation with B. megaterium across the entire fungal genome and specifically within the aflatoxin pathway gene cluster (aflF, aflT, aflS, aflJ, aflL, aflX). Modulating the expression of these genes could be used for controlling aflatoxin contamination in crops such as corn, cotton, and peanut. Importantly, the expression of the regulatory gene aflS was significantly down-regulated during co-cultivation. We present a model showing a hypothesis of the regulatory mechanism of aflatoxin production suppression by AflS and AflR through B. megaterium co-cultivation.

  12. Cinnamaldehyde inhibits fungal growth and aflatoxin B1 biosynthesis by modulating the oxidative stress response of Aspergillus flavus.

    PubMed

    Sun, Qi; Shang, Bo; Wang, Ling; Lu, Zhisong; Liu, Yang

    2016-02-01

    Cinnamaldehyde (CIN) is a promising natural preservative and generally recognized as safe for commodities as well as consumers. In this work, the antifungal effects of CIN on Aspergillus flavus were evaluated both in solid and in liquid culture conditions. Our results indicated that CIN effectively inhibited radial growth, spore production, mycelium formation, and aflatoxin B1 biosynthesis by A. flavus in a dose-dependent manner. At the concentration of 104 mg L(-1), CIN exposure was able to completely inhibit fungal growth as well as aflatoxin B1 production. Furthermore, the inhibitory activities of CIN were closely connected with the treatment period and the tested fungal species. Compared with the control strains, CIN dose dependently changed the morphology and ultrastructure of mycelium in different degree. Especially, the reduction of hydrogen peroxide was considered to follow the destruction of mitochondrial. Meanwhile, CIN significantly cut the levels of lipid peroxidation and reduced glutathione. The activity of total superoxide dismutase was significantly inhibited after CIN treatment at the end of incubation, whereas the activities of catalase and glutathione peroxidase were opposite. These results indicated that the inhibitory effect of CIN could attribute to oxidative stress alleviation possibly induced by modifications of cellular structure as well as redox status. PMID:26585445

  13. Utilization of waste fruit-peels to inhibit aflatoxins synthesis by Aspergillus flavus: a biotreatment of rice for safer storage.

    PubMed

    Naseer, R; Sultana, Bushra; Khan, M Z; Naseer, D; Nigam, Poonam

    2014-11-01

    Antifungal activity in lemon and pomegranate peels was considerable against Aspergillus flavus, higher in pomegranate (DIZ 37mm; MIC 135μg/mL). Powdered peels (5, 10, 20% w/w) were mixed in inoculated rice. The inhibitory effect on fungal-growth and production of aflatoxins by A. flavus was investigated at storage conditions - temperature (25, 30°C) and moisture (18%, 21%) for 9months. The maximum total aflatoxins accumulated at 30°C, 21% moisture and at 25°C, 18% moisture were 265.09 and 163.45ng/g, respectively in control. Addition of pomegranate-peels inhibited aflatoxins production to 100% during four month-storage of rice at 25°C and 18% moisture, while lemon-peels showed similar inhibitory effect for 3months at same conditions. However a linear correlation was observed in aflatoxins level with temperature and moisture. Studies showed that both fruit-wastes are potent preventer of aflatoxin production in rice, useful for a safer and longer storage of rice.

  14. Transcriptional profiles uncover Aspergillus flavus-induced resistance in maize kernels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and during storage, and also a concern in many other crops, such as peanuts, cottonseed, tree nuts, and rice. Although a number of resistant maize lines with low aflatoxin c...

  15. Transcriptional profiles uncover Aspergillus flavus-induced resistance in maize kernels.

    PubMed

    Luo, Meng; Brown, Robert L; Chen, Zhi-Yuan; Menkir, Abebe; Yu, Jiujiang; Bhatnagar, Deepak

    2011-07-01

    Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and through storage. Previous studies have highlighted the constitutive production of proteins involved in maize kernel resistance against A. flavus' infection. However, little is known about induced resistance nor about defense gene expression and regulation in kernels. In this study, maize oligonucleotide arrays and a pair of closely-related maize lines varying in aflatoxin accumulation were used to reveal the gene expression network in imbibed mature kernels in response to A. flavus' challenge. Inoculated kernels were incubated 72 h via the laboratory-based Kernel Screening Assay (KSA), which highlights kernel responses to fungal challenge. Gene expression profiling detected 6955 genes in resistant and 6565 genes in susceptible controls; 214 genes induced in resistant and 2159 genes induced in susceptible inoculated kernels. Defense related and regulation related genes were identified in both treatments. Comparisons between the resistant and susceptible lines indicate differences in the gene expression network which may enhance our understanding of the maize-A. flavus interaction. PMID:22069739

  16. Inhibition of the Aspergillus flavus Growth and Aflatoxin B1 Contamination on Pistachio Nut by Fengycin and Surfactin-Producing Bacillus subtilis UTBSP1

    PubMed Central

    Farzaneh, Mohsen; Shi, Zhi-Qi; Ahmadzadeh, Masoud; Hu, Liang-Bin; Ghassempour, Alireza

    2016-01-01

    In this study, the treatment of pistachio nuts by Bacillus subtilis UTBSP1, a promising isolate to degrade aflatoxin B1 (AFB1), caused to reduce the growth of Aspergillus flavus R5 and AFB1 content on pistachio nuts. Fluorescence probes revealed that the cell free supernatant fluid from UTBSP1 affects spore viability considerably. Using high-performance liquid chromatographic (HPLC) method, 10 fractions were separated and collected from methanol extract of cell free supernatant fluid. Two fractions showed inhibition zones against A. flavus. Mass spectrometric analysis of the both antifungal fractions revealed a high similarity between these anti-A. flavus compounds and cyclic-lipopeptides of surfactin, and fengycin families. Coproduction of surfactin and fengycin acted in a synergistic manner and consequently caused a strong antifungal activity against A. flavus R5. There was a positive significant correlation between the reduction of A. flavus growth and the reduction of AFB1 contamination on pistachio nut by UTBSP1. The results indicated that fengycin and surfactin-producing B. subtilis UTBSP1 can potentially reduce A. flavus growth and AFB1 content in pistachio nut. PMID:27298596

  17. Inhibition of the Aspergillus flavus Growth and Aflatoxin B1 Contamination on Pistachio Nut by Fengycin and Surfactin-Producing Bacillus subtilis UTBSP1.

    PubMed

    Farzaneh, Mohsen; Shi, Zhi-Qi; Ahmadzadeh, Masoud; Hu, Liang-Bin; Ghassempour, Alireza

    2016-06-01

    In this study, the treatment of pistachio nuts by Bacillus subtilis UTBSP1, a promising isolate to degrade aflatoxin B1 (AFB1), caused to reduce the growth of Aspergillus flavus R5 and AFB1 content on pistachio nuts. Fluorescence probes revealed that the cell free supernatant fluid from UTBSP1 affects spore viability considerably. Using high-performance liquid chromatographic (HPLC) method, 10 fractions were separated and collected from methanol extract of cell free supernatant fluid. Two fractions showed inhibition zones against A. flavus. Mass spectrometric analysis of the both antifungal fractions revealed a high similarity between these anti-A. flavus compounds and cyclic-lipopeptides of surfactin, and fengycin families. Coproduction of surfactin and fengycin acted in a synergistic manner and consequently caused a strong antifungal activity against A. flavus R5. There was a positive significant correlation between the reduction of A. flavus growth and the reduction of AFB1 contamination on pistachio nut by UTBSP1. The results indicated that fengycin and surfactin-producing B. subtilis UTBSP1 can potentially reduce A. flavus growth and AFB1 content in pistachio nut. PMID:27298596

  18. Mycotoxin production and predictive modelling kinetics on the growth of Aspergillus flavus and Aspergillus parasiticus isolates in whole black peppercorns (Piper nigrum L).

    PubMed

    Yogendrarajah, Pratheeba; Vermeulen, An; Jacxsens, Liesbeth; Mavromichali, Evangelia; De Saeger, Sarah; De Meulenaer, Bruno; Devlieghere, Frank

    2016-07-01

    The growth and mycotoxin production of three Aspergillus flavus isolates and an Aspergillus parasiticus isolate were studied in whole black peppercorns (Piper nigrum L.) using a full factorial design with seven water activity (aw) (0.826-0.984) levels and three temperatures (22, 30 and 37°C). Growth rates and lag phases were estimated using linear regression. Diverse secondary models were assessed for their ability to describe the radial growth rate as a function of individual and combined effect of aw and temperature. Optimum radial growth rate ranged from 0.75±0.04 to 2.65±0.02mm/day for A. flavus and 1.77±0.10 to 2.50±0.10mm/day for A. parasiticus based on the Rosso cardinal estimations. Despite the growth failure of some isolates at marginal conditions, all the studied models showed good performance to predict the growth rates. Validation of the models was performed on independently derived data. The bias factors (0.73-1.03), accuracy factors (0.97-1.36) and root mean square error (0.050-0.278) show that the examined models are conservative predictors of the colony growth rate of both fungal species in black peppers. The Rosso cardinal model can be recommended to describe the individual aw effect while the extended Gibson model was the best model for describing the combined effect of aw and temperature on the growth rate of both fungal species in peppercorns. Temperature optimum ranged from 30 to 33°C, while aw optimum was 0.87-0.92 as estimated by multi-factorial cardinal model for both species. The estimated minimum temperature and aw for A. flavus and A. parasiticus for growth were 11-16°C and 0.73-0.76, respectively, hence, achieving these conditions should be considered during storage to prevent the growth of these mycotoxigenic fungal species in black peppercorns. Following the growth study, production of mycotoxins (aflatoxins B1, B2, G1, G2, sterigmatocystin and O-methyl sterigmatocystin (OMST)) was quantified using LC-MS/MS. Very small

  19. Mycotoxin production and predictive modelling kinetics on the growth of Aspergillus flavus and Aspergillus parasiticus isolates in whole black peppercorns (Piper nigrum L).

    PubMed

    Yogendrarajah, Pratheeba; Vermeulen, An; Jacxsens, Liesbeth; Mavromichali, Evangelia; De Saeger, Sarah; De Meulenaer, Bruno; Devlieghere, Frank

    2016-07-01

    The growth and mycotoxin production of three Aspergillus flavus isolates and an Aspergillus parasiticus isolate were studied in whole black peppercorns (Piper nigrum L.) using a full factorial design with seven water activity (aw) (0.826-0.984) levels and three temperatures (22, 30 and 37°C). Growth rates and lag phases were estimated using linear regression. Diverse secondary models were assessed for their ability to describe the radial growth rate as a function of individual and combined effect of aw and temperature. Optimum radial growth rate ranged from 0.75±0.04 to 2.65±0.02mm/day for A. flavus and 1.77±0.10 to 2.50±0.10mm/day for A. parasiticus based on the Rosso cardinal estimations. Despite the growth failure of some isolates at marginal conditions, all the studied models showed good performance to predict the growth rates. Validation of the models was performed on independently derived data. The bias factors (0.73-1.03), accuracy factors (0.97-1.36) and root mean square error (0.050-0.278) show that the examined models are conservative predictors of the colony growth rate of both fungal species in black peppers. The Rosso cardinal model can be recommended to describe the individual aw effect while the extended Gibson model was the best model for describing the combined effect of aw and temperature on the growth rate of both fungal species in peppercorns. Temperature optimum ranged from 30 to 33°C, while aw optimum was 0.87-0.92 as estimated by multi-factorial cardinal model for both species. The estimated minimum temperature and aw for A. flavus and A. parasiticus for growth were 11-16°C and 0.73-0.76, respectively, hence, achieving these conditions should be considered during storage to prevent the growth of these mycotoxigenic fungal species in black peppercorns. Following the growth study, production of mycotoxins (aflatoxins B1, B2, G1, G2, sterigmatocystin and O-methyl sterigmatocystin (OMST)) was quantified using LC-MS/MS. Very small

  20. Development of the dichlorvos-ammonia (DV-AM) method for the visual detection of aflatoxigenic fungi.

    PubMed

    Yabe, Kimiko; Hatabayashi, Hidemi; Ikehata, Akifumi; Zheng, Yazhi; Kushiro, Masayo

    2015-12-01

    Aflatoxins (AFs) are carcinogenic and toxic secondary metabolites produced mainly by Aspergillus flavus and Aspergillus parasiticus. To monitor and regulate the AF contamination of crops, a sensitive and precise detection method for these toxigenic fungi in environments is necessary. We herein developed a novel visual detection method, the dichlorvos-ammonia (DV-AM) method, for identifying AF-producing fungi using DV and AM vapor on agar culture plates, in which DV inhibits the esterase in AF biosynthesis, causing the accumulation of anthraquinone precursors (versiconal hemiacetal acetate and versiconol acetate) of AFs in mycelia on the agar plate, followed by a change in the color of the colonies from light yellow to brilliant purple-red by the AM vapor treatment. We also investigated the appropriate culture conditions to increase the color intensity. It should be noted that other species producing the same precursors of AFs such as Aspergillus nidulans and Aspergillus versicolor could be discriminated from the Aspergillus section Flavi based on the differences of their phenotypes. The DV-AM method was also useful for the isolation of nonaflatoxigenic fungi showing no color change, for screening microorganisms that inhibit the AF production by fungi, and for the characterization of the fungi infecting corn kernels. Thus, the DV-AM method can provide a highly sensitive and visible indicator for the detection of aflatoxigenic fungi.

  1. [Effect of alcoholic extracts of wild plants on the inhibition of growth of Aspergillus flavus, Aspergillus niger, Penicillium chrysogenum, Penicillium expansum, Fusarium moniliforme and Fusarium poae moulds].

    PubMed

    Tequida-Meneses, Martín; Cortez-Rocha, Mario; Rosas-Burgos, Ema Carina; López-Sandoval, Susana; Corrales-Maldonado, Consuelo

    2002-06-01

    Fungicidal activity of wild plants Larrea tridentata, Karwinskia humboldtiana, Ricinus communis, Eucalyptus globulus, Ambrosia ambrosioides, Nicotiana glauca, Ambrosia confertiflora, Datura discolor, Baccharis glutinosa, Proboscidea parviflora, Solanum rostratum, Jatropha cinerea, Salpianthus macrodonthus y Sarcostemma cynanchoides was evaluated against the moulds species Aspergillus flavus, Aspergillus niger, Penicillium chrysogenum, Penicillium expansum, Fusarium poae y Fusarium moniliforme moulds species. Alcoholic extracts 6% (w/v) were prepared using six grams of dried plant powders (leaves and stems) and alcohol (70% ethanol or 70% methanol). A spore suspension (1x10(6); ufc/ml) of each mould was prepared by adding saline solution (0.85%) and 0.1% tween 80. The extracts were mixed with Czapeck yeast agar (CYA) at 45-50 degrees C in 1:10 relation on Petri dishes. Triplicate Petri dishes of each treatment and for each mould were centrally inoculated and three Petri dishes were used without treatment as controls. The inoculated dishes and controls were incubated at 25 +/- 2 degrees C for eight days. The incubated dishes were examined each 48 h and after the colony diameter (radial growth) was measured. Two mould species were controlled by L. tridentata, B. glutinosa and P. parviflora. Extracts of L. tridentata in methanol or ethanol at 41.5-100% inhibited all six species of moulds.

  2. Biodiversity of Aspergillus species in some important agricultural products

    PubMed Central

    Perrone, G.; Susca, A.; Cozzi, G.; Ehrlich, K.; Varga, J.; Frisvad, J.C.; Meijer, M.; Noonim, P.; Mahakarnchanakul, W.; Samson, R.A.

    2007-01-01

    The genus Aspergillus is one of the most important filamentous fungal genera. Aspergillus species are used in the fermentation industry, but they are also responsible of various plant and food secondary rot, with the consequence of possible accumulation of mycotoxins. The aflatoxin producing A. flavus and A. parasiticus, and ochratoxinogenic A. niger, A. ochraceus and A. carbonarius species are frequently encountered in agricultural products. Studies on the biodiversity of toxigenic Aspergillus species is useful to clarify molecular, ecological and biochemical characteristics of the different species in relation to their different adaptation to environmental and geographical conditions, and to their potential toxigenicity. Here we analyzed the biodiversity of ochratoxin producing species occurring on two important crops: grapes and coffee, and the genetic diversity of A. flavus populations occurring in agricultural fields. Altogether nine different black Aspergillus species can be found on grapes which are often difficult to identify with classical methods. The polyphasic approach used in our studies led to the identification of three new species occurring on grapes: A. brasiliensis, A. ibericus, and A. uvarum. Similar studies on the Aspergillus species occurring on coffee beans have evidenced in the last five years that A. carbonarius is an important source of ochratoxin A in coffee. Four new species within the black aspergilli were also identified in coffee beans: A. sclerotioniger, A. lacticoffeatus, A. sclerotiicarbonarius, and A. aculeatinus. The genetic diversity within A. flavus populations has been widely studied in relation to their potential aflatoxigenicity and morphological variants L- and S-strains. Within A. flavus and other Aspergillus species capable of aflatoxin production, considerable diversity is found. We summarise the main recent achievements in the diversity of the aflatoxin gene cluster in A. flavus populations, A. parasiticus and the non

  3. Identification of Two Aflatrem Biosynthesis Gene Loci in Aspergillus flavus and Metabolic Engineering of Penicillium paxilli To Elucidate Their Function ▿

    PubMed Central

    Nicholson, Matthew J.; Koulman, Albert; Monahan, Brendon J.; Pritchard, Beth L.; Payne, Gary A.; Scott, Barry

    2009-01-01

    Aflatrem is a potent tremorgenic toxin produced by the soil fungus Aspergillus flavus, and a member of a structurally diverse group of fungal secondary metabolites known as indole-diterpenes. Gene clusters for indole-diterpene biosynthesis have recently been described in several species of filamentous fungi. A search of Aspergillus complete genome sequence data identified putative aflatrem gene clusters in the genomes of A. flavus and Aspergillus oryzae. In both species the genes for aflatrem biosynthesis cluster at two discrete loci; the first, ATM1, is telomere proximal on chromosome 5 and contains a cluster of three genes, atmG, atmC, and atmM, and the second, ATM2, is telomere distal on chromosome 7 and contains five genes, atmD, atmQ, atmB, atmA, and atmP. Reverse transcriptase PCR in A. flavus demonstrated that aflatrem biosynthesis transcript levels increased with the onset of aflatrem production. Transfer of atmP and atmQ into Penicillium paxilli paxP and paxQ deletion mutants, known to accumulate paxilline intermediates paspaline and 13-desoxypaxilline, respectively, showed that AtmP is a functional homolog of PaxP and that AtmQ utilizes 13-desoxypaxilline as a substrate to synthesize aflatrem pathway-specific intermediates, paspalicine and paspalinine. We propose a scheme for aflatrem biosynthesis in A. flavus based on these reconstitution experiments in P. paxilli and identification of putative intermediates in wild-type cultures of A. flavus. PMID:19801473

  4. Molecular variation analysis of Aspergillus flavus using polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer rDNA region

    PubMed Central

    Zarrin, Majid; Erfaninejad, Maryam

    2016-01-01

    Aspergillus flavus is the second most common disease-causing species of Aspergillus in humans. The fungus is frequently associated with life-threatening infections in immunocompromised hosts. The primary aim of the present study was to analyze the genetic variability among different isolates of A. flavus using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP). A total of 62 A. flavus isolates were tested in the study. Molecular variability was searched for by analysis of the PCR amplification of the internal transcribed spacer (ITS) regions of ribosomal DNA using restriction enzymes. PCR using primers for ITS1 and ITS4 resulted in a product of ~600 bp. Amplicons were subjected to digestion with restriction endonucleases EcoRI, HaeIII and TaqI. Digestion of the PCR products using these restriction enzymes produced different patterns of fragments among the isolates, with different sizes and numbers of fragments, revealing genetic variability. In conclusion, ITS-RFLP is a useful molecular tool in screening for nucleotide polymorphisms among A. flavus isolates. PMID:27588085

  5. VeA Is Associated with the Response to Oxidative Stress in the Aflatoxin Producer Aspergillus flavus

    PubMed Central

    Baidya, Sachin; Duran, Rocio M.; Lohmar, Jessica M.; Harris-Coward, Pamela Y.; Cary, Jeffrey W.; Hong, Sung-Yong; Roze, Ludmila V.; Linz, John E.

    2014-01-01

    Survival of fungal species depends on the ability of these organisms to respond to environmental stresses. Osmotic stress or high levels of reactive oxygen species (ROS) can cause stress in fungi resulting in growth inhibition. Both eukaryotic and prokaryotic cells have developed numerous mechanisms to counteract and survive the stress in the presence of ROS. In many fungi, the HOG signaling pathway is crucial for the oxidative stress response as well as for osmotic stress response. This study revealed that while the osmotic stress response is only slightly affected by the master regulator veA, this gene, also known to control morphological development and secondary metabolism in numerous fungal species, has a profound effect on the oxidative stress response in the aflatoxin-producing fungus Aspergillus flavus. We found that the expression of A. flavus homolog genes involved in the HOG signaling pathway is regulated by veA. Deletion of veA resulted in a reduction in transcription levels of oxidative stress response genes after exposure to hydrogen peroxide. Furthermore, analyses of the effect of VeA on the promoters of cat1 and trxB indicate that the presence of VeA alters DNA-protein complex formation. This is particularly notable in the cat1 promoter, where the absence of VeA results in abnormally stronger complex formation with reduced cat1 expression and more sensitivity to ROS in a veA deletion mutant, suggesting that VeA might prevent binding of negative transcription regulators to the cat1 promoter. Our study also revealed that veA positively influences the expression of the transcription factor gene atfB and that normal formation of DNA-protein complexes in the cat1 promoter is dependent on AtfB. PMID:24951443

  6. Control of Aflatoxin Production of Aspergillus flavus and Aspergillus parasiticus Using RNA Silencing Technology by Targeting aflD (nor-1) Gene

    PubMed Central

    Abdel-Hadi, Ahmed M.; Caley, Daniel P.; Carter, David R. F.; Magan, Naresh

    2011-01-01

    Aspergillus flavus and Aspergillus parasiticus are important pathogens of cotton, corn, peanuts and other oil-seed crops, producing toxins both in the field and during storage. We have designed three siRNA sequences (Nor-Ia, Nor-Ib, Nor-Ic) to target the mRNA sequence of the aflD gene to examine the potential for using RNA silencing technology to control aflatoxin production. Thus, the effect of siRNAs targeting of two key genes in the aflatoxin biosynthetic pathway, aflD (structural) and aflR (regulatory gene) and on aflatoxin B1 (AFB1), and aflatoxin G1 (AFG1) production was examined. The study showed that Nor-Ib gave a significant decrease in aflD mRNA, aflR mRNA abundance, and AFB1 production (98, 97 and 97% when compared to the controls) in A. flavus NRRL3357, respectively. Reduction in aflD and aflR mRNA abundance and AFB1 production increased with concentration of siRNA tested. There was a significant inhibition in aflD and AFB1 production by A. flavus EGP9 and AFG1 production by A. parasiticus NRRL 13005. However, there was no significant decrease in AFG1 production by A. parasiticus SSWT 2999. Changes in AFB1 production in relation to mRNA levels of aflD showed a good correlation (R = 0.88; P = 0.00001); changes in aflR mRNA level in relation to mRNA level of aflD also showed good correlation (R = 0.82; P = 0.0001). The correlations between changes in aflR and aflD gene expression suggests a strong relationship between these structural and regulatory genes, and that aflD could be used as a target gene to develop efficient means for aflatoxin control using RNA silencing technology. PMID:22069731

  7. Transcriptional Profiles Uncover Aspergillus flavus-Induced Resistance in Maize Kernels

    PubMed Central

    Luo, Meng; Brown, Robert L.; Chen, Zhi-Yuan; Menkir, Abebe; Yu, Jiujiang; Bhatnagar, Deepak

    2011-01-01

    Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and through storage. Previous studies have highlighted the constitutive production of proteins involved in maize kernel resistance against A. flavus’ infection. However, little is known about induced resistance nor about defense gene expression and regulation in kernels. In this study, maize oligonucleotide arrays and a pair of closely-related maize lines varying in aflatoxin accumulation were used to reveal the gene expression network in imbibed mature kernels in response to A. flavus’ challenge. Inoculated kernels were incubated 72 h via the laboratory-based Kernel Screening Assay (KSA), which highlights kernel responses to fungal challenge. Gene expression profiling detected 6955 genes in resistant and 6565 genes in susceptible controls; 214 genes induced in resistant and 2159 genes induced in susceptible inoculated kernels. Defense related and regulation related genes were identified in both treatments. Comparisons between the resistant and susceptible lines indicate differences in the gene expression network which may enhance our understanding of the maize-A. flavus interaction. PMID:22069739

  8. Biodiversity of Aspergillus section Flavi in Europe in relation to the management of aflatoxin risk

    PubMed Central

    Perrone, Giancarlo; Gallo, Antonia; Logrieco, Antonio F.

    2014-01-01

    Aflatoxins and the producing fungi Aspergillus section Flavi are widely known as the most serious and dangerous mycotoxin issue in agricultural products. In Europe, before the outbreak of aflatoxins on maize (2003–2004) due to new climatic conditions, their contamination was confined to imported foods. Little information is available on molecular biodiversity and population structure of Aspergillus section Flavi in Europe. Preliminary reports evidenced the massive presence of Aspergillus flavus L -morphotype as the predominant species in maize field, no evidence of the highly toxigenic S-morphotype and of other aflatoxigenic species are reported. The risk of a shift in traditional occurrence areas for aflatoxins is expected in the world and in particular in South East of Europe due to the increasing average temperatures. Biological control of aflatoxin risk in the field by atoxigenic strains of A. flavus starts to be widely used in Africa and USA. Studies are necessary on the variation of aflatoxin production in populations of A. flavus to characterize stable atoxigenic A. flavus strains. The aim of present article is to give an overview on biodiversity and genetic variation of Aspergillus section Flavi in Europe in relation to the management of aflatoxins risk in the field. PMID:25101075

  9. Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium–Sulfur Battery

    PubMed Central

    Xu, Maowen; Jia, Min; Mao, Cuiping; Liu, Sangui; Bao, Shujuan; Jiang, Jian; Liu, Yang; Lu, Zhisong

    2016-01-01

    A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m2g−1 by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g−1, which is almost equal to the theoretical capacity of sulfur. The good performance may be ascribed to excellent electronic networks constructed by the high-surface-area carbon species. Moreover, the semi-closed architecture of derived carbons can effectively retard the polysulfides dissolution during charge/discharge, resulting in a capacity of 940 mAh g−1 after 120 charge/discharge cycles. PMID:26732547

  10. Construction and preliminary evaluation of an Aspergillus flavus reporter gene construct as a potential tool for screening aflatoxin resistance.

    PubMed

    Brown, Robert L; Brown-Jenco, Carmen S; Bhatnagar, Deepak; Payne, Gary A

    2003-10-01

    Effective preharvest strategies to eliminate aflatoxin accumulation in crops are not presently available. The molecular biology of aflatoxin biosynthesis has been extensively studied, and genetic and molecular tools such as reporter gene systems for the measurement of fungal growth have been developed. A reporter construct containing the Aspergillus flavus beta-tubulin gene promoter fused to Escherichia coli beta-glucuronidase (GUS) has been shown to be a reliable tool for the indirect measurement of fungal growth in maize kernels. Since cost-saving alternative methods for the direct measurement of aflatoxin levels are needed to facilitate more widespread field and laboratory screening of maize lines, a new reporter gene construct involving the promoter region of the omtA gene of the aflatoxin biosynthetic pathway was constructed and tested. Expression of GUS activity by this construct (omtA::GUS) was correlated with aflatoxin accumulation in culture. In the fungal transformant GAP26-1, which harbors this construct, aflatoxin production and GUS expression on sucrose-containing medium showed the same temporal pattern of toxin induction. Furthermore, GUS expression by GAP26-1 was shown to be associated with aflatoxin accumulation in maize kernels inoculated with this strain. Our results suggest that this and other reporter gene pathway promoter constructs may provide superior alternatives to direct aflatoxin quantification with respect to time, labor, and materials for the screening of maize lines for resistance to aflatoxin accumulation. PMID:14572235

  11. Identification of lipoxygenase (LOX) genes from legumes and their responses in wild type and cultivated peanut upon Aspergillus flavus infection

    PubMed Central

    Song, Hui; Wang, Pengfei; Li, Changsheng; Han, Suoyi; Lopez-Baltazar, Javier; Zhang, Xinyou; Wang, Xingjun

    2016-01-01

    Lipoxygenase (LOX) genes are widely distributed in plants and play crucial roles in resistance to biotic and abiotic stress. Although they have been characterized in various plants, little is known about the evolution of legume LOX genes. In this study, we identified 122 full-length LOX genes in Arachis duranensis, Arachis ipaënsis, Cajanus cajan, Cicer arietinum, Glycine max, Lotus japonicus and Medicago truncatula. In total, 64 orthologous and 36 paralogous genes were identified. The full-length, polycystin-1, lipoxygenase, alpha-toxin (PLAT) and lipoxygenase domain sequences from orthologous and paralogous genes exhibited a signature of purifying selection. However, purifying selection influenced orthologues more than paralogues, indicating greater functional conservation of orthologues than paralogues. Neutrality and effective number of codons plot results showed that natural selection primarily shapes codon usage, except for C. arietinum, L. japonicas and M. truncatula LOX genes. GCG, ACG, UCG, CGG and CCG codons exhibited low relative synonymous codon usage (RSCU) values, while CCA, GGA, GCU, CUU and GUU had high RSCU values, indicating that the latter codons are strongly preferred. LOX expression patterns differed significantly between wild-type peanut and cultivated peanut infected with Aspergillus flavus, which could explain the divergent disease resistance of wild progenitor and cultivars. PMID:27731413

  12. Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium-Sulfur Battery

    NASA Astrophysics Data System (ADS)

    Xu, Maowen; Jia, Min; Mao, Cuiping; Liu, Sangui; Bao, Shujuan; Jiang, Jian; Liu, Yang; Lu, Zhisong

    2016-01-01

    A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m2g-1 by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g-1, which is almost equal to the theoretical capacity of sulfur. The good performance may be ascribed to excellent electronic networks constructed by the high-surface-area carbon species. Moreover, the semi-closed architecture of derived carbons can effectively retard the polysulfides dissolution during charge/discharge, resulting in a capacity of 940 mAh g-1 after 120 charge/discharge cycles.

  13. Effect of Capsicum carotenoids on growth and aflatoxins production by Aspergillus flavus isolated from paprika and chilli.

    PubMed

    Santos, L; Kasper, R; Sardiñas, N; Marín, S; Sanchis, V; Ramos, A J

    2010-12-01

    The aim of this study was to determine the effect of a carotenoid mixture (Capsantal FS-30-NT), containing capsanthin and capsorubin, on growth and aflatoxins (AF) production of AF-producing Aspergillus flavus isolates. Each isolate, previously isolated from paprika and chilli, was inoculated on Czapek Yeast extract Agar (CYA) medium supplemented with different amounts of capsantal (0-1%) and incubated at 10, 15 and 25 °C during 21 days. Growth rates and lag phases were obtained, and AF production was determined at 7, 14 and 21 days. None of the isolates grew at 10 °C and one isolate (UdLTA 3.193) hardly grew at 15 °C. Capsantal addition had no effect over lag phases and growth rates at 15 °C. At 25 °C capsantal reduced growth rates and increased lag phases. However, the effect of capsantal on AF production was inconclusive, because it depended on temperature or time, and most of the times it was not significant. Low temperature has been a crucial factor in AF production, regardless of the capsantal concentration tested. Industrial storage temperature for paprika and chilli use to be approximately 10 °C, so if this temperature is maintained mould growth and AF production should be prevented.

  14. Growth of an Aspergillus flavus transformant expressing Escherichia coli beta-glucuronidase in maize kernels resistant to aflatoxin production.

    PubMed

    Brown, R L; Cleveland, T E; Payne, G A; Woloshuk, C P; White, D G

    1997-01-01

    Kernels of a maize inbred that demonstrated resistance to aflatoxin production in previous studies were inoculated with an Aspergillus flavus strain containing the Escherichia coli beta-D-glucuronidase reporter gene linked to a beta-tubulin gene promoter and assessed for both fungal growth and aflatoxin accumulation. Prior to inoculation, kernels were pin-wounded through the pericarp to the endosperm, pin-wounded in the embryo region, or left unwounded. After 7 days incubation with the fungus, beta-glucuronidase activity (fungal growth) in the kernels was quantified using a fluorogenic assay and aflatoxin B content of the same kernels was analyzed. Kernels of a susceptible inbred, similarly treated, served as controls. Results indicate a positive relationship between aflatoxin levels and the amount of fungal growth. However, resistant kernels wounded through the pericarp to the endosperm before inoculation supported an increase in aflatoxin B over levels observed in nonwounded kernels, without an increase in fungal growth. Wounding kernels of the resistant inbred through the embryo resulted in both the greatest fungal growth and the highest levels of aflatoxin B1 for this genotype. Maintenance of resistance to aflatoxin B1 in endosperm-wounded kernels may be due to the action of a mechanism which limits fungal access to the kernel embryo. PMID:10465048

  15. Construction and preliminary evaluation of an Aspergillus flavus reporter gene construct as a potential tool for screening aflatoxin resistance.

    PubMed

    Brown, Robert L; Brown-Jenco, Carmen S; Bhatnagar, Deepak; Payne, Gary A

    2003-10-01

    Effective preharvest strategies to eliminate aflatoxin accumulation in crops are not presently available. The molecular biology of aflatoxin biosynthesis has been extensively studied, and genetic and molecular tools such as reporter gene systems for the measurement of fungal growth have been developed. A reporter construct containing the Aspergillus flavus beta-tubulin gene promoter fused to Escherichia coli beta-glucuronidase (GUS) has been shown to be a reliable tool for the indirect measurement of fungal growth in maize kernels. Since cost-saving alternative methods for the direct measurement of aflatoxin levels are needed to facilitate more widespread field and laboratory screening of maize lines, a new reporter gene construct involving the promoter region of the omtA gene of the aflatoxin biosynthetic pathway was constructed and tested. Expression of GUS activity by this construct (omtA::GUS) was correlated with aflatoxin accumulation in culture. In the fungal transformant GAP26-1, which harbors this construct, aflatoxin production and GUS expression on sucrose-containing medium showed the same temporal pattern of toxin induction. Furthermore, GUS expression by GAP26-1 was shown to be associated with aflatoxin accumulation in maize kernels inoculated with this strain. Our results suggest that this and other reporter gene pathway promoter constructs may provide superior alternatives to direct aflatoxin quantification with respect to time, labor, and materials for the screening of maize lines for resistance to aflatoxin accumulation.

  16. Efficacy of a coating composed of chitosan from Mucor circinelloides and carvacrol to control Aspergillus flavus and the quality of cherry tomato fruits

    PubMed Central

    de Souza, Evandro L.; Sales, Camila V.; de Oliveira, Carlos E. V.; Lopes, Laênia A. A.; da Conceição, Maria L.; Berger, Lúcia R. R.; Stamford, Thayza C. M.

    2015-01-01

    Cherry tomato (Lycopersicon esculentum Mill) fruits are susceptible to contamination by Aspergillus flavus, which may cause the development of fruit rot and significant postharvest losses. Currently there are significant drawbacks for the use of synthetic fungicides to control pathogenic fungi in tomato fruits, and it has increased the interest in exploring new alternatives to control the occurrence of fungal infections in these fruits. This study evaluated the efficacy of chitosan (CHI) from Mucor circinelloides in combination with carvacrol (CAR) in inhibiting A. flavus in laboratory media and as a coating on cherry tomato fruits (25°C, 12 days and 12°C, 24 days). During a period of storage, the effect of coatings composed of CHI and CAR on autochthonous microflora, as well as on some quality characteristics of the fruits such as weight loss, color, firmness, soluble solids, and titratable acidity was evaluated. CHI and CAR displayed MIC valuesof 7.5 mg/mL and 10 μL/mL, respectively, against A. flavus. The combined application of CHI (7.5 or 3.75 mg/mL) and CAR (5 or 2.5 μL/mL) strongly inhibited the mycelial growth and spore germination of A. flavus. The coating composed of CHI (3.75 mg/mL) and CAR (2.5 or 1.25 μL/mL) inhibited the growth of A. flavus in artificially contaminated fruits, as well as the native fungal microflora of the fruits stored at room or low temperature. The application of the tested coatings preserved the quality of cherry tomato fruits as measured by some physicochemical attributes. From this, composite coatings containing CHI and CAR offer a promising alternative to control postharvest infection caused by A. flavus or native fungal microflora in fresh cherry tomato fruits without negatively affecting their quality over storage. PMID:26257717

  17. Efficacy of a coating composed of chitosan from Mucor circinelloides and carvacrol to control Aspergillus flavus and the quality of cherry tomato fruits.

    PubMed

    de Souza, Evandro L; Sales, Camila V; de Oliveira, Carlos E V; Lopes, Laênia A A; da Conceição, Maria L; Berger, Lúcia R R; Stamford, Thayza C M

    2015-01-01

    Cherry tomato (Lycopersicon esculentum Mill) fruits are susceptible to contamination by Aspergillus flavus, which may cause the development of fruit rot and significant postharvest losses. Currently there are significant drawbacks for the use of synthetic fungicides to control pathogenic fungi in tomato fruits, and it has increased the interest in exploring new alternatives to control the occurrence of fungal infections in these fruits. This study evaluated the efficacy of chitosan (CHI) from Mucor circinelloides in combination with carvacrol (CAR) in inhibiting A. flavus in laboratory media and as a coating on cherry tomato fruits (25°C, 12 days and 12°C, 24 days). During a period of storage, the effect of coatings composed of CHI and CAR on autochthonous microflora, as well as on some quality characteristics of the fruits such as weight loss, color, firmness, soluble solids, and titratable acidity was evaluated. CHI and CAR displayed MIC valuesof 7.5 mg/mL and 10 μL/mL, respectively, against A. flavus. The combined application of CHI (7.5 or 3.75 mg/mL) and CAR (5 or 2.5 μL/mL) strongly inhibited the mycelial growth and spore germination of A. flavus. The coating composed of CHI (3.75 mg/mL) and CAR (2.5 or 1.25 μL/mL) inhibited the growth of A. flavus in artificially contaminated fruits, as well as the native fungal microflora of the fruits stored at room or low temperature. The application of the tested coatings preserved the quality of cherry tomato fruits as measured by some physicochemical attributes. From this, composite coatings containing CHI and CAR offer a promising alternative to control postharvest infection caused by A. flavus or native fungal microflora in fresh cherry tomato fruits without negatively affecting their quality over storage. PMID:26257717

  18. Inhibition of growth and mycotoxin production of Aspergillus flavus and Aspergillus parasiticus by extracts of Agave species.

    PubMed

    Sánchez, Eduardo; Heredia, Norma; García, Santos

    2005-02-15

    In this work, the effect of ethanolic, methanolic and aqueous extracts of Agave asperrima and Agave striata on growth and production of aflatoxin (in A&M medium) and cyclopiazonic acid (CPA; in Czpaek-Dox medium) and on growth in corn under storage conditions was determined. Aspergillus strains were inoculated (10(6) conidia per ml of medium or per 6 g of corn), then plant extracts were added and incubated without shaking at 28 degrees C for 8 days (for aflatoxin-producing analysis) or for 12 days (for CPA-producing analysis). Aflatoxin was assayed by HPLC and cyclopiazonic acid by absorbance at 580 nm using the Erlich reagent. The extracts that most effectively inhibited growth were those from the flowers of both plants. These exhibited an MIC from 0.5 to 2 mg/ml in culture media. Extracts from scape showed an MIC from 15 to 30 mg/ml in culture media. The MIC of the flower extracts was higher (>30 mg/g) when examined in corn. However, concentrations lower than the MIC drastically inhibited production of aflatoxins in culture medium or in corn. Half of the MIC inhibited 99% of the production of aflatoxins and 85% of cyclopiazonic acid.

  19. Correlation and classification of single kernel fluorescence hyperspectral data with aflatoxin concentration in corn kernels inoculated with Aspergillus flavus spores.

    PubMed

    Yao, H; Hruska, Z; Kincaid, R; Brown, R; Cleveland, T; Bhatnagar, D

    2010-05-01

    The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillus flavus and aflatoxin contamination levels within the kernels. Aflatoxin contamination in corn has been a long-standing problem plaguing the grain industry with potentially devastating consequences to corn growers. In this study, aflatoxin-contaminated corn kernels were produced through artificial inoculation of corn ears in the field with toxigenic A. flavus spores. The kernel fluorescence emission data were taken with a fluorescence hyperspectral imaging system when corn kernels were excited with ultraviolet light. Raw fluorescence image data were preprocessed and regions of interest in each image were created for all kernels. The regions of interest were used to extract spectral signatures and statistical information. The aflatoxin contamination level of single corn kernels was then chemically measured using affinity column chromatography. A fluorescence peak shift phenomenon was noted among different groups of kernels with different aflatoxin contamination levels. The fluorescence peak shift was found to move more toward the longer wavelength in the blue region for the highly contaminated kernels and toward the shorter wavelengths for the clean kernels. Highly contaminated kernels were also found to have a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also noted that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green regions. The correlation coefficients of determination, r(2), was 0.72 for the multiple linear regression model. The multivariate analysis of variance found that the fluorescence means of four aflatoxin groups, <1, 1-20, 20-100, and >or=100 ng g(-1) (parts per billion), were significantly different from each other at the 0.01 level of alpha. Classification accuracy under a two-class schema ranged from 0.84 to

  20. Effect of temperature and water activity on gene expression and aflatoxin biosynthesis in Aspergillus flavus on almond medium.

    PubMed

    Gallo, Antonia; Solfrizzo, Michele; Epifani, Filomena; Panzarini, Giuseppe; Perrone, Giancarlo

    2016-01-18

    Almonds are among the commodities at risk of aflatoxin contamination by Aspergillus flavus. Temperature and water activity are the two key determinants in pre and post-harvest environments influencing both the rate of fungal spoilage and aflatoxin production. Varying the combination of these parameters can completely inhibit or fully activate the biosynthesis of aflatoxin, so it is fundamental to know which combinations can control or be conducive to aflatoxin contamination. Little information is available about the influence of these parameters on aflatoxin production on almonds. The objective of this study was to determine the influence of different combinations of temperature (20 °C, 28 °C, and 37 °C) and water activity (0.90, 0.93, 0.96, 0.99 aw) on growth, aflatoxin B1 (AFB1) production and expression of the two regulatory genes, aflR and aflS, and two structural genes, aflD and aflO, of the aflatoxin biosynthetic cluster in A. flavus grown on an almond medium solidified with agar. Maximum accumulation of fungal biomass and AFB1 production was obtained at 28 °C and 0.96 aw; no fungal growth and AFB1 production were observed at 20 °C at the driest tested conditions (0.90 and 0.93 aw). At 20° and 37 °C AFB1 production was 70-90% lower or completely suppressed, depending on aw. Reverse transcriptase quantitative PCR showed that the two regulatory genes (aflR and aflS) were highly expressed at maximum (28 °C) and minimum (20 °C and 37 °C) AFB1 production. Conversely the two structural genes (aflD and aflO) were highly expressed only at maximum AFB1 production (28 °C and 0.96-0.99 aw). It seems that temperature acts as a key factor influencing aflatoxin production which is strictly correlated to the induction of expression of structural biosynthesis genes (aflD and aflO), but not to that of aflatoxin regulatory genes (aflR and aflS), whose functional products are most likely subordinated to other regulatory processes acting at post-translational level

  1. Effect of temperature and water activity on gene expression and aflatoxin biosynthesis in Aspergillus flavus on almond medium.

    PubMed

    Gallo, Antonia; Solfrizzo, Michele; Epifani, Filomena; Panzarini, Giuseppe; Perrone, Giancarlo

    2016-01-18

    Almonds are among the commodities at risk of aflatoxin contamination by Aspergillus flavus. Temperature and water activity are the two key determinants in pre and post-harvest environments influencing both the rate of fungal spoilage and aflatoxin production. Varying the combination of these parameters can completely inhibit or fully activate the biosynthesis of aflatoxin, so it is fundamental to know which combinations can control or be conducive to aflatoxin contamination. Little information is available about the influence of these parameters on aflatoxin production on almonds. The objective of this study was to determine the influence of different combinations of temperature (20 °C, 28 °C, and 37 °C) and water activity (0.90, 0.93, 0.96, 0.99 aw) on growth, aflatoxin B1 (AFB1) production and expression of the two regulatory genes, aflR and aflS, and two structural genes, aflD and aflO, of the aflatoxin biosynthetic cluster in A. flavus grown on an almond medium solidified with agar. Maximum accumulation of fungal biomass and AFB1 production was obtained at 28 °C and 0.96 aw; no fungal growth and AFB1 production were observed at 20 °C at the driest tested conditions (0.90 and 0.93 aw). At 20° and 37 °C AFB1 production was 70-90% lower or completely suppressed, depending on aw. Reverse transcriptase quantitative PCR showed that the two regulatory genes (aflR and aflS) were highly expressed at maximum (28 °C) and minimum (20 °C and 37 °C) AFB1 production. Conversely the two structural genes (aflD and aflO) were highly expressed only at maximum AFB1 production (28 °C and 0.96-0.99 aw). It seems that temperature acts as a key factor influencing aflatoxin production which is strictly correlated to the induction of expression of structural biosynthesis genes (aflD and aflO), but not to that of aflatoxin regulatory genes (aflR and aflS), whose functional products are most likely subordinated to other regulatory processes acting at post-translational level

  2. Biotechnological advances for combating Aspergillus flavus and aflatoxin contamination in crops.

    PubMed

    Bhatnagar-Mathur, Pooja; Sunkara, Sowmini; Bhatnagar-Panwar, Madhurima; Waliyar, Farid; Sharma, Kiran Kumar

    2015-05-01

    Aflatoxins are toxic, carcinogenic, mutagenic, teratogenic and immunosuppressive byproducts of Aspergillus spp. that contaminate a wide range of crops such as maize, peanut, and cotton. Aflatoxin not only affects crop production but renders the produce unfit for consumption and harmful to human and livestock health, with stringent threshold limits of acceptability. In many crops, breeding for resistance is not a reliable option because of the limited availability of genotypes with durable resistance to Aspergillus. Understanding the fungal/crop/environment interactions involved in aflatoxin contamination is therefore essential in designing measures for its prevention and control. For a sustainable solution to aflatoxin contamination, research must be focused on identifying and improving knowledge of host-plant resistance factors to aflatoxin accumulation. Current advances in genetic transformation, proteomics, RNAi technology, and marker-assisted selection offer great potential in minimizing pre-harvest aflatoxin contamination in cultivated crop species. Moreover, developing effective phenotyping strategies for transgenic as well as precision breeding of resistance genes into commercial varieties is critical. While appropriate storage practices can generally minimize post-harvest aflatoxin contamination in crops, the use of biotechnology to interrupt the probability of pre-harvest infection and contamination has the potential to provide sustainable solution. PMID:25804815

  3. Genome-Wide Transcriptome Analysis of Cotton (Gossypium hirsutum L.) Identifies Candidate Gene Signatures in Response to Aflatoxin Producing Fungus Aspergillus flavus

    PubMed Central

    Bedre, Renesh; Rajasekaran, Kanniah; Mangu, Venkata Ramanarao; Sanchez Timm, Luis Eduardo; Bhatnagar, Deepak; Baisakh, Niranjan

    2015-01-01

    Aflatoxins are toxic and potent carcinogenic metabolites produced from the fungi Aspergillus flavus and A. parasiticus. Aflatoxins can contaminate cottonseed under conducive preharvest and postharvest conditions. United States federal regulations restrict the use of aflatoxin contaminated cottonseed at >20 ppb for animal feed. Several strategies have been proposed for controlling aflatoxin contamination, and much success has been achieved by the application of an atoxigenic strain of A. flavus in cotton, peanut and maize fields. Development of cultivars resistant to aflatoxin through overexpression of resistance associated genes and/or knocking down aflatoxin biosynthesis of A. flavus will be an effective strategy for controlling aflatoxin contamination in cotton. In this study, genome-wide transcriptome profiling was performed to identify differentially expressed genes in response to infection with both toxigenic and atoxigenic strains of A. flavus on cotton (Gossypium hirsutum L.) pericarp and seed. The genes involved in antifungal response, oxidative burst, transcription factors, defense signaling pathways and stress response were highly differentially expressed in pericarp and seed tissues in response to A. flavus infection. The cell-wall modifying genes and genes involved in the production of antimicrobial substances were more active in pericarp as compared to seed. The genes involved in auxin and cytokinin signaling were also induced. Most of the genes involved in defense response in cotton were highly induced in pericarp than in seed. The global gene expression analysis in response to fungal invasion in cotton will serve as a source for identifying biomarkers for breeding, potential candidate genes for transgenic manipulation, and will help in understanding complex plant-fungal interaction for future downstream research. PMID:26366857

  4. Genome-Wide Transcriptome Analysis of Cotton (Gossypium hirsutum L.) Identifies Candidate Gene Signatures in Response to Aflatoxin Producing Fungus Aspergillus flavus.

    PubMed

    Bedre, Renesh; Rajasekaran, Kanniah; Mangu, Venkata Ramanarao; Sanchez Timm, Luis Eduardo; Bhatnagar, Deepak; Baisakh, Niranjan

    2015-01-01

    Aflatoxins are toxic and potent carcinogenic metabolites produced from the fungi Aspergillus flavus and A. parasiticus. Aflatoxins can contaminate cottonseed under conducive preharvest and postharvest conditions. United States federal regulations restrict the use of aflatoxin contaminated cottonseed at >20 ppb for animal feed. Several strategies have been proposed for controlling aflatoxin contamination, and much success has been achieved by the application of an atoxigenic strain of A. flavus in cotton, peanut and maize fields. Development of cultivars resistant to aflatoxin through overexpression of resistance associated genes and/or knocking down aflatoxin biosynthesis of A. flavus will be an effective strategy for controlling aflatoxin contamination in cotton. In this study, genome-wide transcriptome profiling was performed to identify differentially expressed genes in response to infection with both toxigenic and atoxigenic strains of A. flavus on cotton (Gossypium hirsutum L.) pericarp and seed. The genes involved in antifungal response, oxidative burst, transcription factors, defense signaling pathways and stress response were highly differentially expressed in pericarp and seed tissues in response to A. flavus infection. The cell-wall modifying genes and genes involved in the production of antimicrobial substances were more active in pericarp as compared to seed. The genes involved in auxin and cytokinin signaling were also induced. Most of the genes involved in defense response in cotton were highly induced in pericarp than in seed. The global gene expression analysis in response to fungal invasion in cotton will serve as a source for identifying biomarkers for breeding, potential candidate genes for transgenic manipulation, and will help in understanding complex plant-fungal interaction for future downstream research.

  5. Cloning and functional expression of the gene encoding an inhibitor against Aspergillus flavus alpha-amylase, a novel seed lectin from Lablab purpureus (Dolichos lablab).

    PubMed

    Kim, Young-Hwa; Woloshuk, Charles P; Cho, Eun Hee; Bae, Jung Myung; Song, Young-Sun; Huh, Gyung Hye

    2007-04-01

    Maize is one of the more important agricultural crops in the world and, under certain conditions, prone to attack from pathogenic fungi. One of these, Aspergillus flavus, produces toxic and carcinogenic metabolites, called aflatoxins, as byproducts of its infection of maize kernels. The alpha-amylase of A. flavus is known to promote aflatoxin production in the endosperm of these infected kernels, and a 36-kDa protein from the Lablab purpureus, denoted AILP, has been shown to inhibit alpha-amylase production and the growth of A. flavus. Here, we report the isolation of six full-length labAI genes encoding AILP and a detailed analysis of the activities of the encoded proteins. Each of the six labAI genes encoded sequences of 274 amino acids, with the deduced amino acid sequences showing approximately 95-99% identity. The sequences are similar to those of lectin members of a legume lectin-arcelin-alpha-amylase inhibitor family reported to function in plant resistance to insect pests. The labAI genes did not show any of the structures characteristic of conserved structures identified in alpha-amylase inhibitors to date. The recombinant proteins of labAI-1 and labAI-2 agglutinated human red blood cells and inhibited A. flavus alpha-amylase in a manner similar to that shown by AILP. These data indicate that labAI genes are a new class of lectin members in legume seeds and that their proteins have both lectin and alpha-amylase inhibitor activity. These results are a valuable contribution to our knowledge of plant-pathogen interactions and will be applicable for developing protocols aimed at controlling A. flavus infection. PMID:17149640

  6. Genome-Wide Transcriptome Analysis of Cotton (Gossypium hirsutum L.) Identifies Candidate Gene Signatures in Response to Aflatoxin Producing Fungus Aspergillus flavus.

    PubMed

    Bedre, Renesh; Rajasekaran, Kanniah; Mangu, Venkata Ramanarao; Sanchez Timm, Luis Eduardo; Bhatnagar, Deepak; Baisakh, Niranjan

    2015-01-01

    Aflatoxins are toxic and potent carcinogenic metabolites produced from the fungi Aspergillus flavus and A. parasiticus. Aflatoxins can contaminate cottonseed under conducive preharvest and postharvest conditions. United States federal regulations restrict the use of aflatoxin contaminated cottonseed at >20 ppb for animal feed. Several strategies have been proposed for controlling aflatoxin contamination, and much success has been achieved by the application of an atoxigenic strain of A. flavus in cotton, peanut and maize fields. Development of cultivars resistant to aflatoxin through overexpression of resistance associated genes and/or knocking down aflatoxin biosynthesis of A. flavus will be an effective strategy for controlling aflatoxin contamination in cotton. In this study, genome-wide transcriptome profiling was performed to identify differentially expressed genes in response to infection with both toxigenic and atoxigenic strains of A. flavus on cotton (Gossypium hirsutum L.) pericarp and seed. The genes involved in antifungal response, oxidative burst, transcription factors, defense signaling pathways and stress response were highly differentially expressed in pericarp and seed tissues in response to A. flavus infection. The cell-wall modifying genes and genes involved in the production of antimicrobial substances were more active in pericarp as compared to seed. The genes involved in auxin and cytokinin signaling were also induced. Most of the genes involved in defense response in cotton were highly induced in pericarp than in seed. The global gene expression analysis in response to fungal invasion in cotton will serve as a source for identifying biomarkers for breeding, potential candidate genes for transgenic manipulation, and will help in understanding complex plant-fungal interaction for future downstream research. PMID:26366857

  7. In vitro effect of some fungicides on growth and aflatoxins production by Aspergillus flavus isolated from Capsicum powder.

    PubMed

    Santos, L; Marin, S; Sanchis, V; Ramos, A J

    2011-01-01

    The aim of this study was to determine the effect of some pre-harvest fungicides on growth and aflatoxin (AF) production of three Aspergillus flavus strains found in Capsicum powder. Each isolate, previously isolated from paprika, chilli and smoked paprika, was inoculated on yeast extract sucrose agar and on a 3% paprika extract agar medium supplemented with different fungicides and incubated at 20 and 30°C during 7 days. Growth measurements were obtained on days 3, 5 and 7, and the AF production was determined on day 7. The significance of the effects of the factors (strain, medium, temperature, time and fungicides) and their interaction over colony diameter and AF production was determined. Temperature constrained the effectiveness of fungicides in reducing growth, the fungicides being most effective at 20°C. The efficacy of the fungicides over AF production depended on the medium used and temperature. The most effective fungicides in inhibiting growth and AF production, regardless of the strain tested or applied conditions, were tebuconazole 25% and mancozeb 80% applied at a concentration of 0.75 and 3.5 g l(-1), respectively. Care should thus be taken in the choice of a suitable fungicide because their effectiveness may depend on intra-specific variation and temperature. Moreover, it is necessary to take into account that the most efficient fungicide in reducing growth is not always the best choice for pre-harvest treatments because it may promote AF production. Thus, the best fungicide is the one that can simultaneous prevent growth and AF production.

  8. A study on trypsin, Aspergillus flavus and Bacillus sp. protease inhibitory activity in Cassia tora (L.) syn Senna tora (L.) Roxb. seed extract

    PubMed Central

    2011-01-01

    Background Proteases play an important role in virulence of many human, plant and insect pathogens. The proteinaceous protease inhibitors of plant origin have been reported widely from many plant species. The inhibitors may potentially be used for multiple therapeutic applications in viral, bacterial, fungal diseases and physiological disorders. In traditional Indian medicine system, Cassia tora (Senna tora) is reportedly effective in treatment of skin and gastrointestinal disorders. The present study explores the protease inhibitory activity of the above plant seeds against trypsin, Aspergillus flavus and Bacillus sp. proteases. Methods The crushed seeds of Cassia tora were washed thoroughly with acetone and hexane for depigmentation and defatting. The proteins were fractionated by ammonium sulphate (0-30, 30-60, 60-90%) followed by dialysis and size exclusion chromatography (SEC). The inhibitory potential of crude seed extract and most active dialyzed fraction against trypsin and proteases was established by spot test using unprocessed x-ray film and casein digestion methods, respectively. Electrophoretic analysis of most active fraction (30-60%) and SEC elutes were carried employing Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Gelatin SDS-PAGE. Inhibition of fungal spore germination was studied in the presence of dialyzed active inhibitor fraction. Standard deviation (SD) and ANOVA were employed as statistical tools. Results The crude seeds' extract displayed strong antitryptic, bacterial and fungal protease inhibitory activity on x-ray film. The seed protein fraction 30-60% was found most active for trypsin inhibition in caseinolytic assay (P < 0.001). The inhibition of caseinolytic activity of the proteases increased with increasing ratio of seed extract. The residual activity of trypsin, Aspergillus flavus and Bacillus sp. proteases remained only 4, 7 and 3.1%, respectively when proteases were incubated with 3 mg ml-1 seed protein

  9. Effects of temperature, water activity and incubation time on fungal growth and aflatoxin B1 production by toxinogenic Aspergillus flavus isolates on sorghum seeds.

    PubMed

    Lahouar, Amani; Marin, Sonia; Crespo-Sempere, Ana; Saïd, Salem; Sanchis, Vicente

    2016-01-01

    Sorghum, which is consumed in Tunisia as human food, suffers from severe colonization by several toxigenic fungi and contamination by mycotoxins. The Tunisian climate is characterized by high temperature and humidity that stimulates mold proliferation and mycotoxin accumulation in foodstuffs. This study investigated the effects of temperature (15, 25 and 37°C), water activity (aw, between 0.85 and 0.99) and incubation time (7, 14, 21 and 28 d) on fungal growth and aflatoxin B1 (AFB1) production by three Aspergillus flavus isolates (8, 10 and 14) inoculated on sorghum grains. The Baranyi model was applied to identify the limits of growth and mycotoxin production. Maximum diameter growth rates were observed at 0.99 a(w) at 37°C for two of the isolates. The minimum aw needed for mycelial growth was 0.91 at 25 and 37°C. At 15°C, only isolate 8 grew at 0.99 a(w). Aflatoxin B1 accumulation could be avoided by storing sorghum at low water activity levels (≤0.91 a(w)). Aflatoxin production was not observed at 15°C. This is the first work on the effects of water activity and temperature on A. flavus growth and AFB1 production by A. flavus isolates on sorghum grains.

  10. [THE EFFECT OF METAL IONES AND SPECIFIC CHEMICAL REAGENTS ON THE ACTIVITY OF ASPERGILLUS FLAVUS VAR. ORYZAE AND BACILLUS SUBTILIS α-AMYLASES].

    PubMed

    Avdiyuk, K V; Varbanets, L D

    2015-01-01

    The effect of cations and anions on the activity of Aspergillus flavus var. oryzae and Bacillus subtilis α-amylases showed that the tested enzymes are sensitive to most of cations and resistant to anions. The most significant inhibitory effects on the activity of A. flavus var. oryzae α-amylase have been demonstrated by Al3+ and Fe3+ ions, while on the activity of B. subtilis α-amylase - Hg2+, Cu2+ and Fe3+ ions. Inactivation of A. flavus var. oryzae and B. subtilis α-amylases in the presence of EGTA is indicated on the presence within their structure of metal ions. An important role in the enzymatic catalysis of both enzymes play carboxyl groups as evidenced by their inhibition of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide. Inhibition of B. subtilis α-amylase by p-chloromercuribenzoate, N-ethylmaleimide and sodium sulfite is indicated on the probable involvement of the sulfhydryl groups in the functioning of the enzyme. Unlike most studied glycosidases the tested enzymes do not contain histidine imidazole group in the active center.

  11. [THE EFFECT OF METAL IONES AND SPECIFIC CHEMICAL REAGENTS ON THE ACTIVITY OF ASPERGILLUS FLAVUS VAR. ORYZAE AND BACILLUS SUBTILIS α-AMYLASES].

    PubMed

    Avdiyuk, K V; Varbanets, L D

    2015-01-01

    The effect of cations and anions on the activity of Aspergillus flavus var. oryzae and Bacillus subtilis α-amylases showed that the tested enzymes are sensitive to most of cations and resistant to anions. The most significant inhibitory effects on the activity of A. flavus var. oryzae α-amylase have been demonstrated by Al3+ and Fe3+ ions, while on the activity of B. subtilis α-amylase - Hg2+, Cu2+ and Fe3+ ions. Inactivation of A. flavus var. oryzae and B. subtilis α-amylases in the presence of EGTA is indicated on the presence within their structure of metal ions. An important role in the enzymatic catalysis of both enzymes play carboxyl groups as evidenced by their inhibition of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide. Inhibition of B. subtilis α-amylase by p-chloromercuribenzoate, N-ethylmaleimide and sodium sulfite is indicated on the probable involvement of the sulfhydryl groups in the functioning of the enzyme. Unlike most studied glycosidases the tested enzymes do not contain histidine imidazole group in the active center. PMID:26422920

  12. Effects of temperature, water activity and incubation time on fungal growth and aflatoxin B1 production by toxinogenic Aspergillus flavus isolates on sorghum seeds.

    PubMed

    Lahouar, Amani; Marin, Sonia; Crespo-Sempere, Ana; Saïd, Salem; Sanchis, Vicente

    2016-01-01

    Sorghum, which is consumed in Tunisia as human food, suffers from severe colonization by several toxigenic fungi and contamination by mycotoxins. The Tunisian climate is characterized by high temperature and humidity that stimulates mold proliferation and mycotoxin accumulation in foodstuffs. This study investigated the effects of temperature (15, 25 and 37°C), water activity (aw, between 0.85 and 0.99) and incubation time (7, 14, 21 and 28 d) on fungal growth and aflatoxin B1 (AFB1) production by three Aspergillus flavus isolates (8, 10 and 14) inoculated on sorghum grains. The Baranyi model was applied to identify the limits of growth and mycotoxin production. Maximum diameter growth rates were observed at 0.99 a(w) at 37°C for two of the isolates. The minimum aw needed for mycelial growth was 0.91 at 25 and 37°C. At 15°C, only isolate 8 grew at 0.99 a(w). Aflatoxin B1 accumulation could be avoided by storing sorghum at low water activity levels (≤0.91 a(w)). Aflatoxin production was not observed at 15°C. This is the first work on the effects of water activity and temperature on A. flavus growth and AFB1 production by A. flavus isolates on sorghum grains. PMID:26920121

  13. Efficacy of Mentha spicata essential oil in suppression of Aspergillus flavus and aflatoxin contamination in chickpea with particular emphasis to mode of antifungal action.

    PubMed

    Kedia, Akash; Dwivedy, Abhishek Kumar; Jha, Dhruva Kumar; Dubey, Nawal Kishore

    2016-05-01

    The present study reports in vivo antifungal and antiaflatoxigenic efficacy of Mentha spicata essential oil (EO) against toxigenic Aspergillus flavus strain LHP(C)-D6 in chickpea food system up to 12 months of storage. In addition, the mode of antifungal action of EO was also determined to understand the mechanism of fungal growth inhibition. The in vivo study with different concentrations of M. spicata EO showed dose-dependent decrease in fungal colony count as well as aflatoxin B1 concentration. The EO caused >50% protection in inoculated sets and >70% protection in uninoculated sets of chickpea food system against A. flavus at 1.0 μL mL(-1) air concentration. However, at the same concentration, EO caused 100% inhibition to aflatoxin B1 production in both sets when analyzed through high-performance liquid chromatography (HPLC). The antifungal target of EO in fumigated cells of A. flavus was found to be the plasma membrane when analyzed through electron microscopic observations and ions leakage test. The EO fumigated chickpea seeds showed 100% seed germination and seedling growth after 12 months of storage. Based on these observations, M. spicata EO can be recommended as plant-based preservative for safe protection of food commodities during storage conditions against fungal and most importantly mycotoxin contaminations.

  14. Transcriptome Analysis of Aspergillus flavus Reveals veA-Dependent Regulation of Secondary Metabolite Gene Clusters, Including the Novel Aflavarin Cluster

    PubMed Central

    Cary, J. W.; Han, Z.; Yin, Y.; Lohmar, J. M.; Shantappa, S.; Harris-Coward, P. Y.; Mack, B.; Ehrlich, K. C.; Wei, Q.; Arroyo-Manzanares, N.; Uka, V.; Vanhaecke, L.; Bhatnagar, D.; Yu, J.; Nierman, W. C.; Johns, M. A.; Sorensen, D.; Shen, H.; De Saeger, S.; Diana Di Mavungu, J.

    2015-01-01

    The global regulatory veA gene governs development and secondary metabolism in numerous fungal species, including Aspergillus flavus. This is especially relevant since A. flavus infects crops of agricultural importance worldwide, contaminating them with potent mycotoxins. The most well-known are aflatoxins, which are cytotoxic and carcinogenic polyketide compounds. The production of aflatoxins and the expression of genes implicated in the production of these mycotoxins are veA dependent. The genes responsible for the synthesis of aflatoxins are clustered, a signature common for genes involved in fungal secondary metabolism. Studies of the A. flavus genome revealed many gene clusters possibly connected to the synthesis of secondary metabolites. Many of these metabolites are still unknown, or the association between a known metabolite and a particular gene cluster has not yet been established. In the present transcriptome study, we show that veA is necessary for the expression of a large number of genes. Twenty-eight out of the predicted 56 secondary metabolite gene clusters include at least one gene that is differentially expressed depending on presence or absence of veA. One of the clusters under the influence of veA is cluster 39. The absence of veA results in a downregulation of the five genes found within this cluster. Interestingly, our results indicate that the cluster is expressed mainly in sclerotia. Chemical analysis of sclerotial extracts revealed that cluster 39 is responsible for the production of aflavarin. PMID:26209694

  15. The major volatile compound 2-phenylethanol from the biocontrol yeast, Pichia anomala, inhibits growth and expression of aflatoxin biosynthetic genes of Aspergillus flavus.

    PubMed

    Hua, Sui Sheng T; Beck, John J; Sarreal, Siov Bouy L; Gee, Wai

    2014-05-01

    Aspergillus flavus is a ubiquitous saprophyte that is able to produce the most potent natural carcinogenic compound known as aflatoxin B1 (AFB1). This toxin frequently contaminates crops including corn, cotton, peanuts, and tree nuts causing substantial economic loss worldwide. Consequently, more than 100 countries have strict regulations limiting AFB1 in foodstuffs and feedstuffs. Plants and microbes are able to produce volatile compounds that act as a defense mechanism against other organisms. Pichia anomala strain WRL-076 is a biocontrol yeast currently being tested to reduce AF contamination of tree nuts in California. We used the SPME-GC/MS analysis and identified the major volatile compound produced by this strain to be 2-phenylethanol (2-PE). It inhibited spore germination and AF production of A. flavus. Inhibition of AF formation by 2-PE was correlated with significant down regulation of clustering AF biosynthesis genes as evidenced by several to greater than 10,000-fold decrease in gene expression. In a time-course analysis we found that 2-PE also altered the expression patterns of chromatin modifying genes, MYST1, MYST2, MYST3, gcn5, hdaA and rpdA. The biocontrol capacity of P. anomala can be attributed to the production of 2-PE, which affects spore germination, growth, toxin production, and gene expression in A. flavus. PMID:24504634

  16. Evaluation of mRNA Expression Levels of cyp51A and mdr1, Candidate Genes for Voriconazole Resistance in Aspergillus flavus

    PubMed Central

    Fattahi, Azam; Zaini, Farideh; Kordbacheh, Parivash; Rezaie, Sasan; Safara, Mahin; Fateh, Roohollah; Farahyar, Shirin; Kanani, Ali; Heidari, Mansour

    2015-01-01

    Background: Voriconazole Resistance (VRC-R) in Aspergillus flavus isolates impacts the management of aspergillosis, since azoles are the first choice for prophylaxis and therapy. However, to the best of our knowledge, the mechanisms underlying voriconazole resistance are poorly understood. Objectives: The present study was designed to evaluate mRNA expression levels of cyp51A and mdr1 genes in voriconazole resistant A. flavus by a Real-Time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) technique. Materials and Methods: Five A. flavus isolates with resistance to VRC were examined by a RT-PCR approach. Results: Four out of five isolates revealed cyp51A and mdr1 mRNA overexpression. Interestingly, the isolate, which was negative for cyp51A and mdr1 mRNA expression showed a high voriconazole Minimum Inhibitory Concentration (MIC). Furthermore, a computational-based analysis predicted that voriconazole resistance could be mediated through cooperation with a network protein interaction. Conclusions: Our experimental and in silico findings may provide new insight in the complex molecular pathways of drug resistance and also could assist design an efficient therapeutic strategy for aspergillosis treatment. PMID:26865941

  17. Suppression of Aflatoxin Biosynthesis in Aspergillus flavus by 2-Phenylethanol Is Associated with Stimulated Growth and Decreased Degradation of Branched-Chain Amino Acids

    PubMed Central

    Chang, Perng-Kuang; Hua, Sui Sheng T.; Sarreal, Siov Bouy L.; Li, Robert W.

    2015-01-01

    The saprophytic soil fungus Aspergillus flavus infects crops and produces aflatoxin. Pichia anomala, which is a biocontrol yeast and produces the major volatile 2-phenylethanol (2-PE), is able to reduce growth of A. flavus and aflatoxin production when applied onto pistachio trees. High levels of 2-PE are lethal to A. flavus and other fungi. However, at low levels, the underlying mechanism of 2-PE to inhibit aflatoxin production remains unclear. In this study, we characterized the temporal transcriptome response of A. flavus to 2-PE at a subinhibitory level (1 µL/mL) using RNA-Seq technology and bioinformatics tools. The treatment during the entire 72 h experimental period resulted in 131 of the total A. flavus 13,485 genes to be significantly impacted, of which 82 genes exhibited decreased expression. They included those encoding conidiation proteins and involved in cyclopiazonic acid biosynthesis. All genes in the aflatoxin gene cluster were also significantly decreased during the first 48 h treatment. Gene Ontology (GO) analyses showed that biological processes with GO terms related to catabolism of propionate and branched-chain amino acids (valine, leucine and isoleucine) were significantly enriched in the down-regulated gene group, while those associated with ribosome biogenesis, translation, and biosynthesis of α-amino acids were over-represented among the up-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that metabolic pathways negatively impacted among the down-regulated genes parallel to those active at 30 °C, a condition conducive to aflatoxin biosynthesis. In contrast, metabolic pathways positively related to the up-regulated gene group resembled those at 37 °C, which favors rapid fungal growth and is inhibitory to aflatoxin biosynthesis. The results showed that 2-PE at a low level stimulated active growth of A. flavus but concomitantly rendered decreased activities in branched-chain amino acid degradation

  18. Suppression of Aflatoxin Biosynthesis in Aspergillus flavus by 2-Phenylethanol Is Associated with Stimulated Growth and Decreased Degradation of Branched-Chain Amino Acids.

    PubMed

    Chang, Perng-Kuang; Hua, Sui Sheng T; Sarreal, Siov Bouy L; Li, Robert W

    2015-10-01

    The saprophytic soil fungus Aspergillus flavus infects crops and produces aflatoxin. Pichia anomala, which is a biocontrol yeast and produces the major volatile 2-phenylethanol (2-PE), is able to reduce growth of A. flavus and aflatoxin production when applied onto pistachio trees. High levels of 2-PE are lethal to A. flavus and other fungi. However, at low levels, the underlying mechanism of 2-PE to inhibit aflatoxin production remains unclear. In this study, we characterized the temporal transcriptome response of A. flavus to 2-PE at a subinhibitory level (1 μL/mL) using RNA-Seq technology and bioinformatics tools. The treatment during the entire 72 h experimental period resulted in 131 of the total A. flavus 13,485 genes to be significantly impacted, of which 82 genes exhibited decreased expression. They included those encoding conidiation proteins and involved in cyclopiazonic acid biosynthesis. All genes in the aflatoxin gene cluster were also significantly decreased during the first 48 h treatment. Gene Ontology (GO) analyses showed that biological processes with GO terms related to catabolism of propionate and branched-chain amino acids (valine, leucine and isoleucine) were significantly enriched in the down-regulated gene group, while those associated with ribosome biogenesis, translation, and biosynthesis of α-amino acids OPEN ACCESS Toxins 2015, 7 3888 were over-represented among the up-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that metabolic pathways negatively impacted among the down-regulated genes parallel to those active at 30 °C, a condition conducive to aflatoxin biosynthesis. In contrast, metabolic pathways positively related to the up-regulated gene group resembled those at 37 °C, which favors rapid fungal growth and is inhibitory to aflatoxin biosynthesis. The results showed that 2-PE at a low level stimulated active growth of A. flavus but concomitantly rendered decreased activities in

  19. Functional characterization of a veA-dependent polyketide synthase gene in Aspergillus flavus necessary for the synthesis of asparasone, a sclerotium-specific pigment.

    PubMed

    Cary, Jeffrey W; Harris-Coward, Pamela Y; Ehrlich, Kenneth C; Di Mavungu, José Diana; Malysheva, Svetlana V; De Saeger, Sarah; Dowd, Patrick F; Shantappa, Sourabha; Martens, Stacey L; Calvo, Ana M

    2014-03-01

    The filamentous fungus, Aspergillus flavus, produces the toxic and carcinogenic, polyketide synthase (PKS)-derived family of secondary metabolites termed aflatoxins. While analysis of the A. flavus genome has identified many other PKSs capable of producing secondary metabolites, to date, only a few other metabolites have been identified. In the process of studying how the developmental regulator, VeA, affects A. flavus secondary metabolism we discovered that mutation of veA caused a dramatic down-regulation of transcription of a polyketide synthase gene belonging to cluster 27 and the loss of the ability of the fungi to produce sclerotia. Inactivation of the cluster 27 pks (pks27) resulted in formation of greyish-yellow sclerotia rather than the dark brown sclerotia normally produced by A. flavus while conidial pigmentation was unaffected. One metabolite produced by Pks27 was identified by thin layer chromatography and mass spectral analysis as the known anthraquinone, asparasone A. Sclerotia produced by pks27 mutants were significantly less resistant to insect predation than were the sclerotia produced by the wild-type and more susceptible to the deleterious effects of ultraviolet light and heat. Normal sclerotia were previously thought to be resistant to damage because of a process of melanization similar to that known for pigmentation of conidia. Our results show that the dark brown pigments in sclerotia derive from anthraquinones produced by Pks27 rather than from the typical tetrahydronapthalene melanin production pathway. To our knowledge this is the first report on the genes involved in the biosynthesis of pigments important for sclerotial survival. PMID:24412484

  20. Isoform patterns of chitinase and beta-1,3-glucanase in maturing corn kernels (Zea mays L.) associated with Aspergillus flavus milk stage infection.

    PubMed

    Ji, C; Norton, R A; Wicklow, D T; Dowd, P F

    2000-02-01

    Isoform patterns of chitinase and beta-1,3-glucanase of maturing kernels of yellow dent corn (Pioneer 3394) infected with Aspergillus flavus at the milk stage were investigated through polyacrylamide gel electrophoresis (PAGE). Proteins on the sodium dodecyl sulfate (SDS) gel with an apparent molecular mass range of 23-46 kDa were differentially present in the kernels infected with both aflatoxin-producing and non-aflatoxin-producing strains of A. flavus. From in-gel (native PAGE) enzyme activity assays, three bands corresponding to chitinase isoforms and two bands corresponding to beta-1,3-glucanase isoforms were detected in the infected kernels. One chitinase isoform of 29 kDa was present only in the infected kernels, and another one of 28 kDa was present in both infected and noninfected kernels. They were judged to be acidic on the basis of their migration on an acrylamide isoelectric focusing (IEF) gel. For the beta-1,3-glucanase, one isoform of 35 kDa was present in both infected and noninfected kernels, but another one, a 33 kDa isoform, was present only in the infected kernels. Both acidic and basic beta-1,3-glucanase isoforms were detected in the IEF gel. The results of this study are the first to demonstrate patterns of enhanced or inducible proteins in maturing corn kernels in response to A. flavus infection at the milk stage. The results also indicate that only particular isoforms of the two hydrolytic enzymes are involved in the maturing corn kernels infected at the milk stage with A. flavus.

  1. Inhibitory Effect of Cinnamaldehyde, Citral, and Eugenol on Aflatoxin Biosynthetic Gene Expression and Aflatoxin B1 Biosynthesis in Aspergillus flavus.

    PubMed

    Liang, Dandan; Xing, Fuguo; Selvaraj, Jonathan Nimal; Liu, Xiao; Wang, Limin; Hua, Huijuan; Zhou, Lu; Zhao, Yueju; Wang, Yan; Liu, Yang

    2015-12-01

    In order to reveal the inhibitory effects of cinnamaldehyde, citral, and eugenol on aflatoxin biosynthesis, the expression levels of 5 key aflatoxin biosynthetic genes were evaluated by real-time PCR. Aspergillus flavus growth and AFB1 production were completely inhibited by 0.80 mmol/L of cinnamaldehyde and 2.80 mmol/L of citral. However, at lower concentration, cinnamaldehyde (0.40 mmol/L), eugenol (0.80 mmol/L), and citral (0.56 mmol/L) significantly reduced AFB1 production with inhibition rate of 68.9%, 95.4%, and 41.8%, respectively, while no effect on fungal growth. Real-time PCR showed that the expressions of aflR, aflT, aflD, aflM, and aflP were down-regulated by cinnamaldehyde (0.40 mmol/L), eugenol (0.80 mmol/L), and citral (0.56 mmol/L). In the presence of cinnamaldehyde, AflM was highly down-regulated (average of 5963 folds), followed by aflP, aflR, aflD, and aflT with the average folds of 55, 18, 6.5, and 5.8, respectively. With 0.80 mmol/L of eugenol, aflP was highly down-regulated (average of 2061-folds), followed by aflM, aflR, aflD, and aflT with average of 138-, 15-, 5.2-, and 4.8-folds reduction, respectively. With 0.56 mmol/L of citral, aflT was completely inhibited, followed by aflM, aflP, aflR, and aflD with average of 257-, 29-, 3.5-, and 2.5-folds reduction, respectively. These results suggest that the reduction in AFB1 production by cinnamaldehyde, eugenol, and citral at low concentration may be due to the down-regulations of the transcription level of aflatoxin biosynthetic genes. Cinnamaldehyde and eugenol may be employed successfully as a good candidate in controlling of toxigenic fungi and subsequently contamination with aflatoxins in practice.

  2. Development of a PCR protocol to detect aflatoxigenic molds in food products.

    PubMed

    Luque, M Isabel; Rodríguez, Alicia; Andrade, María J; Martín, Alberto; Córdoba, Juan J

    2012-01-01

    Aflatoxins are secondary metabolites produced mainly by Aspergillus species growing in foodstuffs. Because aflatoxins have important health effects, the detection of early contamination of foods by aflatoxigenic molds should be useful. In the present work, a reliable conventional PCR method for detecting aflatoxigenic molds of various species was developed. Fifty-six aflatoxigenic and nonaflatoxigenic strains commonly reported in foodstuffs were tested. Aflatoxin production was first confirmed by micellar electrokinetic capillary electrophoresis or/and high-pressure liquid chromatography-mass spectrometry. Based on the conserved regions of the O-methyltransferase gene (omt-1) involved in the aflatoxin biosynthetic pathway, six primer pairs were designed. With only the designed primer pair AFF1-AFR3, the expected PCR product (381 bp) was obtained in all of the tested aflatoxigenic strains of various species and genera. Amplification products were not obtained with this primer pair for any of the nonaflatoxigenic reference molds. However, an amplicon of 453 bp was obtained for all aflatoxigenic and nonaflatoxigenic mold reference strains with a PCR protocol based on the constitutive fungal β-tubulin gene, which was used as a positive fungal control. The PCR protocol based on omt-1 detected as little as 15 pg of DNA from aflatoxigenic molds and 10(2) to 10(3) CFU/g in contaminated food samples. This PCR protocol should be used as a routine technique to detect aflatoxigenic molds in foods. PMID:22221359

  3. Development of a PCR protocol to detect aflatoxigenic molds in food products.

    PubMed

    Luque, M Isabel; Rodríguez, Alicia; Andrade, María J; Martín, Alberto; Córdoba, Juan J

    2012-01-01

    Aflatoxins are secondary metabolites produced mainly by Aspergillus species growing in foodstuffs. Because aflatoxins have important health effects, the detection of early contamination of foods by aflatoxigenic molds should be useful. In the present work, a reliable conventional PCR method for detecting aflatoxigenic molds of various species was developed. Fifty-six aflatoxigenic and nonaflatoxigenic strains commonly reported in foodstuffs were tested. Aflatoxin production was first confirmed by micellar electrokinetic capillary electrophoresis or/and high-pressure liquid chromatography-mass spectrometry. Based on the conserved regions of the O-methyltransferase gene (omt-1) involved in the aflatoxin biosynthetic pathway, six primer pairs were designed. With only the designed primer pair AFF1-AFR3, the expected PCR product (381 bp) was obtained in all of the tested aflatoxigenic strains of various species and genera. Amplification products were not obtained with this primer pair for any of the nonaflatoxigenic reference molds. However, an amplicon of 453 bp was obtained for all aflatoxigenic and nonaflatoxigenic mold reference strains with a PCR protocol based on the constitutive fungal β-tubulin gene, which was used as a positive fungal control. The PCR protocol based on omt-1 detected as little as 15 pg of DNA from aflatoxigenic molds and 10(2) to 10(3) CFU/g in contaminated food samples. This PCR protocol should be used as a routine technique to detect aflatoxigenic molds in foods.

  4. Development of polyclonal antibodies for detection of aflatoxigenic molds involving culture filtrate and chimeric proteins expressed in Escherichia coli.

    PubMed

    Shapira, R; Paster, N; Menasherov, M; Eyal, O; Mett, A; Meiron, T; Kuttin, E; Salomon, R

    1997-03-01

    Polyclonal antibodies (PAb) were raised against an aflatoxigenic strain of Aspergillus parasiticus by using two different sources for antibody elicitation: (i) filtrate of a culture on which the fungus had been grown (ii) and two chimeric proteins, expressed in Escherichia coli as separate products, of the genes ver-1 and apa-2, which are involved in aflatoxin biosynthesis. The gene products were amplified by PCR, and each was cloned into the E. coli expression vector pGEX2T. Upon induction, the bacteria overexpressed 38- and 33-kDa chimeric proteins corresponding to the N-terminal domains of the genes ver-1 and apa-2, respectively. The chimeric proteins were isolated and affinity purified for use as antigens. The specificity of the raised antibodies was examined by enzyme-linked immunosorbent assay (ELISA). The PAbs raised against the culture filtrate reacted with all the species of Aspergillus and Penicillium tested but not with Fusarium species or corn gain. However, the PAbs elicited against the chimeric proteins were highly specific, showing significantly higher ELISA absorbance values (A405) against A. parasiticus and A. flavus than against the other fungi tested and the corn grain. The approach of utilizing gene products associated with aflatoxin biosynthesis for antibody production therefore appears to be feasible. Such a multiantibody system combined with the PCR technique, could provide a useful tool for the rapid, sensitive, and accurate detection of aflatoxin producers present in grains and foods. PMID:9055416

  5. Characterization of Aspergillus species on Brazil nut from the Brazilian Amazonian region and development of a PCR assay for identification at the genus level

    PubMed Central

    2014-01-01

    Background Brazil nut is a protein-rich extractivist tree crop in the Amazon region. Fungal contamination of shells and kernel material frequently includes the presence of aflatoxigenic Aspergillus species from the section Flavi. Aflatoxins are polyketide secondary metabolites, which are hepatotoxic carcinogens in mammals. The objectives of this study were to identify Aspergillus species occurring on Brazil nut grown in different states in the Brazilian Amazon region and develop a specific PCR method for collective identification of member species of the genus Aspergillus. Results Polyphasic identification of 137 Aspergillus strains isolated from Brazil nut shell material from cooperatives across the Brazilian Amazon states of Acre, Amapá and Amazonas revealed five species, with Aspergillus section Flavi species A. nomius and A. flavus the most abundant. PCR primers ASP_GEN_MTSSU_F1 and ASP_GEN_MTSSU_R1 were designed for the genus Aspergillus, targeting a portion of the mitochondrial small subunit ribosomal RNA gene. Primer specificity was validated through both electronic PCR against target gene sequences at Genbank and in PCR reactions against DNA from Aspergillus species and other fungal genera common on Brazil nut. Collective differentiation of the observed section Flavi species A. flavus, A. nomius and A. tamarii from other Aspergillus species was possible on the basis of RFLP polymorphism. Conclusions Given the abundance of Aspergillus section Flavi species A. nomius and A. flavus observed on Brazil nut, and associated risk of mycotoxin accumulation, simple identification methods for such mycotoxigenic species are of importance for Hazard Analysis Critical Control Point system implementation. The assay for the genus Aspergillus represents progress towards specific PCR identification and detection of mycotoxigenic species. PMID:24885088

  6. Use of UHPLC high-resolution Orbitrap mass spectrometry to investigate the genes involved in the production of secondary metabolites in Aspergillus flavus.

    PubMed

    Arroyo-Manzanares, Natalia; Di Mavungu, José Diana; Uka, Valdet; Malysheva, Svetlana V; Cary, Jeffrey W; Ehrlich, Kenneth C; Vanhaecke, Lynn; Bhatnagar, Deepak; De Saeger, Sarah

    2015-01-01

    The fungus Aspergillus flavus is known for its ability to produce the toxic and carcinogenic aflatoxins in food and feed. While aflatoxins are of most concern, A. flavus is predicted to be capable of producing many more metabolites based on a study of its complete genome sequence. Some of these metabolites could be of great importance in food and feed safety. Here we describe an analytical methodology based on Orbitrap HRMS technology that allows the untargeted determination of fungal metabolites, in support of the study of the function of genes involved in secondary metabolism in fungi. The applied strategy implies the detection and identification of differentially expressed metabolites in extracts of wild-type and mutant fungal strains, using Orbitrap high-resolution mass spectrometry (HRMS) accurate mass data. The suitability of this approach was demonstrated by the confirmation of previously characterised genes involved in the aflatoxin biosynthetic pathway, namely a polyketide synthase (pksA), an oxidoreductase (ordA) and a methyltransferase (omtA) gene. Subsequently, the proposed methodology was applied for the detection and identification of metabolites produced by a yet uncharacterised gene cluster in A. favus, cluster 23. Comparative Orbitrap HRMS analysis of extracts of A. flavus wild-type strain and an over-expression mutant for the transcription factor of gene cluster 23 (lepE) demonstrated that this gene cluster is responsible for the production a set of 2-pyridone derivatives, the leporins. Besides the known derivatives leporin B and leporin B precursor that could be identified by automatic de-replication of the accurate mass data, five other compounds belonging to this class of fungal secondary metabolites were detected and identified for the first time, combining MS and multiple-stage MS data. PMID:26278397

  7. Identification and Quantification of a Toxigenic and Non-Toxigenic Aspergillus flavus Strain in Contaminated Maize Using Quantitative Real-Time PCR.

    PubMed

    Mylroie, J Erik; Ozkan, Seval; Shivaji, Renuka; Windham, Gary L; Alpe, Michael N; Williams, W Paul

    2016-01-01

    Aflatoxins, which are produced by Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin. Plant resistance and biological control using non-toxin producing strains are considered effective strategies for reducing aflatoxin accumulation in maize grain. Distinguishing between the toxin and non-toxin producing strains is important in determining the effectiveness of bio-control strategies and understanding inter-strain interactions. Using polymorphisms found in the fungal rRNA intergenic spacer region (IGS) between a toxigenic strain of A. flavus (NRRL 3357) and the non-toxigenic strain used in the biological control agent Afla-Guard(®) (NRRL 21882), we developed a set of primers that allows for the identification and quantification of the two strains using quantitative PCR. This primer set has been used to screen maize grain that was inoculated with the two strains individually and co-inoculated with both strains, and it has been shown to be effective in both the identification and quantification of both strains. Screening of co-inoculated ears from multiple resistant and susceptible genotypic crosses revealed no significant differences in fungal biomass accumulation of either strain in the field tests from 2010 and 2011 when compared across the means of all genotypes. Only one genotype/year combination showed significant differences in strain accumulation. Aflatoxin accumulation analysis showed that, as expected, genotypes inoculated with the toxigenic strain accumulated more aflatoxin than when co-inoculated with both strains or inoculated with only the non-toxigenic strain. Furthermore, accumulation of toxigenic fungal mass was significantly correlated with aflatoxin accumulation while non-toxigenic fungal accumulation was not. This primer set will allow researchers to better determine how the two fungal strains compete on the maize ear and investigate the interaction

  8. Identification and Quantification of a Toxigenic and Non-Toxigenic Aspergillus flavus Strain in Contaminated Maize Using Quantitative Real-Time PCR

    PubMed Central

    Mylroie, J. Erik; Ozkan, Seval; Shivaji, Renuka; Windham, Gary L.; Alpe, Michael N.; Williams, W. Paul

    2016-01-01

    Aflatoxins, which are produced by Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin. Plant resistance and biological control using non-toxin producing strains are considered effective strategies for reducing aflatoxin accumulation in maize grain. Distinguishing between the toxin and non-toxin producing strains is important in determining the effectiveness of bio-control strategies and understanding inter-strain interactions. Using polymorphisms found in the fungal rRNA intergenic spacer region (IGS) between a toxigenic strain of A. flavus (NRRL 3357) and the non-toxigenic strain used in the biological control agent Afla-Guard® (NRRL 21882), we developed a set of primers that allows for the identification and quantification of the two strains using quantitative PCR. This primer set has been used to screen maize grain that was inoculated with the two strains individually and co-inoculated with both strains, and it has been shown to be effective in both the identification and quantification of both strains. Screening of co-inoculated ears from multiple resistant and susceptible genotypic crosses revealed no significant differences in fungal biomass accumulation of either strain in the field tests from 2010 and 2011 when compared across the means of all genotypes. Only one genotype/year combination showed significant differences in strain accumulation. Aflatoxin accumulation analysis showed that, as expected, genotypes inoculated with the toxigenic strain accumulated more aflatoxin than when co-inoculated with both strains or inoculated with only the non-toxigenic strain. Furthermore, accumulation of toxigenic fungal mass was significantly correlated with aflatoxin accumulation while non-toxigenic fungal accumulation was not. This primer set will allow researchers to better determine how the two fungal strains compete on the maize ear and investigate the interaction

  9. An industry perspective on the use of “atoxigenic” strains of Aspergillus flavus as biological control agents and the significance of cyclopiazonic acid

    PubMed Central

    King, Eileen D; (Bobby) Bassi, Albeit B; Ross, David C; Druebbisch, Bernd

    2011-01-01

    Several nonaflatoxigenic strains of Aspergillus flavus have been registered in the United States to reduce aflatoxin accumulation in maize and other crops, but there may be unintended negative consequences if these strains produce cyclopiazonic acid (CPA). AF36, a nonaflatoxigenic, CPA-producing strain has been shown to produce CPA in treated maize and peanuts. Alternative strains, including Afla-Guard® brand biocontrol agent and K49, do not produce CPA and can reduce both aflatoxin and CPA in treated crops. Chronic toxicity of CPA has not been studied, and recent animal studies show significant harmful effects from short-term exposure to CPA at low doses. Grower and industry confidence in this approach must be preserved through transparency. PMID:22844262

  10. A public platform for the verification of the phenotypic effect of candidate genes for resistance to aflatoxin accumulation and Aspergillus flavus infection in maize.

    PubMed

    Warburton, Marilyn L; Williams, William Paul; Hawkins, Leigh; Bridges, Susan; Gresham, Cathy; Harper, Jonathan; Ozkan, Seval; Mylroie, J Erik; Shan, Xueyan

    2011-07-01

    A public candidate gene testing pipeline for resistance to aflatoxin accumulation or Aspergillus flavus infection in maize is presented here. The pipeline consists of steps for identifying, testing, and verifying the association of selected maize gene sequences with resistance under field conditions. Resources include a database of genetic and protein sequences associated with the reduction in aflatoxin contamination from previous studies; eight diverse inbred maize lines for polymorphism identification within any maize gene sequence; four Quantitative Trait Loci (QTL) mapping populations and one association mapping panel, all phenotyped for aflatoxin accumulation resistance and associated phenotypes; and capacity for Insertion/Deletion (InDel) and SNP genotyping in the population(s) for mapping. To date, ten genes have been identified as possible candidate genes and put through the candidate gene testing pipeline, and results are presented here to demonstrate the utility of the pipeline. PMID:22069738

  11. A Public Platform for the Verification of the Phenotypic Effect of Candidate Genes for Resistance to Aflatoxin Accumulation and Aspergillus flavus Infection in Maize

    PubMed Central

    Warburton, Marilyn L.; Williams, William Paul; Hawkins, Leigh; Bridges, Susan; Gresham, Cathy; Harper, Jonathan; Ozkan, Seval; Mylroie, J. Erik; Shan, Xueyan

    2011-01-01

    A public candidate gene testing pipeline for resistance to aflatoxin accumulation or Aspergillus flavus infection in maize is presented here. The pipeline consists of steps for identifying, testing, and verifying the association of selected maize gene sequences with resistance under field conditions. Resources include a database of genetic and protein sequences associated with the reduction in aflatoxin contamination from previous studies; eight diverse inbred maize lines for polymorphism identification within any maize gene sequence; four Quantitative Trait Loci (QTL) mapping populations and one association mapping panel, all phenotyped for aflatoxin accumulation resistance and associated phenotypes; and capacity for Insertion/Deletion (InDel) and SNP genotyping in the population(s) for mapping. To date, ten genes have been identified as possible candidate genes and put through the candidate gene testing pipeline, and results are presented here to demonstrate the utility of the pipeline. PMID:22069738

  12. Efficacy of the combined application of chitosan and Locust Bean Gum with different citrus essential oils to control postharvest spoilage caused by Aspergillus flavus in dates.

    PubMed

    Aloui, Hajer; Khwaldia, Khaoula; Licciardello, Fabio; Mazzaglia, Agata; Muratore, Giuseppe; Hamdi, Moktar; Restuccia, Cristina

    2014-01-17

    This study reports the efficacy of the combined application of chitosan (CH) and Locust Bean Gum (LBG) in combination with different citrus essential oils (EOs) to inhibit Aspergillus flavus in vitro and on artificially infected dates for a storage period of 12 days. The effect of these treatments on the fruits' sensory characteristics was evaluated to verify the complete absence of off-odours and off-flavours. Bergamot EO was the most effective in reducing mycelial growth, followed by bitter orange EO. Both bergamot and bitter orange oils significantly reduced conidial germination and a complete inhibition was obtained at concentrations higher than 2%. The mixtures based on CH-2% (v/v) bergamot EO or CH-2% (v/v) bitter orange EO proved to be the most effective coatings to reduce conidial germination resulting in an 87-90% inhibition compared with the control. In fruit decay assays coatings based on CH incorporating citrus oils were able to reduce fungal decay in the range of 52-62% at day 12. The study results and the complete absence of off-flavours and off-odours demonstrate the potential of CH coatings carrying citrus EOs at sub-inhibitory concentrations to control postharvest growth of A. flavus in dates.

  13. Molecular genetic evidence for the involvement of a specific polygalacturonase, P2c, in the invasion and spread of Aspergillus flavus in cotton bolls.

    PubMed Central

    Shieh, M T; Brown, R L; Whitehead, M P; Cary, J W; Cotty, P J; Cleveland, T E; Dean, R A

    1997-01-01

    Isolates of Aspergillus flavus can be differentiated based on production of the polygalacturonase P2c. One group of isolates produces P2c, whereas the other group does not. In general, the group that produces P2c causes more damage and spreads to a greater extent in cotton bolls than those isolates that do not produce P2c. To determine whether P2c contributes to disease, the expression of pecA, the gene previously determined to encode P2c, was genetically altered. Adding the pecA gene to a strain previously lacking the gene resulted in the ability to cause significantly more damage to the intercarpellary membrane and the ability spread to a greater extent within the adjacent locule compared to the abilities of a control transformant. Conversely, eliminating the expression of pecA by targeted disruption caused a significant reduction in aggressiveness compared to that of a nondisrupted control transformant. These results provide direct evidence that P2c contributes to the invasion and spread of A. flavus during infection of cotton bolls. However, other factors not evaluated in this study also contribute to aggressiveness. PMID:9293005

  14. In vitro experimental environments lacking or containing soil disparately affect competition experiments of Aspergillus flavus and co-occurring fungi in maize grains.

    PubMed

    Falade, Titilayo D O; Syed Mohdhamdan, Sharifah H; Sultanbawa, Yasmina; Fletcher, Mary T; Harvey, Jagger J W; Chaliha, Mridusmita; Fox, Glen P

    2016-07-01

    In vitro experimental environments are used to study interactions between microorganisms, and to predict dynamics in natural ecosystems. This study highlights that experimental in vitro environments should be selected to match closely the natural environment of interest during in vitro studies to strengthen extrapolations about aflatoxin production by Aspergillus and competing organisms. Fungal competition and aflatoxin accumulation were studied in soil, cotton wool or tube (water-only) environments, for Aspergillus flavus competition with Penicillium purpurogenum, Fusarium oxysporum or Sarocladium zeae within maize grains. Inoculated grains were incubated in each environment at two temperature regimes (25 and 30°C). Competition experiments showed interaction between the main effects of aflatoxin accumulation and the environment at 25°C, but not so at 30°C. However, competition experiments showed fungal populations were always interacting with their environments. Fungal survival differed after the 72-h incubation in different experimental environments. Whereas all fungi incubated within the soil environment survived, in the cotton wool environment none of the competitors of A. flavus survived at 30°C. With aflatoxin accumulation, F. oxysporum was the only fungus able to interdict aflatoxin production at both temperatures. This occurred only in the soil environment and fumonisins accumulated instead. Smallholder farmers in developing countries face serious mycotoxin contamination of their grains, and soil is a natural reservoir for the associated fungal propagules, and a drying and storage surface for grains on these farms. Studying fungal dynamics in the soil environment and other environments in vitro can provide insights into aflatoxin accumulation post-harvest.

  15. Genetic Analysis of the Aspergillus flavus Vegetative Compatibility Group to Which a Biological Control Agent That Limits Aflatoxin Contamination in U.S. Crops Belongs

    PubMed Central

    Cotty, Peter J.

    2015-01-01

    Some filamentous fungi in Aspergillus section Flavi produce carcinogenic secondary compounds called aflatoxins. Aflatoxin contamination is routinely managed in commercial agriculture with strains of Aspergillus flavus that do not produce aflatoxins. These non-aflatoxin-producing strains competitively exclude aflatoxin producers and reshape fungal communities so that strains with the aflatoxin-producing phenotype are less frequent. This study evaluated the genetic variation within naturally occurring atoxigenic A. flavus strains from the endemic vegetative compatibility group (VCG) YV36. AF36 is a strain of VCG YV36 and was the first fungus used in agriculture for aflatoxin management. Genetic analyses based on mating-type loci, 21 microsatellite loci, and a single nucleotide polymorphism (SNP) in the aflC gene were applied to a set of 237 YV36 isolates collected from 1990 through 2005 from desert legumes and untreated fields and from fields previously treated with AF36 across the southern United States. One haplotype dominated across time and space. No recombination with strains belonging to VCGs other than YV36 was detected. All YV36 isolates carried the SNP in aflC that prevents aflatoxin biosynthesis and the mat1-2 idiomorph at the mating-type locus. These results suggest that VCG YV36 has a clonal population structure maintained across both time and space. These results demonstrate the genetic stability of atoxigenic strains belonging to a broadly distributed endemic VCG in both untreated populations and populations where the short-term frequency of VCG YV36 has increased due to applications of a strain used to competitively exclude aflatoxin producers. This work supports the hypothesis that strains of this VCG are not involved in routine genetic exchange with aflatoxin-producing strains. PMID:26092465

  16. Vitality Stains and Real Time PCR Studies to Delineate the Interactions of Pichia anomala and Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this study were to probe the effect of the yeast, P. anomala against A flavus by using real time RT-PCR technique and vitality fluorescent stains. Yeast and fungi were inoculated into a 250 ml-flask containing 50 ml potato dextrose broth (PDB) at yeast to fungus (Y : F) ratios of ...

  17. Facing the problem of "false positives": re-assessment and improvement of a multiplex RT-PCR procedure for the diagnosis of A. flavus mycotoxin producers.

    PubMed

    Degola, F; Berni, E; Spotti, E; Ferrero, I; Restivo, F M

    2009-02-28

    The aim of our research project was to consolidate a multiplex RT-PCR protocol to detect aflatoxigenic strains of Aspergillus flavus. Several independent A. flavus strains were isolated from corn and flour samples from the North of Italy and from three European countries. Aflatoxin producing/not producing phenotype was assessed by qualitative and quantitative assays at day five of growth in aflatoxin inducing conditions. Expression of 16 genes belonging to the aflatoxin cluster was assayed by multiplex or monomeric RT-PCR. There is a good correlation between gene expression and aflatoxin production. Strains that apparently transcribed all the relevant genes but did not release aflatoxin in the medium ("false positives") were re-assessed for mycotoxin production after extended growth in inducing condition. All the "false positive" strains in actual fact were positive when aflatoxin determination was performed after 10 days of growth. These strains should then be re-classified as "slow aflatoxin accumulators". To optimise the diagnostic procedure, a quintuplex RT-PCR procedure was designed consisting of a primer set directed against four informative aflatoxin cluster genes and the beta-tubulin gene as an internal amplification control. In conclusion we have provided evidence for the robustness and reliability of our RT-PCR protocol in discriminating mycotoxin producer from non-producer strains of A. flavus. and the molecular procedure we devised is a promising tool with which to screen and control the endemic population of A. flavus colonising different areas of the World.

  18. Influence of sub-lethal antioxidant doses, water potential and temperature on growth, sclerotia, aflatoxins and aflD (=nor-1) expression by Aspergillus flavus RCP08108.

    PubMed

    Passone, María Alejandra; Rosso, Laura Cristina; Etcheverry, Miriam

    2012-09-01

    Effects of interacting conditions of sub-lethal levels of antioxidants, water potential (Ψ) and temperature were evaluated on growth, sclerotial characteristics, aflatoxin B(1) (AFB(1)) production and aflD (=nor-1) gene expression by Aspergillus flavus strain RCP08108. These studies were carried out on peanut meal extract agar osmotically modified to -2.8,-7.1, -9.9 and -16.0 MPa and incubated at 28 and 20°C. The food grade antioxidants added were butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) at (1+1 mM-M1) and (5+5 mM-M2). To relate the aflD expression after toxigenic A. flavus grew under interacting stress conditions, real-time PCR was used. Antioxidant mixtures caused a higher and significant (p<0.001) reduction in growth rate. The major impact on size and volume sclerotia was produced by Ψ; followed by antioxidant mixtures. High AFB(1) levels were observed in response to the M1 applied at -7.1 MPa. Induction of the aflD gene was observed in response to the M1 treatment at -2.8, -7.1 and -9.9 MPa; but significant decreases of AFB(1) production and aflD transcripts were observed; when the fungus grew in the presence of the M2 treatment. These results showed that it is necessary to apply food-grade antioxidants into the peanut storage system at levels higher than 5 mM. This is an important tool to avoid sub-lethal antioxidant doses that can lead to fungal growth, increase resistance structures, and stimulate aflD gene expression and AFB(1) accumulation in this substrate.

  19. Regional differences in production of aflatoxin B1 and cyclopiazonic acid by soil isolates of aspergillus flavus along a transect within the United States.

    PubMed

    Horn, B W; Dorner, J W

    1999-04-01

    Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in regions where peanuts are not commonly grown. The A. flavus isolates were identified as members of either the L strain (n = 774), which produces sclerotia that are >400 micrometer in diameter, or the S strain (n = 309), which produces numerous small sclerotia that are <400 micrometer in diameter. The S-strain isolates generally produced high levels of aflatoxin B1, whereas the L-strain isolates were more variable in aflatoxin production; variation in cyclopiazonic acid production also was greater in the L strain than in the S strain. There was a positive correlation between aflatoxin B1 production and cyclopiazonic acid production in both strains, although 12% of the L-strain isolates produced only cyclopiazonic acid. Significant differences in production of aflatoxin B1 and cyclopiazonic acid by the L-strain isolates were detected among regions. In the western half of Texas and the peanut-growing region of Georgia and Alabama, 62 to 94% of the isolates produced >10 microgram of aflatoxin B1 per ml. The percentages of isolates producing >10 microgram of aflatoxin B1 per ml ranged from 0 to 52% in the remaining regions of the transect; other isolates were often nonaflatoxigenic. A total of 53 of the 126 L-strain isolates that did not produce aflatoxin B1 or cyclopiazonic acid were placed in 17 vegetative compatibility groups. Several of these groups contained isolates from widely separated regions of the transect.

  20. Natural control of corn postharvest fungi Aspergillus flavus and Penicillium sp. using essential oils from plants grown in Argentina.

    PubMed

    Camiletti, Boris X; Asensio, Claudia M; Pecci, María de la Paz Giménez; Lucini, Enrique I

    2014-12-01

    The objective in this study was to evaluate the antifungal activity of essential oils from native and commercial aromatic plants grown in Argentina against corn postharvest fungi and to link the essential oil bioactivity with lipid oxidation and morphological changes in fungus cell membrane. Essential oil (EO) of oregano variety Mendocino (OMen), Cordobes (OCor), and Compacto (OCom), mint variety Inglesa (Mi), and Pehaujo (Mp), Suico (Sui); rosemary (Ro), and Aguaribay (Ag) were tested in vitro against 4 corn fungi: A. flavus (CCC116-83 and BXC01), P. oxalicum (083296), and P. minioluteum (BXC03). The minimum fungicidal concentration (MFC) and the minimum inhibitory concentration (MIC) were determined. The chemical profiles of the EOs were analyzed by GC-MS. Lipid oxidation in cell membrane of fungi was determined by hydroperoxides and related with essential oil antifungal activity. The major compounds were Thymol in OCor (18.66%), Omen (12.18%), and OCom (9.44%); menthol in Mi and Mp; verbenone in Sui; dehydroxy-isocalamendiol in Ag; and eucaliptol in Ro. OCor, Omen, and OCom showed the best antifungal activity. No antifungal activity was observed in Ag and Ro EO. The hydroperoxide value depended on the fungi (P < 0.001) and the antimicrobial agent (P < 0.001).Membrane lipids were oxidized by Sui EO in A. flavus BXC01 and A. flavus CCC116-83 (0.021 and 0.027 meqO2 /kg, respectively). The results suggest that the EOs of OCor, OMen, OCom, Mi, Mp, and Sui grown in Argentina can be used as natural alternatives to control fungi that produce mycotoxin in maize. PMID:25376651

  1. Environmental distribution and genetic diversity of vegetative compatibility groups determine biocontrol strategies to mitigate aflatoxin contamination of maize by Aspergillus flavus.

    PubMed

    Atehnkeng, Joseph; Donner, Matthias; Ojiambo, Peter S; Ikotun, Babatunde; Augusto, Joao; Cotty, Peter J; Bandyopadhyay, Ranajit

    2016-01-01

    Maize infected by aflatoxin-producing Aspergillus flavus may become contaminated with aflatoxins, and as a result, threaten human health, food security and farmers' income in developing countries where maize is a staple. Environmental distribution and genetic diversity of A. flavus can influence the effectiveness of atoxigenic isolates in mitigating aflatoxin contamination. However, such information has not been used to facilitate selection and deployment of atoxigenic isolates. A total of 35 isolates of A. flavus isolated from maize samples collected from three agro-ecological zones of Nigeria were used in this study. Ecophysiological characteristics, distribution and genetic diversity of the isolates were determined to identify vegetative compatibility groups (VCGs). The generated data were used to inform selection and deployment of native atoxigenic isolates to mitigate aflatoxin contamination in maize. In co-inoculation with toxigenic isolates, atoxigenic isolates reduced aflatoxin contamination in grain by > 96%. A total of 25 VCGs were inferred from the collected isolates based on complementation tests involving nitrate non-utilizing (nit(-)) mutants. To determine genetic diversity and distribution of VCGs across agro-ecological zones, 832 nit(-) mutants from 52 locations in 11 administrative districts were paired with one self-complementary nitrate auxotroph tester-pair for each VCG. Atoxigenic VCGs accounted for 81.1% of the 153 positive complementations recorded. Genetic diversity of VCGs was highest in the derived savannah agro-ecological zone (H = 2.61) compared with the southern Guinea savannah (H = 1.90) and northern Guinea savannah (H = 0.94) zones. Genetic richness (H = 2.60) and evenness (E5  = 0.96) of VCGs were high across all agro-ecological zones. Ten VCGs (40%) had members restricted to the original location of isolation, whereas 15 VCGs (60%) had members located between the original source of isolation and a distance

  2. The vegetative compatibility group to which the US biocontrol agent Aspergillus flavus AF36 belongs is also endemic to Mexico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are naturally occurring and carcinogenic mycotoxins produced by several members of Aspergillus section Flavi. These potent toxins frequently contaminate maize in warm production areas. Maize provides over half the caloric intake for the majority of the population of Mexico. However, most ...

  3. Genome Sequences of Eight Aspergillus flavus spp. and One A. parasiticus sp., Isolated from Peanut Seeds in Georgia.

    PubMed

    Faustinelli, Paola C; Wang, Xinye Monica; Palencia, Edwin R; Arias, Renée S

    2016-04-14

    Aspergillus flavusandA. parasiticusfungi produce carcinogenic mycotoxins in peanut seeds, causing considerable impact on both human health and the economy. Here, we report nine genome sequences ofAspergillusspp., isolated from Georgia peanut seeds in 2014. The information obtained will lead to further biodiversity studies that are essential for developing control strategies.

  4. Characterization of species of the Aspergillus section Nigri from corn field isolates co-infected with Aspergillus flavus/parasiticus species and the potential for ochratoxin A production.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Members of the Aspergillus section Nigri, known as black-spored aspergilli, can contaminate several substrates including maize. Although some species within the group can produce plant disease symptoms such as black mold in onions and maize ear rot, the main concern with A. niger aggregate contamina...

  5. Aflatoxins B and g contamination and aflatoxigenic fungi in nutmeg.

    PubMed

    Okano, Kiyoshi; Tomita, Tsuneyoshi; Ohzu, Yuji; Takai, Mitsuhiro; Ose, Ayaka; Kotsuka, Akiko; Ikeda, Naoko; Sakata, Junko; Kumeda, Yuko; Nakamura, Nobuya; Ichinoe, Masakatsu

    2012-01-01

    This study examined the distribution of aflatoxigenic fungi in 25 imported Indonesian nutmeg samples contaminated with aflatoxins Bs or Bs and Gs. The incidence of aflatoxigenic fungi in the samples contaminated with high levels of aflatoxin was significantly higher than that in the samples with low levels of the toxins(r=0.752). The aflatoxin production of isolates from the samples in cultures of YES broth was examined by means of TLC and HPLC analyses. The ability of isolates to produce aflatoxins did not necessarily correlate with the contamination levels of aflatoxin in the samples. We isolated aflatoxins B and G-producing fungi from 3 samples contaminated with the high levels of aflatoxins B and G. The aflatoxigenic isolates were identified as Aspergillus nomius and A. bombycis based on morphological characters, growth rates at 37°C and 42°C and also molecular-genetic methods. Our results indicate that these two species are mainly responsible for aflatoxin G contamination in nutmeg products.

  6. Effects of Temperature, Water Activity, and Incubation Time on Production of Aflatoxins and Cyclopiazonic Acid by an Isolate of Aspergillus flavus in Surface Agar Culture

    PubMed Central

    Gqaleni, N.; Smith, J. E.; Lacey, J.; Gettinby, G.

    1997-01-01

    An experiment with a full factorial design was used to study the effects of and interactions among temperature, water activity (a(infw)), incubation period, and substrate on coproduction of aflatoxins (AF) and cyclopiazonic acid (CPA) by an isolate of Aspergillus flavus. Analysis of variance showed that there was a complex interaction among all of these factors and that this influenced the relative concentrations of the mycotoxins produced. The optimum temperatures for the production of AF and CPA were 30(deg)C and 25(deg)C, respectively. Both mycotoxins were maximally produced (0.306 to 0.330 (mu)g of AF(middot)ml of medium(sup-1), 4.040 to 6.256 (mu)g of CPA(middot)ml of medium(sup-1)) at an a(infw) of 0.996 and after 15 days of incubation. No AF were produced in either yeast extract agar or Czapek yeast autolysate agar medium at an a(infw) of 0.90 at 20 or 37(deg)C after 15 days (minimum conditions), while 0.077 to 0.439 (mu)g of CPA(middot)ml of medium(sup-1) was produced under the same conditions. Yeast extract agar favored maximum AF production, and Czapek yeast autolysate agar favored maximum CPA production. PMID:16535539

  7. Aflatoxin production in six peanut (Arachis hypogaea L.) genotypes infected with Aspergillus flavus and Aspergillus parasiticus, isolated from peanut production areas of Cordoba, Argentina.

    PubMed

    Asis, Ramon; Barrionuevo, Damian L; Giorda, Laura M; Nores, Maria L; Aldao, Mario A

    2005-11-16

    Aflatoxin contamination is one of the main factors affecting peanut seed quality. One of the strategies to decrease the risk of peanut aflatoxin contamination is the use of genotypes with resistance to Aspergillus infection. This laboratory study reports the resistance to Aspergillus infection and aflatoxin contamination of six peanut genotypes inoculated with 21 Aspergillus isolates obtained from the peanut production region of Cordoba, Argentina. The resistance was investigated in the seed coat and cotyledons of three resistant genotypes (J11, PI 337394, and PI 337409) and three breeding lines (Manfredi 68, Colorado Irradiado, and Florman INTA) developed at the Instituto Nacional de Tecnologia Agropecuaria (INTA), Manfredi Experimental Station, Cordoba, Argentina. Resistance to fungal colonization and aflatoxin contamination was found to be associated with seed coat integrity in the PI 337394, PI 337409, and J11 genotypes, whereas the INTA breeding lines such as Colorado Irradiado showed a moderate resistance and the Manfredi 68 and Florman INTA genotypes the least resistance. Furthermore, another type of resistance associated with cotyledons was found only in the PI 337394 genotype.

  8. Colonization of wounded peanut seeds by soil fungi: selectivity for species from Aspergillus section Flavi.

    PubMed

    Horn, Bruce W

    2005-01-01

    Soil is a source of primary inoculum for Aspergillus flavus and A. parasiticus, fungi that produce highly carcinogenic aflatoxins in peanuts. Aflatoxigenic fungi commonly invade peanut seeds during maturation, and the highest concentrations of aflatoxins are found in damaged seeds. A laboratory procedure was developed in which viable peanut seeds were wounded and inoculated with field soil containing natural populations of fungi, then incubated under different conditions of seed water activity and temperature. Densities of Aspergillus section Flavi in soil used for inoculating seeds were low relative to the total numbers of filamentous fungi (<1%). Aspergillus species from section Flavi present in soil included A. flavus morphotypes L and S strains, A. parasiticus, A. caelatus, A. tamarii and A. alliaceus. Wounding was required for high incidences of fungal colonization; viability of wounded seeds had little effect on colonization by Aspergillus species. Peanut seeds were colonized by section Flavi species as well as A. niger over broad ranges of water activity (0.82-0.98) and temperature (15-37 C), and the highest incidences of seed colonization occurred at water activities of 0.92-0.96 at 22-37 C. A. parasiticus colonized peanut seeds at lower temperatures than A. flavus, and cool soil temperatures relative to temperatures of aerial crop fruits might explain why A. parasiticus is found mostly in peanuts. Other fungi, dominated by the genera Penicillium, Fusarium and Clonostachys, colonized seeds primarily at water activities and temperatures suboptimal for section Flavi species and A. niger. Eupenicillium ochrosalmoneum frequently sporulated on the conidial heads of section Flavi species and showed specificity for these fungi. The inoculation of wounded viable peanut seeds with soil containing natural populations of fungi provides a model system for studying the infection process, the interactions among fungi and those factors important in aflatoxin formation.

  9. Improvement of the antifungal activity of Litsea cubeba vapor by using a helium-neon (He-Ne) laser against Aspergillus flavus on brown rice snack bars.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Matan, Nirundorn; Danworaphong, Sorasak; Aewsiri, Tanong

    2015-12-23

    The aim of this study was to improve the antifungal activity of the volatile Litsea cubeba essential oil and its main components (citral and limonene) on brown rice snack bars by applying He-Ne laser treatment. Different volumes (50-200 μL) of L. cubeba, citral or limonene were absorbed into a filter paper and placed inside an oven (18 L). Ten brown rice snack bars (2 cm wide × 4 cm long × 0.5 cm deep) were put in an oven and heated at 180 °C for 20 min. The shelf-life of the treated snack bars at 30 °C was assessed and sensory testing was carried out to investigate their consumer acceptability. A count of total phenolic content (TPC) and Fourier transform infrared spectroscopy (FTIR) on the properties of essential oil, citral, and limonene before and after the laser treatment was studied for possible modes of action. It was found that the laser treatment improved the antifungal activity of the examined volatile L. cubeba and citral with Aspergillus flavus inhibition by 80% in comparison with those of the control not treated with the laser. L. cubeba vapor at 100 μL with the laser treatment was found to completely inhibit the growth of natural molds on the snack bars for at least 25 days; however, without essential oil vapor and laser treatment, naturally contaminating mold was observed in 3 days. Results from the sensory tests showed that the panelists were unable to detect flavor and aroma differences between essential oil treatment and the control. Laser treatment caused an increase in TPC of citral oil whereas the TPC in limonene showed a decrease after the laser treatment. These situations could result from the changing peak of the aliphatic hydrocarbons that was revealed by the FTIR spectra. PMID:26433461

  10. Improvement of the antifungal activity of Litsea cubeba vapor by using a helium-neon (He-Ne) laser against Aspergillus flavus on brown rice snack bars.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Matan, Nirundorn; Danworaphong, Sorasak; Aewsiri, Tanong

    2015-12-23

    The aim of this study was to improve the antifungal activity of the volatile Litsea cubeba essential oil and its main components (citral and limonene) on brown rice snack bars by applying He-Ne laser treatment. Different volumes (50-200 μL) of L. cubeba, citral or limonene were absorbed into a filter paper and placed inside an oven (18 L). Ten brown rice snack bars (2 cm wide × 4 cm long × 0.5 cm deep) were put in an oven and heated at 180 °C for 20 min. The shelf-life of the treated snack bars at 30 °C was assessed and sensory testing was carried out to investigate their consumer acceptability. A count of total phenolic content (TPC) and Fourier transform infrared spectroscopy (FTIR) on the properties of essential oil, citral, and limonene before and after the laser treatment was studied for possible modes of action. It was found that the laser treatment improved the antifungal activity of the examined volatile L. cubeba and citral with Aspergillus flavus inhibition by 80% in comparison with those of the control not treated with the laser. L. cubeba vapor at 100 μL with the laser treatment was found to completely inhibit the growth of natural molds on the snack bars for at least 25 days; however, without essential oil vapor and laser treatment, naturally contaminating mold was observed in 3 days. Results from the sensory tests showed that the panelists were unable to detect flavor and aroma differences between essential oil treatment and the control. Laser treatment caused an increase in TPC of citral oil whereas the TPC in limonene showed a decrease after the laser treatment. These situations could result from the changing peak of the aliphatic hydrocarbons that was revealed by the FTIR spectra.

  11. Microarray-Based Mapping for the Detection of Molecular Markers in Response to Aspergillus flavus Infection in Susceptible and Resistant Maize Lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this study were (1) to evaluate differential gene expression levels for resistance to A. flavus kernel infection in susceptible (Va35) and resistant (Mp313E) maize lines using Oligonucleotide and cDNA microarray analysis, (2) to evaluate differences in A. flavus accumulation betwee...

  12. A systems approach to model the relationship between aflatoxin gene cluster expression, environmental factors, growth and toxin production by Aspergillus flavus

    PubMed Central

    Abdel-Hadi, Ahmed; Schmidt-Heydt, Markus; Parra, Roberto; Geisen, Rolf; Magan, Naresh

    2012-01-01

    A microarray analysis was used to examine the effect of combinations of water activity (aw, 0.995–0.90) and temperature (20–42°C) on the activation of aflatoxin biosynthetic genes (30 genes) in Aspergillus flavus grown on a conducive YES (20 g yeast extract, 150 g sucrose, 1 g MgSO4·7H2O) medium. The relative expression of 10 key genes (aflF, aflD, aflE, aflM, aflO, aflP, aflQ, aflX, aflR and aflS) in the biosynthetic pathway was examined in relation to different environmental factors and phenotypic aflatoxin B1 (AFB1) production. These data, plus data on relative growth rates and AFB1 production under different aw × temperature conditions were used to develop a mixed-growth-associated product formation model. The gene expression data were normalized and then used as a linear combination of the data for all 10 genes and combined with the physical model. This was used to relate gene expression to aw and temperature conditions to predict AFB1 production. The relationship between the observed AFB1 production provided a good linear regression fit to the predicted production based in the model. The model was then validated by examining datasets outside the model fitting conditions used (37°C, 40°C and different aw levels). The relationship between structural genes (aflD, aflM) in the biosynthetic pathway and the regulatory genes (aflS, aflJ) was examined in relation to aw and temperature by developing ternary diagrams of relative expression. These findings are important in developing a more integrated systems approach by combining gene expression, ecophysiological influences and growth data to predict mycotoxin production. This could help in developing a more targeted approach to develop prevention strategies to control such carcinogenic natural metabolites that are prevalent in many staple food products. The model could also be used to predict the impact of climate change on toxin production. PMID:21880616

  13. Effect of antioxidants of aflatoxigenic molds

    SciTech Connect

    Ahmad, M.M.

    1986-01-01

    Growth and aflatoxin production by Aspergillus flavus and A. parasiticus were measured in synthetic media and chicken feed treated with butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ethoxyquin (EXQ), propyl gallate (PG) or t-butylhydroquinone (TBHQ) at 50-250 ..mu..g/g and 50-1000 ..mu..g/g, respectively. BHA at 50 ..mu..g/g in broth or agar inhibited growth and alfatoxin production by both molds. In poultry feeds, 1000 ..mu..g/g BHA was required to depress CO/sub 2/ production at day 5 of incubation, while 200 ..mu..g/g decreased aflatoxin B/sub 1/ 23.8%. BHT, EXQ, and PG had slight effects on mold growth while TBHQ enhanced growth on broth but reduced it on agar. Afaltoxin B/sub 1/ production was stimulated by EXQ, although G/sub 1/ production declines. Measurement of cellular constituents released from mycelia over 5 hours indicated that BHA doubled the release of UV-absorbing materials and increase by threefold the release of previously incorporated radiolabeled compounds. Furthermore, BHA inhibited the uptake of /sup 14/C-amino acids 8 and 44%, /sup 3/H-uridine 65 and 91%, and /sup 3/H-methyl thymidine 67 and 71%, for A. flavus and A. parasiticus, respectively, compared to untreated controls.

  14. Atypical Aspergillus parasiticus isolates from pistachio with aflR gene nucleotide insertion identical to Aspergillus sojae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are the most toxic and carcinogenic secondary metabolites produced primarily by the filamentous fungi Aspergillus flavus and Aspergillus parasiticus. The toxins cause devastating economic losses because of strict regulations on distribution of contaminated products. Aspergillus sojae are...

  15. Microbiological and physicochemical factors affecting Aspergillus section Flavi incidence in Cavendish banana (Musa cavendishii) chips production in Southern Philippines.

    PubMed

    Sales, A C; Azanza, P V; Yoshizawa, T

    2005-01-01

    Microbiological and physicochemical factors affecting the incidence of Aspergillus section Flavi in dried Cavendish banana (Musa cavendishii) chips production in Southern Philippines were examined. The average counts of Aspergillus section Flavi (AFC) in fresh and dried Cavendish bananas from 10 production batches of the Philippine Agro-Industrial Development Cooperative in Davao del Norte, Southern Philippines were 1.2 x 10(2) and 1.6 x 10(2) cfu/g, respectively. Isolates from both samples were identified to be Aspergillus flavus based on spore type and conidial structure of isolates. An increasing trend in the AFC of Cavendish bananas was observed during dried banana chips processing. Variability in the AFC between production batches was attributed to differences in aerobic and fungal populations and physicochemical characteristics of the fruits, peel damage of the raw materials, concentration of AFC in the air and food-contact surfaces of the production area, and temperature and relative humidity (RH) conditions of the environment during production and storage. Physicochemical characteristics of Cavendish bananas from the receipt of raw materials up to the first day of drying were within the reported range of values allowing growth and toxin production by aflatoxigenic fungi. Air-borne AFC varied depending on the section of the production area examined. The close proximity of the waste disposal area from the production operation to the preparation, drying and storage areas suggests that cross-contamination, probably air-borne or insect-borne was a likely occurrence. The hands of workers were also identified as AFC sources. Results of this study highlight the need for the development of strategies to control aflatoxigenic fungi and aflatoxin contamination in Philippine dried Cavendish bananas.

  16. Regulation of aflatoxin biosynthesis and branched-chain amino acids metabolism in Aspergillus flavus by 2-phenylethanol reveal biocontrol mechanism of Pichia anomala

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pichia anomala WRL-076 is a biocontrol yeast which has been shown to inhibit growth and aflatoxin production of A. flavus. Using the SPME-GC/MS analysis we identified that the volatile, 2-phenylethanol (2-PE) produced by this yeast and demonstrated that the compound inhibited aflatoxin production. W...

  17. The biodiversity of Aspergillus section Flavi in brazil nuts: from rainforest to consumer.

    PubMed

    Calderari, Thaiane O; Iamanaka, Beatriz T; Frisvad, Jens C; Pitt, John I; Sartori, Daniele; Pereira, Jose Luiz; Fungaro, Maria Helena P; Taniwaki, Marta H

    2013-01-01

    A total of 288 brazil nut samples (173 kernel and 115 shell) from the Amazon rainforest region and São Paulo State, Brazil were collected at different stages of brazil nut production. Samples were analysed for: percentages of aflatoxigenic fungal species and potential for aflatoxin production and presence of aflatoxins. Aspergillus nomius was the most common species found (1235 isolates) which amounted to 30% of the total species with potential to produce aflatoxins. This species is of concern since 100% of all isolates produced aflatoxins B(1), B(2), G(1) and G(2). Aspergillus flavus was almost equally common (1212 isolates) although only 46% produced aflatoxins under laboratory conditions, and only aflatoxins B(1) and B(2). Low number of other species with the potential to produce aflatoxins was isolated: Aspergillus arachidicola and Aspergillus bombycis produced B and G aflatoxins whilst Aspergillus pseudotamarii produced only aflatoxin B(1). The total aflatoxin levels found in samples taken from the rainforests was 0.7 μg/kg, from processing plants before and after sorting 8.0 and 0.1 μg/kg respectively, from street markets in the Amazon region 6.3 μg/kg and from supermarkets in São Paulo State 0.2 μg/kg. Processing, which included manual or mechanical sorting and drying at 60°C for 30 to 36 h, eliminated on average more than 98% of total aflatoxins. These results showed that sorting is a very effective way to decrease aflatoxin content in brazil nuts.

  18. Efficacy of Some Essential Oils Against Aspergillus flavus with Special Reference to Lippia alba Oil an Inhibitor of Fungal Proliferation and Aflatoxin B1 Production in Green Gram Seeds during Storage.

    PubMed

    Pandey, Abhay K; Sonker, Nivedita; Singh, Pooja

    2016-04-01

    During mycofloral analysis of green gram (Vigna radiata (L.) R. Wilczek) seed samples taken from different grocery stores by agar and standard blotter paper methods, 5 fungal species were identified, of which Aspergillus flavus exhibited higher relative frequency (75.20% to 80.60%) and was found to produce aflatoxin B1 . On screening of 11 plant essential oils against this mycotoxigenic fungi, Lippia alba essential oil was found to be most effective and showed absolute inhibition of mycelia growth at 0.28 μL/mL. The oil of L. alba was fungistatic and fungicidal at 0.14 and 0.28 μL/mL, respectively. Oil had broad range of fungitoxicity at its MIC value and was absolutely inhibited the AFB1 production level at 2.0 μL/mL. Chemical analysis of this oil revealed geranial (36.9%) and neral (29.3%) as major components followed by myrcene (18.6%). Application of a dose of 80 μL/0.25 L air of Lippia oil in the storage system significantly inhibited the fungal proliferation and aflatoxin production without affecting the seed germination rate. By the virtue of fungicidal, antiaflatoxigenic nature and potent efficacy in storage food system, L. alba oil can be commercialized as botanical fungicide for the protection of green gram seeds during storage. PMID:26928885

  19. Impact of bacterial biocontrol agents on aflatoxin biosynthetic genes, aflD and aflR expression, and phenotypic aflatoxin B₁ production by Aspergillus flavus under different environmental and nutritional regimes.

    PubMed

    Al-Saad, Labeed A; Al-Badran, Adnan I; Al-Jumayli, Sami A; Magan, Naresh; Rodríguez, Alicia

    2016-01-18

    The objectives of this study were to examine the efficacy of four bacterial antagonists against Aspergillus flavus using 50:50 ratio of bacterial cells/conidia for the control of aflatoxin B1 (AFB1) production on two different nutritional matrices, nutrient and maize-based media at different water availabilities (0.98, 0.94 water activity (aw) on nutrient medium; 0.995, 0.98 aw on maize meal agar medium) at 35°C. The indicators of efficacy used were the relative expression of one structural and regulatory gene in the biosynthetic pathway (aflD and aflR respectively) and the production of AFB1. These studies showed that some of the bacterial species could significantly inhibit the relative expression of the aflD and aflR genes at both 0.98 and 0.94 aw on nutrient agar. On maize-based media some of the bacterial antagonists reduced the activity of both genes at 0.94 aw and some at 0.995 aw. However, the results for AFB1 production were not consistent with the effects on gene expression. Some bacterial species stimulated AFB1 production on both nutrient and maize-based media regardless of aw. However, some bacterial treatments did inhibit AFB1 production significantly when compared to the control. Overall, this study suggests that temporal studies are required on the biosynthetic genes under different environmental and nutritional conditions to evaluate the potential of antagonists to control AFB1. PMID:26513252

  20. Aspergillus granuloma of the trigeminal ganglion

    PubMed Central

    Wiles, C M; Kocen, R S; Symon, L; Scaravilli, F

    1981-01-01

    A patient is described with aspergillus flavus granuloma of the trigeminal ganglion. The patient was effectively treated by surgical excision of most of the infected tissue followed by intensive chemotherapy with amphotericin B and flucytosine. Images PMID:6973615

  1. Isolation of pathogenic Aspergillus species from commercially-prepared potting media.

    PubMed

    Kenyon, E M; Russell, L H; McMurray, D N

    1984-09-30

    Twelve commercially-prepared potting soils were screened for the presence of pathogenic Aspergillus species. Pathogenic Aspergillus species were isolated from 67% of the soils. A fumigatus was isolated from 42% and A. flavus and A. niger from 33%.

  2. Occurrence of toxigenic Aspergillus spp. and aflatoxins in selected food commodities of Asian origin sourced in the West of Scotland.

    PubMed

    Ruadrew, Sayan; Craft, John; Aidoo, Kofi

    2013-05-01

    The occurrence of Aspergillus moulds and aflatoxins in 12 commercially-available dried foods of Asian origin were examined. All food samples, except green beans and three types of dried fruit, contained multiple genera of moulds of which Aspergillus (55%) was the most frequently detected. Penicillium (15%), Rhizopus (11%), Mucor (3%), Monascus (1%), Eurotium (1%) and unidentified (14%) were also observed. The occurrence of aflatoxigenic moulds, however, did not correspond with the occurrence of aflatoxins in foods. Aflatoxigenic Aspergillus spp. (39 isolates) were recovered from long grain rice, fragrant rice, peanuts, black beans and black pepper. The predominant Aspergillus species was A. parasiticus (61%) while Aspergillus oryzae (3%), Aspergillus utus (5%), Aspergillus niger (5%), Aspergillus ochraceus (3%) and unidentified (23%) were also observed. Long grain rice, fragrant rice, peanuts, black beans and black pepper were positive for Aspergillus but contained undetectable aflatoxins. In contrast, Jasmine brown rice and crushed chilli contained 14.7 and 11.4μg/kg of total aflatoxins, respectively, in the absence of Aspergillus so aflatoxigenic Aspergillus was present at some stage of food production. The results from this study emphasise the need for stricter control measures in reducing occurrence of aflatoxins in foods for export and domestic use.

  3. RNAi-mediated Control of Aflatoxins in Peanut: Method to Analyze Mycotoxin Production and Transgene Expression in the Peanut/Aspergillus Pathosystem.

    PubMed

    Arias, Renée S; Dang, Phat M; Sobolev, Victor S

    2015-12-21

    The Food and Agriculture Organization of the United Nations estimates that 25% of the food crops in the world are contaminated with aflatoxins. That represents 100 million tons of food being destroyed or diverted to non-human consumption each year. Aflatoxins are powerful carcinogens normally accumulated by the fungi Aspergillus flavus and A. parasiticus in cereals, nuts, root crops and other agricultural products. Silencing of five aflatoxin-synthesis genes by RNA interference (RNAi) in peanut plants was used to control aflatoxin accumulation following inoculation with A. flavus. Previously, no method existed to analyze the effectiveness of RNAi in individual peanut transgenic events, as these usually produce few seeds, and traditional methods of large field experiments under aflatoxin-conducive conditions were not an option. In the field, the probability of finding naturally contaminated seeds is often 1/100 to 1/1,000. In addition, aflatoxin contamination is not uniformly distributed. Our method uses few seeds per transgenic event, with small pieces processed for real-time PCR (RT-PCR) or small RNA sequencing, and for analysis of aflatoxin accumulation by ultra-performance liquid chromatography (UPLC). RNAi-expressing peanut lines 288-72 and 288-74, showed up to 100% reduction (p ≤ 0.01) in aflatoxin B1 and B2 compared to the control that accumulated up to 14,000 ng · g(-1) of aflatoxin B1 when inoculated with aflatoxigenic A. flavus. As reference, the maximum total of aflatoxins allowable for human consumption in the United States is 20 ng · g(-1). This protocol describes the application of RNAi-mediated control of aflatoxins in transgenic peanut seeds and methods for its evaluation. We believe that its application in breeding of peanut and other crops will bring rapid advancement in this important area of science, medicine and human nutrition, and will significantly contribute to the international effort to control aflatoxins, and potentially other

  4. RNAi-mediated Control of Aflatoxins in Peanut: Method to Analyze Mycotoxin Production and Transgene Expression in the Peanut/Aspergillus Pathosystem

    PubMed Central

    Arias, Renée S.; Dang, Phat M.; Sobolev, Victor S.

    2015-01-01

    The Food and Agriculture Organization of the United Nations estimates that 25% of the food crops in the world are contaminated with aflatoxins. That represents 100 million tons of food being destroyed or diverted to non-human consumption each year. Aflatoxins are powerful carcinogens normally accumulated by the fungi Aspergillus flavus and A. parasiticus in cereals, nuts, root crops and other agricultural products. Silencing of five aflatoxin-synthesis genes by RNA interference (RNAi) in peanut plants was used to control aflatoxin accumulation following inoculation with A. flavus. Previously, no method existed to analyze the effectiveness of RNAi in individual peanut transgenic events, as these usually produce few seeds, and traditional methods of large field experiments under aflatoxin-conducive conditions were not an option. In the field, the probability of finding naturally contaminated seeds is often 1/100 to 1/1,000. In addition, aflatoxin contamination is not uniformly distributed. Our method uses few seeds per transgenic event, with small pieces processed for real-time PCR (RT-PCR) or small RNA sequencing, and for analysis of aflatoxin accumulation by ultra-performance liquid chromatography (UPLC). RNAi-expressing peanut lines 288-72 and 288-74, showed up to 100% reduction (p≤0.01) in aflatoxin B1 and B2 compared to the control that accumulated up to 14,000 ng.g-1 of aflatoxin B1 when inoculated with aflatoxigenic A. flavus. As reference, the maximum total of aflatoxins allowable for human consumption in the United States is 20 ng.g-1. This protocol describes the application of RNAi-mediated control of aflatoxins in transgenic peanut seeds and methods for its evaluation. We believe that its application in breeding of peanut and other crops will bring rapid advancement in this important area of science, medicine and human nutrition, and will significantly contribute to the international effort to control aflatoxins, and potentially other mycotoxins in major

  5. Biocontrol of Aspergillus flavus by Pichia anomala

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins are extremely potent natural carcinogens and a major food safety concern because of potential contamination of food commodities. Threshold levels set by the U. S. Food and Drug Administration for aflatoxins in foods for domestic consumption are less than 20 parts/ billion (ppb). However, ...

  6. In vitro interactions of antifungal agents and tacrolimus against Aspergillus biofilms.

    PubMed

    Gao, Lujuan; Sun, Yi

    2015-11-01

    Aspergillus biofilms were prepared from Aspergillus fumigatus, Aspergillus flavus, and Aspergillus terreus via a 96-well plate-based method, and the combined antifungal activity of tacrolimus with azoles or amphotericin B against Aspergillus biofilms was investigated via a broth microdilution checkerboard technique system. Our results suggest that combinations of tacrolimus with voriconazole or amphotericin B have synergistic inhibitory activity against Aspergillus biofilms. However, combinations of tacrolimus with itraconazole or posaconazole exhibit no synergistic or antagonistic effects.

  7. Sex and recombination in aflatoxigenic Aspergilli: global implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For most of the half century that aflatoxigenic species have been intensively studied, these molds were known only to reproduce asexually, with parasexuality found only in the laboratory between certain mutant strains. Therefore, the fairly recent discovery of their sexual (teleomorphic) states crea...

  8. Genetic diversity of Aspergillus species isolated from onychomycosis and Aspergillus hongkongensis sp. nov., with implications to antifungal susceptibility testing.

    PubMed

    Tsang, Chi-Ching; Hui, Teresa W S; Lee, Kim-Chung; Chen, Jonathan H K; Ngan, Antonio H Y; Tam, Emily W T; Chan, Jasper F W; Wu, Andrea L; Cheung, Mei; Tse, Brian P H; Wu, Alan K L; Lai, Christopher K C; Tsang, Dominic N C; Que, Tak-Lun; Lam, Ching-Wan; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

    2016-02-01

    Thirteen Aspergillus isolates recovered from nails of 13 patients (fingernails, n=2; toenails, n=11) with onychomycosis were characterized. Twelve strains were identified by multilocus sequencing as Aspergillus spp. (Aspergillus sydowii [n=4], Aspergillus welwitschiae [n=3], Aspergillus terreus [n=2], Aspergillus flavus [n=1], Aspergillus tubingensis [n=1], and Aspergillus unguis [n=1]). Isolates of A. terreus, A. flavus, and A. unguis were also identifiable by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The 13th isolate (HKU49(T)) possessed unique morphological characteristics different from other Aspergillus spp. Molecular characterization also unambiguously showed that HKU49(T) was distinct from other Aspergillus spp. We propose the novel species Aspergillus hongkongensis to describe this previously unknown fungus. Antifungal susceptibility testing showed most Aspergillus isolates had low MICs against itraconazole and voriconazole, but all Aspergillus isolates had high MICs against fluconazole. A diverse spectrum of Aspergillus species is associated with onychomycosis. Itraconazole and voriconazole are probably better drug options for Aspergillus onychomycosis.

  9. Potential of aqueous ozone to control aflatoxigenic fungi in Brazil nuts.

    PubMed

    Freitas-Silva, Otniel; Morales-Valle, Héctor; Venâncio, Armando

    2013-01-01

    This study aimed to verify the use of aqueous ozone as alternative technology for fungal control. Brazil nuts sterilized were inoculated with either 1 × 10(6) or 1 × 10(7) conidia mL(-1) of Aspergillus flavus (MUM 9201) to determine optimal treatment parameters and different aqueous ozone contact times. These assays showed that the effect of ozone is almost immediate against A. flavus, and the optimum ozone concentration depended on the number of initial viable spores on the shell. The remaining viable spores in the ozone solution were recorded, and the rate of inactivation for each treatment was determined by assessing the ratio between the cfu of each treatment and the control. The ozonized nuts were also cultured to recover the fungal population. Aqueous ozone was effective in reducing the conidia of A. flavus and the natural fungal population associated with Brazil nuts. Aqueous ozone presented a great potential to reduce microorganisms counts in Brazil nuts with a great potential use in packing houses for decontamination step.

  10. Potential of Aqueous Ozone to Control Aflatoxigenic Fungi in Brazil Nuts

    PubMed Central

    Morales-Valle, Héctor; Venâncio, Armando

    2013-01-01

    This study aimed to verify the use of aqueous ozone as alternative technology for fungal control. Brazil nuts sterilized were inoculated with either 1 × 106 or 1 × 107 conidia mL−1 of Aspergillus flavus (MUM 9201) to determine optimal treatment parameters and different aqueous ozone contact times. These assays showed that the effect of ozone is almost immediate against A. flavus, and the optimum ozone concentration depended on the number of initial viable spores on the shell. The remaining viable spores in the ozone solution were recorded, and the rate of inactivation for each treatment was determined by assessing the ratio between the cfu of each treatment and the control. The ozonized nuts were also cultured to recover the fungal population. Aqueous ozone was effective in reducing the conidia of A. flavus and the natural fungal population associated with Brazil nuts. Aqueous ozone presented a great potential to reduce microorganisms counts in Brazil nuts with a great potential use in packing houses for decontamination step. PMID:25937982

  11. Development of greenhouse screening for resistance to Aspergillus parasiticus infection and preharvest aflatoxin contamination in peanut.

    PubMed

    Anderson, W F; Holbrook, C C; Wilson, D M

    1996-01-01

    Aspergillus flavus Link ex Fries and A. parasiticus Speare can invade peanut kernels and under certain environmental conditions produce unacceptable levels of the mycotoxin aflatoxin. A concerted effort is underway to reduce aflatoxin contamination in peanut and peanut products. A potentially effective method of control in peanut is the discovery and use of genes for resistance to either fungal invasion or aflatoxin formation. The objective of the present experimental study was to develop an effective and efficient procedure for screening individual plants or pods of single plants for resistance to invasion by the aflatoxigenic fungi and subsequent aflatoxin production. Methods of obtaining adequate drought-stress and fungal infection were developed through this series of experiments. By completely isolating the pods from the root zone and imposing drought-stress only on pegs and pods, high levels of fungal infection were observed. High amounts of preharvest aflatoxin accumulation were also produced by completely isolating the pods from the root zone. Mid-bloom inoculation with A. parasiticus-contaminated cracked corn and drought-stress periods of 40 to 60 days were the most effective procedures. This technique was used to assess peanut genotypes previously identified as being partially resistant to A. parasiticus infection or aflatoxin contamination, and segregating populations from four crosses. Variability in aflatoxin contamination was found among the 11 genotypes evaluated, however, none were significantly lower than the standard cultivars. Broad-sense heritability of four crosses was estimated through evaluation of seed from individual plants in the F2 generation. The heritability estimates of crosses GFA-2 x NC-V11 and Tifton-8 X NC-V11 were 0.46 and 0.29, respectively, but mean aflatoxin contamination levels were high (73,295 and 27,305 ppb). This greenhouse screening method could be an effective tool when genes for superior aflatoxin resistance are

  12. High sequence variations in the region containing genes encoding a cellular morphogenesis protein and the repressor of sexual development help to reveal origins of Aspergillus oryzae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus oryzae and Aspergillus flavus are closely related fungal species. The A. flavus population that produces numerous small sclerotia (S strain) and aflatoxin has a unique 1.5 kb deletion in the norB-cypA region of the aflatoxin gene cluster (the S genotype). Phylogenetic studies have indica...

  13. Development and application of a loop-mediated isothermal amplification assay for rapid identification of aflatoxigenic molds and their detection in food samples.

    PubMed

    Luo, Jie; Vogel, Rudi F; Niessen, Ludwig

    2012-10-15

    Aflatoxins are the most thoroughly studied mycotoxins. They are produced by several members of the genus Aspergillus in section Flavi with Aspergillus flavus, Aspergillus parasiticus, and Aspergillus nomius being frequently isolated from contaminated food sources. In this work, we describe the development and evaluation of loop-mediated isothermal amplification (LAMP) assays for rapid detection of the three species in separate analyses. The acl1-gene of A. flavus and amy1-genes of A. nomius and A. parasiticus were used as target genes. The detection limits were 2.4, 7.6 and 20pg of pure DNA/reaction for A. flavus, A. nomius and A. parasiticus, respectively. For specificity testing, DNA extracted from mycelia of representative strains of 39 Aspergillus species, 23 Penicillium species, 75 Fusarium species and 37 other fungal species was used as a template for the specific LAMP primer sets developed for the three target species. The LAMP assay was combined with a DNA extraction method for the analysis of pure fungal cultures as well as artificially contaminated Brazil nuts, peanuts and green coffee beans. It is suggested that the developed LAMP assay is a promising tool in the prediction of a potential aflatoxin risk in food and food raw materials and may therefore be suitable for high throughput analysis in the food industry. PMID:23107500

  14. Identification of a major xylanase from A flavus as a 14-kD protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus flavus K49 secreted at least two xylanase activities when grown on a medium containing larch (wood) xylan as a sole carbon source. Enzyme activity was assayed using an agar medium containing Remazol Brilliant Blue R conjugated oat spelt xylan as substrate. Crude enzyme preparations wer...

  15. A study on Aspergillus species in houses of asthmatic patients from Sari City, Iran and a brief review of the health effects of exposure to indoor Aspergillus.

    PubMed

    Hedayati, Mohammad T; Mayahi, Sabah; Denning, David W

    2010-09-01

    To study the distribution of Aspergillus spp. in outdoor and indoor air of asthmatic patients' houses, as well as a review on the health effects of exposure to indoor Aspergillus. Open plates containing malt extract agar media were used to isolate fungi from the indoor (n = 360) and outdoor (n = 180) air of 90 asthmatic patients' houses living in Sari City, Iran. Plates were incubated at room temperature for 7-14 days. Cultured Aspergillus spp. were identified by standard mycological techniques. All culture plates grew fungi, a testament to the ubiquitous nature of fungal exposure. Cladosporium spp. (29.2%), Aspergillus spp. (19.0%), and Penicillium spp. (18.3%) were most common inside the houses while Cladosporium spp. (44.5%), Aspergillus spp. (12.4%), and Alternaria spp. (11.1%) were most common outside the houses. Aspergillus flavus (30.1%) and A. fumigatus (23.1%) are the most commonly isolated species in indoor air. Aspergillus flavus (44.5%) and A. fumigatus (42.6%) were the most prevalent Aspergillus spp. outside. The most colony numbers of Aspergillus were isolated from kitchens (30.4%) and the least from bedrooms (21.1%). Aspergillus flavus was the most prevalent species in all sampled rooms except in the kitchen where A. fumigatus was the most common. Aspergillus flavus is the most prevalent species among the Aspergillus spp. in the indoor and outdoor of a warm climate area. In these areas, A. flavus can be a major source of allergen in the air. Therefore, minimizing indoor fungal exposure could play an important role in reducing allergic symptoms in susceptible persons. PMID:19697147

  16. Chronological aging in conidia of pathogenic Aspergillus: Comparison between species.

    PubMed

    Oliveira, Manuela; Pereira, Clara; Bessa, Cláudia; Araujo, Ricardo; Saraiva, Lucília

    2015-11-01

    Aspergillus fumigatus, Aspergillus flavus, Aspergillus terreus and Aspergillus niger are common airborne fungi, and the most frequent causative agents of human fungal infections. However, the resistance and lifetime persistence of these fungi in the atmosphere, and the mechanism of aging of Aspergillus conidia are unknown.With this work, we intended to study the processes underlying conidial aging of these four relevant and pathogenic Aspergillus species. Chronological aging was therefore evaluated in A. fumigatus, A. flavus, A. terreus and A. niger conidia exposed to environmental and human body temperatures. The results showed that the aging process in Aspergillus conidia involves apoptosis,with metacaspase activation, DNA fragmentation, and reactive oxygen species production, associated with secondary necrosis. Distinct results were observed for the selected pathogenic species. At environmental conditions, A. niger was the species with the highest resistance to aging, indicating a higher adaption to environmental conditions, whereas A. flavus followed by A. terreus were the most sensitive species. At higher temperatures (37 °C), A. fumigatus presented the longest lifespan, in accordance with its good adaptation to the human body temperature. Altogether,with this work new insights regarding conidia aging are provided, which may be useful when designing treatments for aspergillosis.

  17. Septic arthritis due to tubercular and Aspergillus co-infection.

    PubMed

    Kumar, Mukesh; Thilak, Jai; Zahoor, Adnan; Jyothi, Arun

    2016-01-01

    Aspergillus septic arthritis is a rare and serious medical and surgical problem. It occurs mainly in immunocompromised patients. Aspergillus fumigatus is the most common causative organism followed by Aspergillus flavus. The most common site affected is knee followed by shoulder, ankle, wrist, hip and sacroiliac joint. Debridement and voriconazole are primary treatment of articular aspergilosis. To the best of our knowledge, there are no reported cases of co-infection of tuberculosis (TB) and Aspergillus infecting joints. We report a case of co-infection of TB and A. flavus of hip and knee of a 60-year-old male, with type 2 diabetes mellitus. He was treated with debridement, intravenous voriconazole, and antitubercular drugs.

  18. Involvement of the nadA gene in formation of G-group aflatoxins in Aspergillus parasiticus.

    PubMed

    Cai, Jingjing; Zeng, Hongmei; Shima, Yoko; Hatabayashi, Hidemi; Nakagawa, Hiroyuki; Ito, Yasuhiro; Adachi, Yoshikazu; Nakajima, Hiromitsu; Yabe, Kimiko

    2008-07-01

    The nadA gene is present at the end of the aflatoxin gene cluster in the genome of Aspergillus parasiticus as well as in Aspergillus flavus. RT-PCR analyses showed that the nadA gene was expressed in an aflatoxin-inducible YES medium, but not in an aflatoxin-non-inducible YEP medium. The nadA gene was not expressed in the aflR gene-deletion mutant, irrespective of the culture medium used. To clarify the nadA gene's function, we disrupted the gene in aflatoxigenic A. parasiticus. The four nadA-deletion mutants that were isolated commonly accumulated a novel yellow-fluorescent pigment (named NADA) in mycelia as well as in culture medium. When the mutants and the wild-type strain were cultured for 3 days in YES medium, the mutants each produced about 50% of the amounts of G-group aflatoxins that the wild-type strain produced. In contrast, the amounts of B-group aflatoxins did not significantly differ between the mutants and the wild-type strain. The NADA pigment was so unstable that it could non-enzymatically change to aflatoxin G(1) (AFG(1)). LC-MS measurement showed that the molecular mass of NADA was 360, which is 32 higher than that of AFG(1). We previously reported that at least one cytosol enzyme, together with two other microsome enzymes, is necessary for the formation of AFG(1) from O-methylsterigmatocystin (OMST) in the cell-free system of A. parasiticus. The present study confirmed that the cytosol fraction of the wild-type A.parasiticus strain significantly enhanced the AFG(1) formation from OMST, whereas the cytosol fraction of the nadA-deletion mutant did not show the same activity. Furthermore, the cytosol fraction of the wild-type strain showed the enzyme activity catalyzing the reaction from NADA to AFG(1), which required NADPH or NADH, indicating that NADA is a precursor of AFG(1); in contrast, the cytosol fraction of the nadA-deletion mutant did not show the same enzyme activity. These results demonstrated that the NadA protein is the cytosol enzyme

  19. The distribution of Aspergillus spp. opportunistic parasites in hives and their pathogenicity to honey bees.

    PubMed

    Foley, Kirsten; Fazio, Géraldine; Jensen, Annette B; Hughes, William O H

    2014-03-14

    Stonebrood is a disease of honey bee larvae caused by fungi from the genus Aspergillus. As very few studies have focused on the epidemiological aspects of stonebrood and diseased brood may be rapidly discarded by worker bees, it is possible that a high number of cases go undetected. Aspergillus spp. fungi are ubiquitous and associated with disease in many insects, plants, animals and man. They are regarded as opportunistic pathogens that require immunocompromised hosts to establish infection. Microbiological studies have shown high prevalences of Aspergillus spp. in apiaries which occur saprophytically on hive substrates. However, the specific conditions required for pathogenicity to develop remain unknown. In this study, an apiary was screened to determine the prevalence and diversity of Aspergillus spp. fungi. A series of dose-response tests were then conducted using laboratory reared larvae to determine the pathogenicity and virulence of frequently occurring isolates. The susceptibility of adult worker bees to Aspergillus flavus was also tested. Three isolates (A. flavus, Aspergillus nomius and Aspergillus phoenicis) of the ten species identified were pathogenic to honey bee larvae. Moreover, adult honey bees were also confirmed to be highly susceptible to A. flavus infection when they ingested conidia. Neither of the two Aspergillus fumigatus strains used in dose-response tests induced mortality in larvae and were the least pathogenic of the isolates tested. These results confirm the ubiquity of Aspergillus spp. in the apiary environment and highlight their potential to infect both larvae and adult bees.

  20. Draft genome sequences of two closely-related aflatoxigenic Aspergillus species obtained from the Ivory Coast

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genomes of the A. ochraceoroseus and A. rambellii type strains were sequenced using a personal genome machine, followed by annotation of their genes. The genome size for A. ochraceoroseus was found to be approximately 23 Mb and contained 7,837 genes, while the A. rambellii genome was found to be...

  1. Molecular identification of Aspergillus and Eurotium species isolated from rice and their toxin-producing ability.

    PubMed

    Yazdani, D; Zainal Abidin, M A; Tan, Y H; Kamaruzaman, S

    2011-01-01

    Thirty milled rice samples were collected from retailers in 4 provinces of Malaysia. These samples were evaluated for Aspergillus spp. infection by direct plating on malt extract salt agar (MESA). All Aspergillus holomorphs were isolated and identified using nucleotide sequences of ITS 1 and ITS 2 of rDNA. Five anamorphs (Aspergillus flavus, A. oryzae, A. tamarii, A. fumigatus and A. niger) and 5 teleomorphs (Eurotium rubrum, E. amstelodami, E. chevalieri, E. cristatum and E. tonophilum) were identified. The PCR-sequencing based technique for sequences of ITS 1 and ITS 2 is a fast technique for identification of Aspergillus and Eurotium species, although it doesn't work flawlessly for differentiation of Eurotium species. All Aspergillus and Eurotium isolates were screened for their ability to produce aflatoxin and ochratoxin A (OTA) by HPLC and TLC techniques. Only A. flavus isolate UPM 89 was able to produce aflatoxins B1 and B2. PMID:22168015

  2. Toxigenic Aspergillus and Penicillium Isolates from Weevil-Damaged Chestnuts

    PubMed Central

    Wells, John M.; Payne, Jerry A.

    1975-01-01

    Aspergillus and Penicillium were among the most common genera of fungi isolated on malt-salt agar from weevil-damaged Chinese chestnut kernels (16.8 and 40.7% occurrence, respectively). Chloroform extracts of 21 of 50 Aspergillus isolates and 18 of 50 representative Penicillium isolates, grown for 4 weeks at 21.1 C on artificial medium, were toxic to day-old cockerels. Twelve of the toxic Aspergillus isolates were identified as A. wentii, eight as A. flavus, and one as A. flavus var. columnaris. Nine of the toxic Penicillium isolates were identified as P. terrestre, three as P. steckii, two each as P. citrinum and P. funiculosum, and one each as P. herquei (Series) and P. roqueforti (Series). Acute diarrhea was associated with the toxicity of A. wentii and muscular tremors with the toxicity of P. terrestre, one isolate of P. steckii, and one of P. funiculosum. PMID:1190758

  3. Does fungicide application in vineyards induce resistance to medical azoles in Aspergillus species?

    PubMed

    Lago, Magali; Aguiar, Ana; Natário, André; Fernandes, Carla; Faria, Miguel; Pinto, Eugénia

    2014-09-01

    This study assessed if the use of sterol demethylase inhibitor fungicides in vineyard production can induce resistance to azoles in Aspergillus strains and if it can induce selection of resistant species. We also tried to identify the Aspergillus species most prevalent in the vineyards. Two vineyards from northern Portugal were selected from "Vinhos Verdes" and "Douro" regions. The vineyards were divided into plots that were treated or not with penconazole (PEN). In each vineyard, air, soil, and plant samples were collected at three different times. The strains of Aspergillus spp. were isolated and identified by morphological and molecular techniques. We identified 46 Aspergillus section Nigri, eight Aspergillus fumigatus, seven Aspergillus lentulus, four Aspergillus wentii, two Aspergillus flavus, two Aspergillus terreus, one Aspergillus calidoustus, one Aspergillus westerdijkiae, one Aspergillus tamarii, and one Eurotium amstelodami. Aspergillus strains were evaluated for their susceptibility to medical azoles used in human therapy (itraconazole, posaconazole, and voriconazole) and to agricultural azoles (PEN) used in the prevention and treatment of plant diseases. The isolates showed moderate susceptibility to voriconazole. We did not observe any decrease of susceptibility to the medical azoles tested throughout the testing period in any of the treated plots, although some of the resistant species were isolated from there.

  4. [Occurrence of indole alkaloids among secondary metabolites of soil Aspergillus].

    PubMed

    Vinokurova, N G; Khmel'nitskaia, I I; Baskunov, B P; Arinbasarov, M U

    2003-01-01

    The occurrence of indole alkaloids among secondary fungal metabolites was studied in species of the genus Aspergillus, isolated from soils that were sampled in various regions of Russia (a total of 102 isolates of the species A. niger, A. phoenicis, A. fumigatus, A. flavus, A. versicolor, A. ustus, A. clavatus, and A. ochraceus). Clavine alkaloids were represented by fumigaclavine, which was formed by A. fumigatus. alpha-Cyclopiazonic acid was formed by isolates of A. fumigatus, A. flavus, A. versicolor, A. phoenicis, and A. clavatus. The occurrence of indole-containing diketopiperazine alkaloids was documented for isolates of A. flavus, A. fumigatus, A. clavatus, and A. ochraceus. No indole-containing metabolites were found among the metabolites of A. ustus or A. niger. PMID:12722658

  5. Platelets enhance activity of antimycotic substances against non-Aspergillus fumigatus Aspergillus species in vitro.

    PubMed

    Perkhofer, Susanne; Trappl, Krista; Striessnig, Barbara; Nussbaumer, Walter; Lass-Flörl, Cornelia

    2011-02-01

    Platelets are known to be part of haemostasis but they are also players in innate host defense. Recently, we observed that platelets attenuate the virulence of Aspergillus spp. in vitro. However, little is known about the antifungal effects of platelets in the presence of antimycotics against non-A. fumigatus Aspergillus species. We therefore investigated whether platelets increase the in vitro activity of amphotericin B, voriconazole, posaconazole and caspofungin against two clinical isolates each of Aspergillus flavus, Aspergillus terreus and Aspergillus niger. The antifungal activity was evaluated by assessing germination percentages, hyphal elongation and hyphal damage by use of XTT. The combination of platelets plus amphotericin B significantly (P < 0.05) enhanced the reduction of germination percentage compared to either substance alone. Among triazoles, voriconazole exhibited significant effects with platelets for all tested aspergilli. Overall, these findings suggest that among the tested antimycotic substances, amphotericin B in combination with platelets has enhancing effects in reducing germination and hyphal elongation in the tested non-A. fumigatus Aspergillus species. These data indicate that platelets act beneficially with antimycotics in an early stage of fungal growth by blocking and/or delaying fungal germination and hyphal elongation; both crucial mechanisms in the development of invasive fungal disease.

  6. Comparison of the aflR gene sequences of strains in Aspergillus section Flavi.

    PubMed

    Lee, Chao-Zong; Liou, Guey-Yuh; Yuan, Gwo-Fang

    2006-01-01

    Aflatoxins are polyketide-derived secondary metabolites produced by Aspergillus parasiticus, Aspergillus flavus, Aspergillus nomius and a few other species. The toxic effects of aflatoxins have adverse consequences for human health and agricultural economics. The aflR gene, a regulatory gene for aflatoxin biosynthesis, encodes a protein containing a zinc-finger DNA-binding motif. Although Aspergillus oryzae and Aspergillus sojae, which are used in fermented foods and in ingredient manufacture, have no record of producing aflatoxin, they have been shown to possess an aflR gene. This study examined 34 strains of Aspergillus section Flavi. The aflR gene of 23 of these strains was successfully amplified and sequenced. No aflR PCR products were found in five A. sojae strains or six strains of A. oryzae. These PCR results suggested that the aflR gene is absent or significantly different in some A. sojae and A. oryzae strains. The sequenced aflR genes from the 23 positive strains had greater than 96.6 % similarity, which was particularly conserved in the zinc-finger DNA-binding domain. The aflR gene of A. sojae has two obvious characteristics: an extra CTCATG sequence fragment and a C to T transition that causes premature termination of AFLR protein synthesis. Differences between A. parasiticus/A. sojae and A. flavus/A. oryzae aflR genes were also identified. Some strains of A. flavus as well as A. flavus var. viridis, A. oryzae var. viridis and A. oryzae var. effuses have an A. oryzae-type aflR gene. For all strains with the A. oryzae-type aflR gene, there was no evidence of aflatoxin production. It is suggested that for safety reasons, the aflR gene could be examined to assess possible aflatoxin production by Aspergillus section Flavi strains.

  7. Aflatoxin Production in Peanut Varieties by aspergillus flavus Link and Aspergillus parasiticus Speare

    PubMed Central

    Nagarajan, V.; Bhat, Ramesh V.

    1973-01-01

    Levels of aflatoxin produced in peanuts differed with the genetic variety of plant and with the species and strain of invading fungus. Possibilities for identifying groundnut varieties partially resistant to aflatoxin production are discussed. PMID:4632857

  8. Inactivation of the lipoxygenase ZmLOX3 increases susceptibility of maize to Aspergillus spp

    PubMed Central

    Gao, Xiquan; Brodhagen, Marion; Isakeit, Tom; Brown, Sigal Horowitz; Göbel, Cornelia; Betran, Javier; Feussner, Ivo; Keller, Nancy P.; Kolomiets, Michael V.

    2009-01-01

    Plant and fungal lipoxygenases catalyze the oxidation of polyunsaturated fatty acids, creating fatty acid hydroperoxides (oxylipins). Fungal oxylipins are required for normal fungal development and secondary metabolism, and plant host-derived oxylipins interfere with these processes in fungi, presumably by signal mimicry. The maize lipoxygenase gene ZmLOX3 has been implicated previously in seed-Aspergillus interactions, so we tested the interactions of a mutant maize line (lox3–4, in which ZmLOX3 is disrupted) with the mycotoxigenic seed-infecting fungi Aspergillus flavus and Aspergillus nidulans. The lox3–4 mutant was more susceptible than wild type maize to both Aspergillus species. All strains of A. flavus and A. nidulans produced more conidia and aflatoxin (or the precursor sterigmatocystin) on lox3–4 kernels than on wild type kernels, in vitro and under field conditions. Although oxylipins did not differ detectably between A. flavus-infected kernels of the lox3–4 and WT maize, oxylipin precursors (free fatty acids) and a downstream metabolite (jasmonic acid) accumulated to greater levels in lox3–4 than in WT kernels. The increased resistance of the lox3–4 mutant to other fungal pathogens (Fusarium, Colletotrichum, Cochliobolus, and Exserohilum) is in sharp contrast with results described herein for Aspergillus, suggesting that outcomes of lipoxygenase-governed host-pathogen interactions are pathogen-specific. PMID:19132874

  9. PCR-RFLP on β-tubulin gene for rapid identification of the most clinically important species of Aspergillus.

    PubMed

    Nasri, Tuba; Hedayati, Mohammad Taghi; Abastabar, Mahdi; Pasqualotto, Alessandro C; Armaki, Mojtaba Taghizadeh; Hoseinnejad, Akbar; Nabili, Mojtaba

    2015-10-01

    Aspergillus species are important agents of life-threatening infections in immunosuppressed patients. Proper speciation in the Aspergilli has been justified based on varied fungal virulence, clinical presentations, and antifungal resistance. Accurate identification of Aspergillus species usually relies on fungal DNA sequencing but this requires expensive equipment that is not available in most clinical laboratories. We developed and validated a discriminative low-cost PCR-based test to discriminate Aspergillus isolates at the species level. The Beta tubulin gene of various reference strains of Aspergillus species was amplified using the universal fungal primers Bt2a and Bt2b. The PCR products were subjected to digestion with a single restriction enzyme AlwI. All Aspergillus isolates were subjected to DNA sequencing for final species characterization. The PCR-RFLP test generated unique patterns for six clinically important Aspergillus species, including Aspergillus flavus, Aspergillus fumigatus, Aspergillus nidulans, Aspergillus terreus, Aspergillus clavatus and Aspergillus nidulans. The one-enzyme PCR-RFLP on Beta tubulin gene designed in this study is a low-cost tool for the reliable and rapid differentiation of the clinically important Aspergillus species.

  10. 2-hydroxyisocaproic acid is fungicidal for Candida and Aspergillus species.

    PubMed

    Sakko, M; Moore, C; Novak-Frazer, L; Rautemaa, V; Sorsa, T; Hietala, P; Järvinen, A; Bowyer, P; Tjäderhane, L; Rautemaa, R

    2014-04-01

    The amino acid derivative 2-hydroxyisocaproic acid (HICA) is a nutritional additive used to increase muscle mass. Low levels can be detected in human plasma as a result of leucine metabolism. It has broad antibacterial activity but its efficacy against pathogenic fungi is not known. The aim was to test the efficacy of HICA against Candida and Aspergillus species. Efficacy of HICA against 19 clinical and reference isolates representing five Candida and three Aspergillus species with variable azole antifungal sensitivity profiles was tested using a microdilution method. The concentrations were 18, 36 and 72 mg ml(-1) . Growth was determined spectrophotometrically for Candida isolates and by visual inspection for Aspergillus isolates, viability was tested by culture and impact on morphology by microscopy. HICA of 72 mg ml(-1) was fungicidal against all Candida and Aspergillus fumigatus and Aspergillus terreus isolates. Lower concentrations were fungistatic. Aspergillus flavus was not inhibited by HICA. HICA inhibited hyphal formation in susceptible Candida albicans and A. fumigatus isolates and affected cell wall integrity. In conclusion, HICA has broad antifungal activity against Candida and Aspergillus at concentrations relevant for topical therapy. As a fungicidal agent with broad-spectrum bactericidal activity, it may be useful in the topical treatment of multispecies superficial infections.

  11. Use of benzo analogs to enhance antimycotic activity of kresoxim methyl for control of aflatoxigenic fungal pathogens

    PubMed Central

    Kim, Jong H.; Mahoney, Noreen; Chan, Kathleen L.; Campbell, Bruce C.; Haff, Ronald P.; Stanker, Larry H.

    2014-01-01

    The aim of this study was to examine two benzo analogs, octylgallate (OG) and veratraldehyde (VT), as antifungal agents against strains of Aspergillus parasiticus and A.flavus (toxigenic or atoxigenic). Both toxigenic and atoxigenic strains used were capable of producing kojic acid, another cellular secondary product. A. fumigatus was used as a genetic model for this study. When applied independently, OG exhibits considerably higher antifungal activity compared to VT. The minimum inhibitory concentrations (MICs) of OG were 0.3–0.5 mM, while that of VT were 3.0–5.0 mM in agar plate-bioassays. OG or VT in concert with the fungicide kresoxim methyl (Kre-Me; strobilurin) greatly enhanced sensitivity of Aspergillus strains to Kre-Me. The combination with OG also overcame the tolerance of A. fumigatus mitogen-activated protein kinase (MAPK) mutants to Kre-Me. The degree of compound interaction resulting from chemosensitization of the fungi by OG was determined using checkerboard bioassays, where synergistic activity greatly lowered MICs or minimum fungicidal concentrations. However, the control chemosensitizer benzohydroxamic acid, an alternative oxidase inhibitor conventionally applied in concert with strobilurin, did not achieve synergism. The level of antifungal or chemosensitizing activity was also “compound—strain” specific, indicating differential susceptibility of tested strains to OG or VT, and/or heat stress. Besides targeting the antioxidant system, OG also negatively affected the cell wall-integrity pathway, as determined by the inhibition of Saccharomyces cerevisiae cell wall-integrity MAPK pathway mutants. We concluded that certain benzo analogs effectively inhibit fungal growth. They possess chemosensitizing capability to increase efficacy of Kre-Me and thus, could reduce effective dosages of strobilurins and alleviate negative side effects associated with current antifungal practices. OG also exhibits moderate antiaflatoxigenic activity. PMID

  12. Negative regulation and developmental competence in Aspergillus

    PubMed Central

    Lee, Mi-Kyung; Kwon, Nak-Jung; Lee, Im-Soon; Jung, Seunho; Kim, Sun-Chang; Yu, Jae-Hyuk

    2016-01-01

    Asexual development (conidiation) in the filamentous fungus Aspergillus nidulans is governed by orchestrated gene expression. The three key negative regulators of conidiation SfgA, VosA, and NsdD act at different control point in the developmental genetic cascade. Here, we have revealed that NsdD is a key repressor affecting the quantity of asexual spores in Aspergillus. Moreover, nullifying both nsdD and vosA results in abundant formation of the development specific structure conidiophores even at 12 h of liquid culture, and near constitutive activation of conidiation, indicating that acquisition of developmental competence involves the removal of negative regulation exerted by both NsdD and VosA. NsdD’s role in repressing conidiation is conserved in other aspergilli, as deleting nsdD causes enhanced and precocious activation of conidiation in Aspergillus fumigatus or Aspergillus flavus. In vivo NsdD-DNA interaction analyses identify three NsdD binding regions in the promoter of the essential activator of conidiation brlA, indicating a direct repressive role of NsdD in conidiation. Importantly, loss of flbC or flbD encoding upstream activators of brlA in the absence of nsdD results in delayed activation of brlA, suggesting distinct positive roles of FlbC and FlbD in conidiation. A genetic model depicting regulation of conidiation in A. nidulans is presented. PMID:27364479

  13. Population structure and aflatoxin production by Aspergillus Sect. Flavi from maize in Nigeria and Ghana.

    PubMed

    Perrone, Giancarlo; Haidukowski, Miriam; Stea, Gaetano; Epifani, Filomena; Bandyopadhyay, Ranajit; Leslie, John F; Logrieco, Antonio

    2014-08-01

    Aflatoxins are highly toxic carcinogens that contaminate crops worldwide. Previous studies conducted in Nigeria and Ghana found high concentrations of aflatoxins in pre- and post-harvest maize. However, little information is available on the population structure of Aspergillus Sect. Flavi in West Africa. We determined the incidence of Aspergillus Sect. Flavi and the level of aflatoxin contamination in 91 maize samples from farms and markets in Nigeria and Ghana. Aspergillus spp. were recovered from 61/91 maize samples and aflatoxins B1 and/or B2 occurred in 36/91 samples. Three samples from the farms also contained aflatoxin G1 and/or G2. Farm samples were more highly contaminated than were samples from the market, in terms of both the percentage of the samples contaminated and the level of mycotoxin contamination. One-hundred-and-thirty-five strains representative of the 1163 strains collected were identified by using a multilocus sequence analysis of portions of the genes encoding calmodulin, β-tubulin and actin, and evaluated for aflatoxin production. Of the 135 strains, there were 110 - Aspergillus flavus, 20 - Aspergillus tamarii, 2 - Aspergillus wentii, 2 - Aspergillus flavofurcatus, and 1 - Aspergillus parvisclerotigenus. Twenty-five of the A. flavus strains and the A. parvisclerotigenus strain were the only strains that produced aflatoxins. The higher contamination of the farm than the market samples suggests that the aflatoxin exposure of rural farmers is even higher than previously estimated based on reported contamination of market samples. The relative infrequency of the A. flavus SBG strains, producing small sclerotia and high levels of both aflatoxins (B and G), suggests that long-term chronic exposure to this mycotoxin are a much higher health risk in West Africa than is the acute toxicity due to very highly contaminated maize in east Africa.

  14. Metabolomics Analysis Reveals Specific Novel Tetrapeptide and Potential Anti-Inflammatory Metabolites in Pathogenic Aspergillus species.

    PubMed

    Lee, Kim-Chung; Tam, Emily W T; Lo, Ka-Ching; Tsang, Alan K L; Lau, Candy C Y; To, Kelvin K W; Chan, Jasper F W; Lam, Ching-Wan; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

    2015-01-01

    Infections related to Aspergillus species have emerged to become an important focus in infectious diseases, as a result of the increasing use of immunosuppressive agents and high fatality associated with invasive aspergillosis. However, laboratory diagnosis of Aspergillus infections remains difficult. In this study, by comparing the metabolomic profiles of the culture supernatants of 30 strains of six pathogenic Aspergillus species (A. fumigatus, A. flavus, A. niger, A. terreus, A. nomius and A. tamarii) and 31 strains of 10 non-Aspergillus fungi, eight compounds present in all strains of the six Aspergillus species but not in any strain of the non-Aspergillus fungi were observed. One of the eight compounds, Leu-Glu-Leu-Glu, is a novel tetrapeptide and represents the first linear tetrapeptide observed in Aspergillus species, which we propose to be named aspergitide. Two other closely related Aspergillus-specific compounds, hydroxy-(sulfooxy)benzoic acid and (sulfooxy)benzoic acid, may possess anti-inflammatory properties, as 2-(sulfooxy)benzoic acid possesses a structure similar to those of aspirin [2-(acetoxy)benzoic acid] and salicylic acid (2-hydroxybenzoic acid). Further studies to examine the potentials of these Aspergillus-specific compounds for laboratory diagnosis of aspergillosis are warranted and further experiments will reveal whether Leu-Glu-Leu-Glu, hydroxy-(sulfooxy)benzoic acid and (sulfooxy)benzoic acid are virulent factors of the pathogenic Aspergillus species. PMID:26090713

  15. Metabolomics Analysis Reveals Specific Novel Tetrapeptide and Potential Anti-Inflammatory Metabolites in Pathogenic Aspergillus species.

    PubMed

    Lee, Kim-Chung; Tam, Emily W T; Lo, Ka-Ching; Tsang, Alan K L; Lau, Candy C Y; To, Kelvin K W; Chan, Jasper F W; Lam, Ching-Wan; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

    2015-06-17

    Infections related to Aspergillus species have emerged to become an important focus in infectious diseases, as a result of the increasing use of immunosuppressive agents and high fatality associated with invasive aspergillosis. However, laboratory diagnosis of Aspergillus infections remains difficult. In this study, by comparing the metabolomic profiles of the culture supernatants of 30 strains of six pathogenic Aspergillus species (A. fumigatus, A. flavus, A. niger, A. terreus, A. nomius and A. tamarii) and 31 strains of 10 non-Aspergillus fungi, eight compounds present in all strains of the six Aspergillus species but not in any strain of the non-Aspergillus fungi were observed. One of the eight compounds, Leu-Glu-Leu-Glu, is a novel tetrapeptide and represents the first linear tetrapeptide observed in Aspergillus species, which we propose to be named aspergitide. Two other closely related Aspergillus-specific compounds, hydroxy-(sulfooxy)benzoic acid and (sulfooxy)benzoic acid, may possess anti-inflammatory properties, as 2-(sulfooxy)benzoic acid possesses a structure similar to those of aspirin [2-(acetoxy)benzoic acid] and salicylic acid (2-hydroxybenzoic acid). Further studies to examine the potentials of these Aspergillus-specific compounds for laboratory diagnosis of aspergillosis are warranted and further experiments will reveal whether Leu-Glu-Leu-Glu, hydroxy-(sulfooxy)benzoic acid and (sulfooxy)benzoic acid are virulent factors of the pathogenic Aspergillus species.

  16. Localization of pyruvate carboxylase in organic acid-producing Aspergillus strains.

    PubMed

    Bercovitz, A; Peleg, Y; Battat, E; Rokem, J S; Goldberg, I

    1990-06-01

    The localization of pyruvate carboxylase (cytosolic or mitochondrial) was studied in nine different Aspergillus species (14 strains). In some species (A. aculeatus, A. flavus, A. foetidus, A. nidulans, A. ochraceus, and A. sojae), the pyruvate carboxylase activity could be detected only in the cytosolic fraction of the cells. Pyruvate carboxylase has been found only in the mitochondrial fraction of two strains of Aspergillus wentii. In Aspergillus oryzae and in five strains of Aspergillus niger, pyruvate carboxylase activity was detected both in the mitochondrial fraction and in the cytosol. There was no quantitative or qualitative correlation between the activities of pyruvate carboxylase in the mitochondrial and cytosolic fractions of the cells and the ability of the various Aspergillus strains to accumulate different organic acids.

  17. Comparison of different inoculating methods to evaluate the pathogenicity and virulence of Aspergillus niger on two maize hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-year field study was conducted to determine the effects of inoculation techniques on the aggressiveness of Aspergillus niger kernel infection in A. flavus resistant and susceptible maize hybrids. Ears were inoculated with the silk-channel, side-needle, and spray techniques 7 days after midsilk...

  18. DOPA and DHN pathway orchestrate melanin synthesis in Aspergillus species.

    PubMed

    Pal, Anuradha K; Gajjar, Devarshi U; Vasavada, Abhay R

    2014-01-01

    Melanins are high molecular weight hydrophobic pigments that have been studied for their role in the virulence of fungal pathogens. We investigated the amount and type of melanin in 20 isolates of Aspergillus spp.; A. niger (n = 3), A. flavus (n = 5), A. tamarii (n = 3), A. terreus (n = 3), A. tubingensis (n = 3), A. sydowii (n = 3). Aspergillus spp. were identified by sequencing the internal transcribed spacer (ITS) region. Extraction of melanin from culture filtrate and fungal biomass was done and followed by qualitative and quantitative analysis of melanin pigment. Ultraviolet (UV), Fourier transformed infrared (FT-IR), and electron paramagnetic resonance (EPR) spectra analyses confirmed the presence of melanin. The melanin pathway was studied by analyzing the effects of inhibitors; kojic acid, tropolone, phthalide, and tricyclazole. The results indicate that in A. niger and A. tubingensis melanin was found in both culture filtrate and fungal biomass. For A. tamarii and A. flavus melanin was extracted from biomass only, whereas melanin was found only in culture filtrate for A. terreus. A negligible amount of melanin was found in A. sydowii. The maximum amount of melanin from culture filtrate and fungal biomass was found in A. niger and A. tamarrii, respectively. The DOPA (3,4-dihydroxyphenylalanine) pathway produces melanin in A. niger, A. tamarii and A. flavus, whereas the DHN (1,8-dihydroxynaphthalene) pathway produces melanin in A. tubingensis and A. terreus. It can be concluded that the amount and type of melanin in aspergilli largely differ from species to species.

  19. Characterization of filamentous fungi isolated from Moroccan olive and olive cake: toxinogenic potential of Aspergillus strains.

    PubMed

    Roussos, Sevastianos; Zaouia, Nabila; Salih, Ghislane; Tantaoui-Elaraki, Abdelrhafour; Lamrani, Khadija; Cheheb, Mostafa; Hassouni, Hicham; Verhé, Fréderic; Perraud-Gaime, Isabelle; Augur, Christopher; Ismaili-Alaoui, Mustapha

    2006-05-01

    During the 2003 and 2004 olive oil production campaigns in Morocco, 136 samples from spoiled olive and olive cake were analyzed and 285 strains were isolated in pure culture. Strains included 167 mesophilic strains belonging to ten genera: Penicillium, Aspergillus, Geotrichum, Mucor, Rhizopus, Trichoderma, Alternaria, Acremonium, Humicola, Ulocladium as well as 118 thermophilic strains isolated in 2003 and 2004, mainly belonging to six species: Aspergillus fumigatus, Paecilomyces variotii, Mucor pusillus, Thermomyces lanuginosus, Humicola grisea, and Thermoascus aurantiacus. Penicillium and Aspergillus, respectively, 32.3 and 26.9% of total isolates represented the majority of mesophilic fungi isolated. When considering total strains (including thermotolerant strains) Aspergillus were the predominant strains isolated; follow-up studies on mycotoxins therefore focused primarily on aflatoxins (AFs) and ochratoxin A (OTA) from the latter strains. All isolated Aspergillus flavus strains (9) and Aspergillus niger strains (36) were studied in order to evaluate their capacity to produce AFs and OTA, respectively, when grown on starch-based culture media. Seven of the nine tested A. flavus strains isolated from olive and olive cake produced AF B1 at concentrations between 48 and 95 microg/kg of dry rice weight. As for the A. niger strains, 27 of the 36 strains produced OTA.

  20. Bioleaching of serpentine group mineral by fungus Talaromyces flavus: application for mineral carbonation

    NASA Astrophysics Data System (ADS)

    Li, Z.; Lianwen, L.; Zhao, L.; Teng, H.

    2011-12-01

    Many studies of serpentine group mineral dissolution for mineral carbonation have been published in recent years. However, most of them focus mainly on either physical and chemical processes or on bacterial function, rather than fungal involvement in the bioleaching of serpentine group mineral. Due to the excessive costs of the magnesium dissolution process, finding a lower energy consumption method will be meaningful. A fungal strain Talaromyces flavus was isolated from serpentinic rock of Donghai (China). No study of its bioleaching ability is currently available. It is thus of great significance to explore the impact of T. flavus on the dissolution of serpentine group mineral. Serpentine rock-inhabiting fungi belonging to Acremonium, Alternaria, Aspergillus, Botryotinia, Cladosporium, Clavicipitaceae, Cosmospora, Fusarium, Monascus, Paecilomyces, Penicillium, Talaromyces, Trichoderma were isolated. These strains were chosen on the basis of resistance to magnesium and nickel characterized in terms of minimum inhibiting concentration (MIC). Specifically, the strain Talaromyces flavus has a high tolerance to both magnesium (1 mol/L) and nickel (10 mM/L), and we examine its bioleaching ability on serpentine group mineral. Contact and separation experiments (cut-off 8 000-14 000 Da), as well as three control experiments, were set up for 30 days. At least three repeated tests were performed for each individual experiment. The results of our experiments demonstrate that the bioleaching ability of T. flavus towards serpentine group mineral is evident. 39.39 wt% of magnesium was extracted from lizardite during the bioleaching period in the contact experiment, which showed a dissolution rate at about a constant 0.126 mM/d before reaching equilibrium in 13 days. The amount of solubilized Mg from chrysotile and antigorite were respectively 37.79 wt% and 29.78 wt% in the contact experiment. These results make clear the influence of mineral structure on mineral bioleaching

  1. In vitro activity of disinfectants against Aspergillus spp.

    PubMed

    Mattei, A S; Madrid, I M; Santin, R; Schuch, L F D; Meireles, M C A

    2013-01-01

    Fungi of the Aspergillus genus are widespread and contaminate the environment. Thousands of conidia are released from each phialide and dispersed in the air every day. These fungi are considered important mycose-causing agents in hospitals. Due to this, research to determine prevalent fungi from the Aspergillus genus in hospital environments, and an adequate disinfection program in these areas is are needed. This study evaluated the susceptibility of Aspergillus spp. isolated from a veterinary environment against four disinfectants. Successive dilutions of disinfectants (log2) were used according to CLSI M38-A2 microdilution technique adapted to chemical agents against 18 isolates of this genus. After 72 hours of incubation, the Minimum Inhibiting Concentration and Minimum Fungicidal Concentration capable of inhibiting 50% and 90% of the isolates were determined. Chlorexidine-cetrimine, benzalconium chloride and a chlorophenol derivative proved to be effective against all isolates with a lower MIC than that suggested by the manufacturer, except for the A. flavus strain. Sodium hypochlorite was ineffective against three A. fumigatus, three A. flavus and one A. niger isolate. These results demonstrated that all studied disinfectants were effective against environmental isolates, with the exception of sodium hypochlorite, which showed lower effectiveness.

  2. Biosynthesis and Characterization of Silver Nanoparticles by Aspergillus Species.

    PubMed

    Zomorodian, Kamiar; Pourshahid, Seyedmohammad; Sadatsharifi, Arman; Mehryar, Pouyan; Pakshir, Keyvan; Rahimi, Mohammad Javad; Arabi Monfared, Ali

    2016-01-01

    Currently, researchers turn to natural processes such as using biological microorganisms in order to develop reliable and ecofriendly methods for the synthesis of metallic nanoparticles. In this study, we have investigated extracellular biosynthesis of silver nanoparticles using four Aspergillus species including A. fumigatus, A. clavatus, A. niger, and A. flavus. We have also analyzed nitrate reductase activity in the studied species in order to determine the probable role of this enzyme in the biosynthesis of silver nanoparticles. The formation of silver nanoparticles in the cell filtrates was confirmed by the passage of laser light, change in the color of cell filtrates, absorption peak at 430 nm in UV-Vis spectra, and atomic force microscopy (AFM). There was a logical relationship between the efficiencies of studied Aspergillus species in the production of silver nanoparticles and their nitrate reductase activity. A. fumigatus as the most efficient species showed the highest nitrate reductase activity among the studied species while A. flavus exhibited the lowest capacity in the biosynthesis of silver nanoparticles which was in accord with its low nitrate reductase activity. The present study showed that Aspergillus species had potential for the biosynthesis of silver nanoparticles depending on their nitrate reductase activity. PMID:27652264

  3. Biosynthesis and Characterization of Silver Nanoparticles by Aspergillus Species

    PubMed Central

    Pourshahid, Seyedmohammad; Mehryar, Pouyan; Pakshir, Keyvan; Rahimi, Mohammad Javad; Arabi Monfared, Ali

    2016-01-01

    Currently, researchers turn to natural processes such as using biological microorganisms in order to develop reliable and ecofriendly methods for the synthesis of metallic nanoparticles. In this study, we have investigated extracellular biosynthesis of silver nanoparticles using four Aspergillus species including A. fumigatus, A. clavatus, A. niger, and A. flavus. We have also analyzed nitrate reductase activity in the studied species in order to determine the probable role of this enzyme in the biosynthesis of silver nanoparticles. The formation of silver nanoparticles in the cell filtrates was confirmed by the passage of laser light, change in the color of cell filtrates, absorption peak at 430 nm in UV-Vis spectra, and atomic force microscopy (AFM). There was a logical relationship between the efficiencies of studied Aspergillus species in the production of silver nanoparticles and their nitrate reductase activity. A. fumigatus as the most efficient species showed the highest nitrate reductase activity among the studied species while A. flavus exhibited the lowest capacity in the biosynthesis of silver nanoparticles which was in accord with its low nitrate reductase activity. The present study showed that Aspergillus species had potential for the biosynthesis of silver nanoparticles depending on their nitrate reductase activity. PMID:27652264

  4. In vitro activity of disinfectants against Aspergillus spp

    PubMed Central

    Mattei, A.S.; Madrid, I.M.; Santin, R.; Schuch, L.F.D.; Meireles, M.C.A.

    2013-01-01

    Fungi of the Aspergillus genus are widespread and contaminate the environment. Thousands of conidia are released from each phialide and dispersed in the air every day. These fungi are considered important mycose-causing agents in hospitals. Due to this, research to determine prevalent fungi from the Aspergillus genus in hospital environments, and an adequate disinfection program in these areas is are needed. This study evaluated the susceptibility of Aspergillus spp. isolated from a veterinary environment against four disinfectants. Successive dilutions of disinfectants (log2) were used according to CLSI M38-A2 microdilution technique adapted to chemical agents against 18 isolates of this genus. After 72 hours of incubation, the Minimum Inhibiting Concentration and Minimum Fungicidal Concentration capable of inhibiting 50% and 90% of the isolates were determined. Chlorexidine-cetrimine, benzalconium chloride and a chlorophenol derivative proved to be effective against all isolates with a lower MIC than that suggested by the manufacturer, except for the A. flavus strain. Sodium hypochlorite was ineffective against three A. fumigatus, three A. flavus and one A. niger isolate. These results demonstrated that all studied disinfectants were effective against environmental isolates, with the exception of sodium hypochlorite, which showed lower effectiveness. PMID:24294243

  5. Biosynthesis and Characterization of Silver Nanoparticles by Aspergillus Species

    PubMed Central

    Pourshahid, Seyedmohammad; Mehryar, Pouyan; Pakshir, Keyvan; Rahimi, Mohammad Javad; Arabi Monfared, Ali

    2016-01-01

    Currently, researchers turn to natural processes such as using biological microorganisms in order to develop reliable and ecofriendly methods for the synthesis of metallic nanoparticles. In this study, we have investigated extracellular biosynthesis of silver nanoparticles using four Aspergillus species including A. fumigatus, A. clavatus, A. niger, and A. flavus. We have also analyzed nitrate reductase activity in the studied species in order to determine the probable role of this enzyme in the biosynthesis of silver nanoparticles. The formation of silver nanoparticles in the cell filtrates was confirmed by the passage of laser light, change in the color of cell filtrates, absorption peak at 430 nm in UV-Vis spectra, and atomic force microscopy (AFM). There was a logical relationship between the efficiencies of studied Aspergillus species in the production of silver nanoparticles and their nitrate reductase activity. A. fumigatus as the most efficient species showed the highest nitrate reductase activity among the studied species while A. flavus exhibited the lowest capacity in the biosynthesis of silver nanoparticles which was in accord with its low nitrate reductase activity. The present study showed that Aspergillus species had potential for the biosynthesis of silver nanoparticles depending on their nitrate reductase activity.

  6. Ultraviolet irradiation: An effective inactivation method of Aspergillus spp. in water for the control of waterborne nosocomial aspergillosis.

    PubMed

    Nourmoradi, H; Nikaeen, M; Stensvold, C R; Mirhendi, H

    2012-11-15

    Invasive aspergillosis is the second most common cause of nosocomial fungal infections and occurring mainly by Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger. There is evidence that nosocomial aspergillosis may be waterborne. This study was conducted to evaluate the ultraviolet (UV) irradiation efficiency in terms of inactivating the most important Aspergillus species in water since these are potential sources for nosocomial aspergillosis. A continuous flow UV reactor which could be used as a point-of-use (POU) system was used to survey Aspergillus inactivation by UV irradiation. The inactivation efficiency of UV fluence (4.15-25 mJ/cm(2)) was measured by determination of fungal density in water before and after radiation. Because turbidity and iron concentration are two major water quality factors impacting UV disinfection effectiveness, the potential influence of these factors on UV inactivation of Aspergillus spp. was also measured. The 4 log inactivation for A. fumigatus, A. niger and A. flavus at a density of 1000 cfu/ml was achieved at UV fluences of 12.45 mJ/cm(2), 16.6 mJ/cm(2) and 20.75 mJ/cm(2), respectively. The inactivation efficiency for lower density (100 cfu/ml) was the same as for the higher density except for A. flavus. The removal efficiency of Aspergillus spp. was decreased by increasing the turbidity and iron concentration. UV disinfection could effectively inactivate Aspergillus spores from water and eliminate potential exposure of high-risk patients to fungal aerosols by installation of POU UV systems.

  7. The Shewanella algae strain YM8 produces volatiles with strong inhibition activity against Aspergillus pathogens and aflatoxins.

    PubMed

    Gong, An-Dong; Li, He-Ping; Shen, Lu; Zhang, Jing-Bo; Wu, Ai-Bo; He, Wei-Jie; Yuan, Qing-Song; He, Jing-De; Liao, Yu-Cai

    2015-01-01

    Aflatoxigenic Aspergillus fungi and associated aflatoxins are ubiquitous in the production and storage of food/feed commodities. Controlling these microbes is a challenge. In this study, the Shewanella algae strain YM8 was found to produce volatiles that have strong antifungal activity against Aspergillus pathogens. Gas chromatography-mass spectrometry profiling revealed 15 volatile organic compounds (VOCs) emitted from YM8, of which dimethyl trisulfide was the most abundant. We obtained authentic reference standards for six of the VOCs; these all significantly reduced mycelial growth and conidial germination in Aspergillus; dimethyl trisulfide and 2,4-bis(1,1-dimethylethyl)-phenol showed the strongest inhibitory activity. YM8 completely inhibited Aspergillus growth and aflatoxin biosynthesis in maize and peanut samples stored at different water activity levels, and scanning electron microscopy revealed severely damaged conidia and a complete lack of mycelium development and conidiogenesis. YM8 also completely inhibited the growth of eight other agronomically important species of phytopathogenic fungi: A. parasiticus, A. niger, Alternaria alternate, Botrytis cinerea, Fusarium graminearum, Fusarium oxysporum, Monilinia fructicola, and Sclerotinia sclerotiorum. This study demonstrates the susceptibility of Aspergillus and other fungi to VOCs from marine bacteria and indicates a new strategy for effectively controlling these pathogens and the associated mycotoxin production during storage and possibly in the field. PMID:26500631

  8. The Shewanella algae strain YM8 produces volatiles with strong inhibition activity against Aspergillus pathogens and aflatoxins

    PubMed Central

    Gong, An-Dong; Li, He-Ping; Shen, Lu; Zhang, Jing-Bo; Wu, Ai-Bo; He, Wei-Jie; Yuan, Qing-Song; He, Jing-De; Liao, Yu-Cai

    2015-01-01

    Aflatoxigenic Aspergillus fungi and associated aflatoxins are ubiquitous in the production and storage of food/feed commodities. Controlling these microbes is a challenge. In this study, the Shewanella algae strain YM8 was found to produce volatiles that have strong antifungal activity against Aspergillus pathogens. Gas chromatography-mass spectrometry profiling revealed 15 volatile organic compounds (VOCs) emitted from YM8, of which dimethyl trisulfide was the most abundant. We obtained authentic reference standards for six of the VOCs; these all significantly reduced mycelial growth and conidial germination in Aspergillus; dimethyl trisulfide and 2,4-bis(1,1-dimethylethyl)-phenol showed the strongest inhibitory activity. YM8 completely inhibited Aspergillus growth and aflatoxin biosynthesis in maize and peanut samples stored at different water activity levels, and scanning electron microscopy revealed severely damaged conidia and a complete lack of mycelium development and conidiogenesis. YM8 also completely inhibited the growth of eight other agronomically important species of phytopathogenic fungi: A. parasiticus, A. niger, Alternaria alternate, Botrytis cinerea, Fusarium graminearum, Fusarium oxysporum, Monilinia fructicola, and Sclerotinia sclerotiorum. This study demonstrates the susceptibility of Aspergillus and other fungi to VOCs from marine bacteria and indicates a new strategy for effectively controlling these pathogens and the associated mycotoxin production during storage and possibly in the field. PMID:26500631

  9. Aspergillus surveillance project at a large tertiary-care hospital.

    PubMed

    Curtis, L; Cali, S; Conroy, L; Baker, K; Ou, C-H; Hershow, R; Norlock-Cruz, F; Scheff, P

    2005-03-01

    A one-year surveillance project was conducted at a large tertiary hospital, which had extensive indoor renovation and extensive demolition/building at several nearby sites. This study collected viable fungi samples in the hospital every six days and analysed 74 duct dust samples for Aspergillus fumigatus mycelial asp f1 protein. Mean total fungi were 257.8 cfu/m3 outdoors, 53.2 cfu/m3 in all indoor samples and 83.5 cfu/m3 in the bone marrow transplant patient rooms. Mean total aspergillus was 6.8 cfu/m3 outdoors, 12.1 cfu/m3 in all indoor samples and 7.3 cfu/m3 in the bone marrow transplant patient rooms. The five most prevalent Aspergillus species collected inside the hospital (mean cfu/m3) were Aspergillus niger 7.57 cfu/m3, Aspergillus candidus 1.72 cfu/m3, Aspergillus flavus 0.97 cfu/m3, A. fumigatus 0.88 cfu/m3 and Aspergillus glaucus 0.45 cfu/m3. In rooms undergoing duct cleaning, mean A. fumigatus concentrations were 11.0 cfu/m3. Forty-eight of 74 (65%) duct dust samples had measurable levels of asp f1 protein, with a mean level of 0.41 ppm and maximum level of 1.94 ppm. Three major incidents involved increased hospital aspergillus concentrations. A. niger levels reached 680 cfu/m3 in an organ transplant room after a water leak from a ceiling pipe. Total aspergillus concentrations rose to 77 cfu/m3 in a bone marrow transplant patient room after improper sealing and water infiltration of the unit's dedicated high-efficiency particulate air filter system. Total aspergillus levels of 160 cfu/m3 were recorded in a renovation area during wood cutting. The higher concentrations of aspergillus seen inside the hospital compared with outdoors and the various moisture/HEPA filter/renovation incidents suggest that numerous small to moderate sources of aspergillus exist in the hospital. PMID:15694975

  10. Aspergillus section Flavi and aflatoxins in Algerian wheat and derived products.

    PubMed

    Riba, Amar; Bouras, Noureddine; Mokrane, Salim; Mathieu, Florence; Lebrihi, Ahmed; Sabaou, Nasserdine

    2010-10-01

    Wheat and its derivatives are a very important staple food for North African populations. The aim of this study was to analyze populations of Aspergillus section Flavi from local wheat based on aflatoxins (AFs), cyclopiazonic acid (CPA) and sclerotia production, and also to evaluate AFs-contaminated wheat collected from two different climatic regions in Algeria. A total of 108 samples of wheat were collected during the following phases: pre-harvest, storage in silos and after processing. The results revealed that among the Aspergillus species isolated, those belonging to section Flavi were predominant. Of the 150 strains of Aspergillus section Flavi isolated, 144 were identified as Aspergillus flavus and 6 as Aspergillus tamarii. We showed that 72% and 10% of the A. flavus strains produced AFs and CPA, respectively. Among the 150 strains tested, 60 produced amounts of AFB1 ranging from 12.1 to 234.6 microg/g of CYA medium. Also, we showed that most strains produced large sclerotia. AFB1was detected by HPLC in 56.6% of the wheat samples and derived products (flour, semolina and bran) with contamination levels ranging from 0.13 to 37.42 microg/kg.

  11. Host-Induced Gene Silencing (HIGS) of aflatoxin synthesis genes in peanut and maize: use of RNA interference and genetic diversity of Aspergillus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Approximately 4.5 billion people are chronically exposed to aflatoxins, these are powerful carcinogens produced by Aspergillus flavus and A. parasiticus. High levels of aflatoxins in crops result in approximately 100 million metric tons of cereals, ¬nuts, root crops and other agricultural products ...

  12. Development of RFLP-PCR method for the identification of medically important Aspergillus species using single restriction enzyme MwoI.

    PubMed

    Diba, K; Mirhendi, H; Kordbacheh, P; Rezaie, S

    2014-01-01

    In this study we attempted to modify the PCR-RFLP method using restriction enzyme MwoI for the identification of medically important Aspergillus species. Our subjects included nine standard Aspergillus species and 205 Aspergillus isolates of approved hospital acquired infections and hospital indoor sources. First of all, Aspergillus isolates were identified in the level of species by using morphologic method. A twenty four hours culture was performed for each isolates to harvest Aspergillus mycelia and then genomic DNA was extracted using Phenol-Chloroform method. PCR-RFLP using single restriction enzyme MwoI was performed in ITS regions of rDNA gene. The electrophoresis data were analyzed and compared with those of morphologic identifications. Total of 205 Aspergillus isolates included 153 (75%) environmental and 52 (25%) clinical isolates. A. flavus was the most frequently isolate in our study (55%), followed by A. niger 65(31.7%), A. fumigatus 18(8.7%), A. nidulans and A. parasiticus 2(1% each). MwoI enabled us to discriminate eight medically important Aspergillus species including A. fumigatus, A. niger, A. flavus as the most common isolated species. PCR-RFLP method using the restriction enzyme MwoI is a rapid and reliable test for identification of at least the most medically important Aspergillus species.

  13. What can comparative genomics tell us about species concepts in the genus Aspergillus?

    SciTech Connect

    Rokas, Antonis; payne, gary; Federova, Natalie D.; Baker, Scott E.; Machida, Masa; yu, Jiujiang; georgianna, D. R.; Dean, Ralph A.; Bhatnagar, Deepak; Cleveland, T. E.; Wortman, Jennifer R.; Maiti, R.; Joardar, V.; Amedeo, Paolo; Denning, David W.; Nierman, William C.

    2007-12-15

    Understanding the nature of species" boundaries is a fundamental question in evolutionary biology. The availability of genomes from several species of the genus Aspergillus allows us for the first time to examine the demarcation of fungal species at the whole-genome level. Here, we examine four case studies, two of which involve intraspecific comparisons, whereas the other two deal with interspecific genomic comparisons between closely related species. These four comparisons reveal significant variation in the nature of species boundaries across Aspergillus. For example, comparisons between A. fumigatus and Neosartorya fischeri (the teleomorph of A. fischerianus) and between A. oryzae and A. flavus suggest that measures of sequence similarity and species-specific genes are significantly higher for the A. fumigatus - N. fischeri pair. Importantly, the values obtained from the comparison between A. oryzae and A. flavus are remarkably similar to those obtained from an intra-specific comparison of A. fumigatus strains, giving support to the proposal that A. oryzae represents a distinct ecotype of A. flavus and not a distinct species. We argue that genomic data can aid Aspergillus taxonomy by serving as a source of novel and unprecedented amounts of comparative data, as a resource for the development of additional diagnostic tools, and finally as a knowledge database about the biological differences between strains and species.

  14. Evaluation of Chenopodium ambrosioides oil as a potential source of antifungal, antiaflatoxigenic and antioxidant activity.

    PubMed

    Kumar, Rajesh; Mishra, Ajay Kumar; Dubey, N K; Tripathi, Y B

    2007-04-10

    Essential oil extracted from the leaves of Chenopodium ambrosioides Linn. (Chenopodiaceae) was tested against the aflatoxigenic strain of test fungus Aspergillus flavus Link. The oil completely inhibited the mycelial growth at 100 microg/ml. The oil exhibited broad fungitoxic spectrum against Aspergillus niger, Aspergillus fumigatus, Botryodiplodia theobromae, Fusarium oxysporum, Sclerotium rolfsii, Macrophomina phaseolina, Cladosporium cladosporioides, Helminthosporium oryzae and Pythium debaryanum at 100 microg/ml. The oil showed significant efficacy in inhibiting the aflatoxin B1 production by the aflatoxigenic strain of A. flavus. During in vivo investigation it protected stored wheat from different storage fungi for one year. Chenopodium oil also exhibited potent antioxidant activity when tested by ABTS method. All these observations suggest the possible exploitation of the Chenopodium oil as potential botanical fungitoxicant in ecofriendly control of post harvest biodeterioration of food commodities from storage fungi.

  15. Aspergillus pragensis sp. nov. discovered during molecular reidentification of clinical isolates belonging to Aspergillus section Candidi.

    PubMed

    Hubka, Vit; Lyskova, Pavlina; Frisvad, Jens C; Peterson, Stephen W; Skorepova, Magdalena; Kolarik, Miroslav

    2014-08-01

    The identity of nine clinical isolates recovered from Czech patients and presumptively identified as Aspergillus sp. section Candidi based on colony morphology was revised using sequences of β-tubulin, calmodulin gene sequence, and internal transcribed spacer rDNA. Six isolates were from suspected and proven onychomycosis, one from otitis externa, and two associated with probable invasive aspergillosis. The results showed that one Aspergillus candidus isolate was the cause of otitis externa, and both isolates obtained from sputa of patients with probable invasive aspergillosis were reidentified as A. carneus (sect. Terrei) and A. flavus (sect. Flavi). Three isolates from nail scrapings were identified as A. tritici, a verified agent of nondermatophyte onychomycosis. One isolate from toenail was determined to be A. candidus and the two isolates belonged to a hitherto undescribed species, Aspergillus pragensis sp. nov. This species is well supported by phylogenetic analysis based on β-tubulin and calmodulin gene and is distinguishable from other members of sect. Candidi by red-brown reverse on malt extract agar, slow growth on Czapek-Dox agar and inability to grow at 37°C. A secondary metabolite analysis was also provided with comparison of metabolite spectrum to other species. Section Candidi now encompasses five species for which a dichotomous key based on colony characteristics is provided. All clinical isolates were tested for susceptibilities to selected antifungal agents using the Etest and disc diffusion method. Overall sect. Candidi members are highly susceptible to common antifungals.

  16. Detection of Aspergillus-specific antibodies by agar gel double immunodiffusion and IgG ELISA in feline upper respiratory tract aspergillosis.

    PubMed

    Barrs, V R; Ujvari, B; Dhand, N K; Peters, I R; Talbot, J; Johnson, L R; Billen, F; Martin, P; Beatty, J A; Belov, K

    2015-03-01

    Feline upper respiratory tract aspergillosis (URTA) is an emerging infectious disease. The aims of this study were: (1) to assess the diagnostic value of detection of Aspergillus-specific antibodies using an agar gel double immunodiffusion (AGID) assay and an indirect immunoglobulin G (IgG) ELISA; and (2) to determine if an aspergillin derived from mycelia of Aspergillus fumigatus, Aspergillus niger and Aspergillus flavus can be used to detect serum antibodies against cryptic Aspergillus spp. in Aspergillus section Fumigati. Sera from cats with URTA (group 1: n = 21) and two control groups (group 2: cats with other upper respiratory tract diseases, n = 25; group 3: healthy cats and cats with non-respiratory, non-fungal illness, n = 84) were tested. Isolates from cats with URTA comprised A. fumigatus (n = 5), A. flavus (n = 1) and four cryptic species: Aspergillus felis (n = 12), Aspergillus thermomutatus (Neosartorya pseudofischeri, n = 1), Aspergillus lentulus (n = 1) and Aspergillus udagawae (n = 1). Brachycephalic purebred cats were significantly more likely to develop URTA than other breeds (P = 0.013). The sensitivity (Se) of the AGID was 43% and the specificity (Sp) was 100%. At a cut-off value of 6 ELISA units/mL, the Se of the IgG ELISA was 95.2% and the Sp was 92% and 92.9% for groups 2 and 3 cats, respectively. Aspergillus-specific antibodies against all four cryptic species were detected in one or both assays. Assay Se was not associated with species identity. Detection of Aspergillus-specific antibodies by IgG ELISA has high Se and Sp for diagnosis of feline URTA.

  17. The Prevalence of Aflatoxinogenic Aspergillus parasiticus in Jordan

    PubMed Central

    Al-Hmoud, Nisreen; Ibrahim, Mohammed A.; Al-Rousan, Hiyam; Alseyah, Abbas

    2012-01-01

    Aflatoxins are potent carcinogens and produced by almost all Aspergillus parasiticus isolates and about 35% of Aspergillus flavus isolates. Chemical methods are used for detection of aflatoxins in food and feed. These methods cannot detect aflatoxinogenic fungi in samples, which contain undetectable amounts of aflatoxins. The objective of this research work was to ascertain the importance of molecular and microbiological methods in detection of aflatoxinogenic fungus A. parasiticus in food and feed samples in Jordan. Specific media for the detection of aflatoxins showed the prevalence of A. parasiticus (6–22%) in contaminated food and feed samples. HPLC method confirmed the presence of aflatoxins B1, B2, G1, and G2 in food sample contaminated with A. parasiticus. Primer set OmtBII-F and OmtBII-R amplified DNA fragment of 611 base pairs from genomic DNA of aflatoxinogenic A. parasiticus isolated from food and feed samples but could not amplify DNA fragment of nonaflatoxinogenic A. flavus. The results of this study showed the prevalence of aflatoxinogenic A. parasiticus in food and feed samples in Jordan and give further evidence of suitability of microbiological and molecular methods in detection of aflatoxins, which are reliable low-cost approach to determine food and feed biosafety. PMID:22606204

  18. Effects of atmospheric pressure non-thermal plasma treatments on aflatoxigenic fungi and its host

    NASA Astrophysics Data System (ADS)

    Chen, Bo-Chen

    2015-09-01

    This experiment tests the ability of atmospheric pressure non-thermal plasma treatments in the prevention of fungi infection. There are charged particles, electric field, radicals and UV light inside plasmas and these elements might trigger different physical or chemical effects during non-thermal plasma treatments. In this experiment, the experimental samples received indirect plasma treatments with different time duration and gas compositions which mean only the remote effects caused by plasma treatments could be seen. In this work, plasmas were produced by dielectric barrier discharge method. The operation gases were air and a mixed gas of 97% He and 3%O2. After plasma treatments, fungi growth rate was observed by taking pictures and the existence of aflatoxin was qualitatively detected by black light method. The final results show that the radicals in both He/O2 and air plasma might facilitate fungi growth rate which means peanuts received indirect plasma treatments grew fungi faster than control group. The outcomes of aflatoxin detection also shows that the fungi grown on all the sample are aflatoxigenic fungi.

  19. Characterization of Aspergillus section Flavi isolated from organic Brazil nuts using a polyphasic approach.

    PubMed

    Reis, T A; Baquião, A C; Atayde, D D; Grabarz, F; Corrêa, B

    2014-09-01

    Brazil nut (Bertholletia excelsa), an important non-timber forest product from Amazonia, is commercialized in worldwide markets. The main importers of this nut are North America and European countries, where the demand for organic products has grown to meet consumers concerned about food safety. Thus, the precise identification of toxigenic fungi is important because the Brazil nut is susceptible to colonization by these microorganisms. The present study aimed to characterize by polyphasic approach strains of Aspergillus section Flavi from organic Brazil nuts. The results showed Aspergillus flavus as the main species found (74.4%), followed by Aspergillus nomius (12.7%). The potential mycotoxigenic revealed that 80.0% of A. flavus were toxin producers, 14.3% of which produced only aflatoxin B (AFB), 22.85% of which produced only cyclopiazonic acid (CPA), and 42.85% produced both them. All strains of A. nomius were AFB and AFG producers and did not produce CPA. There is no consensus about what Aspergillus species predominates on Brazil nuts. Apparently, the origin, processing, transport and storage conditions of this commodity influence the species that are found. The understanding about population of fungi is essential for the development of viable strategies to control aflatoxins in organic Brazil nuts. PMID:24929714

  20. Characterization of Aspergillus section Flavi isolated from organic Brazil nuts using a polyphasic approach.

    PubMed

    Reis, T A; Baquião, A C; Atayde, D D; Grabarz, F; Corrêa, B

    2014-09-01

    Brazil nut (Bertholletia excelsa), an important non-timber forest product from Amazonia, is commercialized in worldwide markets. The main importers of this nut are North America and European countries, where the demand for organic products has grown to meet consumers concerned about food safety. Thus, the precise identification of toxigenic fungi is important because the Brazil nut is susceptible to colonization by these microorganisms. The present study aimed to characterize by polyphasic approach strains of Aspergillus section Flavi from organic Brazil nuts. The results showed Aspergillus flavus as the main species found (74.4%), followed by Aspergillus nomius (12.7%). The potential mycotoxigenic revealed that 80.0% of A. flavus were toxin producers, 14.3% of which produced only aflatoxin B (AFB), 22.85% of which produced only cyclopiazonic acid (CPA), and 42.85% produced both them. All strains of A. nomius were AFB and AFG producers and did not produce CPA. There is no consensus about what Aspergillus species predominates on Brazil nuts. Apparently, the origin, processing, transport and storage conditions of this commodity influence the species that are found. The understanding about population of fungi is essential for the development of viable strategies to control aflatoxins in organic Brazil nuts.

  1. Characterization of experimentally induced, nonaflatoxigenic variant strains of Aspergillus parasiticus.

    PubMed Central

    Kale, S P; Cary, J W; Bhatnagar, D; Bennett, J W

    1996-01-01

    Six previously isolated, nonaflatoxigenic variants of Aspergillus parasiticus, designated sec mutants, were characterized morphologically by electron microscopy, biochemically by biotransformation studies with an aflatoxin precursor, and genetically by Northern (RNA) hybridization analysis of aflatoxin biosynthetic gene transcripts. Scanning electron micrographs clearly demonstrated that compared with the parental sec+ forms, the variant sec forms had an abundance of vegetative mycelia, orders of magnitude reduced number of conidiophores and conidia, and abnormal metulae. Conidiospores were detected in sec cultures only at higher magnifications (x 500), in contrast to the sec+ (wild-type) strain, in which abundant conidiospores (masking the vegetative mycelia) were observed at even lower magnifications (x 300). All sec+ forms, but none of the sec forms, showed bioconversion of sterigmatocystin to aflatoxins. Northern blots probed with pathway genes demonstrated lack of expression of both the aflatoxin biosynthetic pathway structural (nor-1 and omtA) and regulatory (aflR) genes in the sec forms; PCR and Southern hybridization analysis confirmed the presence of the genes in the sec genomes. Thus, the loss of aflatoxigenic capabilities in the sec form is correlated with alterations in the conidial morphology of the fungus, suggesting that the regulation of aflatoxin synthesis and conidiogenesis may be interlinked. PMID:8795232

  2. Aspergillus spinal epidural abscess

    SciTech Connect

    Byrd, B.F. III; Weiner, M.H.; McGee, Z.A.

    1982-12-17

    A spinal epidural abscess developed in a renal transplant recipient; results of a serum radioimmunoassay for Aspergillus antigen were positive. Laminectomy disclosed an abscess of the L4-5 interspace and L-5 vertebral body that contained hyphal forms and from which Aspergillus species was cultured. Serum Aspergillus antigen radioimmunoassay may be a valuable, specific early diagnostic test when systemic aspergillosis is a consideration in an immunosuppressed host.

  3. Antimycotic activity of 5'-prenylisoflavanones of the plant Geoffroea decorticans, against Aspergillus species.

    PubMed

    Quiroga, Emma N; Sampietro, Diego A; Sgariglia, Melina A; Soberón, José R; Vattuone, Marta A

    2009-06-01

    The antifungal activity of the ethanolic extract (EE), (3R)-5,7,2',3'-tetrahydroxy-4'-methoxy-5'-prenylisoflavanone (1) and (3R)-7-2'-3'-trihydroxy-4'-methoxy-5'-prenylisoflavanone (2) isolated from Geoffroea decorticans was evaluated against four different species of Aspergillus. Their effect was compared with that displayed by synthetic products. The antifungal activity was assayed by bioautography, hyphal radial growth, hyphal extent and microdilution in liquid medium. The percentage of hyphal radial growth inhibition produced by EE varied between 18.4+/-0.1 and 39.6+/-0.2 for Aspergillus nomius VSC23 and Aspergillus nomius 13137, respectively; and the same value for 1 and 2 were between 31.2+/-0.1-60.8+/-1.5 and 28.9+/-0.7-57.2+/-0.6 for Aspergillus flavus (IEV 018) and Aspergillus nomius 13137, respectively. The values of MIC/MFC determined for EE, 1 and 2 were compared with the actions of ascorbic and sorbic acids, and clotrimazole. The sequence of antifungal potency was clotrimazole>1>2>ascorbic acid>sorbic acid>EE. Consequently, EE as well as the purified substances from Geoffroea decorticans would be used as biopesticides against Aspergillus species. The cytotoxicity was evaluated.

  4. Environmental contamination by Aspergillus spp. in laying hen farms and associated health risks for farm workers.

    PubMed

    Cafarchia, Claudia; Camarda, Antonio; Iatta, Roberta; Danesi, Patrizia; Favuzzi, Vincenza; Di Paola, Giancarlo; Pugliese, Nicola; Caroli, Anna; Montagna, Maria Teresa; Otranto, Domenico

    2014-03-01

    Data on the occurrence and epidemiology of Aspergillus spp. in laying hens farms are scant. With the aims of determining levels of airborne contamination in laying hen farms and evaluating the potential risk of infection for workers and animals, 57 air samples from 19 sheds (Group I), 69 from faeces (Group II), 19 from poultry feedstuffs (Group III) and 60 from three anatomical sites (i.e. nostrils, pharynx, ears) of 20 farm workers (Group IV) were cultured. The Aspergillus spp. prevalence in samples ranged from 31.6% (Group III) to 55.5% (Group IV), whereas the highest conidia concentration was retrieved in Group II (1.2 × 10(4) c.f.u. g(-1)) and in Group III (1.9 × 10(3) c.f.u. g(-1)). The mean concentration of airborne Aspergillus spp. conidia was 70 c.f.u. m(-3) with Aspergillus fumigatus (27.3%) being the most frequently detected species, followed by Aspergillus flavus (6.3%). These Aspergillus spp. were also isolated from human nostrils (40%) and ears (35%) (P<0.05) (Group IV). No clinical aspergillosis was diagnosed in hens. The results demonstrate a relationship between the environmental contamination in hen farms and presence of Aspergillus spp. on animals and humans. Even if the concentration of airborne Aspergillus spp. conidia (i.e. 70 c.f.u. m(-3)) herein detected does not trigger clinical disease in hens, it causes human colonization. Correct management of hen farms is necessary to control environmental contamination by Aspergillus spp., and could lead to a significant reduction of animal and human colonization.

  5. Integrative analyses reveal transcriptome-proteome correlation in biological pathways and secondary metabolism clusters in A. flavus in response to temperature

    PubMed Central

    Bai, Youhuang; Wang, Sen; Zhong, Hong; Yang, Qi; Zhang, Feng; Zhuang, Zhenhong; Yuan, Jun; Nie, Xinyi; Wang, Shihua

    2015-01-01

    To investigate the changes in transcript and relative protein levels in response to temperature, complementary transcriptomic and proteomic analyses were used to identify changes in Aspergillus flavus grown at 28 °C and 37 °C. A total of 3,886 proteins were identified, and 2,832 proteins were reliably quantified. A subset of 664 proteins was differentially expressed upon temperature changes and enriched in several Kyoto Encyclopedia of Genes and Genomes pathways: translation-related pathways, metabolic pathways, and biosynthesis of secondary metabolites. The changes in protein profiles showed low congruency with alterations in corresponding transcript levels, indicating that post-transcriptional processes play a critical role in regulating the protein level in A. flavus. The expression pattern of proteins and transcripts related to aflatoxin biosynthesis showed that most genes were up-regulated at both the protein and transcript level at 28 °C. Our data provide comprehensive quantitative proteome data of A. flavus at conducive and nonconducive temperatures. PMID:26416011

  6. Molecular analysis of Aspergillus section Flavi isolated from Brazil nuts.

    PubMed

    Gonçalves, Juliana Soares; Ferracin, Lara Munique; Carneiro Vieira, Maria Lucia; Iamanaka, Beatriz Thie; Taniwaki, Marta Hiromi; Pelegrinelli Fungaro, Maria Helena

    2012-04-01

    Brazil nuts are an important export market in its main producing countries, including Brazil, Bolivia, and Peru. Approximately 30,000 tons of Brazil nuts are harvested each year. However, substantial nut contamination by Aspergillus section Flavi occurs with subsequent production of aflatoxins. In our study, Aspergillus section Flavi were isolated from Brazil nuts (Bertholletia excelsa), and identified by morphological and molecular means. We obtained 241 isolates from nut samples, 41% positive for aflatoxin production. Eighty-one isolates were selected for molecular investigation. Pairwise genetic distances among isolates and phylogenetic relationships were assessed. The following Aspergillus species were identified: A. flavus, A. caelatus, A. nomius, A. tamarii, A. bombycis, and A. arachidicola. Additionally, molecular profiles indicated a high level of nucleotide variation within β-tubulin and calmodulin gene sequences associated with high genetic divergence from RAPD data. Among the 81 isolates analyzed by molecular means, three of them were phylogenetically distinct from all other isolates representing the six species of section Flavi. A putative novel species was identified based on molecular profiles.

  7. Toxigenic potential of Aspergillus species occurring on maize kernels from two agro-ecological zones in Kenya.

    PubMed

    Okoth, Sheila; Nyongesa, Beatrice; Ayugi, Vincent; Kang'ethe, Erastus; Korhonen, Hannu; Joutsjoki, Vesa

    2012-10-25

    Two agro-ecological zones in Kenya were selected to compare the distribution in maize of Aspergillus spp. and their toxigenicity. These were Nandi County, which is the main maize growing region in the country but where no human aflatoxicoses have been reported, and Makueni County where most of the aflatoxicosis cases have occurred. Two hundred and fifty-five households were sampled in Nandi and 258 in Makueni, and Aspergillus was isolated from maize. Aspergillus flavus and A. parasiticus isolates were tested for the presence of aflD and aflQ genes. Positive strains were induced to produce aflatoxins on yeast extract sucrose and quantified using liquid chromatography-tandem mass spectrometry (LCMSMS). Aspergillus flavus was the most common contaminant, and the incidence of occurrence in Nandi and Makueni was not significantly different (82.33% and 73.26%, respectively). Toxigenic strains were more prevalent than non-toxigenic strains. All the toxigenic strains from Makueni were of the S-type while those from Nandi belonged to the l-type. Quantitative differences in aflatoxin production in vitro between isolates and between strains were detected with S strains producing relatively larger amounts of total aflatoxins, B toxins and lower values for G toxins. This was in accord with the frequent aflatoxicosis outbreaks in Makueni. However some L strains produced considerable amounts of B toxins. Given the widespread distribution of toxigenic strains in both regions, the risk of aflatoxin poisoning is high when favorable conditions for toxin production occur.

  8. New Perspectives for the Application of Bioplastic Materials in the Biocontrol of Aspergillus flavus in Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mycotoxins are secondary metabolities produced by certain filamentous fungi that can contaminate a large variety of agricultural commodities before and after harvest. Among different mycotoxins, aflatoxins and especially aflatoxin B1 are of particular concern because they are potent natural carcino...

  9. 40 CFR 180.1254 - Aspergillus flavus NRRL 21882; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover....

  10. 40 CFR 180.1254 - Aspergillus flavus NRRL 21882; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover....

  11. 40 CFR 180.1254 - Aspergillus flavus NRRL 21882; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover....

  12. 40 CFR 180.1254 - Aspergillus flavus NRRL 21882; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover....

  13. 40 CFR 180.1254 - Aspergillus flavus NRRL 21882; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover....

  14. 40 CFR 180.1206 - Aspergillus flavus AF36; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob with husk removed; corn, sweet, forage; corn, sweet, stover; corn, pop, grain; and corn, pop, stover, when applied/used as an antifungal agent....

  15. Blocking aflatoxins in corn by using non-toxigenic strains of Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are over 500 previously reported mycotoxins. However, only a few have been identified as important for food safety, including aflatoxins, fumonisins, cyclopiazonic acid (CPA), trichothecenes, zearalenone, ochratoxins, and patulin. Mycotoxins contaminate plant materials, causing acute and ch...

  16. Effects of hydrogen peroxide on different toxigenic and atoxigenic isolates of Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought stress in the field has been shown to exacerbate aflatoxin contamination of maize and peanut. Drought and heat stress also produce reactive oxygen species (ROS) in plant tissues. Given the potential correlation between ROS and exacerbated aflatoxin production under drought and heat stress, t...

  17. Hypersensitivity Pneumonitis in a Housewife Exposed to Aspergillus flavus in Poor Living Conditions: A Case Report

    PubMed Central

    Estibeiro, Anita Sandhya Mendonca; Mesquita, Anthony Menezes

    2016-01-01

    Hypersensitivity Pneumonitis (HP) or Extrinsic Allergic Alveolitis (EAA) is a disease resulting from immunologically induced inflammation in response to inhalation of a wide variety of airborne allergens. The condition develops mainly in non atopic individuals sensitized to organic dust due to repeated exposures. It is a relatively rare disease constituting upto 2% of interstitial lung diseases. Knowledge of classical High Resolution Computed Tomography (HRCT) of lung findings aid in early diagnosis. We report a case of subacute hypersensitivity pneumonitis in a housewife who despite being symptomatic remained undiagnosed for two years. She showed a good response to therapy, but soon relapsed. Visit to her home revealed that she lived in a damp house full of moldy walls. PMID:26894116

  18. Aflatoxin production and environmental oxidative stress in Aspergillus flavus: Implications forhost resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The contamination of maize kernel tissues with aflatoxin is of major concern in global food production, particularly in developing countries. Resistance to aflatoxin is negatively influenced by environmental stress, namely drought stress. Given that reactive oxygen species (ROS) are known to accumul...

  19. Aspergillus Collagen-Like Genes (acl): Identification, Sequence Polymorphism, and Assessment for PCR-Based Pathogen Detection

    PubMed Central

    Tuntevski, Kiril; Durney, Brandon C.; Snyder, Anna K.; LaSala, P. Rocco; Nayak, Ajay P.; Green, Brett J.; Beezhold, Donald H.; Rio, Rita V. M.; Holland, Lisa A.

    2013-01-01

    The genus Aspergillus is a burden to public health due to its ubiquitous presence in the environment, its production of allergens, and wide demographic susceptibility among cystic fibrosis, asthmatic, and immunosuppressed patients. Current methods of detection of Aspergillus colonization and infection rely on lengthy morphological characterization or nonstandardized serological assays that are restricted to identifying a fungal etiology. Collagen-like genes have been shown to exhibit species-specific conservation across the noncollagenous regions as well as strain-specific polymorphism in the collagen-like regions. Here we assess the conserved region of the Aspergillus collagen-like (acl) genes and explore the application of PCR amplicon size-based discrimination among the five most common etiologic species of the Aspergillus genus, including Aspergillus fumigatus, A. flavus, A. nidulans, A. niger, and A. terreus. Genetic polymorphism and phylogenetic analysis of the aclF1 gene were additionally examined among the available strains. Furthermore, the applicability of the PCR-based assay to identification of these five species in cultures derived from sputum and bronchoalveolar fluid from 19 clinical samples was explored. Application of capillary electrophoresis on nanogels was additionally demonstrated to improve the discrimination between Aspergillus species. Overall, this study demonstrated that Aspergillus acl genes could be used as PCR targets to discriminate between clinically relevant Aspergillus species. Future studies aim to utilize the detection of Aspergillus acl genes in PCR and microfluidic applications to determine the sensitivity and specificity for the identification of Aspergillus colonization and invasive aspergillosis in immunocompromised subjects. PMID:24123732

  20. Sexual development and cryptic sexuality in fungi: insights from Aspergillus species.

    PubMed

    Dyer, Paul S; O'Gorman, Céline M

    2012-01-01

    Major insights into sexual development and cryptic sexuality within filamentous fungi have been gained from investigations using Aspergillus species. Here, an overview is first given into sexual morphogenesis in the aspergilli, describing the different types of sexual structures formed and how their production is influenced by a variety of environmental and nutritional factors. It is argued that the formation of cleistothecia and accessory tissues, such as Hülle cells and sclerotia, should be viewed as two independent but co-ordinated developmental pathways. Next, a comprehensive survey of over 75 genes associated with sexual reproduction in the aspergilli is presented, including genes relating to mating and the development of cleistothecia, sclerotia and ascospores. Most of these genes have been identified from studies involving the homothallic Aspergillus nidulans, but an increasing number of studies have now in addition characterized 'sex-related' genes from the heterothallic species Aspergillus fumigatus and Aspergillus flavus. A schematic developmental genetic network is proposed showing the inter-relatedness between these genes. Finally, the discovery of sexual reproduction in certain Aspergillus species that were formerly considered to be strictly asexual is reviewed, and the importance of these findings for cryptic sexuality in the aspergilli as a whole is discussed.

  1. LAMP-PCR detection of ochratoxigenic Aspergillus species collected from peanut kernel.

    PubMed

    Al-Sheikh, H M

    2015-01-30

    Over the last decade, ochratoxin A (OTA) has been widely described and is ubiquitous in several agricultural products. Ochratoxins represent the second-most important mycotoxin group after aflatoxins. A total of 34 samples were surveyed from 3 locations, including Mecca, Madina, and Riyadh, Saudi Arabia, during 2012. Fungal contamination frequency was determined for surface-sterilized peanut seeds, which were seeded onto malt extract agar media. Aspergillus niger (35%), Aspergillus ochraceus (30%), and Aspergillus carbonarius (25%) were the most frequently observed Aspergillius species, while Aspergillus flavus and Aspergillus phoenicis isolates were only infrequently recovered and in small numbers (10%). OTA production was evaluated on yeast extract sucrose medium, which revealed that 57% of the isolates were A. niger and 60% of A. carbonarius isolates were OTA producers; 100% belonged to A. ochraceus. Only one isolate, morphologically identified as A. carbonarius, and 3 A. niger isolates unstably produced OTA. A polymerase chain reaction (PCR)-based identification and detection assay was used to identify A. ochraceus isolates. Using the primer sets OCRA1/OCRA2, 400-base pair PCR fragments were produced only when genomic DNA from A. ochraceus isolates was used. Recently, the loop-mediated isothermal amplification assay using recombinase polymerase amplification chemistry was used for A. carbonarius and A. niger DNA identification. As a non-gel-based technique, the amplification product was directly visualized in the reaction tube after adding calcein for naked-eye examination.

  2. Diversity, molecular phylogeny and fingerprint profiles of airborne Aspergillus species using random amplified polymorphic DNA.

    PubMed

    Kermani, Firoozeh; Shams-Ghahfarokhi, Masoomeh; Gholami-Shabani, Mohammadhassan; Razzaghi-Abyaneh, Mehdi

    2016-06-01

    In the present study, diversity and phylogenetic relationship of Aspergillus species isolated from Tehran air was studied using random amplified polymorphic DNA (RAPD)-polymerase chain reaction (RAPD-PCR). Thirty-eight Aspergillus isolates belonging to 12 species i.e. A. niger (28.94 %, 11 isolates), A. flavus (18.42 %, 7 isolates), A. tubingensis (13.15 %, 5 isolates), A. japonicus (10.52 %, 4 isolates), A. ochraceus (10.52 %, 4 isolates), and 2.63 %, 1 isolate from each A. nidulans, A. amstelodami, A. oryzae, A. terreus, A. versicolor, A. flavipes and A. fumigatus were obtained by settle plate method which they were distributed in 18 out of 22 sampling sites examined. Fungal DNA was extracted from cultured mycelia of all Aspergillus isolates on Sabouraud Dextrose Agar and used for amplification of gene fragments in RAPD-PCR using 11 primers. RAPD-PCR data was analyzed using UPGMA software. Resulting dendrogram of combined selected primers including PM1, OPW-04, OPW-05, P160, P54, P10 and OPA14 indicated the distribution of 12 Aspergillus species in 8 major clusters. The similarity coefficient of all 38 Aspergillus isolates ranged from 0.02 to 0.40 indicating a wide degree of similarities and differences within and between species. Taken together, our results showed that various Aspergillus species including some important human pathogenic ones exist in the outdoor air of Tehran by different extents in distribution and diversity and suggested inter- and intra-species genetic diversity among Aspergillus species by RAPD-PCR as a rapid, sensitive and reproducible method. PMID:27116962

  3. Biodegradation of HDPE by Aspergillus spp. from marine ecosystem of Gulf of Mannar, India.

    PubMed

    Sangeetha Devi, Rajendran; Rajesh Kannan, Velu; Nivas, Duraisamy; Kannan, Kanthaiah; Chandru, Sekar; Robert Antony, Arokiaswamy

    2015-07-15

    High density polyethylene (HDPE) is the most commonly found non-degradable solid waste among the polyethylene. In this present study, HDPE degrading various fungal strains were isolated from the polyethylene waste dumped marine coastal area and screened under in vitro condition. Based on weight loss and FT-IR Spectrophotometric analysis, two fungal strains designated as VRKPT1 and VRKPT2 were found to be efficient in HDPE degradation. Through the sequence analysis of ITS region homology, the isolated fungi were identified as Aspergillus tubingensis VRKPT1 and Aspergillus flavus VRKPT2. The biofilm formation observed under epifluorescent microscope had shown the viability of fungal strains even after one month of incubation. The biodegradation of HDPE film nature was further investigated through SEM analysis. HDPE poses severe environmental threats and hence the ability of fungal isolates was proved to utilize virgin polyethylene as the carbon source without any pre-treatment and pro-oxidant additives. PMID:26006776

  4. Biodegradation of HDPE by Aspergillus spp. from marine ecosystem of Gulf of Mannar, India.

    PubMed

    Sangeetha Devi, Rajendran; Rajesh Kannan, Velu; Nivas, Duraisamy; Kannan, Kanthaiah; Chandru, Sekar; Robert Antony, Arokiaswamy

    2015-07-15

    High density polyethylene (HDPE) is the most commonly found non-degradable solid waste among the polyethylene. In this present study, HDPE degrading various fungal strains were isolated from the polyethylene waste dumped marine coastal area and screened under in vitro condition. Based on weight loss and FT-IR Spectrophotometric analysis, two fungal strains designated as VRKPT1 and VRKPT2 were found to be efficient in HDPE degradation. Through the sequence analysis of ITS region homology, the isolated fungi were identified as Aspergillus tubingensis VRKPT1 and Aspergillus flavus VRKPT2. The biofilm formation observed under epifluorescent microscope had shown the viability of fungal strains even after one month of incubation. The biodegradation of HDPE film nature was further investigated through SEM analysis. HDPE poses severe environmental threats and hence the ability of fungal isolates was proved to utilize virgin polyethylene as the carbon source without any pre-treatment and pro-oxidant additives.

  5. Sex, drugs and recombination: the wild life of Aspergillus.

    PubMed

    Fisher, Matthew C; Henk, Daniel A

    2012-03-01

    Throughout the eukaryotes, sexual reproduction is an almost universal phenomenon. However, within the Kingdom Fungi, this relationship is not so clear-cut. Fungi exhibit a spectrum of reproductive modes and life-cycles; amongst the better known species, sexual reproduction is often facultative, can be rare, and in over half of the known Ascomycota (the moulds) is unknown (Taylor et al. 1999). However, over the last decade, it has become apparent that many of these asexual mitosporic taxa undergo cryptic recombination via unobserved mechanisms and that wholly asexual fungi are, in fact, a rarity (Taylor et al. 1999, 2001; Heitman 2010). This revolution in our understanding of fungal sexuality has come about in two ways: Firstly, sexual reproduction leaves an imprint on fungal genomes by maintaining genes required for mating and by generating patterns of mutation and recombination restricted to meiotic processes. Secondly, scientists have become better at catching fungi in flagrante delicto. The genus Aspergillus is one such fungus where a combination of population genetics, genomics and taxonomy has been able to intuit the existence of sex, then to catch the fungus in the act and formally describe their sexual stages. So, why are sexy moulds exciting? One species in particular, Aspergillus flavus, is notorious for its ability to produce a diverse array of secondary metabolites, of which the polyketide aflatoxins (AF) are carcinogenic and others (such as cyclopiazonic acid) are toxigenic. Because of the predilection of A. flavus to grow on crops, such as peanuts, corn and cotton, biocontrol is widely used to mitigate infection by pre-applying nonaflatoxigenic (AF-) strains to competitively exclude the wild-type AF+ strains. However, the eventual fate in nature of these biocontrol strains is not known. In this issue of Molecular Ecology, Olarte et al. (2012) make an important contribution by using laboratory crosses of A. flavus to show that not only is AF highly

  6. New species of Aspergillus producing sterigmatocystin.

    PubMed Central

    Rabie, C J; Steyn, M; van Schalkwyk, G C

    1977-01-01

    A number of species belonging to the genus Aspergillus were evaluated for their toxicity to ducklings and the ability to produce sterigmatocystin. Three new species capable of producing sterigmatocystin were found, namely, Aspergillus aurantio-brunneus, Aspergillus quadrilineatus, and Aspergillus ustus. All three were toxic to ducklings. The production of sterigmatocystin by Aspergillus rugulosus was confirmed, and the toxicity of Aspergillus stellatus and Aspergillus multicolor is described. PMID:406838

  7. Development in Aspergillus

    PubMed Central

    Krijgsheld, P.; Bleichrodt, R.; van Veluw, G.J.; Wang, F.; Müller, W.H.; Dijksterhuis, J.; Wösten, H.A.B.

    2013-01-01

    The genus Aspergillus represents a diverse group of fungi that are among the most abundant fungi in the world. Germination of a spore can lead to a vegetative mycelium that colonizes a substrate. The hyphae within the mycelium are highly heterogeneous with respect to gene expression, growth, and secretion. Aspergilli can reproduce both asexually and sexually. To this end, conidiophores and ascocarps are produced that form conidia and ascospores, respectively. This review describes the molecular mechanisms underlying growth and development of Aspergillus. PMID:23450714

  8. Occupational exposure to Aspergillus by swine and poultry farm workers in Portugal.

    PubMed

    Sabino, R; Faísca, V M; Carolino, E; Veríssimo, C; Viegas, C

    2012-01-01

    Aspergillus is among a growing list of allergens that aggravate asthmatic responses. Significant pulmonary pathology is associated with Aspergillus-induced allergic and asthmatic lung disease. Environments with high levels of exposure to fungi are found in animal production facilities such as for swine and poultry, and farmers working with these are at increased risk for occupational respiratory diseases. Seven Portuguese poultry and seven swine farms were analyzed in order to estimate the prevalence, amount, and distribution of Aspergillus species, as well as to determine the presence of clinical symptoms associated with asthma and other allergy diseases in these highly contaminated settings. From the collected fungal isolates (699), an average incidence of 22% Aspergillus was detected in poultry farms, while the prevalence at swine farms was 14%. The most frequently isolated Aspergillus species were A. versicolor, A. flavus, and A. fumigatus. In poultry farms, A. flavus presented the highest level of airborne spores (>2000 CFU/m³), whereas in swine farms the highest was A. versicolor, with an incidence fourfold greater higher than the other mentioned species. Eighty workers in these settings were analyzed, ranging in age from 17 to 93 yr. The potentially hazardous exposure of poultry workers to mold allergens using sensitization markers was evaluated. Although no significant positive association was found between fungal contamination and sensitization to fungal antigens, a high incidence of respiratory symptoms in professionals without asthma was observed, namely, wheezing associated with dyspnea (23.8%) and dyspnea after strenuous activities (12.3%), suggesting underdiagnosed respiratory disturbances. Further, 32.5% of all exposed workers noted an improvement of respiratory ability during resting and holidays. From all the analyzed workers, seven were previously diagnosed with asthma and four reported the first attack after the age of 40 yr, which may be

  9. Mycoflora and ochratoxin A producing strains of Aspergillus in Algerian wheat.

    PubMed

    Riba, A; Mokrane, S; Mathieu, F; Lebrihi, A; Sabaou, N

    2008-02-29

    Wheat is a basic staple food for very large segments of the population of Algeria. The aim of this study is to analyse ochratoxin A (OTA)-producing mould and OTA-contaminated wheat. To evaluate the mycoflora and the potential for OTA production by Aspergillus strains, a total of 85 samples of wheat destined for human consumption were collected from two regions in Algeria (Tizi Ouzou and Setif) during the following phases: preharvest, storage in silos, and after processing. The mean value counts of fungi ranged from 275 to 1277 CFU g(-1). The dominant genus was Aspergillus, predominantly A. flavus, A. niger and A. versicolor. The other isolated species were A. ochraceus, A. alliaceus, A. carbonarius, A. terreus, A. fumigatus, A. candidus and Aspergillus spp. The occurrence and the levels of the genus Penicillium, Fusarium, Alternaria and Mucor were substantially lower than those of Aspergillus. The storage in silos shows high levels of Aspergillus (66 to 84%), especially A. flavus, but A. niger and other fungi were isolated at relatively low percentages. Equal distribution of the fungal contamination into the bran, flour and semolina fractions was observed from Flour Mill and Semolina Mill. The genus Aspergillus remained present at high levels at several phases of the production process. In addition, the ability to produce OTA by 135 isolates belonging to eleven species of Aspergillus and 23 isolates of Penicillium spp. was analyzed using fluorescent detection-based HPLC. Thus, it was found that 51 isolates (32.3%) were ochratoxigenic. All isolated strains of A. ochraceus (12) and A. alliaceus (6) produced OTA at concentrations ranging from 0.23 to 11.50 microg g(-1). Most of the A. carbonarius strains (80%) were OTA producers (0.01 to 9.35 microg g(-1)), whereas A. terreus (50%), A. niger (28%), A. fumigatus (40%), A. versicolor (18%) and Penicillium spp. (21.7%) were low level producers (0.01 to 0.07 microg g(-1)). The concentration of OTA was determined in 30

  10. Application of essential oils in maize grain: impact on Aspergillus section Flavi growth parameters and aflatoxin accumulation.

    PubMed

    Bluma, Romina V; Etcheverry, Miriam G

    2008-04-01

    The antifungal activity of Pimpinella anisum L. (anise), Pëumus boldus Mol (boldus), Hedeoma multiflora Benth (mountain thyme), Syzygium aromaticum L. (clove), and Lippia turbinate var. integrifolia (griseb) (poleo) essential oils (EOs) against Aspergillus section Flavi was evaluated in sterile maize grain under different water activity (a(w)) condition (0.982, 0.955, and 0.90). The effect of EOs added to maize grains on growth rate, lag phase, and aflatoxin B(1) (AFB(1)) accumulation of Aspergillus section Flavi were evaluated at different water activity conditions. The five EOs analyzed have been shown to influence lag phase and growth rate. Their efficacy depended mainly on the essential oil concentrations and substrate water activity conditions. All EOs showed significant impact on AFB(1) accumulation. This effect was closely dependent on the water activity, concentration, and incubation periods. Important reduction of AFB(1) accumulation was observed in the majority of EO treatments at 11 days of incubation. Boldus, poleo, and mountain thyme EO completely inhibited AFB(1) at 2000 and 3000 microg g(-1). Inhibition of AFB(1) accumulation was also observed when aflatoxigenic isolates grew with different concentration of EOs during 35 days. PMID:18206775

  11. [Aspergillus insulicola Sp. Nov].

    PubMed

    de Montemayor, L; Santiago, A R

    1975-04-30

    A strain of Aspergillus sp. is described and proposed as a new species under the name "Aspergillus insulicola sp. nov." Montemayor & Santiago, 1973. This strain was isolated from soil samples taken in "Aves Island" during a scientific expedition.--Aves Island, situated at 15 degrees, 40 feet, 42 inches N and 63 degrees, 36 feet, 47 inches W, about 665 Km of the coast of Venezuela, has very special ecological conditions. Due to its smallness: 550 m long and 40 to 120 m across and to its low profile only 3 m over sea level, it is swept by the sea during the periodical storms and hurricanes in the area. It has thus a very interesting fauna and flora. We took a series of soil samples to study its mycological flora. Forty samples were inoculated by dilution method. In this first paper a species is described and proposed as a new species because of its macroscopic and microscopic characteristics, as well as by its biological properties, under the name "Aspergillus insulicola sp. nov.". In its study we have tried to follow as closely as possible the methods recommended by Kennet B. Raper & Dorothy Fenell, world authorities on the genera Aspergillus and Penicillium. The strain is being kept in USB under the number T1, and has been sent to ATCC & CBSC to be incorporated in their collections.

  12. Inhibitory effect of seven Allium plants upon three Aspergillus species.

    PubMed

    Yin, M C; Tsao, S M

    1999-08-01

    Antifungal activity and minimal fungicidal concentration (MFC) of extracts of garlic, bakeri garlic, Chinese leek, Chinese chive, scallion, onion bulb and shallot bulb against Aspergillus niger, A. flavus and A. fumigatus were examined. These Allium plants possessed antifungal activity, with garlic showing the lowest MFC. With the exception of scallion, the inhibitory effect of Allium plants against three Aspergillus species decreased with increasing incubation and heating temperature (P < 0.05). Acetic acid treatments of the extracts increased the inhibitory effect for all plants against three fungi (P < 0.05), and there was no significant difference in this effect among the three pH (2, 4, 6) treatments (P > 0.05) investigated. Acetic acid, at pH = 4, plus heat treatments of the extracts resulted in a greater inhibitory effect for all Allium plants against the three fungi than heat treatment alone (P < 0.05). Treatments of the extracts with NaCl, at concentrations of 0.2 and 0.4 M, did not affect the inhibitory effect of the plant extracts. The combination of acetic acid plus Allium plants was indicated to be an effective way to inhibit fungal growth. PMID:10477070

  13. Identification by Molecular Methods and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry and Antifungal Susceptibility Profiles of Clinically Significant Rare Aspergillus Species in a Referral Chest Hospital in Delhi, India.

    PubMed

    Masih, Aradhana; Singh, Pradeep K; Kathuria, Shallu; Agarwal, Kshitij; Meis, Jacques F; Chowdhary, Anuradha

    2016-09-01

    Aspergillus species cause a wide spectrum of clinical infections. Although Aspergillus fumigatus and Aspergillus flavus remain the most commonly isolated species in aspergillosis, in the last decade, rare and cryptic Aspergillus species have emerged in diverse clinical settings. The present study analyzed the distribution and in vitro antifungal susceptibility profiles of rare Aspergillus species in clinical samples from patients with suspected aspergillosis in 8 medical centers in India. Further, a matrix-assisted laser desorption ionization-time of flight mass spectrometry in-house database was developed to identify these clinically relevant Aspergillus species. β-Tubulin and calmodulin gene sequencing identified 45 rare Aspergillus isolates to the species level, except for a solitary isolate. They included 23 less common Aspergillus species belonging to 12 sections, mainly in Circumdati, Nidulantes, Flavi, Terrei, Versicolores, Aspergillus, and Nigri Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identified only 8 (38%) of the 23 rare Aspergillus isolates to the species level. Following the creation of an in-house database with the remaining 14 species not available in the Bruker database, the MALDI-TOF MS identification rate increased to 95%. Overall, high MICs of ≥2 μg/ml were noted for amphotericin B in 29% of the rare Aspergillus species, followed by voriconazole in 20% and isavuconazole in 7%, whereas MICs of >0.5 μg/ml for posaconazole were observed in 15% of the isolates. Regarding the clinical diagnoses in 45 patients with positive rare Aspergillus species cultures, 19 (42%) were regarded to represent colonization. In the remaining 26 patients, rare Aspergillus species were the etiologic agent of invasive, chronic, and allergic bronchopulmonary aspergillosis, allergic fungal rhinosinusitis, keratitis, and mycetoma. PMID:27413188

  14. The potential of Origanum vulgare L. (Lamiaceae) essential oil in inhibiting the growth of some food-related Aspergillus species

    PubMed Central

    Carmo, Egberto Santos; de Oliveira Lima, Edeltrudes; de Souza, Evandro Leite

    2008-01-01

    Origanum vulgare L. (Lamiaceae) has been currently known for their interesting antimicrobial activity being regarded as alternative antimicrobial for use is food conservation systems. This study aimed to evaluate the effectiveness of O. vulgare essential oil in inhibiting the growth of some food-related Aspergillus species (A. flavus, A. parasiticus, A. terreus, A. ochraceus, A. fumigatus and A. niger). The essential oil revealed a strong anti-Aspergillus property providing an inhibition of all assayed mould strains. MIC values were between 80 and 20 μL/mL being found a MIC50 of 40 μL/mL. The essential oil at concentration of 80 and 40 μL/mL provided a fungicidal effect on A. flavus, A. fumigatus and A. niger noted by a total inhibition of the radial mycelial growth along 14 days of interaction. In addition, the essential oil was able to inhibit the mould spores germination when assayed at concentrations of 80 and 40 μL/mL. Our results showed the interesting anti-Aspergillus activity of O. vulgare essential oil supporting their possible use as anti-mould compound in food conservation. PMID:24031231

  15. Isolation of culturable mycobiota from agricultural soils and determination of tolerance to glyphosate of nontoxigenic Aspergillus section Flavi strains.

    PubMed

    Carranza, Cecilia S; Barberis, Carla L; Chiacchiera, Stella M; Dalcero, Ana María; Magnoli, Carina E

    2016-01-01

    Glyphosate-based herbicides are extensively used in Argentina's agricultural system to control undesirable weeds. This study was conducted to evaluate the culturable mycobiota [colony forming units (CFU) g(-1) and frequency of fungal genera or species] from an agricultural field exposed to pesticides. In addition, we evaluated the tolerance of A. oryzae and nontoxigenic A. flavus strains to high concentrations (100 to 500 mM - 17,000 to 84,500 ppm) of a glyphosate commercial formulation. The analysis of the mycobiota showed that the frequency of the main fungal genera varied according to the analyzed sampling period. Aspergillus spp. or Aspergillus section Flavi strains were isolated from 20 to 100% of the soil samples. Sterilia spp. were also observed throughout the sampling (50 to 100%). Aspergillus section Flavi tolerance assays showed that all of the tested strains were able to develop at the highest glyphosate concentration tested regardless of the water availability conditions. In general, significant reductions in growth rates were observed with increasing concentrations of the herbicide. However, a complete inhibition of fungal growth was not observed with the concentrations assayed. This study contributes to the knowledge of culturable mycobiota from agricultural soils exposed to pesticides and provides evidence on the effective growth ability of A. oryzae and nontoxigenic A. flavus strains exposed to high glyphosate concentrations in vitro. PMID:26549415

  16. Isolation of culturable mycobiota from agricultural soils and determination of tolerance to glyphosate of nontoxigenic Aspergillus section Flavi strains.

    PubMed

    Carranza, Cecilia S; Barberis, Carla L; Chiacchiera, Stella M; Dalcero, Ana María; Magnoli, Carina E

    2016-01-01

    Glyphosate-based herbicides are extensively used in Argentina's agricultural system to control undesirable weeds. This study was conducted to evaluate the culturable mycobiota [colony forming units (CFU) g(-1) and frequency of fungal genera or species] from an agricultural field exposed to pesticides. In addition, we evaluated the tolerance of A. oryzae and nontoxigenic A. flavus strains to high concentrations (100 to 500 mM - 17,000 to 84,500 ppm) of a glyphosate commercial formulation. The analysis of the mycobiota showed that the frequency of the main fungal genera varied according to the analyzed sampling period. Aspergillus spp. or Aspergillus section Flavi strains were isolated from 20 to 100% of the soil samples. Sterilia spp. were also observed throughout the sampling (50 to 100%). Aspergillus section Flavi tolerance assays showed that all of the tested strains were able to develop at the highest glyphosate concentration tested regardless of the water availability conditions. In general, significant reductions in growth rates were observed with increasing concentrations of the herbicide. However, a complete inhibition of fungal growth was not observed with the concentrations assayed. This study contributes to the knowledge of culturable mycobiota from agricultural soils exposed to pesticides and provides evidence on the effective growth ability of A. oryzae and nontoxigenic A. flavus strains exposed to high glyphosate concentrations in vitro.

  17. Fumigant antifungal activity of Myrtaceae essential oils and constituents from Leptospermum petersonii against three Aspergillus species.

    PubMed

    Kim, Eunae; Park, Il-Kwon

    2012-01-01

    Commercial plant essential oils obtained from 11 Myrtaceae plant species were tested for their fumigant antifungal activity against Aspergillus ochraceus, A. flavus, and A. niger. Essential oils extracted from Leptospermum petersonii at air concentrations of 56 × 10(-3) mg/mL and 28 × 10(-3) mg/mL completely inhibited the growth of the three Aspergillus species. However, at an air concentration of 14 × 10(-3) mg/mL, inhibition rates of L. petersonii essential oils were reduced to 20.2% and 18.8% in the case of A. flavus and A. niger, respectively. The other Myrtaceae essential oils (56 × 10(-3) mg/mL) only weakly inhibited the fungi or had no detectable affect. Gas chromatography-mass spectrometry analysis identified 16 compounds in L. petersonii essential oil. The antifungal activity of the identified compounds was tested individually by using standard or synthesized compounds. Of these, neral and geranial inhibited growth by 100%, at an air concentration of 56 × 10(-3) mg/mL, whereas the activity of citronellol was somewhat lover (80%). The other compounds exhibited only moderate or weak antifungal activity. The antifungal activities of blends of constituents identified in L. petersonii oil indicated that neral and geranial were the major contributors to the fumigant and antifungal activities. PMID:22945026

  18. Effect of Carum copticum essential oil on growth and aflatoxin formation by Aspergillus strains.

    PubMed

    Kazemi, M

    2015-01-01

    The objectives of this study were to determine the antiaflatoxin B1 activity in vitro of the essential oil (EO) extracted from the seeds of Carum copticum and to evaluate its antifungal activity in vivo as a potential food preservative. The C. copticum EO exhibited noticeable inhibition on dry mycelium and synthesis of aflatoxin B1 (AFB1) by Aspergillus flavus, completely inhibiting AFB1 production at 4 μL/mL. C. copticum EOs showed the lowest percentages of decayed cherry tomatoes for all fungi compared with the control at 100 μL/mL with values of 5.01 ± 67% for A. flavus and 5.98 ± 54% for Aspergillus niger. The results indicated that the percentage of infected fruits is significantly (p < 0.01) reduced by the EO at 16°C for 30 days. In this case, the oil at 100 μL/mL concentration showed the highest inhibition of fungal infection with a value of 80.45% compared with the control. Thus, the EO of dill could be used to control food spoilage and as a potential source of food preservative.

  19. Radiosensitivity of toxigenic Aspergillus isolated from spices and destruction of aflatoxins by gamma-irradiation

    NASA Astrophysics Data System (ADS)

    Kume, Tamikazu; Ito, Hitoshi; Soedarman, Harsono; Ishigaki, Isao

    Radiosensitivities of Aspergillus flavus var columnaris isolated from spices were investigated. The D10 values and induction doses were 267-293 Gy and 75-165 Gy in wet conditions, respectively. In dry conditions, the survival curves were exponential and D10 values were 538-600 Gy. The survival curves of standard strain of A. parasiticus IFO 30179 were similar both in wet and dry conditions. The necessary dose of 8 kGy for the destruction of these toxigenic Aspergillus was calculated from these values. Two of 11 strains of A. flavus var columnaris produced aflatoxins and the content of B 1 was especially high. In the study of irradiation effect on aflatoxins produced on polished rice, aflatoxins G 1 and B 1 were more radiosensitive than G 2 and B 2. However, these aflatoxins were very stable to radiation and the dose required for destruction was found to be more than 500 kGy. It is therfore concluded that the decontamination of molds by irradiation is necessary prior to their production of aflatoxins.

  20. Effect of Carum copticum essential oil on growth and aflatoxin formation by Aspergillus strains.

    PubMed

    Kazemi, M

    2015-01-01

    The objectives of this study were to determine the antiaflatoxin B1 activity in vitro of the essential oil (EO) extracted from the seeds of Carum copticum and to evaluate its antifungal activity in vivo as a potential food preservative. The C. copticum EO exhibited noticeable inhibition on dry mycelium and synthesis of aflatoxin B1 (AFB1) by Aspergillus flavus, completely inhibiting AFB1 production at 4 μL/mL. C. copticum EOs showed the lowest percentages of decayed cherry tomatoes for all fungi compared with the control at 100 μL/mL with values of 5.01 ± 67% for A. flavus and 5.98 ± 54% for Aspergillus niger. The results indicated that the percentage of infected fruits is significantly (p < 0.01) reduced by the EO at 16°C for 30 days. In this case, the oil at 100 μL/mL concentration showed the highest inhibition of fungal infection with a value of 80.45% compared with the control. Thus, the EO of dill could be used to control food spoilage and as a potential source of food preservative. PMID:25342249

  1. Effects of conidia of various Aspergillus species on apoptosis of human pneumocytes and bronchial epithelial cells.

    PubMed

    Féménia, F; Huet, D; Lair-Fulleringer, S; Wagner, M C; Sarfati, J; Shingarova, L; Guillot, J; Boireau, P; Chermette, R; Berkova, N

    2009-05-01

    Aspergillus species can cause mycoses in human and animals. Previously, we demonstrated that A. fumigatus conidia from a human isolate inhibited apoptosis in human pneumocytes and bronchial epithelial cells. In the current study, we studied the effects of A. fumigatus conidia non-human origin and A. flavus, A. nidulans, A. niger and A. oryzae conidia on human cells apoptosis. Human pneumocytes or bronchial epithelial cells were simultaneously exposed to apoptotic inductors and aspergilli conidia. The cell cultures were analyzed by flow cytometry, immunoblotting, and examination of nuclear morphology. Similar to A. fumigatus conidia, A. flavus conidia inhibited cellular apoptosis while A. nidulans, A. niger and A. oryzae conidia did not affect apoptosis. We further studied the species specificity of conidia: there were no differences in the inhibition of apoptosis by A. fumigatus conidia from either human or bird isolates. In order to determine whether the inhibition of apoptosis by conidia is limited to certain strains, the effect on human cell apoptosis of different A. fumigatus human clinical isolates and A. fumigatus of environmental origin was evaluated. All A. fumigatus isolates inhibited apoptosis; an anti-apoptotic factor was released by conidia. For TNF-induced apoptosis, the anti-apoptotic effect of conidia of all isolates was found to be associated with a reduction of caspase-3 in human cells. The results suggest that suppression of apoptosis may play a role in reducing the efficacy of host defense mechanisms during infection with Aspergillus species. PMID:19117118

  2. Environmental and clinical epidemiology of Aspergillus terreus: data from a prospective surveillance study.

    PubMed

    Rüping, M J G T; Gerlach, S; Fischer, G; Lass-Flörl, C; Hellmich, M; Vehreschild, J J; Cornely, O A

    2011-07-01

    Aspergillus terreus may be resistant to amphotericin B and is associated with significant morbidity and mortality in immunocompromised patients. Local incidence is influenced by the density of airborne Aspergillus spp. spores which may in turn depend on meteorological factors. Once-weekly environmental samples were collected prospectively inside and outside the University Hospital of Cologne, Germany (UHC) and haematological patients were screened for nasal Aspergillus spp. colonisation and monitored for invasive fungal disease (IFD). RAPD (rapid amplification of polymorphic DNA)-polymerase chain reaction (PCR) and amphotericin B susceptibility testing were performed on all A. terreus isolates. A total of 4919 colony-forming units (cfu) were isolated (2212 indoors, 2707 outdoors). Further identification revealed A. fumigatus (73.5%), A. niger (4.3%), A. flavus (1.7%), A. terreus (0.2%) and non-Aspergillus fungi (20.3%). RAPD-PCR did not reveal clonal relationships between the A. terreus isolates. All A. terreus isolates displayed complete resistance to amphotericin. The B. Aspergillus spp. conidia exposure was lowest in June and highest in November inside and outside UHC. Conidia load correlated with the season and the relative humidity, with increasing spore counts during dry periods. One out of 855 nasal swabs was positive for A. niger. The patient did not develop IFD. A. terreus is unlikely to be a relevant pathogen at the UHC. Results from RAPD-PCR suggested a wide epidemiological variety of strains rather than a common source of contamination. Nasal swab surveillance cultures for early detection of Aspergillus spp. colonisation were not useful in identifying patients who may develop IFD. The risk of IFD at the UHC may increase in autumn and during dry periods.

  3. Chemodiversity in the genus Aspergillus.

    PubMed

    Frisvad, Jens C; Larsen, Thomas O

    2015-10-01

    Isolates of Aspergillus species are able to produce a large number of secondary metabolites. The profiles of biosynthetic families of secondary metabolites are species specific, whereas individual secondary metabolite families can occur in other species, even those phylogenetically and ecologically unrelated to Aspergillus. Furthermore, there is a high degree of chemo-consistency from isolate to isolate in a species even though certain metabolite gene clusters are silenced in some isolates. Genome sequencing projects have shown that the diversity of secondary metabolites is much larger in each species than previously thought. The potential of finding even further new bioactive drug candidates in Aspergillus is evident, despite the fact that many secondary metabolites have already been structure elucidated and chemotaxonomic studies have shown that many new secondary metabolites have yet to be characterized. The genus Aspergillus is cladistically holophyletic but phenotypically polythetic and very diverse and is associated to quite different sexual states. Following the one fungus one name system, the genus Aspergillus is restricted to a holophyletic clade that include the morphologically different genera Aspergillus, Dichotomomyces, Phialosimplex, Polypaecilum and Cristaspora. Secondary metabolites common between the subgenera and sections of Aspergillus are surprisingly few, but many metabolites are common to a majority of species within the sections. We call small molecule extrolites in the same biosynthetic family isoextrolites. However, it appears that secondary metabolites from one Aspergillus section have analogous metabolites in other sections (here also called heteroisoextrolites). In this review, we give a genus-wide overview of secondary metabolite production in Aspergillus species. Extrolites appear to have evolved because of ecological challenges rather than being inherited from ancestral species, at least when comparing the species in the different

  4. Effect of essential oils on Aspergillus spore germination, growth and mycotoxin production: a potential source of botanical food preservative

    PubMed Central

    Gemeda, Negero; Woldeamanuel, Yimtubezinash; Asrat, Daniel; Debella, Asfaw

    2014-01-01

    Objective To investigate effect of essential oils on Aspergillus spore germination, growth and mycotoxin production. Method In vitro antifungal and antiaflatoxigenic activity of essential oils was carried out using poisoned food techniques, spore germination assay, agar dilution assay, and aflatoxin arresting assay on toxigenic strains of Aspergillus species. Results Cymbopogon martinii, Foeniculum vulgare and Trachyspermum ammi (T. ammi) essential oils were tested against toxicogenic isolates of Aspergillus species. T. ammi oil showed highest antifungal activity. Absolute mycelial inhibition was recorded at 1 µl/mL by essential oils of T. ammi. The oil also showed, complete inhibition of spore germination at a concentration of 2 µl/mL. In addition, T. ammi oil showed significant antiaflatoxigenic potency by totally inhibiting aflatoxin production from Aspergillus niger and Aspergillus flavus at 0.5 and 0.75 µl/mL, respectively. Cymbopogon martinii, Foeniculum vulgare and T. ammi oils as antifungal were found superior over synthetic preservative. Moreover, a concentration of 5 336.297 µl/kg body weight was recorded for LC50 on mice indicating the low mammalian toxicity and strengthening its traditional reputations. Conclusions In conclusion, the essential oils from T. ammi can be a potential source of safe natural food preservative for food commodities contamination by storage fungi. PMID:25183114

  5. Aspergillus: sex and recombination.

    PubMed

    Varga, János; Szigeti, Gyöngyi; Baranyi, Nikolett; Kocsubé, Sándor; O'Gorman, Céline M; Dyer, Paul S

    2014-12-01

    The genus Aspergillus is one of the most widespread groups of fungi on Earth, comprised of about 300-350 species with very diverse lifestyles. Most species produce asexual propagula (conidia) on conidial heads. Despite their ubiquity, a sexual cycle has not yet been identified for most of the aspergilli. Where sexual reproduction is present, species exhibit either homothallic (self fertile) or heterothallic (obligate outcrossing) breeding systems. A parasexual cycle has also been described in some Aspergillus species. As in other fungi, sexual reproduction is governed by mating-type (MAT) genes, which determine sexual identity and are involved in regulating later stages of sexual development. Previous population genetic studies have indicated that some supposedly asexual aspergilli exhibit evidence of a recombining population structure, suggesting the presence of a cryptic sexual cycle. In addition, genome analyses have revealed networks of genes necessary for sexual reproduction in several Aspergillus species, again consistent with latent sexuality in these fungi. Knowledge of MAT gene presence has then successfully been applied to induce sexual reproduction between MAT1-1 and MAT1-2 isolates of certain supposedly asexual aspergilli. Recent progress in understanding the extent and significance of sexual reproduction is described here, with special emphasis on findings that are relevant to clinically important aspergilli.

  6. Aspergillus: sex and recombination.

    PubMed

    Varga, János; Szigeti, Gyöngyi; Baranyi, Nikolett; Kocsubé, Sándor; O'Gorman, Céline M; Dyer, Paul S

    2014-12-01

    The genus Aspergillus is one of the most widespread groups of fungi on Earth, comprised of about 300-350 species with very diverse lifestyles. Most species produce asexual propagula (conidia) on conidial heads. Despite their ubiquity, a sexual cycle has not yet been identified for most of the aspergilli. Where sexual reproduction is present, species exhibit either homothallic (self fertile) or heterothallic (obligate outcrossing) breeding systems. A parasexual cycle has also been described in some Aspergillus species. As in other fungi, sexual reproduction is governed by mating-type (MAT) genes, which determine sexual identity and are involved in regulating later stages of sexual development. Previous population genetic studies have indicated that some supposedly asexual aspergilli exhibit evidence of a recombining population structure, suggesting the presence of a cryptic sexual cycle. In addition, genome analyses have revealed networks of genes necessary for sexual reproduction in several Aspergillus species, again consistent with latent sexuality in these fungi. Knowledge of MAT gene presence has then successfully been applied to induce sexual reproduction between MAT1-1 and MAT1-2 isolates of certain supposedly asexual aspergilli. Recent progress in understanding the extent and significance of sexual reproduction is described here, with special emphasis on findings that are relevant to clinically important aspergilli. PMID:25118872

  7. The effect of humidity after gamma-irradiation on aflatoxin B-1 production of A. Flavus in ground nutmeg and peanut

    NASA Astrophysics Data System (ADS)

    Hilmy, N.; Chosdu, R.; Matsuyama, A.

    1995-02-01

    The effect of humidity of 75 up to 97% after irradiation on radiosensitivity and aflatoxin B1 production of Aspergillus flavus isolated from Indonesian nutmeg were examined. Irradiation doses used were 0;0.5;1 and 3 kGy. Mould free ground nutmeg and peanut were used as the growth media, and about 10 8 of spores were used to contaminate each of the media. Aflatoxin productions were measured after having incubated 3 days up to 5 months under humidity of 91 and 97%. Prior to HPLC analysis, aflatoxin was cleaned-up using an immunoaffinity column. The results were: (1) A. flavus indicated no or almost no growth under RH of 85% or less. (2) Under 91-97% RH, growth of mycelium and toxin production were inhibited more or less by irradiation up to 1 kGy, although the effectiveness of irradiation varied with different RH and media during postirradiation incubation. (3) By 3 kGy or more, both mycelium growth and toxin production of the mould were found to be completely inhibited. (4) The production of aflatoxin in nutmeg began after having incubated for 25 and 45 days and in peanut for 3 and 6 days under 97 and 91% RH, respectively.

  8. A preliminary study on the occurrence of Aspergillus spp. and aflatoxin B1 in imported wheat and barley in Penang, Malaysia.

    PubMed

    Reddy, K R N; Salleh, Baharuddin

    2010-11-01

    Thirty samples consisting of wheat (15) and barley (15) were collected from different markets in Penang, Malaysia, originating from India and Thailand, respectively. All samples were analyzed for occurrence of Aspergillus spp. and aflatoxin B1 (AFB1). Aspergillus flavus was dominant in all samples followed by A. niger. AFB1 could be detected in three wheat samples ranging from 0.42 to 1.89 μg/kg and one barley sample had 0.58 μg/kg of AFB1. The AFB1 levels in all the samples were below the Malaysian regulatory limits (<35 μg/kg). The frequency and quantity of AFB1 levels in this study were very low in wheat and barley samples compared to other agricultural commodities reported in India and Thailand. This is the first report on determination of Aspergillus spp. and AFB1 in imported wheat and barley grains in Penang, Malaysia.

  9. The Potential Inhibitory Effect of Cuminum Cyminum, Ziziphora Clinopodioides and Nigella Sativa Essential Oils on the Growth of Aspergillus Fumigatus and Aspergillus

    PubMed Central

    Khosravi, A.R.; Minooeianhaghighi, M.H.; Shokri, H.; Emami, S.A.; S.M., Alavi; Asili, J.

    2011-01-01

    The goals of this study were to evaluate the effectiveness of Cuminum cyminum, Ziziphora clinopodioides and Nigella sativa essential oils to inhibit the growth of Aspergillus fumigatus and A. flavus and to evoke ultrastructural changes. The fungi were cultured into RPMI 1640 media in the presence of oils at concentrations of 8, 6, 5, 4, 3, 2, 1.5, 1.25, 1, 0.75 and 0.5 mg/ml in broth microdilution and 2, 1.5, 1 and 0.5 mg/ml in broth macrodilution methods with shaking for 48 h at 28oC. Conidial and mycelial samples exposed to 0.25, 0.5, 1, 1.5 and 2 mg essential oils/ml for 5 days in 2% yeast extract granulated plus 15% Saccharose media were processed for transmission electron microscopy (TEM). Based on broth dilution methods, C. cyminum and to a lesser extent Z. clinopodioides oils exhibited the strongest activity against A. fumigatus and A. flavus with MIC90 ranging from 0.25 to 1.5 mg/ml, while the oil from N. sativa exhibited relatively moderate activity against two above fungi with MIC90 ranging from 1.5 to 2 mg/ml. The main changes observed by TEM were in the cell wall, plasma membrane and membranous organelles; in particular, in the nuclei and mitochondria. These modifications in fungal structure were associated with the interference of the essential oils with the enzymes responsible for cell wall synthesis, which disturbed normal growth. Moreover, the essential oils caused high vacuolation of the cytoplasm, detachment of fibrillar layer of cell wall, plasma membrane disruption and disorganization of the nuclear and mitochondrial structures. Aspergillus fumigatus and A. flavus growth inhibition induced by these oils were found to be well-correlated with subsequent morphological changes of the fungi exposed to different fungistatic concentrations of the oils. Our results show the anti-Aspergillus activities of C. cyminum, Z. clinopodioides and N. sativa essential oils, which strengthens the potential use of these substances as anti-mould in the future. PMID

  10. Metabolomics of Aspergillus fumigatus.

    PubMed

    Frisvad, Jens C; Rank, Christian; Nielsen, Kristian F; Larsen, Thomas O

    2009-01-01

    Aspergillus fumigatus is the most important species in Aspergillus causing infective lung diseases. This species has been reported to produce a large number of extrolites, including secondary metabolites, acids, and proteins such as hydrophobins and extracellular enzymes. At least 226 potentially bioactive secondary metabolites have been reported from A. fumigatus that can be ordered into 24 biosynthetic families. Of these families we have detected representatives from the following families of secondary metabolites: fumigatins, fumigaclavines, fumiquinazolines, trypacidin and monomethylsulochrin, fumagillins, gliotoxins, pseurotins, chloroanthraquinones, fumitremorgins, verruculogen, helvolic acids, and pyripyropenes by HPLC with diode array detection and mass spectrometric detection. There is still doubt whether A. fumigatus can produce tryptoquivalins, but all isolates produce the related fumiquinazolines. We also tentatively detected sphingofungins in A. fumigatus Af293 and in an isolate of A. lentulus. The sphingofungins may have a similar role as the toxic fumonisins, found in A. niger. A further number of mycotoxins, including ochratoxin A, and other secondary metabolites have been reported from A. fumigatus, but in those cases either the fungus or its metabolite appear to be misidentified. PMID:18763205

  11. Previously unknown species of Aspergillus.

    PubMed

    Gautier, M; Normand, A-C; Ranque, S

    2016-08-01

    The use of multi-locus DNA sequence analysis has led to the description of previously unknown 'cryptic' Aspergillus species, whereas classical morphology-based identification of Aspergillus remains limited to the section or species-complex level. The current literature highlights two main features concerning these 'cryptic' Aspergillus species. First, the prevalence of such species in clinical samples is relatively high compared with emergent filamentous fungal taxa such as Mucorales, Scedosporium or Fusarium. Second, it is clearly important to identify these species in the clinical laboratory because of the high frequency of antifungal drug-resistant isolates of such Aspergillus species. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been shown to enable the identification of filamentous fungi with an accuracy similar to that of DNA sequence-based methods. As MALDI-TOF MS is well suited to the routine clinical laboratory workflow, it facilitates the identification of these 'cryptic' Aspergillus species at the routine mycology bench. The rapid establishment of enhanced filamentous fungi identification facilities will lead to a better understanding of the epidemiology and clinical importance of these emerging Aspergillus species. Based on routine MALDI-TOF MS-based identification results, we provide original insights into the key interpretation issues of a positive Aspergillus culture from a clinical sample. Which ubiquitous species that are frequently isolated from air samples are rarely involved in human invasive disease? Can both the species and the type of biological sample indicate Aspergillus carriage, colonization or infection in a patient? Highly accurate routine filamentous fungi identification is central to enhance the understanding of these previously unknown Aspergillus species, with a vital impact on further improved patient care. PMID:27263029

  12. Resurgence and persistence of Dorymyrmex flavus after reduction of Solenopsis invicta buren with a broadcast bait.

    PubMed

    Calixto, Alejandro A; Harris, Marvin K; Barr, Charles

    2007-06-01

    The effects of bait treatment(s) on population dynamics of Solenopsis invicta and Dorymyrmex flavus were studied, and various factors underlying the resurgence and persistence of D. flavus to reinvasion by S. invicta were studied in more detail. Pitfall traps, bait vials, transect sampling, and direct inspections were used to monitor densities of these two species, and inspections of D. flavus midden contents, video monitoring of D. flavus colonies, and studies of the fate of marked S. invicta were used to further clarify interactions of these two species, D. flavus abundance increased after the reduction of S. invicta with baits. D. flavus was also observed to sustain higher densities for an extended period (2 yr) after cessation of bait treatment and to exhibit antagonistic behaviors toward S. invicta, showing an ability to resist reinvasion of the treated area by S. invicta. Given these findings, D. flavus may retard domination of the ant assemblage by S. invicta. Additional studies are justified regarding how to enhance the role of this species in affected ecosystems. PMID:17540063

  13. Aspergillus parasiticus SU-1 genome sequence, predicted chromosome structure, and comparative gene expression under aflatoxin-inducing conditions: evidence that differential expression contributes to species phenotype.

    PubMed

    Linz, John E; Wee, Josephine; Roze, Ludmila V

    2014-08-01

    The filamentous fungi Aspergillus parasiticus and Aspergillus flavus produce the carcinogenic secondary metabolite aflatoxin on susceptible crops. These species differ in the quantity of aflatoxins B1, B2, G1, and G2 produced in culture, in the ability to produce the mycotoxin cyclopiazonic acid, and in morphology of mycelia and conidiospores. To understand the genetic basis for differences in biochemistry and morphology, we conducted next-generation sequence (NGS) analysis of the A. parasiticus strain SU-1 genome and comparative gene expression (RNA sequence analysis [RNA Seq]) analysis of A. parasiticus SU-1 and A. flavus strain NRRL 3357 (3357) grown under aflatoxin-inducing and -noninducing culture conditions. Although A. parasiticus SU-1 and A. flavus 3357 are highly similar in genome structure and gene organization, we observed differences in the presence of specific mycotoxin gene clusters and differential expression of specific mycotoxin genes and gene clusters that help explain differences in the type and quantity of mycotoxins synthesized. Using computer-aided analysis of secondary metabolite clusters (antiSMASH), we demonstrated that A. parasiticus SU-1 and A. flavus 3357 may carry up to 93 secondary metabolite gene clusters, and surprisingly, up to 10% of the genome appears to be dedicated to secondary metabolite synthesis. The data also suggest that fungus-specific zinc binuclear cluster (C6) transcription factors play an important role in regulation of secondary metabolite cluster expression. Finally, we identified uniquely expressed genes in A. parasiticus SU-1 that encode C6 transcription factors and genes involved in secondary metabolism and stress response/cellular defense. Future work will focus on these differentially expressed A. parasiticus SU-1 loci to reveal their role in determining distinct species characteristics. PMID:24951444

  14. In-vitro activity of the new triazole D0870 compared with amphotericin B and itraconazole against Aspergillus spp.

    PubMed

    Moore, C B; Law, D; Denning, D W

    1993-12-01

    The in-vitro activity of D0870, a new triazole, was compared with amphotericin B (AMP B) and itraconazole (ITZ) against 40 Aspergillus isolates, which included 25 isolates of Aspergillus fumigatus, using a broth macro-dilution method at 37 degrees C. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) (killing of > or = 98%) were measured. For 40 isolates, geometric mean (GM) MIC values and ranges were D0870 10.55 and 2-32, ITZ 2.26 and 0.5-64, AMP B 2.42 and 1-64 mg/L. Differences in susceptibilities between species were apparent with Aspergillus flavus (n = 5) being the most susceptible to D0870 (GM 2.64, range 2-8 mg/L). MFC values were within one dilution of the MIC value for 90% of isolates (D0870 and ITZ) and 95% of isolates (AMP B). In reproducibility studies, seven, eight and four of eight isolates retested gave MIC results within one dilution for D0870, AMP B, and ITZ, respectively. Therefore, in-vitro mould testing with D0870 is feasible and reproducible with clear MIC and MFC end-points. D0870 is active against most Aspergillus spp., but at higher concentrations than either ITZ or AMP B. PMID:8144422

  15. The potential hazards of Aspergillus sp. in foods and feeds, and the role of biological treatment: a review.

    PubMed

    Sheikh-Ali, Sheikh Imranudin; Ahmad, Akil; Mohd-Setapar, Siti-Hamidah; Zakaria, Zainul Akmal; Abdul-Talib, Norfahana; Khamis, Aidee Kamal; Hoque, Md Enamul

    2014-10-01

    The contamination of food and feed by Aspergillus has become a global issue with a significant worldwide economic impact. The growth of Aspergillus is unfavourable to the development of food and feed industries, where the problems happen mostly due to the presence of mycotoxins, which is a toxic metabolite secreted by most Aspergillus groups. Moreover, fungi can produce spores that cause diseases, such as allergies and asthma, especially to human beings. High temperature, high moisture, retarded crops, and poor food storage conditions encourage the growth of mold, as well as the development of mycotoxins. A variety of chemical, biological, and physical strategies have been developed to control the production of mycotoxins. A biological approach, using a mixed culture comprised of Saccharomyces cerevisiae and Lactobacillus rhamnosus resulted in the inhibition of the growth of fungi when inoculated into fermented food. The results reveal that the mixed culture has a higher potential (37.08%) to inhibit the growth of Aspergillus flavus (producer of Aflatoxin) compared to either single culture, L. rhamnosus NRRL B-442 and S. cerevisiae, which inhibit the growth by 63.07% and 64.24%, respectively.

  16. The potential hazards of Aspergillus sp. in foods and feeds, and the role of biological treatment: a review.

    PubMed

    Sheikh-Ali, Sheikh Imranudin; Ahmad, Akil; Mohd-Setapar, Siti-Hamidah; Zakaria, Zainul Akmal; Abdul-Talib, Norfahana; Khamis, Aidee Kamal; Hoque, Md Enamul

    2014-10-01

    The contamination of food and feed by Aspergillus has become a global issue with a significant worldwide economic impact. The growth of Aspergillus is unfavourable to the development of food and feed industries, where the problems happen mostly due to the presence of mycotoxins, which is a toxic metabolite secreted by most Aspergillus groups. Moreover, fungi can produce spores that cause diseases, such as allergies and asthma, especially to human beings. High temperature, high moisture, retarded crops, and poor food storage conditions encourage the growth of mold, as well as the development of mycotoxins. A variety of chemical, biological, and physical strategies have been developed to control the production of mycotoxins. A biological approach, using a mixed culture comprised of Saccharomyces cerevisiae and Lactobacillus rhamnosus resulted in the inhibition of the growth of fungi when inoculated into fermented food. The results reveal that the mixed culture has a higher potential (37.08%) to inhibit the growth of Aspergillus flavus (producer of Aflatoxin) compared to either single culture, L. rhamnosus NRRL B-442 and S. cerevisiae, which inhibit the growth by 63.07% and 64.24%, respectively. PMID:25269603

  17. Disinfection efficacy of chlorine and peracetic acid alone or in combination against Aspergillus spp. and Candida albicans in drinking water.

    PubMed

    Sisti, Maurizio; Brandi, Giorgio; De Santi, Mauro; Rinaldi, Laura; Schiavano, Giuditta F

    2012-03-01

    The aim of the present study was to evaluate the fungicidal activity of chlorine and peracetic acid in drinking water against various pathogenic Aspergillus spp. and Candida albicans strains. A. nidulans exhibited the greatest resistance, requiring 10 ppm of chlorine for 30 min contact time for a complete inactivation. Under the same experimental conditions, peracetic acid was even less fungicidal. In this case, A. niger proved to be the most resistant species (50 ppm for 60 min for complete inactivation). All Aspergillus spp. were insensitive to 10 ppm even with extended exposure (>5 h). The combination of chlorine and peracetic acid against Aspergillus spp. did not show synergistic effects except in the case of A. flavus. Complete growth inhibition of C. albicans was observed after about 3 h contact time with 0.2 ppm. C. albicans was less sensitive to peracetic acid. Hence the concentrations of chlorine that are usually present in drinking water distribution systems are ineffective against several Aspergillus spp. and peracetic acid cannot be considered an alternative to chlorine for disinfecting drinking water. The combination of the two biocides is not very effective in eliminating filamentous fungi at the concentrations permitted for drinking water disinfection.

  18. Aspergillus prosthetic valve endocarditis.

    PubMed Central

    Petheram, I S; Seal, R M

    1976-01-01

    The clinical, laboratory, and histopathological features of seven cases of Aspergillus fumigatus prosthetic valve endocarditis are presented. The exact nature of the lesion, a combination of infective fungal endocarditis and thrombosis on the prosthetic valve, is discussed and the difficulties in clinical diagnosis are emphasized. Helpful indications were sudden unexplained heart failure with the appearance of new murmurs, and emboli to large or medium-sized systemic arteries. Fever and anaemia were inconstant, and in no case was blood culture or precipitin investigation helpful. Spore contamination of operating theatre air was the likely source of infection, and measures taken to overcome this and other predisposing factors are discussed. Since medical diagnosis is usually late and the few reported cures in this condition have included replacement of the prosthesis, early surgical intervention combined with antifungal chemotherapy is advised. Images PMID:788218

  19. Tremorgenic Mycotoxins from Aspergillus Caespitosus

    PubMed Central

    Schroeder, H. W.; Cole, R. J.; Hein, H.; Kirksey, J. W.

    1975-01-01

    Two tremorgenic mycotoxins were isolated from Aspergillus caespitosus, and identified as verruculogen and fumitremorgin B. They were produced at the rate of 172 and 325 mg per kg, respectively, on autoclaved cracked field corn. PMID:1155935

  20. Tremorgenic mycotoxins from Aspergillus caespitosus.

    PubMed

    Schroeder, H W; Cole, R J; Hein, H; Kirksey, J W

    1975-06-01

    Two tremorgenic mycotoxins were isolated from Aspergillus caespitosus, and identified as verruculogen and fumitremorgin B. They were produced at the rate of 172 and 325 mg per kg, respectively, on autoclaved cracked field corn. PMID:1155935

  1. Modulation of antimicrobial metabolites production by the fungus Aspergillus parasiticus

    PubMed Central

    Bracarense, Adriana A.P.; Takahashi, Jacqueline A.

    2014-01-01

    Biosynthesis of active secondary metabolites by fungi occurs as a specific response to the different growing environments. Changes in this environment alter the chemical and biological profiles leading to metabolites diversification and consequently to novel pharmacological applications. In this work, it was studied the influence of three parameters (fermentation length, medium composition and aeration) in the biosyntheses of antimicrobial metabolites by the fungus Aspergillus parasiticus in 10 distinct fermentation periods. Metabolism modulation in two culturing media, CYA and YES was evaluated by a 22 full factorial planning (ANOVA) and on a 23 factorial planning, role of aeration, medium composition and carbohydrate concentration were also evaluated. In overall, 120 different extracts were prepared, their HPLC profiles were obtained and the antimicrobial activity against A. flavus, C. albicans, E. coli and S. aureus of all extracts was evaluated by microdilution bioassay. Yield of kojic acid, a fine chemical produced by the fungus A. parasiticus was determined in all extracts. Statistical analyses pointed thirteen conditions able to modulate the production of bioactive metabolites by A. parasiticus. Effect of carbon source in metabolites diversification was significant as shown by the changes in the HPLC profiles of the extracts. Most of the extracts presented inhibition rates higher than that of kojic acid as for the extract obtained after 6 days of fermentation in YES medium under stirring. Kojic acid was not the only metabolite responsible for the activity since some highly active extracts showed to possess low amounts of this compound, as determined by HPLC. PMID:24948950

  2. Cowpeas as growth substrate do not support the production of aflatoxin byAspergillus sp.

    PubMed

    Houssou, P A; Schmidt-Heydt, M; Geisen, R; Fandohan, P; Ahohuendo, B C; Hounhouigan, D J; Jakobsen, M

    2008-06-01

    A number of 21Aspergillus sp. strains isolated from cowpeas from Benin (Africa) were characterized by RAPD methodology. Seven of these strains grouped withA. flavus in the dendrogram generated with the RAPD data. Only three were able to produce aflatoxin in significant amounts. Twelve other isolates grouped withA. parasiticus. All of these strains except 3 produced aflatoxin. Two additional strains neither fit with theA. flavus group, nor theA. parasiticus group according to their RAPD pattern. Both did not produce aflatoxin in measurable amounts.Generally the aflatoxin positive strains produced high amounts of aflatoxin after growth on YES medium. However after growth on cowpea based medium aflatoxin biosynthesis was strongly ceased, albeit the growth of the colony was only partly reduced. This was true for media made either with the whole cowpea seed or with cowpea seed without seed coat. Interestingly when the cowpea medium was heat sterilized the fungus was able to produce high amounts of aflatoxin. This, however, was not the case after the use of gamma irradiation as sterilization method for the medium. The expression of thenor- 1 gene, which is one of the early genes involved in aflatoxin biosynthesis, was significantly repressed after growth on gamma irradiated cowpea medium in contrast to YES medium. PMID:23604687

  3. The evolutionary imprint of domestication on genome variation and function of the filamentous fungus Aspergillus oryzae.

    PubMed

    Gibbons, John G; Salichos, Leonidas; Slot, Jason C; Rinker, David C; McGary, Kriston L; King, Jonas G; Klich, Maren A; Tabb, David L; McDonald, W Hayes; Rokas, Antonis

    2012-08-01

    The domestication of animals, plants, and microbes fundamentally transformed the lifestyle and demography of the human species [1]. Although the genetic and functional underpinnings of animal and plant domestication are well understood, little is known about microbe domestication [2-6]. Here, we systematically examined genome-wide sequence and functional variation between the domesticated fungus Aspergillus oryzae, whose saccharification abilities humans have harnessed for thousands of years to produce sake, soy sauce, and miso from starch-rich grains, and its wild relative A. flavus, a potentially toxigenic plant and animal pathogen [7]. We discovered dramatic changes in the sequence variation and abundance profiles of genes and wholesale primary and secondary metabolic pathways between domesticated and wild relative isolates during growth on rice. Our data suggest that, through selection by humans, an atoxigenic lineage of A. flavus gradually evolved into a "cell factory" for enzymes and metabolites involved in the saccharification process. These results suggest that whereas animal and plant domestication was largely driven by Neolithic "genetic tinkering" of developmental pathways, microbe domestication was driven by extensive remodeling of metabolism.

  4. Occurrence of Aspergillus spp. and aflatoxin B1 in Malaysian foods used for human consumption.

    PubMed

    Reddy, Kasa R N; Farhana, Nazira I; Salleh, Baharuddin

    2011-05-01

    Malaysian population widely consumes the cereal-based foods, oilseeds, nuts, and spices in their daily diet. Mycotoxigenic fungi are well known to invade food products under storage conditions and produce mycotoxins that have threat to human and animal health. Therefore, determining toxigenic fungi and aflatoxin B(1) (AFB1) in foods used for human consumption is of prime importance to develop suitable management strategies and to minimize risk. Ninety-five food products marketed in Penang, Malaysia were randomly collected from different supermarkets and were analyzed for presence of Aspergillus spp. by agar plate assay and AFB1 by enzyme-linked immunosorbent assay (ELISA). A. flavus was the dominant fungi in all foods followed by A. niger. Fifty-five A. flavus strains were tested for their ability to produce aflatoxins on rice grain substrate. Thirty-six (65.4%) strains out of 55 produced AFB1 ranging from 1700 to 4400 μg/kg and 17 strains (31%) produced AFB2 ranging from 620 to 1670 μg/kg. Natural occurrence of AFB1 could be detected in 72.6% food products ranging from 0.54 to 15.33 μg/kg with a mean of 1.95 μg/kg. Maximum AFB1 levels were detected in peanut products ranging from 1.47 to 15.33 μg/kg. AFB1 levels detected in all food products were below the Malaysian permissible limits (<35 μg/kg). Aspergillus spp. and AFB1 was not detected in any cookies tested. Although this survey was not comprehensive, it provides valuable information on aflatoxin levels in foods marketed in Malaysia.

  5. Epidemiological and Genomic Landscape of Azole Resistance Mechanisms in Aspergillus Fungi

    PubMed Central

    Hagiwara, Daisuke; Watanabe, Akira; Kamei, Katsuhiko; Goldman, Gustavo H.

    2016-01-01

    Invasive aspergillosis is a life-threatening mycosis caused by the pathogenic fungus Aspergillus. The predominant causal species is Aspergillus fumigatus, and azole drugs are the treatment of choice. Azole drugs approved for clinical use include itraconazole, voriconazole, posaconazole, and the recently added isavuconazole. However, epidemiological research has indicated that the prevalence of azole-resistant A. fumigatus isolates has increased significantly over the last decade. What is worse is that azole-resistant strains are likely to have emerged not only in response to long-term drug treatment but also because of exposure to azole fungicides in the environment. Resistance mechanisms include amino acid substitutions in the target Cyp51A protein, tandem repeat sequence insertions at the cyp51A promoter, and overexpression of the ABC transporter Cdr1B. Environmental azole-resistant strains harboring the association of a tandem repeat sequence and punctual mutation of the Cyp51A gene (TR34/L98H and TR46/Y121F/T289A) have become widely disseminated across the world within a short time period. The epidemiological data also suggests that the number of Aspergillus spp. other than A. fumigatus isolated has risen. Some non-fumigatus species intrinsically show low susceptibility to azole drugs, imposing the need for accurate identification, and drug susceptibility testing in most clinical cases. Currently, our knowledge of azole resistance mechanisms in non-fumigatus Aspergillus species such as A. flavus, A. niger, A. tubingensis, A. terreus, A. fischeri, A. lentulus, A. udagawae, and A. calidoustus is limited. In this review, we present recent advances in our understanding of azole resistance mechanisms particularly in A. fumigatus. We then provide an overview of the genome sequences of non-fumigatus species, focusing on the proteins related to azole resistance mechanisms. PMID:27708619

  6. Distribution and toxigenicity of Aspergillus species isolated from maize kernels from three agro-ecological zones in Nigeria.

    PubMed

    Atehnkeng, Joseph; Ojiambo, Peter S; Donner, Matthias; Ikotun, T; Sikora, Richard A; Cotty, Peter J; Bandyopadhyay, Ranajit

    2008-02-29

    Maize samples were collected during a survey in three agro-ecological zones in Nigeria to determine the distribution and aflatoxin-producing potential of members of Aspergillus section Flavi. The three agro-ecological zones were, Derived Savannah (DS) and Southern Guinea Savannah (SGS) in the humid south and North Guinea Savannah (NGS) in the drier north. Across agro-ecological zones, Aspergillus was the most predominant fungal genera identified followed by Fusarium with mean incidences of 70 and 24%, respectively. Among Aspergillus, A. flavus was the most predominant and L-strains constituted >90% of the species identified, while the frequency of the unnamed taxon S(BG) was <3%. The incidence of atoxigenic strains of A. flavus was higher in all the districts surveyed except in the Ogbomosho and Mokwa districts in DS and SGS zones, respectively, where frequency of toxigenic strains were significantly (P<0.05) higher than that of atoxigenic strains. The highest and lowest incidence of aflatoxin positive samples was recorded in the SGS (72%) and NGS (20%), respectively. Aflatoxin contamination in grain also followed a similar trend and the highest mean levels of B-aflatoxins were detected in maize samples obtained from Bida (612 ng g(-1)) and Mokwa (169 ng g(-1)) districts, respectively, in the SGS. Similarly, the highest concentrations of G-aflatoxins were detected in samples from Akwanga district in the SGS with a mean of 193 and 60 ng g(-1), respectively. When agro-ecological zones were compared, B-aflatoxins were significantly (P<0.05) higher in SGS than in NGS, and intermediate in maize samples from the DS agro-ecological zone.

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

    PubMed

    Prakash, Bhanu; Singh, Priyanka; Goni, Reema; Raina, Ajay Kumar Pandit; Dubey, N K

    2015-04-01

    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. PMID:25829603

  8. Aspergillus fumigatus and Aspergillosis

    PubMed Central

    Latgé, Jean-Paul

    1999-01-01

    Aspergillus fumigatus is one of the most ubiquitous of the airborne saprophytic fungi. Humans and animals constantly inhale numerous conidia of this fungus. The conidia are normally eliminated in the immunocompetent host by innate immune mechanisms, and aspergilloma and allergic bronchopulmonary aspergillosis, uncommon clinical syndromes, are the only infections observed in such hosts. Thus, A. fumigatus was considered for years to be a weak pathogen. With increases in the number of immunosuppressed patients, however, there has been a dramatic increase in severe and usually fatal invasive aspergillosis, now the most common mold infection worldwide. In this review, the focus is on the biology of A. fumigatus and the diseases it causes. Included are discussions of (i) genomic and molecular characterization of the organism, (ii) clinical and laboratory methods available for the diagnosis of aspergillosis in immunocompetent and immunocompromised hosts, (iii) identification of host and fungal factors that play a role in the establishment of the fungus in vivo, and (iv) problems associated with antifungal therapy. PMID:10194462

  9. Transformation of Aspergillus parasiticus with a homologous gene (pyrG) involved in pyrimidine biosynthesis

    SciTech Connect

    Skory, C.D.; Horng, J.S.; Pestka, J.J.; Linz, J.E. )

    1990-11-01

    The lack of efficient transformation methods for aflatoxigenic Aspergillus parasiticus has been a major constraint for the study of aflatoxin biosynthesis at the genetic level. A transformation system with efficiencies of 30 to 50 stable transformants per {mu}g of DNA was developed for A. parasiticus by using homologous pyrG gene. The pyrG gene from A. parasiticus was isolated by in situ plaque hybridization of a lambda genomic DNA library. Uridine auxotrophs of A. parasiticus ATCC 36537, a mutant blocked in aflatoxin biosynthesis, were isolated by selection on 5-fluoroorotic acid following nitrosoguanidine mutagenesis. Isolates with mutations in the pyrG gene resulting in elimination of orotidine monophosphate (OMP) decarboxylase activity were detected by assaying cell extracts for their ability to convert ({sup 14}C)OMP to ({sup 14}C)UMP. Transformation of A. parasiticus pyrG protoplasts with the homologous pyrG gene restored the fungal cells to prototrophy. Enzymatic analysis of cell extracts of transformant clones demonstrated that these extracts had the ability to convert ({sup 14}C)OMP to ({sup 14}C)UMP. Southern analysis of DNA purified from transformant clones indicated that both pUC19 vector sequences and pyrG sequences were integrated into the genome. The development of this pyrG transformation system should allow cloning of the aflatoxin-biosynthetic genes, which will be useful in studying the regulation of aflatoxin biosynthesis and may ultimately provide a means for controlling aflatoxin production in the field.

  10. VeA is associated with the response to oxidative stress in the aflatoxin producer Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Survival of fungal species depends on the ability of these organisms to respond to environmental stresses. Osmotic stress or high levels of reactive oxygen species (ROS) can cause stress in fungi resulting in growth inhibition. Both eukaryotic and prokaryotic cells have developed numerous mechanisms...

  11. 77 FR 14287 - Aspergillus flavus AF36; Amendment to an Exemption From the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ...) 305-5805. II. Background and Statutory Findings In the Federal Register of April 20, 2011 (76 FR 22067... Register of July 14, 2003 (68 FR 41535) (FRL-7311-6). ``Those health effects data were the basis for... July 14, 2003) and corn (see the Federal Register of March 23, 2011 (76 FR 16297) (FRL-8868-7))...

  12. Larval preference and performance of Amyelois transitella (Navel orangeworm, Lepidoptera: Pyralidae) in relation to the fungus Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The navel orangeworm, Amyelois transitella (Walker), is a polyphagous pest of California nut crops and is responsible for extensive losses in the United States. It directly damages crops by feeding and contaminating nuts with frass and webbing and vectors saprophytic fungi that infect crops. The nav...

  13. Potential roles of secondary metabolite production in environmental oxidative stress responses revealed in the Aspergillus flavus transcriptome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The contamination of agricultural crops with aflatoxins is exacerbated in the dry and hot season worldwide, and poses a serious food security concern, particularly in developing countries. Drought stress results in the accumulation of reactive oxygen species (ROS) in the tissues of plants. Previousl...

  14. Improved Enzyme Catalytic Characteristics upon Glutaraldehyde Cross-Linking of Alginate Entrapped Xylanase Isolated from Aspergillus flavus MTCC 9390

    PubMed Central

    Bhushan, Bharat; Pal, Ajay; Jain, Veena

    2015-01-01

    Purified fungal xylanase was entrapped in alginate beads. Its further cross-linking using glutaraldehyde resulted in large enzyme aggregates which may function as both a catalyst and a support material for numerous substrate molecules. Enzyme cross-linking presented a negative impact on enzyme leaching during repeated washings and recovery of enzyme activity was substantial after twelve cycles of usage. The entrapment followed by cross-linking doubled the total bound activity and also greatly improved the enzyme stability at extreme chemical environment. The wide pH stability, better thermo- and storage stability, lowered Km value, and protection from some metal ions are salient achievements of present immobilization. The study shows the efficacy, durability, and sustainability of immobilized catalytic system which could be efficiently used for various juice processing operations. PMID:26347814

  15. Determination of unique microbial volatile organic compounds produced by five Aspergillus species commonly found in problem buildings.

    PubMed

    Gao, Pengfei; Korley, Frederick; Martin, Jennifer; Chen, Bean T

    2002-01-01

    This study identified unique microbial volatile organic compounds (UMVOCs) produced by five Aspergillus species (A. fumigatus, A. versicolor, A. sydowi, A. flavus, and A. niger) cultivated on malt extract agar and gypsum board. The hypothesis was that UMVOCs can be used to predict the presence of Aspergillus species. During the cultivation humidified air was continually supplied and evenly distributed through each of the culture flasks. Volatile metabolites were collected using Tenax TA tubes on Days 8, 16, and 30 after inoculation. The volatile metabolites were determined by gas chromatography/mass spectroscopy after thermal desorption. Nine compounds recognized as UMVOCs--3-methyl-1-butanol; 2-methyl-1-propanol; terpineol; 2-heptanone; 1-octen-3-ol; dimethyl disulfide; 2-hexanone; 3-octanone; and 2-pentylfuran--were found on the cultures in detectable amounts. The first two compounds were detected at the highest frequency when combining both media. The first four compounds were found to be the dominant UMVOCs on gypsum board, which could be used as chemical markers of the common Aspergillus species grown indoors.

  16. Keratitis caused by Aspergillus pseudotamarii.

    PubMed

    Baranyi, Nikolett; Kocsubé, Sándor; Szekeres, András; Raghavan, Anita; Narendran, Venkatapathy; Vágvölgyi, Csaba; Panneer Selvam, Kanesan; Babu Singh, Yendremban Randhir; Kredics, László; Varga, János; Manikandan, Palanisamy

    2013-04-12

    A male patient presented with complaints of redness, pain and defective vision in the left eye. The infiltrate healed completely after two weeks of topical natamycin administration. A polyphasic approach was used to identify the isolate as Aspergillus pseudotamarii, which produced aflatoxins in inducing medium.

  17. Aspergillus infections in cystic fibrosis.

    PubMed

    King, Jill; Brunel, Shan F; Warris, Adilia

    2016-07-01

    Patients with cystic fibrosis (CF) suffer from chronic lung infection and airway inflammation. Respiratory failure secondary to chronic or recurrent infection remains the commonest cause of death and accounts for over 90% of mortality. Bacteria as Staphylococcus aureus, Pseudomonas aeruginosa and Burkholderia cepacia complex have been regarded the main CF pathogens and their role in progressive lung decline has been studied extensively. Little attention has been paid to the role of Aspergillus spp. and other filamentous fungi in the pathogenesis of non-ABPA (allergic bronchopulmonary aspergillosis) respiratory disease in CF, despite their frequent recovery in respiratory samples. It has become more apparent however, that Aspergillus spp. may play an important role in chronic lung disease in CF. Research delineating the underlying mechanisms of Aspergillus persistence and infection in the CF lung and its link to lung deterioration is lacking. This review summarizes the Aspergillus disease phenotypes observed in CF, discusses the role of CFTR (cystic fibrosis transmembrane conductance regulator)-protein in innate immune responses and new treatment modalities. PMID:27177733

  18. Sexual recombination in Aspergillus tubingensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspergillus tubingensis from section Nigri (Black Aspergilli) is closely related to A. niger and is used extensively in the industrial production of enzymes and organic acids. We recently discovered sexual reproduction in A. tubingensis and in this study, demonstrate that the progeny are products o...

  19. Keratitis caused by Aspergillus pseudotamarii

    PubMed Central

    Baranyi, Nikolett; Kocsubé, Sándor; Szekeres, András; Raghavan, Anita; Narendran, Venkatapathy; Vágvölgyi, Csaba; Panneer Selvam, Kanesan; Babu Singh, Yendremban Randhir; Kredics, László; Varga, János; Manikandan, Palanisamy

    2013-01-01

    A male patient presented with complaints of redness, pain and defective vision in the left eye. The infiltrate healed completely after two weeks of topical natamycin administration. A polyphasic approach was used to identify the isolate as Aspergillus pseudotamarii, which produced aflatoxins in inducing medium. PMID:24432226

  20. Nutritional limitation and resistance to opportunistic Aspergillus parasites in honey bee larvae.

    PubMed

    Foley, Kirsten; Fazio, Géraldine; Jensen, Annette B; Hughes, William O H

    2012-09-15

    Honey bees are threatened by land use changes which reduce the availability and diversity of pollen and nectar resources. There is concern that poor nutrition may be involved in recent population declines, either directly or due to indirect effects on immunocompetence. The larval stage is likely to be the most vulnerable to a poor diet, but the effects of larval nutrition on the disease susceptibility of bees are not well known. In this study we used laboratory-reared honey bee larvae to investigate the effects of diet quality on disease susceptibility to the opportunistic fungal parasites Aspergillus flavus, Aspergillus phoenicis and A. fumigatus. Larvae fed on a nutritionally poor diet were found to be significantly more susceptible to A. fumigatus. Larval resistance to A. fumigatus was enhanced by feeding with a diet supplemented with either dandelion or polyfloral pollens. This indicates that dandelion and polyfloral pollens contain elements that enhance resistance to this fungal disease, illustrating an interaction between nutrition and parasitism and emphasising the benefit of diverse floral resources in the environment to maintain honey bee health.