Mycotoxin and strategies to mitigate its production and contamination of feedstuff

There are more than 10000 known species of fungi. Fortunately, the majority of them are useful to humans in the manufacturing of bread, cheese, antibiotics, and other products. About 50 fungal species that are dangerous to livestock, poultry, and humans are known to create toxins, which are referred to as mycotoxins.

Mycotoxins are secondary metabolites of fungi that contaminate food and feed, posing a serious threat to health of humans and animal health and productivity. Mycotoxin-producing fungi include Aspergillus, Fusarium, and Penicillium. Mycotoxins are produced in response to environmental circumstances, plant stress, and damage to grains caused by rodents and pests, as well as abiotic variables such as feed pH and moisture content. The tropical climate in the India, along with poor feed storage, encourages fungal development and, as a result, the formation of mycotoxin (Reddy and Raghavender, 2007).

These silent killers can be found in every part of the planet, and their influence on animal productivity and human health is significant. According to the Food and Agriculture Organization of the United Nations (FAO), mycotoxins are present in about 25% of the world’s grain supply with annual loss of 1 billion metric tonnes of food and food products. In India, the concentrate feed resource includes cereal grain (maize, wheat, barley), cakes & meal (groundnut cakes, cotton seed cakes, soybean meals) which are more prone to mycotoxin contamination.

Aflatoxin B1 is major concern in dairy animals because its affects the health and productivity of animals (table 1). Also it converted to Aflatoxin M1 by enzymes located largely in the liver (Cytochrome P450). Aflatoxin M1 is a toxin and carcinogen found in milk that has negative impact on human health. Aflatoxin is easily transferred from feed to milk; roughly 1.0 to 6.0 percent of Aflatoxin B1 in feed is converted to Aflatoxin M1 in milk (Maximum permissible levels of aflatoxin as stated by different agencies are given in table 2). To reduce the amount of Aflatoxin M1 in milk and milk products, strict management of Aflatoxin B1 levels in dairy animal feeds, keep eye on factors responsible for funfal growth and use of mitigation strategies are essential.

Table 1. Common mycotoxin, their source and effects on animal health

Table 2. Maximum permissible levels of aflatoxin as stated by different agencies

Factors responsible for the growth of fungi

There are several factors that affects the growth of fungi in feeds its include temperature, relative humidity, moisture, pH, CO₂ and O2 tension (Fig. 1)

Strategies to mitigate mycotoxin production and contamination of feedstuff

Pre-Harvest mycotoxin mitigate strategies

Good agricultural practises (GAPs), good manufacturing practises (GMPs), acceptable environmental conditions, and favourable storage techniques are all examples of pre-harvest preventive strategies. Crop rotation, the use of registered pesticides, fungicides, and herbicides for insect control, fungal infection, and weed eradication, correct seed bed preparation, soil analysis to assess the need for fertilisers, and genetic synthesis enhancement to reduce mycotoxin formation are indeed GAPs (Alberts et al., 2017; Adebiyi et al., 2019). Moreover, biological control agents, such as antagonistic fungi, are an important pre-harvest strategy to prevent mycotoxin contamination in staple cereals, grapes, and apples (Sarrocco and Vannacci, 2018; Sarrocco et al., 2019). To work in tandem with hazard analysis and critical control points (HACCP), GMPs must be used in conjunction with GAPs (Sarrocco et al., 2019).

Post-Harvest mycotoxin mitigate strategies

Natural methods such as thermal insulation, radiation therapy, low-temperature plasma, chemical methods such as oxidation, reduction, hydrolysis, and absorption, and biological approaches involving biological agents can all be used to eradicate mycotoxins (Lyagin and Efremenko, 2019).

Characteristics of an ideal mycotoxin binder

Binding mycotoxins to an inert chemical before they can be absorbed from the intestines is the most efficient way of neutralising them in feed. “Which mycotoxin binder is most effective?” is a question that feed manufacturers and milk producers regularly ask.

The following are the “ideal” characteristics of a good mycotoxin binder:

• Ability to bind a wide range of mycotoxins
• Low effective inclusion rate in feed
• Rapid and uniform dispersion in feed during mixing
• Heat stability during pelleting, extrusion, and storage
• No affinity for vitamins, minerals, or other nutrients

Type of mycotoxin binder

1) Nutritional modifications

Nutritional routes for protection against mycotoxins include higher levels of methionine, selenium and vitamin supplementation of affected diets.

 2) Chemical detoxification

The chemicals tested for their ability to detoxify/ inactivate mycotoxins, ammonia, sodium bisulfite, peroxide, acids, bases and gases are effective. However, most of the chemical methods are not practical and they do not fulfill all the requirements, specifically those concerning the safety of reaction products and the palatability of the feed.

3) Biological methods

Advances in biotechnology have opened a new avenue for tackling mycotoxicosis. It includes Saccharomyces cerevisiae, Lactobacillus, Leuconostoc Streptococcus and Enterococcus strains has shown considerable binding ability with commonly occurring mycotoxins (Devegowda and Murthy, 2005) and is found beneficial in minimizing the adverse effects of mycotoxins in livestock and poultry (Raju and Devegowda, 2002).

4) Application of mineral clays

Many types of clay have been tested for counteracting mycotoxins. These include bentonites, zeolites and aluminosilicates. Several studies have demonstrated that sodium aluminosilicate, sodium calcium aluminosilicate, and sodium bentonites can adsorb Aflatoxins (Phillips et al., 1990; Mahesh and Devegowda, 1996). A hydrated sodium calcium aluminosilicate (HSCAS) is the most widely studied mycotoxin sequestering agent among the mineral clays.

5) Herbal toxin binder

Phytophenols, as a plant secondary metabolite, were discovered to have around 8000 structures. These structures are similar to those found in tannin and phenolic acid (Dai and Mumper, 2010). Antiallergenic, antioxidant, antiinflammatory, antibacterial, antiorthrogenic, and antithrombotic properties were found in phytophenols (Ajila et al., 2010).   The antifungal and anti-aflatoxigenic properties of phenolic components of plant extracts were recently discovered in a study (Hua et al., 2010; Kim et al., 2005) The plant phenolic chemicals syringaldehyde, sinapic acid, and acetosyringone reduced the synthesis of aflatoxin B1 (Hua et al., 1999). However, phenolic substances such as salicylic acid, thymol, vanillyl acetone, cinnamic acid, and vanillin inhibited A. flavus development by targeting oxidative mitochondrial stress as a defensive system (Kim et al., 2006).

Herbal utility of toxin binder

1) Neem (Azadirachta indica)

Azadirachta indica (Neem) is a subtropical tree found in Asia and Africa’s drier regions. It is native to the Indian subcontinent and has been used in agriculture, medicine, and cosmetics for thousands of years. The therapeutic, antiviral, antibacterial, antiprotozoal, insecticidal, insect repellant, antifungal, and antinematode effects of neem components are well known (Badman et al., 1999; Khan et al., 1988). Several active compounds have been discovered in various areas of the tree. Terpenoids, desactylimbin, quercetin, and sitosterol are found in extracts from various portions of the tree (Schaaf et al., 2000; Siddiqui et al., 2000). The main feature of neem extracts particularly those derived from leaves is that they do not cause retardation in fungal growth but interfere with aflatoxin production. Neem extract (50 % v/v) inhibited 90% aflatoxin production through mycelia’s antioxidant mechanism and morphological alteration.

2) Amla (Emblica officinalis)

Amla commonly as Indian gooseberry, has long been utilised as a strong rasayana, or herbal compound that aids in lifespan and rejuvenation, in ancient Indian Ayurveda (Satyavati et al., 1996). The antioxidative, anticancer, lipid-lowering, anti-sclerotic, hepatoprotective, and anti-HIV properties of Emblica officinalis extract have been demonstrated (Rajak et al., 2004; Rao et al., 2005). Emblica officinalis is a high-nutrient plant that is a good source of vitamin C, minerals, and amino acids. Protein concentration is three times more in edible fruit tissue than in apple, while ascorbic acid concentration is 160 times higher.

After 45 days of Emblica officinalis aqueous extract (2 mg/animal/day) supplementation, ochratoxin-induced lipid peroxidation in mouse liver and kidney was considerably reduced (Chakraborty and Verma, 2010)

3) Ajwain (Trachyspermum ammi)

Trachyspermum ammi, often known as ‘Ajwain,’ is a plant native to India that is primarily grown in Gujarat and Rajasthan. It contains phenolic compounds and saponin, which have been shown to have antifungal, antioxidant, antimicrobial, antinociceptive, cytotoxic, hypolipidemic, antihypertensive in studies.

500 µl of T. ammi extract degrade 91% of aflatoxin when incubated with 50 ng of Aflatoxin G1 at 37 ℃ for 24 h (Velazhahan et al., 2010). So, The T. ammi extract may provide a biologically safe method to protect poultry or livestock feeds and other agricultural commodities from aflatoxins.

4) Tulsi (Ocimum tenuiflorum)

It is a well-known herbal remedy in the east, and its numerous medicinal capabilities have been employed in ayurveda, an alternative medicine system native to the Indian subcontinent, for thousands of years. Saponins, flavonoids, tannins, and triterpenoids are all found in the leaf. The aqueous extract has also been shown to boost antioxidant enzyme activity.

Some studies have also been carried out on the effect of Ocimum species on A. flavus growth and AFB1 production. The essential oil of O. sanctum contain eugenol was found to efficiently inhibit A. flavus growth and AFB1 production (Kumar et al. 2010). The powdered leaves of O. sanctum inhibited A. flavus growth by 40, 65 and 78% and inhibited the AFB1 production by 61.4, 74 and 85.7%, respectively when added in concentration of 3, 4 and 5 g/kg, respectively.

The aqueous extract of Ocimum tenuiflorum reduced aflatoxin B1 production by 64% (Panda and Mehta, 2013).

Other herbal utility

Olive callus contain caffeic acid, coumarin, catechin, and ethanolic extract reduced 90% of aflatoxin synthesis. Garlic and clove at 10% (w/v) and carrot at 2% inhibited the Aspergillus growth and reduced aflatoxin production in rice. Garlic extract inhibited 61.94% fungus growth. However, onion extract ceased about 60.44% aflatoxin synthesis while eugenol extract reduced 60.35% aflatoxins synthesis.

Commercial products available in market

Conclusion

Mycotoxins are among the most prominent and dangerous toxins associated with food safety and adverse effect on animal and human health, causing significant economic loss in livestock and agriculture production system. Adding of toxin binder in feed reduced adverse effect of mycotoxin. Being component of nature, herbs and their preparation are considered safe, cost effective and environment friendly with no side effect.

References

1. Adebiyi, J.A., Kayitesi, E., Adebo, O.A., Changwa, R. and Njobeh, P.B., 2019. Food fermentation and mycotoxin detoxification: An African perspective. Food Control, 106, p.106731.
2. Ajila, C.M., Aalami, M., Leelavathi, K. and Rao, U.P., 2010. Mango peel powder: A potential source of antioxidant and dietary fiber in macaroni preparations. Innovative Food Science & Emerging Technologies, 11(1), pp.219-224.
3. Alberts, J.F., Lilly, M., Rheeder, J.P., Burger, H.M., Shephard, G.S. and Gelderblom, W.C.A., 2017. Technological and community-based methods to reduce mycotoxin exposure. Food Control, 73, pp.101-109.
4. Ashok K, Ravindra S, Priyanka S and Nawal K. D., 2010. Chemical composition, antifungal and antiaflatoxigenic activities of Ocimum sanctum L. essential oil and its safety assessment as plant based antimicrobial. Food and Chemical Toxicology 48, 539–543.
5. Badman, L., Joshi, S.P. and Bedekar, S.S. 1999. In vitro antiviral activity of neem (Azadirachta indica A.Juss) leaf extract against coxsachieviruses. J. Commun. Dis. 31:79-90.
6. Chakraborty, D. and Verma, R., 2010. Ameliorative effect of Emblica officinalis aqueous extract on ochratoxin-induced lipid peroxidation in the kidney and liver of mice. International journal of occupational medicine and environmental health, 23(1), pp.63-73.
7. Dai, J. and Mumper, R.J., 2010. Plant phenolics: extraction, analysis and their antioxidant and anticancer properties. Molecules, 15(10), pp.7313-7352.
8. Hua, Y., Sahashi, K., Hung, G., Rigo, F., Passini, M.A., Bennett, C.F. and Krainer, A.R., 2010. Antisense correction of SMN2 splicing in the CNS rescues necrosis in a type III SMA mouse model. Genes & development, 24(15), pp.1634-1644.
9. Khan, M., Schneider, B., Wassilew, S.W. and Splanemann, V. 1988. Experimental study of the effect of raw materials of the neem tree and neem extracts on dermatophytes, yeast and molds. Z. Hautkr. 63:499-502.
10. Kim, W., Spear, E.D. and Ng, D.T., 2005. Yos9p detects and targets misfolded glycoproteins for ER-associated degradation. Molecular cell, 19(6), pp.753-764.
11. Lyagin, I. and Efremenko, E. 2019. Enzymes for detoxification of various mycotoxins: Origins and mechanisms of catalytic action. Molecules, 24, 1–39.
12. Panda, P. and Mehta, A., 2013. Aflatoxin detoxification potential of O cimum Tenuiflorum. Journal of Food Safety, 33(3), pp.265-272.
13. Reddy, B.N. and Raghavender, C.R., 2007. Outbreaks of aflatoxicoses in India. African journal of food, agriculture, nutrition and development, 7(5).
14. Sarrocco, S. and Vannacci, G. Preharvest application of beneficial fungi as a strategy to prevent postharvest mycotoxin contamination: A review. Crop Prot. 2018, 110, 160–170.
15. Sarrocco, S., Mauro, A. and Battilani, P., 2019. Use of competitive filamentous fungi as an alternative approach for mycotoxin risk reduction in staple cereals: State of art and future perspectives. Toxins, 11(12), p.701.
16. Schaaf, O., Jarvis, A.P., Van der Esch, S.A., Giagnacovo, G. and Oldham, N.J. 2000. Rapid and sensitive analysis of azadirachtin and related triterpenoids from neem (Azadirachta indica) by high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. J. Chromatogr. A. 886:89-97.
17. Siddiqui, B.S., Afshan, F., Ghiasuddin, Faizi, S., Naqvi, S.N. and Tariq, R.M. 2000. Two insecticidal tetranorcidals from Azadirachta indica. Phytochemistry 53:371-371.
18. Velazhahan, R., Vijayanandraj, S., Vijayasamundeeswari, A., Paranidharan, V., Samiyappan, R., Iwamoto, T., Friebe, B. and Muthukrishnan, S., 2010. Detoxification of aflatoxins by seed extracts of the medicinal plant, Trachyspermum ammi (L.) Sprague ex Turrill–structural analysis and biological toxicity of degradation product of aflatoxin G1. Food control, 21(5), pp.719-725.