scholarly journals Control of Aflatoxigenic Molds by Antagonistic Microorganisms: Inhibitory Behaviors, Bioactive Compounds, Related Mechanisms, and Influencing Factors

Toxins ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 24 ◽  
Author(s):  
Xianfeng Ren ◽  
Qi Zhang ◽  
Wen Zhang ◽  
Jin Mao ◽  
Peiwu Li
Keyword(s):  
Bioactive Compounds ◽  
Crop Production ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Key Factors ◽  
Toxicological Effects ◽  
Factors Influencing ◽  
Antagonistic Microorganisms ◽  
Aflatoxigenic Fungi ◽  
Food And Feed

Aflatoxin contamination has been causing great concern worldwide due to the major economic impact on crop production and their toxicological effects to human and animals. Contamination can occur in the field, during transportation, and also in storage. Post-harvest contamination usually derives from the pre-harvest infection of aflatoxigenic molds, especially aflatoxin-producing Aspergilli such as Aspergillus flavus and A. parasiticus. Many strategies preventing aflatoxigenic molds from entering food and feed chains have been reported, among which biological control is becoming one of the most praised strategies. The objective of this article is to review the biocontrol strategy for inhibiting the growth of and aflatoxin production by aflatoxigenic fungi. This review focuses on comparing inhibitory behaviors of different antagonistic microorganisms including various bacteria, fungi and yeasts. We also reviewed the bioactive compounds produced by microorganisms and the mechanisms leading to inhibition. The key factors influencing antifungal activities of antagonists are also discussed in this review.

Study on the Key Environmental Factors Aspergillus flavus Growth and Aflatoxin Production

2014 ◽  
Vol 668-669 ◽  
pp. 1550-1553 ◽  
Author(s):  
Chu Shu Zhang ◽  
Qin Zhao ◽  
Jian Xiong Feng ◽  
Jie Sun ◽  
Li Na Yu ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Aspergillus Flavus ◽  
Prevention And Control ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Key Factors ◽  
Culture Time ◽  
Burman Design ◽  
And Control ◽  
Plackett Burman Design

Single factor and Plackett-Burman design were used to determine the key environmental factors for Aspergillus flavus growth and aflatoxin production. The results showed that the key factors were culture time, moisture content. So Controling of moisture was crucial for Aflatoxin contamination prevention and control.

Bioactive compounds in Diospyros mafiensis roots inhibit growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus

2017 ◽  
Vol 10 (3) ◽  
pp. 237-248
Author(s):  
J.A. Mmongoyo ◽  
M.G. Nair ◽  
J.E. Linz ◽  
F. Wu ◽  
J.K. Mugula ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Bioactive Compounds ◽  
Vegetative Growth ◽  
Aspergillus Parasiticus ◽  
Fungal Infections ◽  
Aflatoxin Production ◽  
Enzyme Linked Immunosorbent Assay ◽  
Root Bark ◽  
Total Aflatoxin ◽  
Food And Feed

Diospyros mafiensis F. White is a medicinal shrub or small tree (6 m tall) widely distributed in the Zanzibar-Inhambane regional mosaic and traditionally used to treat leprosy, diarrhoea, and skin fungal infections in Tanzania and Mozambique. Our objective was to determine the anti-aflatoxigenic properties of compounds from D. mafiensis root bark against vegetative growth, sporulation and aflatoxin production by Aspergillus flavus and Aspergillus parasiticus. Bioassay-guided extraction, fractionation, and isolation of bioactive compounds using A. parasiticus B62 were employed. The bioactive compounds were elucidated using 1H and 13CNMR and LC-MS. Growth inhibition was determined by measuring the colony diameter of A. flavus AF3357 and A. parasiticus SU-1 ATCC56775. Inhibitory effects on sporulation were estimated using a haemocytometer. Total aflatoxin was quantified by direct competitive enzyme-linked immunosorbent assay (ELISA). Bioactive compounds diosquinone (DQ) and 3-hydroxydiosquinone (3HDQ) were identified. DQ weakly inhibited A. flavus and A. parasiticus vegetative growth (MIC50 > 100 µg/ml) and 3HDQ strongly inhibited A. flavus (MIC50 = 14.9 µg/ml) and A. parasiticus (MIC50 = 39.1 µg/ml). DQ strongly reduced total aflatoxin production by A. flavus from 157 to 36 ng/plate, and by A. parasiticus from 1,145 ng/plate to 45 ng/plate at 100 µg/ml. 3HDQ reduced total aflatoxin production by A. parasiticus from 1,145 to 32 ng/plate; stimulated production by A. flavus from 157 to 872 ng/plate at 12.5 µg/ml but reduced to 45 ng/plate at 100 µg/ml. In summary, DQ and 3HDQ could be used as natural antifungal compounds to prevent mould growth and aflatoxin accumulation in food and feed.

Challenges facing the biological control strategy for eliminating aflatoxin contamination

2015 ◽  
Vol 8 (2) ◽  
pp. 225-233 ◽  
Author(s):  
K.C. Ehrlich ◽  
G.G. Moore ◽  
J.E. Mellon ◽  
D. Bhatnagar
Keyword(s):  
Animal Health ◽  
Cost Benefit ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Persistent Problem ◽  
Cost Benefit Ratio ◽  
Food And Feed ◽  
Potential Damage ◽  
The Stability ◽  
Biocontrol Strain

Competition with Aspergillus flavus isolates incapable of aflatoxin production is currently the most widely used biocontrol method for reducing aflatoxin contamination in maize and cottonseed where aflatoxin contamination is a persistent problem for human and animal health. The method involves spreading non-aflatoxigenic A. flavus spores onto the field prior to harvest. How competition works is not fully understood. Current theories suggest that atoxigenic A. flavus either simply displaces aflatoxin-producing isolates or that competition is an active inhibition process that occurs when the fungi occupy the same locus on the plant. In this paper we describe several challenges that the biocontrol strategy should address before this practice is introduced worldwide. These include the need to better understand the diversity of A. flavus populations in the agricultural soil, the effects of climate change on both this diversity and on plant susceptibility, the ability of the introduced biocontrol strain to outcross with existing aflatoxin-producing A. flavus, the adaptation of certain A. flavus isolates for predominant growth on the plant rather than in the soil, the difficulty in timing the application or controlling the stability of the inoculum, the effect of the introduction of the biocontrol strain on the soil microenvironment, the potential damage to the plant from the introduced strain, and the overall need to better understand the entire A. flavus toxin burden, beyond that of aflatoxin, that may result from A. flavus contamination. In addition, the cost/benefit ratio for the biocontrol method should be considered in comparing this method to other methods for reducing food and feed contamination with aflatoxins.

scholarly journals Determination of Aflatoxin Concentrations in Cereals and Legumes Marketed in Zaria Metropolis, Kaduna State, Nigeria

2021 ◽  
Vol 6 (1) ◽  
pp. 208-218
Author(s):  
S. Shitu ◽  
◽  
M. Attahiru ◽  
H. Umar
Keyword(s):  
Immunosorbent Assay ◽  
Uv Light ◽  
Aflatoxin Production ◽  
Neutral Red ◽  
Proximate Analysis ◽  
Aflatoxin Contamination ◽  
Enzyme Linked Immunosorbent Assay ◽  
High Concentration ◽  
Crude Lipid ◽  
Food And Feed

Aflatoxins are group of secondary fungal metabolites produced by Aspergillus species, such as Aspergillus flavus and Aspergillus parasiticus. The aflatoxin producing moulds can grow on cereals and legumes in the field, poorly dried harvested crops in storage, processed food, and feed products. The study was carried out with the aim to determine the level of aflatoxin contamination of cereals grain and legumes in Zaria metropolis, Kaduna State, Nigeria. Ninety (90) samples were collected, which comprises of 18 samples each of millet, sorghum, maize, beans, and groundnuts respectively. The samples were subjected to proximate analysis. The grains were further subjected to cultural isolation and microscopic identification. The isolates were then screened for aflatoxin production ability with neutral red desiccated coconut agar and viewed under UV light (365nm). The remaining portions of the samples was grounded and extracted with 80% (v/v) methanol. The enzyme-linked Immunosorbent Assay (ELISA) technique was used in quantifying the total aflatoxin content of the samples. The results revealed that all the cereals and legumes analysed contain organic and inorganic nutrients that can support the growth of aflatoxigenic moulds and production of aflatoxins. Some major parameters such as carbohydrate content, crude protein, crude lipid, and ash contents were statistically significant (p < 0.05). Thirty-one (31) isolates from the 90 samples were confirmed to be A. flavus and seventeen (17) were A. Parasiticus, with percentage occurrence of 34.4% and 18.9% respectively. All the isolates were screened and demonstrated ability for aflatoxin production under UltraViolent light (390nm). The results also revealed a high concentration of aflatoxin (11.04 µg/kg) in millet and a low concentration in sorghum (1.07 µg/kg). The contamination levels within the grains were found to be statistically significant (p < 0.05). Aflatoxin contaminations also occurred in 48 samples out of the 90 samples analysed. The grains samples analysed were found to be contaminated with varying amounts of aflatoxins, which is harmful to humans and animals. Therefore, steps should be taken to ensure that grains are properly dried prior to storage. Keywords: aflatoxin, A. flavus, A. parasiticus, cereals, Enzyme-linked Immunosorbent Assay, legumes

scholarly journals Temperature Influences on Interactions Among Aflatoxigenic Species of Aspergillus Section Flavi During Maize Colonization

2021 ◽  
Vol 2 ◽  
Author(s):  
Connel Ching'anda ◽  
Joseph Atehnkeng ◽  
Ranajit Bandyopadhyay ◽  
Kenneth A. Callicott ◽  
Marc J. Orbach ◽  
...  
Keyword(s):  
Species Interactions ◽  
Type Species ◽  
Animal Health ◽  
Aflatoxin Production ◽  
Fungal Species ◽  
Aflatoxin Contamination ◽  
Fungal Metabolites ◽  
Food And Feed ◽  
Temporal And Spatial ◽  
Maize Kernels

Fungal species within Aspergillus section Flavi contaminate food and feed with aflatoxins. These toxic fungal metabolites compromise human and animal health and disrupt trade. Genotypically and phenotypically diverse species co-infect crops, but temporal and spatial variation in frequencies of different lineages suggests that environmental factors such as temperature may influence structure of aflatoxin-producing fungal communities. Furthermore, though most species within Aspergillus section Flavi produce sclerotia, divergent sclerotial morphologies (small or S-type sclerotia vs. large or L-type sclerotia) and differences in types and quantities of aflatoxins produced suggest lineages are adapted to different life strategies. Temperature is a key parameter influencing pre- and post-harvest aflatoxin contamination of crops. We tested the hypothesis that species of aflatoxin-producing fungi that differ in sclerotial morphology will vary in competitive ability and that outcomes of competition and aflatoxin production will be modulated by temperature. Paired competition experiments between highly aflatoxigenic S-type species (A. aflatoxiformans and Lethal Aflatoxicosis Fungus) and L-type species (A. flavus L morphotype and A. parasiticus) were conducted on maize kernels at 25 and 30°C. Proportions of each isolate growing within and sporulating on kernels were measured using quantitative pyrosequencing. At 30°C, S-type fungi were more effective at host colonization compared to L-type isolates. Total aflatoxins and the proportion of B vs. G aflatoxins were greater at 30°C compared to 25°C. Sporulation by L-type isolates was reduced during competition with S-type fungi at 30°C, while relative quantities of conidia produced by S-type species either increased or did not change during competition. Results indicate that both species interactions and temperature can shape population structure of Aspergillus section Flavi, with warmer temperatures favoring growth and dispersal of highly toxigenic species with S-type sclerotia.

scholarly journals Factors Influencing Aflatoxin Contamination in Before and After Harvest Peanuts: A Review

2014 ◽  
Vol 4 (1) ◽  
pp. 148 ◽  
Author(s):  
Enjie Diao ◽  
Haizhou Dong ◽  
Hanxue Hou ◽  
Zheng Zhang ◽  
Ning Ji ◽  
...  
Keyword(s):  
Supply Chain ◽  
Secondary Metabolites ◽  
Economic Loss ◽  
Aflatoxin Contamination ◽  
Post Harvest ◽  
Toxicological Effects ◽  
Factors Influencing ◽  
Before And After ◽  
The 1960S ◽  
Fungal Secondary Metabolites

<p>Aflatoxin contamination of peanuts has been of worldwide concern since the 1960s. Aflatoxins are fungal secondary metabolites that have been associated with severe toxicological effects to human and animals, which can cause enormous economic loss to producers, handlers, processors and marketers of contaminated peanuts. Aflatoxin contamination of peanuts is unavoidable due to the varied factors in pre-harvest, harvesting, and post-harvest stages of peanuts. The review summarizes the factors influencing aflatoxin contamination in the whole supply chain of peanuts.</p>

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.

scholarly journals Molecular Characterisation of Aflatoxigenic and Non-Aflatoxigenic Strains of Aspergillus Section Flavi Isolated from Imported Peanuts along the Supply Chain in Malaysia

Toxins ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 501 ◽  
Author(s):  
Mahror Norlia ◽  
Selamat Jinap ◽  
Mahmud Ab Rashid Nor-Khaizura ◽  
Son Radu ◽  
Cheow Keat Chin ◽  
...  
Keyword(s):  
Aflatoxin Production ◽  
Storage Conditions ◽  
Aflatoxin Contamination ◽  
Aflatoxin Biosynthesis ◽  
Asian Countries ◽  
Aspergillus Section Flavi ◽  
Aflatoxigenic Fungi ◽  
Tropical Weather ◽  
Southeast Asian Countries ◽  
Aspergillus Section

Peanuts are widely consumed in many local dishes in southeast Asian countries, especially in Malaysia which is one of the major peanut-importing countries in this region. Therefore, Aspergillus spp. and aflatoxin contamination in peanuts during storage are becoming major concerns due to the tropical weather in this region that favours the growth of aflatoxigenic fungi. The present study thus aimed to molecularly identify and characterise the Aspergillus section Flavi isolated from imported peanuts in Malaysia. The internal transcribed spacer (ITS) and β-tubulin sequences were used to confirm the species and determine the phylogenetic relationship among the isolates, while aflatoxin biosynthesis genes (aflR, aflP (omtA), aflD (nor-1), aflM (ver-1), and pksA) were targeted in a multiplex PCR to determine the toxigenic potential. A total of 76 and one isolates were confirmed as A. flavus and A. tamarii, respectively. The Maximum Likelihood (ML) phylogenetic tree resolved the species into two different clades in which all A. flavus (both aflatoxigenic and non-aflatoxigenic) were grouped in the same clade and A. tamarii was grouped in a different clade. The aflatoxin biosynthesis genes were detected in all aflatoxigenic A. flavus while the non-aflatoxigenic A. flavus failed to amplify at least one of the genes. The results indicated that both aflatoxigenic and non-aflatoxigenic A. flavus could survive in imported peanuts and, thus, appropriate storage conditions preferably with low temperature should be considered to avoid the re-emergence of aflatoxigenic A. flavus and the subsequent aflatoxin production in peanuts during storage.

scholarly journals Biodiversity of Aflatoxigenic Aspergillus Species in Dairy Feeds in Bulawayo, Zimbabwe

2021 ◽  
Vol 11 ◽  
Author(s):  
Nancy Nleya ◽  
Lubanza Ngoma ◽  
Modupeade C. Adetunji ◽  
Mulunda Mwanza
Keyword(s):  
Species Diversity ◽  
Dairy Cows ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Production Potential ◽  
Aflatoxigenic Fungi ◽  
Different Types ◽  
Spent Grain ◽  
Food Commodities ◽  
Feed Samples

The presence of molds, especially certain species of Aspergillus, in food commodities may contribute to aflatoxin contamination. The aim of this study was to determine the biodiversity of Aspergillus species in dairy feeds from farms in select locations in Zimbabwe and assess their aflatoxin production potential using a polyphasic approach. A total of 96 feed samples were collected, which consisted of dairy feed concentrate, mixed ration, brewers’ spent grain, and grass from 13 farms during the dry season (August–October, 2016) and the following rainy season (January–March, 2017). A total of 199 presumptive isolates representing four sections from genus Aspergillus (Nigri, Fumigati, Flavi, and Circumdati) were recovered from the feeds. Section Flavi, which includes several aflatoxin producers, constituted 23% (n = 46) of the isolates. Species from this section were A. flavus, A. nomius, A. oryzae, A. parasiticus, and A. parvisclerotigenus, and 39 (84.4%) of these showed evidence of aflatoxin production in plate assays. Of the 46 section Flavi isolates examined, some lacked one or more of the five targeted aflatoxin cluster genes (aflD, aflR, aflS, aflM, and aflP). The presence of the five genes was as follows: aflD (76.9%), aflR (48.7%), aflS (74.4%), aflM (64.1%), and aflP (79.5%). This study highlights the species diversity of aflatoxigenic fungi that have the potential to contaminate different types of feed for dairy cows. Our findings underscore the importance of preventing contamination of feedstuffs by these fungi so that aflatoxins do not end up in the diets of consumers.

Consumers‟ Acceptance of „Halal‟ Credit Card Services: An Empirical Analysis

2015 ◽  
Vol 3 (1) ◽  
pp. 51 ◽  
Author(s):  
Zaimy Johana Johan ◽  
Lennora Putit
Keyword(s):  
Perceived Control ◽  
Credit Card ◽  
Credit Cards ◽  
Product Knowledge ◽  
Key Factors ◽  
Developing Nation ◽  
Business Transactions ◽  
Factors Influencing ◽  
Financial Credit ◽  
Survey Questionnaires

Many past researches have been carried out in an attempt to continuously understand individuals‟ consumption behaviour. This study was conducted to investigate key factors influencing consumers‟ potential acceptance of halal (or permissible) financial credit card services. Specifically, it anticipated the influence of attitude, social influences and perceived control on consumers‟ behavioural intention to accept such services. In addition, factors such as religiosity and product knowledge were also postulated to affect consumers‟ attitude towards the act of using halal credit cards for any retail or business transactions. Using non-probability sampling approach, a total of 500 survey questionnaires was distributed to targeted respondents in a developing nation but only 220 usable feedbacks were received for subsequent data analysis. Regression results revealed that religiosity and product knowledge significantly influence consumers‟ attitude toward using halal credit card services.  Attitude in turn, subsequently has a significant impact on consumers‟ intention to accept halal financial credit card services. Several theoretical and managerial contributions were observed in this study.   

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