scholarly journals 393 The Potential of Saprophytic Yeasts Antagonistic to Aspergillus flavus in Reducing Aflatoxin Contamination of Tree Nuts

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 511E-511
Author(s):  
S.-S.T. Hua ◽  
J.L. Baker ◽  
M. Flores-Espiritu
Keyword(s):  
Fungal Pathogens ◽  
Maximum Level ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Penicillium Expansum ◽  
Orange Pigment ◽  
Tree Nuts ◽  
Norsolorinic Acid ◽  
Low Degrees ◽  
Aflatoxin B

California is the major state for producing almonds, pistachios, and walnuts, with a total market value of $1.6 billion. Both domestic and export markets of these nuts presently allow a maximum level of aflatoxin B1 contamination in the edible nuts to be 20 ppb. Even very low degrees of infection of the nuts by A. flavus can result in aflatoxin levels above the mandatory standards. Biological control to reduce the population of and to inhibit the biosynthesis of A. flavus in orchards may be useful to decrease infection and thus aflatoxin content in the edible nuts. Certain saprophytic yeasts were shown to effectively compete with postharvest fungal pathogens such as Penicillium expansum and Botrytis cinerea. The potential of saprophytic yeasts to reduce aflatoxin contamination in tree nuts has not been hitherto extensively explored. A safe visual bioassay for screening yeasts antagonistic to A. flavus has been developed. The nor mutant of A. flavus has a defective norsolorinic acid reductase and blocks the aflatoxin biosynthetic pathway, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We used the nor mutant in the assay to screen yeasts strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment as well as the growth and sporulation of the fungus. Yeast strains that reduced the red-orange pigment accumulation in the nor mutant were identified and shown to inhibit aflatoxin biosynthesis of several toxigenic strains of A. flavus.

scholarly journals Interactions of Saprophytic Yeasts with anor Mutant of Aspergillus flavus

1999 ◽  
Vol 65 (6) ◽  
pp. 2738-2740 ◽  
Author(s):  
Sui-Sheng T. Hua ◽  
James L. Baker ◽  
Melanie Flores-Espiritu
Keyword(s):  
Aspergillus Flavus ◽  
Agar Plate ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Orange Pigment ◽  
Yeast Strains ◽  
Norsolorinic Acid ◽  
Aflatoxin Accumulation ◽  
Food Commodities ◽  
Pigment Accumulation

ABSTRACT The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the normutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.

Extracts of Agave americana inhibit aflatoxin production in Aspergillus parasiticus

2011 ◽  
Vol 4 (1) ◽  
pp. 37-42 ◽  
Author(s):  
A. Rosas-Taraco ◽  
E. Sanchez ◽  
S. García ◽  
N. Heredia ◽  
D. Bhatnagar
Keyword(s):  
Aspergillus Parasiticus ◽  
Public Awareness ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Aqueous Extracts ◽  
Total Aflatoxin ◽  
Toxigenic Fungi ◽  
Agave Americana ◽  
Acid Accumulation ◽  
Norsolorinic Acid

Toxigenic fungi invade crops prior to harvest as well as during storage and produce harmful, even carcinogenic toxins such as aflatoxins. Since consumers demand safe commodities, and due to enhanced public awareness of the dangers of many synthetic fungicides, the importance of investigating alternative, natural products to control these toxigenic fungi is clear. This study investigated the effect of aqueous extracts of Agave americana on growth, conidia and aflatoxin production. Aspergillus parasiticus strains SRRC 148, SRRC 143 (Su-1), and A. parasiticus SRRC 162, a mutant (nor-) that accumulates norsolorinic acid (NOR, an orange-coloured intermediate of the aflatoxin pathway), were first inoculated into Adye and Mateles liquid medium, then plant extracts were added, and incubated at 28 °C for 7 days. Aflatoxin and norsolorinic acid were assayed by HPLC and spectrophotometry, respectively. While the extract of A. americana stimulated growth of the studied fungi, conidiogenesis, norsolorinic acid accumulation (in the nor- mutant), and aflatoxin production were significantly affected. The reduction was produced by the extracts at concentrations higher than 5-10 mg/ml, where all types of total aflatoxin analysed (aflatoxins B1, B2, G1 and G2) were reduced from 64% to >99% in the whole culture, and a reduction of 75% of norsolorinic acid. The results of the present work indicate that extracts of A. americana may be promising safe alternatives to harmful fungicides for controlling aflatoxin contamination.

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.

Aflatoxin B1 contamination of feedstuff on a dairy farm in Northern Peru and aflatoxin M1 concentrations in raw milk

2021 ◽  
pp. 1-6
Author(s):  
I. Salazar ◽  
I. López ◽  
P. Glorio-Paulet ◽  
C. Gomez
Keyword(s):  
Soybean Meal ◽  
Dairy Farm ◽  
Maximum Level ◽  
Raw Milk ◽  
Aflatoxin Contamination ◽  
Aflatoxin M1 ◽  
Significant Difference ◽  
Northern Peru ◽  
Contamination Levels ◽  
Aflatoxin B

Research regarding aflatoxin contamination levels in Peru is limited, although aflatoxin M1 (AFM1) and aflatoxin B1 (AFB1) require surveillance because of their toxicity. European regulations state that the harmonised maximum level (ML) is 5 μg/kg for AFB1 in feedstuffs and 0.05 μg/kg for AFM1 in milk. Our study aimed to determine the annual variation levels of AFB1 in ingredients used in feedstuffs for dairy cows and those of AFM1 in milk at a typical intensive dairy farm in Northern Peru. For 1 year, milk (n=529) and feedstuff samples (n=235) were collected and aflatoxin levels were determined using a lateral flow immunoassay. We found that 16% of milk samples had AFM1 contamination above the ML. AFM1 level was significantly higher (P<0.05) in December (end of spring) than that in all other months. Throughout the year, the most used feedstuffs were maize, soybean meal and whole soybean. Among the maize samples (n=77), 2.59% had an AFB1 level above the ML, whereas 45% had an AFB1 level below the ML. On the other hand, neither the soybean meal (n=69) nor whole soybean samples (n=64) had an AFB1 level above the ML, 46.4 and 20%, respectively. In 50% (n=10) of cottonseed meal samples, AFB1 level was above the ML; in 20% of wheat middling samples, it was above the ML. Cottonseed and wheat middling samples were used for 2 and 5 months, respectively. AFB1 level in feedstuff showed a significant difference in December (P<0.05) compared with other months, specifically for maize and soybean meal. As the AFM1 level in milk results from AFB1 contaminated feedstuff, our results emphasise the need to implement specific quality measures to reduce contamination.

scholarly journals Occurrence and Exposure Assessment of Aflatoxin B1 in Omena (Rastrineobola argentea) from Kenya

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Esther Marijani ◽  
Harrison Charo-Karisa ◽  
Emmanuel Kigadye ◽  
Sheila Okoth
Keyword(s):  
Health Risk ◽  
Maximum Level ◽  
Exposure Dose ◽  
Aflatoxin Contamination ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Consumption ◽  
Fish Feed ◽  
Potential Health ◽  
Feed Production ◽  
Aflatoxin B

Omena (Rastrineobola argentea) is the most consumed fish species in Kenya. In this study, we assessed the occurrence of aflatoxin B1 (AFB1) in Omena and the potential health risk of AFB1 to Kenyan consumers of this fish. A total of 74 samples comprising Omena intended for human consumption and fish feed production were analyzed in this study. Aflatoxin levels in Omena were determined using the enzyme-linked immunosorbent assay (ELISA). Omena intended for fish feed production was most contaminated with a mean concentration of 46.93 μg·kg−1 (2.24–115.23 μg·kg−1) compared with Omena intended for human consumption (mean = 19.42 μg·kg−1, range = 2.01–49.30 μg·kg−1). Thirty-five positive samples (83.3%) exceeded the maximum level permitted (5 μg·kg−1) by the East Africa Community standard for food used for human consumption. The exposure dose of AFB1 from consuming Omena was estimated to be 1.34 ng·kg−1 BW day−1, and margin of exposure (MoE) value for AFB1 was found to be 126.3, which indicates health risk to Omena consumers. The results suggest that the current situation of aflatoxin contamination in Omena has an adverse effect on the health of the consumers as well as the animals. Therefore, more surveys are needed to understand the scope and extent of aflatoxin contamination in Omena.

scholarly journals Aspergillus flavus and Aflatoxin Contamination of Leguminous Trees of the Sonoran Desert in Arizona

2001 ◽  
Vol 91 (9) ◽  
pp. 913-919 ◽  
Author(s):  
María L. Boyd ◽  
Peter J. Cotty
Keyword(s):  
Aspergillus Flavus ◽  
Sonoran Desert ◽  
Aflatoxin Production ◽  
Common Species ◽  
Aflatoxin Contamination ◽  
Leguminous Trees ◽  
Significant Growth ◽  
Tree Legumes ◽  
Aflatoxin B

Aspergillus spp. in section Flavi were frequently associated with desert tree legumes in uncultivated areas of the Sonoran Desert. Of 270 samples of debris and fruits of mesquite (Prosopis spp.), ironwood (Olneya tesota), acacia (Acacia spp.), and palo verde (Cercidium and Parkinsonia spp.), 87% were positive for A. flavus (S and L strains) and A. tamarii. A. flavus was the most common species (87%) among the 3,763 isolates examined. Mesquite pods were both the substrate from which A. flavus was recovered most frequently and the substrate from native habitats with the greatest aflatoxin content. In vitro, most desert legumes supported significant growth, reproduction, and aflatoxin production by A. flavus, with mesquite pods yielding 1 × 1010 propagules/g and 5,000 μg/kg of aflatoxin B1. Twenty percent of legume pods collected in the desert contained measurable quantities of aflatoxin, ranging from 1 to >2,500 μg/kg. Insect-damaged mesquite pods had significantly higher aflatoxin than intact pods. Legumes are apparently important reservoirs of aflatoxin-producing fungi and significant sources of aflatoxin contamination in the native Sonoran Desert habitats of Arizona.

Factors influencing the inhibition of aflatoxin production in corn by Aspergillus niger

1983 ◽  
Vol 29 (9) ◽  
pp. 1087-1091 ◽  
Author(s):  
B. W. Horn ◽  
D. T. Wicklow
Keyword(s):  
Aspergillus Niger ◽  
Sodium Citrate ◽  
Water Extract ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Factors Influencing ◽  
Effects Of Ph ◽  
Aflatoxin B ◽  
Corn Kernels ◽  
Substrate Ph

Aspergillus niger, a mold commonly associated with Aspergillus flavus in damaged corn, interferes with the production of aflatoxin when grown with A. flavus on autoclaved corn. The pH of com-meal disks was adjusted using NaOH–HCl, citric acid–sodium citrate, or a water extract of A. niger fermented corn. Aflatoxin formation was completely inhibited below pH 2.8–3.0, irrespective of the system used for pH adjustment. When grown in association with A. flavus NRRL 6432 on autoclaved corn kernels, A. niger NRRL 6411 lowered substrate pH sufficiently to suppress aflatoxin production. The biodegradation of aflatoxin B1or its conversion to aflatoxin B2a were eliminated as potential mechanisms by which A. niger reduces aflatoxin contamination. A water extract of corn kernels fermented with A. niger caused an additional inhibition of aflatoxin formation apart from the effects of pH.

A study of the 2013 Western European issue of aflatoxin contamination of maize from the Balkan area

2015 ◽  
Vol 8 (5) ◽  
pp. 641-651 ◽  
Author(s):  
T.C. de Rijk ◽  
H.P. van Egmond ◽  
H.J. van der Fels-Klerx ◽  
R. Herbes ◽  
M. de Nijs ◽  
...  
Keyword(s):  
Maximum Level ◽  
Storage Conditions ◽  
Aflatoxin Contamination ◽  
Fungal Identification ◽  
Sampling Protocols ◽  
Food And Feed ◽  
Slurry Method ◽  
Improved Performance ◽  
Aflatoxin B ◽  
Sampling Procedures

In March 2013 a large shipment of maize, intended for feed was subject of an alert in the Rapid Alert System for Food and Feed of the European Commission (EC) because the aflatoxin B1 (AFB1) level in the load exceeded the EC regulated maximum level of 20 μg/kg. Since the shipment had passed import controls and was already distributed (mainly to German farms), a massive recall followed. The aim of the current study was to investigate questions, raised by authorities and industry, related to the effectivity of EU sampling procedures, the influence of sample homogenisation procedures and sample storage conditions on the test results, and fungal identification as unexpected mycotoxins were identified during this study. The Netherlands Food and Consumer Product Safety Authority seized a shipload of maize in July 2013, suspected to be contaminated with AFB1. The shipload was sampled according to the 2009 and 2013 EC Sampling Regulations to compare the outcomes of both sampling protocols. Mycotoxin analysis of the incremental samples showed high mean levels of AFB1, aflatoxin G1 (AFG1), and ochratoxin A (OTA). Also an extreme inhomogeneous distribution of aflatoxins and OTA was proven. Analysis of samples homogenised according to the slurry method showed improved performance as compared to samples homogenised through dry homogenisation. Sampling and sample homogenisation according to the Regulation from 2013 showed a closer estimate of the ‘true’ AFB1 content as compared to sampling according to the Regulation from 2009. No influence of laboratory storage conditions on AFB1 concentration could be determined. Fungal identification revealed Aspergillus flavus as the main source of AFB1 in this shipment. Infrequent occurrence of Aspergillus parasiticus might have been the source of AFG1. The occurrence of sometimes large amounts of OTA could not be explained, however it was suggested that Aspergillus welwitschiae might have played a role.

Visual Estimation of Aflatoxin Production in Peanut with Aspergillus Norsolorinic Acid Mutants1

1998 ◽  
Vol 25 (2) ◽  
pp. 92-99 ◽  
Author(s):  
Y. López ◽  
N. P. Keller ◽  
B. Sarr ◽  
T. D. Phillips ◽  
R. G. Cuero ◽  
...  
Keyword(s):  
High Performance ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Peanut Seed ◽  
Visual Rating ◽  
Interfacial Surface ◽  
Norsolorinic Acid ◽  
Low Levels ◽  
Layer Chromatography ◽  
Rating Scheme

Abstract Peanut seed and pods are susceptible to contamination by aflatoxin (AF), a carcinogenic mycotoxin produced by Aspergillus flavus Links Fr. and A. parasiticus Speare. Efforts to evaluate peanut lines for resistance to AF contamination have been impeded by limitations to the methodologies available for AF detection. AF cannot be seen by visible light and its detection involves grinding seed tissue in organic solvents, separation of phases, and detection by ELISA, high performance liquid chromatography (HPLC) or thin layer chromatography. These methodologies are time-consuming, expensive, labor-intensive, and are uninformative in defining the tissues of the peanut seed and pod that are most frequently contaminated with AF. Aspergillus AF mutants which accumulate norsolorinic acid (NOR), an orange-pigmented AF pathway intermediate, provide an easy and convenient mean to detect AF contamination. A visual rating scheme for NOR contamination of peanut seed was developed that correlated favorably to HPLC detection of both NOR and AF (r = 0.96 and 0.95, respectively). When screening the 38 plant progenies that comprise Tamspan 90 (a spanish cultivar), NOR was first seen in the intercotyledonary cavity and the interfacial surface of cotyledons and testae in seeds examined from infected pods. Immature pods were often heavily contaminated with NOR. Six of the 38 lines accumulated low levels of NOR in two laboratory tests. Additional studies are needed to determine if these results are predictive of aflatoxin contamination under field conditions.

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.

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