Mycotoxins

MycotoxinsGzde ren Yardmc & Bra Gltekin

REHIS Trainers' Seminar, October 2009

What is a Mycotoxin?Secondary metabolites (chemicals) of a fungus that produce toxic results in another organism.Toxigenic moulds - Aspergillus, Penicillium, Fusarium are found on human food and animal feed - animal productsOther toxigenic moulds may be present in the environment.Cytotoxic: disrupt cell structures such as membranes, and processes such as protein, DNA, and RNA synthesis.Lack of visible appearance of fungus does not negate presence of mycotoxins. Toxins can remain in the organism after fungus has been removed.Less selective in organism selection, can cross plant species barrier.Can be heat stable, not destroyed by canning or other processes.


Different moulds and mycotoxins have been regularly reported with a variety of food items, including cereals, grains, nuts,fruits, vegetables, and spices (Prakash et al., 2014). Mycotoxin Chain of Events


Mycotoxin Chain of Eventshttp://www.foodtech-international.com/papers/images/mycotoxins/figure1.gif


Fungal toxinsUnlike bacterial toxins, fungal toxins (mycotoxins) are not proteins and therefore are not usually detectable by the immune systems of humans and animalsSuch small molecules induce no response in human immune system !Major danger of mycotoxin in diet is our inability to detect them biologically.


Mycotoxins are highly stable and are difficult to destroy by traditional food processing conditions

Mycotoxins can cause acute disease manifested by kidney or liver failure or chronic disease including carcinoma, birth defects, skin irritation, neurotoxicity, and death.

Three general mechanisms of mycotoxin action are described as mutagenic, teratogenic, or carcinogenic.


During the mutagenic action, toxin binds to DNA, especially the liver mitochondrial DNA resulting in point mutation addition or substitution in DNA and affect liver function (hence hepatotoxic).

Teratogenic action leads to birth defects

The carcinogenic effect cause irreversible defects in cell physiology resulting in abnormal cell growth and metastasis.


Mycotoxigenic filamentous fungiRhizopus spp.Byssochlamys spp.Claviceps spp.Eupenicillium spp.Eurotium spp.Neosartorya spp.Talaromyces spp.Alternaria spp.Aspergillus spp.

Penicillium spp.Fusarium spp.Cladosporium spp.Geotrichum candidumPaecilomyces variotiiPhomopsis spp.Stachybotrys spp.Trichoderma virideWallemia sebi


Types of mycotoxinsThere are over 300 mycotoxins but the commonly occurring ones in food and feed.

About 20 mycotoxins occur in food at levels and frequency to be of food safety concern.


Mycotoxins associated with food and feedAflatoxins (B1, B2, G1, G2, M1)Ochratoxin AZearalenoneFumonisinsTrichothecenesPatulinMoniliformSterigmatocystin

CitrininCyclopiazonic acidKojic acidMaltoryzine-nitropropionic acidAspergillic acidPenicillic acidRoquefortine C


Aflatoxins

Aflatoxin is a common contaminant of foods, particularly in the staple diets of many developing countries. Among 18 different types of aflatoxins identified , major members are aflatoxin B1,B2,G1 and G2.Aflatoxin M1 , M2 which excreted in the milk of animal feed contaminated with Aflatoxin B1 , B2 .Its order of toxicity is B1 > G1 > B2 > G2


The individual members of aflatoxins are designated by a letter which relates to some physical or other characteristics of the compound ( Corrado et al., 1971).Aflatoxin B1 , B2 (fluorescing blue (B)in ultra violet light(365n.m) or Aflatoxin G1 , G2 (fluorescing green (G)in ultra violet light(365n.m)) .

Aflatoxins


Aflatoxin (Aspergillus flavus toxin) is produced by Aspergillus flavus and parasiticus ,when the temperature is between 24and 35,and they will form within many commodities whenever the moisture content exceeds 7%.(Williams et al., 2004)

The allowable toxin limits are 20 ppb in nuts .

Allowable limit in meats, corn, and wheat is also 0.5 ppb.

The acute lethal dose for adult human is thought to be 1020 mg.

The main biological effects of aflatoxins are carcinogenicity, immunosuppression, mutagenicity and teratogenicity (Betina, 1989).

It can cause liver cancer with colon and lung cancer. Classified aflatoxin B1 as a group I carcinogen.

Aflatoxins


Aflatoxin B-1Definite link to cancer in animals.Possible link to cancer in humans. Primarily attacks the liver, in cases of cirrhosis, necrosis, and carcinomas with a secondary affect of immune suppression. Risk factor for neonatal jaundice, in areas of maternal consumption.Does not stay in the body for long periods of time, usually excreted within 96 hours, in animals.In milk, for human consumption, advisory level is .5 ppb.


Aflatoxin M1Aflatoxin M1 is an oxidative metabolite of Aflatoxin B1.(ie produced from AFB1 in mammals)Aflatoxin M1 may be present in milk and dairy products.Aflatoxin M1 has been reported in human breast milk particularly in developing countries - Middle East, Africa, South Asia.The carry-over of aflatoxin B, and its metabolic transformation product, the aflatoxin M, into tissues suitable for human consumption, eggs and milk of food-producing animals, has been described for different animal species (Veldman et al., 1992).


Aflatoxin structure


Chronic Aflatoxin Exposure and Human HealthCarcinogenicityLiver cancer is a serious consequence of long-term exposure to aflatoxins.Hepatitis B infection may exacerbate the effects of aflatoxin exposure and vaccination against Hepatitis B can help reduce carcinogenicity of the toxin. Other consequences of chronic exposure include decreased immune and reproductive function.Children chronically exposed may experience growth failure.Infants may be exposed through breast milk.The fetus may be exposed during pregnancy if the mother consumes aflatoxins.No level of aflatoxin exposure is considered safe for humans.


Symptoms of AflatoxicosisAcute hepatitisConvulsionCirrhosisCarcinoma of liverAcute necrosisMalaise


Examples of Aflatoxin-Related EventsUnited Kingdom1960s: Turkey X disease and bird die-offs attributed to syndrome XBoth incidents were the result of acute aflatoxicosis

IndiaIn 1974, an outbreak of hepatitis in India affected 400 people resulting in 100 deaths;Cause of death: aflatoxins in corn ( >15 mg/kg)Kenya

2004-2005: Acute Aflatoxicosis and human mortalityAflatoxin contamination of maize caused over 317 cases 125 human deaths


Examples of Aflatoxin-Related EventsUnited States1998: Crop contaminationAflatoxin contamination of maize (corn) in the south-eastern U.S. led to rejection rates of corn of up to 50%.Aflatoxin contamination reached 1500 ppb (5 times the 300 ppb highest acceptable limit in animal feed set by the U.S. Food and Drug Administration)2006-2007: Crop contaminationDrought conditions and moisture stress led to aflatoxin on corn in Missouri which caused rejection of some harvested corn by buyers


Aflatoxins and Environmental Conditions Conditions favoring aflatoxin formation include:High temperatureHigh humidity Presence of external plant stressors:Periods of droughtInsect infestationSoil conditions conducive to Aspergillus growthHigh organic contentHigh moisture


Strategies for Reducing Aflatoxin ExposureRegulationsAgricultural production quality controlFood processing and crop storage safetyEarly recognition and medical management of health effects Educational outreachCommunity Individual


Ochratoxin

Ochratoxin A (OTA) is a mycotoxin produced by fungi of the genera Aspergillus and Penicillium that contaminates a great variety of foodstuffs, such as cereals, coffee, cocoa, beans, grapes and dried fruit (Vettorazi et al., 2014).

The family of ochratoxins consists of three members, A, B, and C.Ochratoxin A is the most abundant and also the most toxic of the three

Penicillium verrucosum, is a common storage fungus and is the source of ochratoxin A in crops.

Ochratoxin is found in a large variety of foods including wheat,corn, soybeans, oats, barley, coffee beans, meats and cheese.

Barley is thought to be the predominant source.

Ochratoxin is hepatotoxic and nephrotoxic and a potent carcinogen.


Ochratoxin toxicityOchrotoxicosis, the disease state induced by ochratoxin with levels of ochratoxin in feed ranging from 0.3 to 16 ug/g (Wyatt,1979).The main target organ is the kidney, the liver also affected to a lesser degree.The kidneys of affected birds become enlarged, the livers exhibit a tan colored appearance and have an increased glycogen content.


Fumonisins

Fumonisins are produced by Fusarium verticillioides, F. proliferatum, and F. nygamai. Fusarium verticillioides under ideal conditions can infect corn

Corns, tomatoes, asparagus, and garlic are the major source of fumonisins.

Fumonisins are highly water soluble and they do not have any aromatic

Fumonisins are highly stable to a variety of heat and chemical processing treatments.

Fumonisins are associated with a variety of adverse health effects in livestock and experimental animals. Currently, there is no direct evidence that fumonisins cause adverse health effects in humans because available studies demonstrate only inconclusive associations between fumonisins and human cancer (FDA).


Fumonisins

ProductTotal FumonisinsDegermed dry milled corn products (e.g., flaking grits, corn grits, corn meal, corn flour with fat content of < 2.25%, dry weight basis)2 parts per million (ppm)Whole or partially degermed dry milled corn products (e.g., flaking grits, corn grits, corn meal, corn flour with fat content of>2.25 %, dry weight basis)4 ppmDry milled corn bran4 ppmCleaned corn intended for masa production4 ppmCleaned corn intended for popcorn3 ppm


Patulin

Patulin is produced by Penicillium clariform, P. expansum, P. patulum and by Aspergillus spp.

Bread, sausage, fruits (apricots, grapes, peaches, pears, and apples), and apple juice are the major source for this toxin (Soliman et al., 2015).

Patulin is needed in high dosage to show pathogenesis. It is a carcinogenic toxin and is reported to be responsible for subcutaneous sarcoma.

Maximum US FDA limit of 50 ppb


Fungi SubstrateMycotoxinAspergillus flavusMaize, groundnut, oilseed, cotton seedAflatoxinAspergillus parasiticusMaize, groundnut, oilseed, cotton seedAflatoxinAspergillus nomiusMaize, groundnut, oilseed, cotton seedAflatoxinAspergillus ochraceusBarkey wheatOchratoxinAspergillus carboneriusGrapes wine coffeeOchratoxinFusarium oxysporumWheat barley maizeFumonisinsFusarium sp.Wheat barley maizeT-2 toxinPenicillium verrucosumWheat barley maizeOchratoxinClaviceps purpureaRyeErgot alkaloidsStachybotryshaysatratoxins


Mycotoxins and world food supply

It is estimated that 25% of worlds food crops are affected annually by variable levels of Mycotoxins (Williams et al., 2004).

>100 countries have regulations regarding levels of mycotoxins in food and feed.


DETECTION AND CONTROLLING THE MYCOTOXINS


IntroductionMycotoxins are frequently formed in field crops as a result of contamination and growth of toxigenic plant pathogenic fungi. Commodities frequently contaminated include cereals (e.g. corn, wheat, barley, maize, oats and rye), nuts (peanuts, pistachios), dried fruit (figs), spices and pulses.


Requirements for ControlAnalysis of mycotoxins forms an important tool in the control strategy and requires;Comply with mycotoxin legislation.Analytical methodology must allow determination of mycotoxin at least down to the specified regulatory levels.It is crucial in establishing HACCP for control of mycotoxin contaminationFit-for-purpose tests are also valuable elements in a companys overall due diligence programme, including trouble shooting.


Classical analytical methodsClassical analytical methods for mycotoxins;Thin-layer chromatography (TLC),High-performance liquid chromatography (HPLC)Gas chromatography (GC) Mass spectrometry (MS).

Immunoaffinity techniques to simplify extraction and improve mycotoxin recovery and measurement from foodstuffs.


Commercial techniquesReliable and robust results can only be obtained from a fit-for-purpose method that has undergone rigorous optimization, evaluation and validation studies.Commercial techniquesCommercial immunological techniques for mycotoxins are based on specific monoclonal and polyclonal antibodies produced against the toxin, and divided broadly into immunoaffinity (IAC) column-based analysis and enzyme-linked immunosorbent assay (ELISA)


Commercial techniquesThe IAC are used effectively to clean-up complex matrices and allow isolation and concentration of the specific toxin.In the case of ELISAs, the clean-up procedures are generally not as intensive as the other analytical techniques. ELISAs are generally used to screen for the presence above a certain level (or absence) of a mycotoxin in the test sample. Many different ELISA formats are commercially available for mycotoxin analysis (e.g. single disposable membrane-based test, microtitre plate and tube assays).


Alternative techniquesAlternative techniques for mycotoxin analysisBiosensorsA range of biosensors has been reported for mycotoxin analysis, including those based on optical and surface acoustic wave principles.Capillary electrophoresis (CE) with fluorescence detectionAutomation


New technologiesNew technologies to the analysis of mycotoxinsLab-on-a-chip (LOC) and microarraysThe science of miniaturizationFood matrix effects: scope of innovative technologiesMultianalyte screening


Controlling the MycotoxinsIn order to keep mycotoxin occurance under control, some important cases have to be handled;The use of HACCP in the control of mycotoxinsEnvironmental conditions affecting mycotoxinsControl of mycotoxins in storage and techniques for their decontaminationControl of mycotoxins: secondary processingRisk assessment and managementControlling mycotoxins in animal feed


Prevention1. Primary preventionThe step of prevention should be initially carried out before the fungal infestation and mycotoxin contamination. This level of prevention is the most important and effective plan for reducing fungal growth and mycotoxin production. Several practices have been recommended to keep the conditions unfavorable for any fungal growth. These include:development of fungal resistant varieties of growing plants;control field infection by fungi of planting crops;making schedule for suitable pre-harvest, harvest and post-harvest;lowering moisture content of plant seeds, after post harvesting and during storage;Store commodities at low temperature whenever possible;Using fungicides and preservatives against fungal growth;Control insect infestation in stored bulk grains with approved insecticides.

Prevention and control of mycotoxins, FAO


Prevention2. Secondary preventionIf the invasion of some fungi begins in commodities at early phase, this level of prevention will then be required. The existing toxigenic-fungi should be eliminated or its growth to be stopped to prevent further deterioration and mycotoxin contamination. Several measures are suggested as follows:Stop growth of infested fungi by re-drying the products;Removal of contaminated seeds;Inactivation or detoxification of mycotoxins contaminated;Protect stored products from any conditions which favour continuing fungal growth.



Prevention3. Tertiary preventionOnce the products are heavily infested by toxic fungi, the primary and secondary preventions would not be then feasible. Any action would not be as effective as the practices mentioned above, since it will be quite late to completely stop toxic fungi and reduce their toxin formation. However, some measures should be done to prevent the transfer of fungi and their health hazardous toxins highly contaminated in products into our daily foods and environment. For example, peanut oil extracted from poor-graded peanut seeds always contains very high levels of aflatoxins and the oil-soluble toxin has to be eliminated by absorption and alkalinization during oilrefining process. Only a few practices are recommended:Complete destruction of the contaminated products;Detoxification or destruction of mycotoxins to the minimal level.



AFLATOXIN in TURKEY


Introduction

Aflatoxins can occur in foods, such as groundnuts, tree nuts, maize, rice, figs and other dried foods, spices and crude vegetable oils, and cocoa beans, as a result of fungal contamination before and after harvest. Also can be present in raw milk and raw milk products made by the milk secreted from animals those feed with contaminated provender.


IntroductionIn our country;

Our peoples healt?Economic aspects?


Aspergillus flavus produces aflatoxins B1 (AFB1) and B2 (AFB2) while A. parasiticus also produces aflatoxins G1 (AFG1) and G2 (AFG2) (Xu et al., 2000). Aflatoxin B1 is considered to be the most potent naturally occurring carcinogen known (Squire, 1989). Aflatoxin M1 is a derivative of AFB1 that is formed and excreted in the milk of humans and animals following consumption of foodstuffs contaminated with AFB1.


Asperigillus flavus


Turkish Food Codex Contaminants Regulations (2011)


2,010,05,02,04,04,02,04,0


2,04,0


Codex Sets Limits for Aflatoxin in FoodsUSA food safety regulations include a limit of 20 g/kg for total aflatoxins (B1, B2, G1and G2) in all foods except milk and a limit of 0.5 g/kg for M1in milk. Higher limits apply in animal feeds. Brazil nuts, pistachios, raw peanuts, and peanut products are covered by separate guides.

Australia and Canada sets limits of 15 g/kg for total aflatoxins (B1, B2, G1and G2) in nuts. This is the same as the international limit recommended for raw peanuts by the Codex Alimentarius Commission.


Peanut


PeanutsWe only produce peanuts just to consume, not for exportation. Main production area is Osmaniye. Anually 47 thousand ton peanuts are harvesting and a project is proposed to avoid aflatoxin that occurs during drying process in this October by Min. of Food Agr. and Livest. provincial directorate of Osmaniye.


HazelnutThe main hazelnut producing countries are Turkey, Italy, Spain, USA and Greece. Turkey is the first world hazelnut producer and exporter. In addition, it covers approximately 70percent and 82percent of the world`s production and export respectively. We gave an urgent importance on the aflatoxin levels of hazelnut.Mould growth in hazelnut starts on tree and earth and increase gradually during harvest and further processing. Water activity and relative humidity are the key factors.


HazelnutConsumer countries and world marketplaces aim to decrease aflatoxin limits of hazardous for aflatoxin products down to zero. In this way, in many countries, aflatoxin B1 and total aflatoxin (B1+B2+G1+G2) limit is diminished from 5 ppb to 2 ppb and 10 ppb to 4 ppb in hazelnut (FDA, EU Reg.).


Herbs and SpicesTurkish herbs and spices are exported to around 100 countries throughout world. Themajority of exports are oriented to NorthAmerica, the European Union Countries, LatinAmerica, theFar East andNorthAfrica.The U.S.A,Germany,Vietnam,the Netherlands,Poland,Brazil,Canada,Italy,Belgium,Greece,FranceandJapanhead thelist.Mainherbsandspicesproduced and exported following thyme, oregano,laurel (bay) leaves, cumin seeds, anise seeds, red pepper, juniperberries,mahaleb,fenugreek,rosemary,licorice,mint,sage and lindenflowers.

Begining at 1999, nowadays, irradiation and modern techniques ensures safe spices and herbs in our country.*

*Turkish Food Safety Association


Dried FigExport of dry fig, which Turkey is the leading country for both production and exportation is reached up to 80 million 779 thousand dollars with a raise of 15% since the early days of season in September,2013.


ConclusionWith the cooperation of the universities, producers and trade associations, rapid alarm feedbacks decreased nearly 80% especially for dry fruits like fig and besides hazelnut and spice and exportation of our products increased.

FRUCOM (EUROPEAN FEDERATION OF THE TRADE IN DRIED FRUIT & EDIBLE NUTSPROCESSED FRUIT & VEGETABLES PROCESSED FISHERY PRODUCTSSPICESHONEY)


DECONTAMINATION


Decontamination is a type for controlling the mycotoxins. The ideal solution to the health hazards that mycotoxins pose is the prevention of mycotoxin contamination in the field.But somehow production is inevitable and detoxification is required to eliminate the mycotoxins.


Decontamination/detoxification procedures are useful for restoring mycotoxin-contaminated commodities. The ideal decontamination procedure should:completely inactivate, destroy, or remove the toxin, or reduce its concentration to acceptable levels;not produce or leave toxic residues in the food/feed;preserve the nutritive value of the food/feed;not alter the acceptability or the technological properties of the product;destroy fungal spores and mycelia so as to prevent revival and toxin production;be integrated, if possible, into the regular food-processing and preparation steps;be cost-effective;be easy to use;not destroy or damage equipment or pose a health hazard to workers;be approved by regulatory agencies.


Mycotoxins in Foods, 2004


In 1993, Park indicated that aflatoxin may be eliminated or inactivated by physical, chemical or biological methods.

But used physical and chemical method is not economically feasible in addition this method cause losses in nutritional and organoleptic qualities of food.


Physical decontamination of mycotoxinsHeatMycotoxins differ in their stability under heat treatments. Many thermal food-processing operations (e.g. roasting, cooking, frying, baking) causes mycotoxin decomposition.Aflatoxins are relatively resistant to thermal inactivation and are destroyed only at temperatures of around 250 C. Therefore, processes which include heating should reach that temperature range.Ochratoxin A is highly stable to heat treatment and it is not destroyed even at 200 C (Trivedi et al., 1992).Most of the Fusarium mycotoxins are relatively resistant to heat. Zearalenone was not destroyed in corn, even after 44 h, at 150 C (Bennett et al., 1978).


Physical decontamination of mycotoxinsMicrowavesWhen a rapidly oscillating radio frequency or microwave field (500 MHz10 GHz) is applied, the water molecules reorient with each change in field direction, creating intermolecular friction and generating heat.Aflatoxin (pure or in a food model) is destroyed when exposed to microwaves, but the rate of destruction depends on the microwave power and exposure time.A reduction of at least 95 % in aflatoxin content in peanuts occurred following a 16 min treatment at a microwave power level of 1.6 kW or a 5 min treatment at a power level of 3.2 kW (Luter et al., 1982).


Physical decontamination of mycotoxinsIrradiation

It has attracted interest due to used as a multi-purpose method for the eradication of all the biotic factors responsible for food deterioration (insects, moulds, mites). Users should be careful about advantages and disadvantages;

The dosages required to degrade a pure mycotoxin vary, depending on the state of the toxin being tested (e.g. powder vs dissolved, type of solvent) and the concentration.The dosages required to destroy a pure mycotoxin are not the same as those needed for its detoxification in foods.The dosages needed to degrade any particular toxin might depend on the produce MC. Irradiated fungal inocula may produce large amounts of toxins [in the case ofaflatoxins and ochratoxin but not patulin .Mycotoxin production on irradiated grains is sometimes significantly higher than on non-irradiated material. However, the findings on this question are controversial (Sharma, 1998).


Physical decontamination of mycotoxinsSorption of Mycotoxins

A novel approach to the prevention of aflatoxin intoxication in some animals is the inclusion in their diet of aflatoxin-selective clays that tightly bind these poisons in the gastrointestinal tract, thus significantly decreasing their bio-availability and associated toxicity (Phillips et al., 1994).

These methods aim at preventing the deleterious effects of mycotoxins by sequestering them to various sorbent materials in the gastrointestinal tract, thereby altering their uptake into the blood and deposition in target organs.

Binding agents (e.g. activated charcoal, zeolite, HSCAS, bentonite, kaoline, montmorillonite)


Physical decontamination of mycotoxinsRemoval by solvent extraction

Solvent extraction is one of the most practical means for mycotoxin removal since it can be integrated into food-processing lines. It is also highly effective: in the case of aflatoxins, 8095 % of the toxin can be removed (depending on the extraction system used) during processing operations (Ellis et al., 1991). However, solvent extraction is associated with possible disadvantages and limitations, including the extraction of vital nutritional components, the introduction of off-flavours, additional costs, and the possible need for specialized equipment and safe procedures for the disposal of the mycotoxin extracts.


Chemical decontamination of mycotoxinsChemical decontamination

Criteria; the treated product should not contain any toxic residues; the nutritional value and/or the technological properties of the treated material should not be altered. It is only when these criteria economically convenient.

Chemicals which are useful for large-scale aflatoxin detoxification are: methylamine, sodium hydroxide and formaldehyde; hydrogen peroxide; sodium hypochlorite; bisulfite; and ammonia.

But some chemical are not a good match to commerical implementation (e.g. damaging rheologic prp.)


Chemical decontamination of mycotoxinsChemical decontamination

Nixtamalization (alkaline cooking and heating), a technology used for preparing traditional foods from corn (tortillas, for example), significantly reduced the concentration of aflatoxin. However, much of the original aflatoxin was re-formed when the product was acidified (Elias-Orozco et al., 2002).Ammoniation is used for generally animal feed, maize, cottonseeds.The application of ozone (O3) is used generally degrade aflatoxin in animal feed.


Microbial Detoxification of MycotoxinsAlthough numerous physical and chemical detoxification methods have been tested, none really fulfills the efficacy and safety (Mishra and Das, 2003).

Cost-effective methods needed to minimize potential losses to the farmer and toxicological hazards to the consumer (Young et al., 2007).

Development of (micro) biological detoxification methods is essential (Sweeney and Dobson, 1999).


Microbial Detoxification of MycotoxinsCiegler et al. (1966) identified Flavobacterium aurantiacum NRRL B-184, which could irreversibly remove AFB1 from a variety of food products including milk, oil, peanut butter, peanuts and maize without leaving toxic by-products. A variety of lactic acid bacteria originating from fermented products were reported to inhibit mutagenic activity of AFB1 (Park and Rhee, 2001).A total of 6 isolates of Bacillus pumilus were tested for their ability to inhibit aflatoxin production by Aspergillus parasiticus in yeast extract sucrose broth. The inhibitory effect due to extracellular metabolites (Munimbazi et al., 1997).


Overview of the different classes and subclasses of mycotoxin detoxifiers (adapted from EFSA (2009)).


Flavobacterium aurantiacumGram-negative non-motileand motile rod-shapedbacteriathat consists of ten recognized species.Flavobacteria are found in soil and fresh water in a variety of environments. Several species are known to cause disease in freshwater fish.Characteristically producing yellow, orange, red, or yellow-brown pigments.Also known as Nocardia corynebacteriodes


Bacteria metabolize aflatoxin and can transform it into decomposition products which can be dissolved in water and chloroform, and CO2.The transformation did not lead to a toxic product (Lillehoj et al. 1967) and that an intracellular enzyme was involved (Smiley and Draughon 2000).Smiley and Draughon (2000), have also stated that dead bacteria cells can also bond some aflatoxin but can not decompose it in a more advanced level.F. aurantiacum (NRRLB - 184) can decompose aflatoxin B1 in both solution and various products such as: corn and corn oil, peanut cream and soybean (Line and Brackett, 1995).Flavobacterium aurantiacum


Flavobacterium aurantiacum


Bacillus subtilis was also able to detoxify AFB1-contaminated feed and thus facilitate animal growth rate (Petchkongkaew et al., 2008).

Actinomyceta, such as Mycobacterium fluoranthenivorans,were shown to remove AFB1 from contaminated media (Hormisch et al. 2004).

Teniola et al. (2005) succeeded in isolating extracellular enzymes from Rhodococcus erythropolis, responsible for the transformation of AFB1.

Other modifiers


OTA transformationCertain bacteria, moulds, yeasts and plants are able to transform OTA, with many being able to transform OTA into OT (Pe teri et al. 2007), a less toxic compound.This transformation leads to the formation of phenylalanineAureobasidium pullulans was used as a biocontrol agent in wine, preventing OTA accumulation in grapes and decreasing aspergillosis symptoms (De Felice et al., 2008).


Overview of the different classes and subclasses of mycotoxin detoxifiers (adapted from EFSA (2009)).


LactobacillusGram-positiveFacultative anaerobicormicroaerophilicCatalase negativeNon sporingRod-shaped bacteria.They are a major part of thelactic acid bacteriagroup, because It convertlactoseand othersugarstolactic acid. In humans they are present in thegastrointestinal tract, make up a small portion of thegut flora.The production of lactic acid makes its environment acidic, which inhibits the growth of some harmful bacteria. (Hassan and Lloyd., 1995) studied mixture of Lactobacillus species from a commercial silage inoculums reduced mold growth and inhibited aflatoxin production by Aspergillus flavus subsp. Parasiticus.


The parietal structures of some lactic acid bacteria, propionibacteria and bifidobacteria have the capacity to bind mycotoxins (El-Nezami et al. 2000 2002a).The binding appears to be physical and associated with hydrophobic pockets on the bacterial surface (Haskard et al. 2000).Lahtinen et al. [9], Lactobacillus rhamnosus GG (LGG) strain has been determined to be the most effective microorganism to remove AFB1 and zearalenon from liquid medium (it has also been reported that bonding of AFB1 has occurred outside the cell physically on a study executed within viable and heat-treated bacteria).

Lactobacillus


Lactobacillus


Yeasts are another microorganisms absorbing mycotoxin. Saccharomyces cerevisiae, which has been shown to bind with AFB1 (Shetty and Jespersen 2006) and reduce the detrimental effects of AFB1 in broiler diets (Stanley et al. 1993) or on rats (Madrigal-Santillan et al. 2006).Yeasts as binders


ConclusionChemical treatment for the detoxification of aflatoxins using ammonia is the only application currently licensed in the United States.Chemical treatment is not allowed within the European Union for products used by humans (EU Commission Regulation 2001) as recourse to chemical transformation may lead to toxic derivatives in the treated products.Adsorption by yeast cell walls added to feed is used most frequently in the industrial context.Legislation is changing to allow the marketing of mycotoxin binders whereas, up to now, these products have been sold for other applications, such as increasing antioxidising activity.Transformation of mycotoxins for detoxification purposes is not much used in industry, which may be due to lack of information on transformation mechanisms, the toxicity of products derived from transformation or the effect of transformation reactions on the nutritional value of food and feed.The stability of transformations and their potential side-effects needs to be investigated further.


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******************Another strategy to control mycotoxicoses in animalsis the application of microorganisms and theirenzymes, called mycotoxin modifi ers or mycotoxinbiotransforming agents.*Mycotoxin binders (adsorbing or sequesteringagents) are large molecular weight compounds thatare able to bind the mycotoxins in the gastrointestinaltract of the animal. In this way, the toxin bindercomplex passes through the animal, and is eliminatedvia the feces.*

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