scholarly journals The Interaction between Tribolium castaneum and Mycotoxigenic Aspergillus flavus in Maize Flour

Insects ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 730
Author(s):  
Sónia Duarte ◽  
Ana Magro ◽  
Joanna Tomás ◽  
Carolina Hilário ◽  
Paula Alvito ◽  
...  

Tribolium castaneum is one of the most common insect pests of stored products. Its presence makes cereals more susceptible to the spread of the fungi Aspergillus flavus, which may produce mycotoxins. The aim of this work was to evaluate the influence of T. castaneum adults on the development of a mycotoxigenic A. flavus strain in maize flour as well as the influence of this fungus on the insects. Maize flour was exposed to T. castaneum, spores of A. flavus or to both. The results revealed an interaction between T. castaneum and A. flavus as the flour exposed to both organisms was totally colonized by the fungus whereas almost all the insects were killed. Aflatoxin B1 (AFB1) revealed a significantly higher concentration in the flour inoculated with both organisms (18.8 µg/kg), being lower when exposed only to A. flavus, suggesting that the presence of insects may trigger fungal development and enhance mycotoxin production. The ability of these organisms to thrive under the same conditions and the chemical compounds they release makes the interaction between them a subject of great importance to maintain the safety of stored maize. This is the first work evaluating the interaction between T. castaneum and A. flavus mycotoxin production.

2021 ◽  
Author(s):  
Sónia Duarte ◽  
Ana Magro ◽  
Joanna Tomás ◽  
Carolina Hilário ◽  
Paula Alvito ◽  
...  

1986 ◽  
Vol 49 (6) ◽  
pp. 445-448 ◽  
Author(s):  
V. SANCHIS ◽  
N. SALA ◽  
A. PALOMES ◽  
P. SANTAMARINA ◽  
P. A. BURDASPAL

A survey was carried out to obtain data on the occurrence of aflatoxin and aflatoxigenic mold contamination of foods in Spain. A variety of commodities amounting to 338 samples were analyzed, comprising cereal grains, mixed feeds, edible nuts, wheat flour for bread-making, biscuits, sliced bread, soya beans and breakfast cereals. The results reveal a rather low incidence of aflatoxin contamination in samples tested. Aflatoxins were detected in 4 of 27 samples of mixed feeds at levels below 5 μg/kg; one sample of peanuts was contaminated with 120 μg aflatoxin B1/kg and 22 μg aflatoxin B2/kg. Aflatoxins B1 and B2 were also detected in a lot of whole maize flour, averaging 8 μg/kg and 3 μg/kg, respectively. Of a total of 288 samples tested, 100% showed variable incidences of fungal contamination. Maize samples were the ones most frequently contaminated with Aspergillus flavus (54.5%). Strains of A. flavus isolated from maize samples also showed the highest proportion of aflatoxigenic molds (17.2%) compared with those isolated from other sources.


2020 ◽  
Vol 31 (1) ◽  
pp. 24-35 ◽  
Author(s):  
Somiahnadar Rajendran

Insects are a common problem in stored produce. The author describes the extent of the problem and approaches to countering it. Stored products of agricultural and animal origin, whether edible or non-edible, are favourite food for insect pests. Durable agricultural produce comprising dry raw and processed commodities and perishables (fresh produce) are vulnerable to insect pests at various stages from production till end-use. Similarly, different animal products and museum objects are infested mainly by dermestids. Insect pests proliferate due to favourable storage conditions, temperature and humidity and availability of food in abundance. In addition to their presence in food commodities, insects occur in storages (warehouses, silos) and processing facilities (flour mills, feed mills). Insect infestation is also a serious issue in processed products and packed commodities. The extent of loss in stored products due to insects varies between countries depending on favourable climatic conditions, and pest control measures adopted. In stored food commodities, insect infestation causes loss in quantity, changes in nutritional quality, altered chemical composition, off-odours, changes in end-use products, dissemination of toxigenic microorganisms and associated health implications. The insects contribute to contaminants such as silk threads, body fragments, hastisetae, excreta and chemical secretions. Insect activity in stored products increases the moisture content favouring the growth of moulds that produce mycotoxins (e.g., aflatoxin in stored peanuts). Hide beetle, Dermestes maculatus infesting silkworm cocoons has been reported to act as a carrier of microsporidian parasite Nosema bombycis that causes pebrine disease in silkworms. In dried fish, insect infestation leads to higher bacterial count and uric acid levels. Insects cause damage in hides and skins affecting their subsequent use for making leather products. The trend in stored product insect pest management is skewing in favour of pest prevention, monitoring, housekeeping and finally control. Hermetic storage system can be supplemented with CO2 or phosphine application to achieve quicker results. Pest detection and monitoring has gained significance as an important tool in insect pest management. Pheromone traps originally intended for detection of infestations have been advanced as a mating disruption device ensuing pest suppression in storage premises and processing facilities; pheromones also have to undergo registration protocols similar to conventional insecticides in some countries. Control measures involve reduced chemical pesticide use and more non-chemical inputs such as heat, cold/freezing and desiccants. Furthermore, there is an expanding organic market where physical and biological agents play a key role. The management options for insect control depend on the necessity or severity of pest incidence. Generally, nonchemical treatments, except heat, require more treatment time or investment in expensive equipment or fail to achieve 100% insect mortality. Despite insect resistance, environmental issues and residue problems, chemical control is inevitable and continues to be the most effective and rapid control method. There are limited options with respect to alternative fumigants and the alternatives have constraints as regards environmental and health concerns, cost, and other logistics. For fumigation of fresh agricultural produce, new formulations of ethyl formate and phosphine are commercially applied replacing methyl bromide. Resistance management is now another component of stored product pest management. In recent times, fumigation techniques have improved taking into consideration possible insect resistance. Insect control deploying nanoparticles, alone or as carriers for other control agents, is an emerging area with promising results. As there is no single compound with all the desired qualities, a necessity has arisen to adopt multiple approaches. Cocktail applications or combination treatments (IGRs plus organophosphorus insecticides, diatomaceous earth plus contact insecticides, nanoparticles plus insecticides/pathogens/phytocompounds and conventional fumigants plus CO2; vacuum plus fumigant) have been proved to be more effective. The future of store product insect pest management is deployment of multiple approaches and/or combination treatments to achieve the goal quickly and effectively.


Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 391
Author(s):  
Christopher Hernandez ◽  
Laura Cadenillas ◽  
Anwar El Maghubi ◽  
Isaura Caceres ◽  
Vanessa Durrieu ◽  
...  

Aflatoxin B1 (AFB1) is a potent carcinogenic mycotoxin that contaminates numerous crops pre- and post-harvest. To protect foods and feeds from such toxins without resorting to pesticides, the use of plant extracts has been increasingly studied. The most interesting candidate plants are those with strong antioxidative activity because oxidation reactions may interfere with AFB1 production. The present study investigates how an aqueous extract of Mimosa tenuiflora bark affects both the growth of Aspergillus flavus and AFB1 production. The results reveal a dose-dependent inhibition of toxin synthesis with no impact on fungal growth. AFB1 inhibition is related to a down-modulation of the cluster genes of the biosynthetic pathway and especially to the two internal regulators aflR and aflS. Its strong anti-oxidative activity also allows the aqueous extract to modulate the expression of genes involved in fungal oxidative-stress response, such as msnA, mtfA, atfA, or sod1. Finally, a bio-guided fractionation of the aqueous extract demonstrates that condensed tannins play a major role in the anti-aflatoxin activity of Mimosa tenuiflora bark.


Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 385
Author(s):  
Alaa Baazeem ◽  
Alicia Rodriguez ◽  
Angel Medina ◽  
Naresh Magan

Pistachio nuts are an important economic tree nut crop which is used directly or processed for many food-related activities. They can become colonized by mycotoxigenic spoilage fungi, especially Aspergillus flavus, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO2 levels increase, and episodes of extreme wet/dry cycles occur due to human industrial activity. The objectives of this study were to evaluate the effect of interacting Climate Change (CC)-related abiotic factors of temperature (35 vs. 37 °C), CO2 (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, aw) on (a) growth (b) aflD and aflR biosynthetic gene expression and (c) AFB1 production by two strains A. flavus (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The A. flavus strains were resilient in terms of growth on pistachio-based media and the colonisation of pistachio nuts with no significant difference when exposed to the interacting three-way climate-related abiotic factors. However, in vitro studies showed that AFB1 production was significantly stimulated (p < 0.05), especially when exposed to 1000 ppm CO2 at 0.98–0.95 aw and 35 °C, and sometimes in the 37 °C treatment group at 0.98 aw. The relative expression of the structural aflD gene involved in AFB1 biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the aw level examined. For the regulatory aflR gene expression, there was a significant (p < 0.05) increase in 1000 ppm CO2 and 37 °C for both strains, especially at 0.95 aw. The in situ colonization of pistachio nuts resulted in a significant (p < 0.05) stimulation of AFB1 production at 35 °C and 1000 ppm CO2 for both strains, especially at 0.98 aw. At 37 °C, AFB1 production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO2. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO2 and the level of water stress on AFB1 production.


Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1759
Author(s):  
Neda Motamedi ◽  
Mahmood Barani ◽  
Azadeh Lohrasbi-Nejad ◽  
Mojtaba Mortazavi ◽  
Ali Riahi-Medvar ◽  
...  

The improvement in the enzyme activity of Aspergillus flavus urate oxidase (Uox) was attained by immobilizing it on the surface of a Ni-based magnetic metal–organic framework (NimMOF) nanomaterial; physicochemical properties of NimMOF and its application as an enzyme stabilizing support were evaluated, which revealed a significant improvement in its stability upon immobilization on NimMOF (Uox@NimMOF). It was affirmed that while the free Uox enzyme lost almost all of its activity at ~40–45 °C, the immobilized Uox@NimMOF retained around 60% of its original activity, even retaining significant activity at 70 °C. The activation energy (Ea) of the enzyme was calculated to be ~58.81 kJ mol−1 after stabilization, which is approximately half of the naked Uox enzyme. Furthermore, the external spectroscopy showed that the MOF nanomaterials can be coated by hydrophobic areas of the Uox enzyme, and the immobilized enzyme was active over a broad range of pH and temperatures, which bodes well for the thermal and long-term stability of the immobilized Uox on NimMOF.


Eisei kagaku ◽  
1991 ◽  
Vol 37 (2) ◽  
pp. 107-116 ◽  
Author(s):  
MITSUO NAKAZATO ◽  
SATOSHI MOROZUMI ◽  
KAZUO SAITO ◽  
KENJI FUJINUMA ◽  
TAICHIRO NISHIMA ◽  
...  

2006 ◽  
pp. 655-658 ◽  
Author(s):  
M.M. Moghaddam ◽  
E.M. Goltapeh ◽  
H. Hokmabadi ◽  
M. Haghdel ◽  
A.M. Mortazavi

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