scholarly journals Relationship Between Aflatoxin Content and Buoyancy of Florunner Peanut Kernels

1989 ◽  
Vol 16 (1) ◽  
pp. 48-51 ◽  
Author(s):  
J. W. Kirksey ◽  
R. J. Cole ◽  
J. W. Dorner
Keyword(s):  
Fungal Growth ◽  
Kernel Density ◽  
Positive Association ◽  
Aflatoxin Production ◽  
Total Sample ◽  
Aflatoxin Contamination ◽  
Lumen Volume ◽  
Aflatoxin Content ◽  
Hollow Space ◽  
Flotation Method

Abstract A water flotation method was used to study the distribution of aflatoxin relative to kernel density in naturally contaminated samples of shelled farmers stock peanuts. Five-hundred gram samples of visibly undamaged, contaminated peanuts were added to 2000 mL of tapwater, and approximately 15–30% of the kernels rose to the surface as buoyant kernels. These buoyant kernels contained an average of 95 + % of the total sample aflatoxin content. Buoyant kernels, when examined internally, all had a hollow space or “lumen” inside the kernel between the two cotyledons. Data showed an association between aflatoxin content, kernel lumen volume, and the propensity of kernels to float. The lumen may provide a reservoir of air for flotation, fungal growth, and aflatoxin production. The positive association between the presence of a lumen and aflatoxin contamination may provide a possible resistance strategy, if the presence or absence of a lumen is genetically controlled or if it can be manipulated physiologically.

No Effect of Soybean Lipoxygenase on Aflatoxin Production in Aspergillus flavus–Inoculated Seeds

2002 ◽  
Vol 65 (12) ◽  
pp. 1984-1987 ◽  
Author(s):  
J. E. MELLON ◽  
P. J. COTTY
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Pathogens ◽  
Seed Viability ◽  
Soybean Seed ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Soybean Seeds ◽  
Heat Treated ◽  
Significant Difference

Soybean lines lacking lipoxygenase (LOX) activity were compared with soybean lines having LOX activity for the ability to support growth and aflatoxin B1 production by the fungal seed pathogen Aspergillus flavus. Whole seeds, broken seeds, and heat-treated (autoclaved) whole seeds were compared. Broken seeds, irrespective of LOX presence, supported excellent fungal growth and the highest aflatoxin levels. Autoclaved whole seeds, with or without LOX, produced good fungal growth and aflatoxin levels approaching those of broken seeds. Whole soybean seeds supported sparse fungal growth and relatively low aflatoxin levels. There was no significant difference in aflatoxin production between whole soybean seeds either with or without LOX, although there did seem to be differences among the cultivars tested. The heat treatment eliminated LOX activity (in LOX+ lines), yet aflatoxin levels did not change substantially from the broken seed treatment. Broken soybean seeds possessed LOX activity (in LOX+ lines) and yet yielded the highest aflatoxin levels. The presence of active LOX did not seem to play the determinant role in the susceptibility of soybean seeds to fungal pathogens. Seed coat integrity and seed viability seem to be more important characteristics in soybean seed resistance to aflatoxin contamination. Soybean seeds lacking LOX seem safe from the threat of increased seed pathogen susceptibility.

scholarly journals Chestnut Drying Is Critical in Determining Aspergillus flavus Growth and Aflatoxin Contamination

Toxins ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 530 ◽  
Author(s):  
Simona Prencipe ◽  
Ilenia Siciliano ◽  
Carlotta Gatti ◽  
Maria Gullino ◽  
Angelo Garibaldi ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Total Phenol ◽  
Fungal Colonization ◽  
Total Phenol Content ◽  
Phenol Content ◽  
Drying Treatment ◽  
Drying Conditions

Chestnut drying is used to prevent postharvest losses and microorganism contamination during storage. Several studies reported the contamination by aflatoxins (AFs) produced by Aspergillus spp. in chestnuts. The effect of drying temperatures (from 30 to 50 °C) was evaluated on the growth of A. flavus and the production of aflatoxins in chestnuts. The influence of the treatment on the proximate composition, the total phenol content and antioxidant activity of chestnuts was considered. Fungal colonization was observed on the nuts dried at 30, 35, and 40 °C; the incidence was lower at 40 °C. The highest concentrations of AFB1 and AFB2 were produced at 40 °C. No aflatoxins were detected at 45 or 50 °C. At 40 °C A. flavus was under suboptimal conditions for growth (aw 0.78), but the fungus was able to synthesize aflatoxins. As the temperatures applied increased, the total phenol content increased, while the antioxidant activity decreased. A drying treatment at 45 °C for seven days (aw 0.64) could be a promising method to effectively control both the growth of aflatoxigenic fungi and the production of aflatoxins. This study provides preliminary data useful to improve the current drying conditions used in chestnut mills, to reduce both fungal growth and aflatoxin production.

Evaluation of Post-harvest Aflatoxin Production in Peanut Germplasm with Resistance to Seed Colonization and Pre-harvest Aflatoxin Contamination

2004 ◽  
Vol 31 (2) ◽  
pp. 124-134 ◽  
Author(s):  
H. Q. Xue ◽  
T. G. Isleib ◽  
G. A. Payne ◽  
G. OBrian
Keyword(s):  
Genotypic Variation ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Block Designs ◽  
Plastic Bags ◽  
Arachis Hypogaea L ◽  
Seed Colonization ◽  
Highly Correlated

Abstract Contamination of peanut (Arachis hypogaea L.) with aflatoxin produced by species of Aspergillus remains a problem for the U.S. peanut industry. Several peanut genotypes were reported to be resistant to in vitro seed colonization by Aspergillus flavus Link ex Fries (IVSCAF), to field seed colonization by A. flavus (FSCAF), or to preharvest aflatoxin contamination (PAC), but few to production of aflatoxin per se. Cotyledons of 39 peanut genotypes reportedly resistant to IVSCAF, FSCAF, or PAC, and eight susceptible to PAC were evaluated in four tests for their ability to support aflatoxin production after inoculation with A. flavus. Cultivars Perry and Gregory were used as checks in each test. Seed cotyledons were separated, manually blanched, inoculated with conidia of A. flavus, placed on moistened filter paper in petri dishes, and incubated for 8 d at 28 C. Dishes were arranged on plastic trays enclosed in plastic bags and stacked with PVC spacers between trays. Incomplete block designs were used for all tests. In each test, none of the genotypes examined was completely resistant to aflatoxin production, but significant genotypic variation was observed in the amount of total aflatoxin accumulated in seeds. Genotypes previously reported to be resistant to IVSCAF, FSCAF, or PAC exhibited differential abilities to support aflatoxin production. PI 590325, PI 590299, PI 290626, and PI 337409 supported reduced levels of aflatoxin, and their degree of resistance was consistent across tests. Fungal growth was highly correlated with aflatoxin production in three tests. The results from this study suggested that there were no absolute relationships of aflatoxin production resistance with IVSCAF, FSCAF, or PAC resistance, but that it should be possible to identify a genotype with high IVSCAF, FSCAF, or PAC resistance and reduced capacity for aflatoxin production by A. flavus.

scholarly journals Inhibition of Aflatoxin Production by Paraquat and External Superoxide Dismutase in Aspergillus flavus

Toxins ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 107 ◽  
Author(s):  
Tomohiro Furukawa ◽  
Shohei Sakuda
Keyword(s):  
Superoxide Dismutase ◽  
Aspergillus Flavus ◽  
Regulatory Protein ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Sod Activity ◽  
Fungal Cell ◽  
Cell Extracts ◽  
Ic50 Value

Aflatoxin contamination of crops is a worldwide problem, and elucidation of the regulatory mechanism of aflatoxin production, for example relative to the oxidative–antioxidative system, is needed. Studies have shown that oxidative stress induced by reactive oxygen species promotes aflatoxin production. However, superoxide has been suggested to have the opposite effect. Here, we investigated the effects of the superoxide generator, paraquat, and externally added superoxide dismutase (SOD) on aflatoxin production in Aspergillus flavus. Paraquat with an IC50 value of 54.9 µM inhibited aflatoxin production without affecting fungal growth. It increased cytosolic and mitochondrial superoxide levels and downregulated the transcription of aflatoxin biosynthetic cluster genes, including aflR, a key regulatory protein. The addition of bovine Cu/ZnSOD to the culture medium suppressed the paraquat-induced increase in superoxide levels, but it did not fully restore paraquat-inhibited aflatoxin production because bovine Cu/ZnSOD with an IC50 value of 17.9 µg/mL itself inhibited aflatoxin production. Externally added bovine Cu/ZnSOD increased the SOD activity in fungal cell extracts and upregulated the transcription of genes encoding Cu/ZnSOD and alcohol dehydrogenase. These results suggest that intracellular accumulation of superoxide impairs aflatoxin production by downregulating aflR expression, and that externally added Cu/ZnSOD also suppresses aflatoxin production by a mechanism other than canonical superoxide elimination activity.

Hazelnuts as Possible Substrate for Aflatoxin Production1

1988 ◽  
Vol 51 (4) ◽  
pp. 289-292 ◽  
Author(s):  
V. SANCHIS ◽  
Mª L. QUILEZ ◽  
R. VILADRICH ◽  
I. VIÑAS ◽  
R. CANELA
Keyword(s):  
Water Activity ◽  
Aspergillus Parasiticus ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Potassium Sorbate ◽  
Fungal Contamination ◽  
Activity Temperature ◽  
High Production

A study was carried out on the fungal contamination of commercially available hazelnuts, and the effect of different factors (water activity, temperature and presence of potassium sorbate) on fungal growth and aflatoxin production in hazelnuts. All samples (100%) of raw hazelnuts showed fungal contamination. None of the samples showed aflatoxin contamination, but when hazelnuts were inoculated with Aspergillus parasiticus, and water activity and temperature were optimal formold growth, high production of aflatoxin was found. Potassium sorbate at subinhibitory levels seemed to inhibit fungal growth, but enhanced aflatoxin production.

Lack of aflatoxin production by Aspergillus flavus is associated with reduced fungal growth and delayed expression of aflatoxin pathway genes

2015 ◽  
Vol 8 (3) ◽  
pp. 335-340 ◽  
Author(s):  
H. Zhang ◽  
L.L. Scharfenstein ◽  
C. Carter-Wientjes ◽  
P.-K. Chang ◽  
D. Zhang ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Animal Feed ◽  
Regulatory Gene ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Resistance Factors ◽  
Crop Varieties ◽  
Crop Resistance ◽  
Underlying Mechanisms

Aflatoxins, produced by Aspergillus flavus and Aspergillus parasiticus, are the most toxic fungal secondary metabolites that contaminate agricultural commodities such as peanuts, cotton and maize. Understanding the underlying mechanisms of crop resistance to fungal infection is an important step for plant breeders to develop better and improved crop varieties for safe production of human food and animal feed. Infection studies have identified a resistant (R) peanut line, GT-C20, which is able to decrease aflatoxin contamination. The mycelial growth of A. flavus NRRL3357 on the R peanut line was much lower than that on the susceptible (S) peanut line, Tifrunner. Besides reducing fungal growth, the R line compared to the S line inhibited aflatoxin production completely. Real-time RT-PCR assays of both the R and S lines infected by A. flavus showed that expression of five aflatoxin biosynthetic pathway genes, the aflR regulatory gene and the aflD, aflM, aflP and aflQ structural genes, was not reduced but was significantly delayed on the R line. The results suggested that resistance factors of the R line acted negatively on A. flavus growth and also altered fungal development. The dysfunction in development changed the timing and the pattern of aflatoxin gene expression, which in part rendered A. flavus unable to produce aflatoxins.

scholarly journals Sabotage at the Powerhouse? Unraveling the Molecular Target of 2-Isopropylbenzaldehyde Thiosemicarbazone, a Specific Inhibitor of Aflatoxin Biosynthesis and Sclerotia Development in Aspergillus flavus, Using Yeast as a Model System

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2971
Author(s):  
Cristina Dallabona ◽  
Marianna Pioli ◽  
Giorgio Spadola ◽  
Nicolò Orsoni ◽  
Franco Bisceglie ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Specific Inhibitor ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Molecular Target ◽  
Model System ◽  
Aflatoxin Contamination ◽  
Great Promise ◽  
Fungal Cell ◽  
Yeast Saccharomyces Cerevisiae

Amongst the various approaches to contain aflatoxin contamination of feed and food commodities, the use of inhibitors of fungal growth and/or toxin biosynthesis is showing great promise for the implementation or the replacement of conventional pesticide-based strategies. Several inhibition mechanisms were found taking place at different levels in the biology of the aflatoxin-producing fungal species such as Aspergillus flavus: compounds that influence aflatoxin production may block the biosynthetic pathway through the direct control of genes belonging to the aflatoxin gene cluster, or interfere with one or more of the several steps involved in the aflatoxin metabolism upstream. Recent findings pointed to mitochondrial functionality as one of the potential targets of some aflatoxin inhibitors. Additionally, we have recently reported that the effect of a compound belonging to the class of thiosemicarbazones might be related to the energy generation/carbon flow and redox homeostasis control by the fungal cell. Here, we report our investigation about a putative molecular target of the 3-isopropylbenzaldehyde thiosemicarbazone (mHtcum), using the yeast Saccharomyces cerevisiae as model system, to demonstrate how the compound can actually interfere with the mitochondrial respiratory chain.

scholarly journals Comparison of Aflatoxin Production in Normal- and High-Oleic Backcross-Derived Peanut Lines

Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1360-1365 ◽  
Author(s):  
H. Q. Xue ◽  
T. G. Isleib ◽  
G. A. Payne ◽  
R. F. Wilson ◽  
W. P. Novitzky ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Latin Square ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
High Oleic ◽  
Plastic Bags ◽  
The Mean ◽  
Petri Dishes ◽  
The Difference

The effect of the high-oleate trait of peanut on aflatoxin production was tested by comparing normal oleic lines with high-oleic backcross-derived lines. Seeds were blanched, quartered, and inoculated with Aspergillus flavus conidia, placed on moistened filter paper in petri dishes, and incubated for 8 days. In one experiment, dishes were stacked in plastic bags in a Latin square design with bags and positions in stacks as blocking variables. High-oleic lines averaged nearly twice as much aflatoxin as normal lines. Background genotype had no significant effect on aflatoxin content, and interaction between background genotype and oleate level was not detected. In a second experiment, dishes were arranged on plastic trays enclosed in plastic bags and stacked with PVC spacers between trays. Fungal growth and aflatoxin production were greater than in the first experiment. Background genotype, oleate level, and their interaction were significant. The mean of high-oleic lines was almost twice that of normal lines, but the magnitude of the difference varied with background genotype. Special care should be taken with high-oleic lines to prevent growth of Aspergillus spp. and concomitant development of aflatoxin contamination.

Production of Aflatoxin in Cocoa Beans

1979 ◽  
Vol 62 (5) ◽  
pp. 1076-1079 ◽  
Author(s):  
Lawrence M Lenovich ◽  
W Jeffrey Hurst
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Ivory Coast ◽  
Aspergillus Parasiticus ◽  
Aflatoxin Production ◽  
Growth Conditions ◽  
Aflatoxin Contamination ◽  
Cocoa Beans ◽  
Total Aflatoxin ◽  
Substrate Variation

Abstract Aflatoxin was produced in both non-autoclaved and autoclaved Ivory Coast cocoa beans inoculated with Aspergillus parasiticus NRRL 2999 under optimum laboratory growth conditions. Total aflatoxin levels ranged from 213 to 5597 ng/g substrate. Aflatoxin was quantitated by using high pressure liquid chromatography (HPLC). Raw, non-autoclaved cocoa beans, also inoculated with aspergilli, produced 6359 ng aflatoxin/g substrate. Variation in aflatoxin production between bean varieties was observed. Total aflatoxin levels of 10,446 and 23,076 ng/g substrate were obtained on Ivory Coast beans inoculated with A. parasiticus NRRL 2999 and NRRL 3240, respectively. Aflatoxin production on Trinidad and Malaysian beans was 28 and 65 ng aflatoxin/g substrate. These data support previously reported low level natural aflatoxin contamination in cocoa.

A Phytoalexin and Aflatoxin Producing Peanut Seed Culture System

1994 ◽  
Vol 21 (2) ◽  
pp. 130-134 ◽  
Author(s):  
S. M. Basha ◽  
R. J. Cole ◽  
S. K. Pancholy
Keyword(s):  
Water Stress ◽  
Culture System ◽  
Fungal Growth ◽  
Aflatoxin Contamination ◽  
Peanut Seed ◽  
Seed Culture ◽  
Murashige And Skoog Medium ◽  
Yellow Orange ◽  
Increased Susceptibility

Abstract An in vitro seed culture system was established to grow peanut seed of different maturities viz. white, yellow, orange, brown and black, using a modified Murashige and Skoog medium. Under this system peanut seed of yellow, orange, brown and black maturity categories grew to maturity as measured by increase in their size and germinability. In vitro cultured seeds produced significant amounts of phytoalexins and were contaminated with aflatoxins following their inoculation with Aspergillus spp. while the noninoculated sterile controls did not produce any phytoalexins. Exposure of seed cultures to water stress using various concentrations of mannitol (0 to 1 M) and polyethylene glycol 8000 (0-30% w/v) caused a significant decrease in their phytoalexin producing ability, and enhanced fungal growth compared to the nonstressed controls. The seeds that were stressed with mannitol and subsequently inoculated with A. flavus and A. parasiticus showed a significant increase in the aflatoxin contamination of stressed seed compared to the unstressed control. This would indicate that in vitro grown seeds responded to water stress similar to the field grown peanuts by loosing their ability to produce phytoalexins and increased susceptibility to aflatoxin contamination. Hence, this system has a potential application in evaluating peanut genotypes for aflatoxin resistance under water stress.

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