Toxicity, metabolism, and impact of mycotoxins on humans and animals.

Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: an oestrogenic mycotoxin.

Mycotoxins: occurrence, toxicology, and exposure assessment.

https://cyberleninka.org/article/n/1218695.pdf

Impact of mycotoxins on humans and animals

A review of worldwide contamination of cereal grains and animal feed with Fusarium mycotoxins

Fusarium mycotoxins: a review of global implications for animal health, welfare and productivity

The major mycotoxigenic species of Fusarium and Aspergillus phytopathogens have been identified in this review. Since fungicides are widely used to control crop diseases caused by these fungi, it is pertinent to assess efficacy with respect to mycotoxin production. In both laboratory studies with pure cultures of phytopathogens and field trials with crop plants, the overall evidence concerning the effectiveness of fungicides is contradictory and in certain cases somewhat unexpected. In particular, at sub-lethal doses of a number of fungicides including carbendazim, tridemorph, difenoconazole and tebuconazole with triadimenol, mycotoxin production from Fusarium phytopathogens may increase. Furthermore, the efficacy of propiconazole and thiabendazole in the control of deoxynivalenol production from F. graminearum is not consistent. Evidence has been presented to suggest, for the first time, that fungicide-resistance in F. culmorum may be accompanied by a more persistent pattern of mycotoxin production. The limited evidence on the effects of fungicides on mycotoxin production in Aspergillus species is also conflicting. Under laboratory conditions, miconazole and fenpropimorph have been shown to increase aflatoxin production from A. parasiticus. Moreover, fenpropimorph increased production of the more toxic aflatoxin B1. Since fungal infection of plant products is often preceded by insect damage, there is interest in the effectiveness of insecticides to reduce infestation, infection and mycotoxin contamination. Additionally, insecticides may be effective in their own right, causing a direct effect on mycotoxin synthesis. The bulk of the evidence relates to effects on aflatoxin (AF) components B1, B2, G1 and G2. Under laboratory conditions, AFB1 production was most resistant to inhibition by insecticides, followed by AFG1, AFG2 and AFB2. This pattern of inhibition was particularly consistent for the organophosphorus insecticides. In one field study, Bux and carbaryl were considerably more effective than naled in reducing AFB1 contamination of maize kernels. It is concluded that if pesticide control is to be more effective in the future, additional criteria may be required in developing evaluation protocols for candidate compounds. In particular, the issue of fungicide-resistance in relation to mycotoxin production needs to be addressed in a concerted programme of research. Additionally, the potential of breeding and selecting cultivars resistant to disease caused by toxigenic fungi needs to be exploited in a parallel search for an environmentally acceptable solution to the question of mycotoxin contamination of plant products.

Pesticide Use and Mycotoxin Production in Fusarium and Aspergillus Phytopathogens

Mycelial yield and production of three trichothecenes, namely T-2 toxin, diacetoxyscirpenol (DAS) and neosolaniol (NEO) were compared in control (CS) and carbendazim-resistant strains (RS) ofFusarium sporotrichioides. Each strain was exposed to graded concentrations of carbendazim (0, 1, 2, and 4 μg/ml media) for 2, 5 and 7 days under shake-culture conditions at an incubation temperature of 25°C. Mycelial yield was significantly (P<0.001) affected by strain, carbendazim concentration and incubation time. The strain differences in mycelial mass at 2 days (P<0.05) became more pronounced at 5 and 7 days of incubation (P<0.001). However, mycelial growth differences between the two strains were greatest following exposure to carbendazim, with the effects becoming more divergent with time. Combined results for the three incubation times showed dose related effects in carbendazim inhibition of T-2 toxin production by CS isolates. In contrast, RS cultures exposed to the 2 μg/ml addition of carbendazim significantly increased T-2 toxin production (P<0.05 or better). At 1 and 4 μg/ml additions, T-2 toxin inhibition occurred but the effect was less marked than in the CS series. RS yielded more DAS than CS at 5 days (P<0.05) and at 7 days (P<0.01) of incubation. The major component of this strain difference arose from the effects of the 2 μg/ml addition of carbendazim (P<0.01). NEO production was also higher in RS than in CS, with the difference becoming progressively more pronounced from day 5 (P<0.05) to day 7 (P<0.01) of incubation. However, these differences reflected enhanced NEO output with carbendazim addition of 4 μg/ml (P<0.05) in day 5 extracts and of both 2 μg/ml (P<0.01) and 4 μg/ml additions (P<0.05) in day 7 samples. Moreover, the ratio of NEO to T-2 toxin production was affected by an interaction involving incubation time, strain and carbendazim dose (P<0.05 or better). On day 5, this ratio was greater in CS exposed to 2 μg/ml, but at 4 μg/ml, the ratio was higher in RS. It is concluded that carbendazim resistance induced genuine differences in the synthesis of T-2 toxin and NEO. It is suggested that the strain difference may reside in the conversion of NEO to T-2 toxin which may be sensitive to fungicide concentration. This would imply that carbendazim resistance induces changes in the terminal rather than initial phases of trichothecene biosynthesis.

Mycotoxin production in a carbendazim-resistant strain of fusarium sporotrichioides.

The production of the mycotoxin, 3-acetyl deoxynivalenol (3-ADON), was investigated in a strain ofFusarium culmorum insensitive to the systemic fungicide, difenoconazole. On exposure to graded concentrations of the fungicide, the insensitive strain continued to synthesise 3-ADON when difenoconazole levels of 100 and 200μg/ ml media were used. In contrast, a control (sensitive) strain ceased production of 3-ADON at difenoconazole levels of 100 μg/ml. Differences between the two strains were also observed for 3-ADON production with time. Following incubation with fungicide at 0.1 μg/ ml, 3-ADON production occurred more rapidly in CS than in IS cultures. This is the first report of increased persistence and alteration of the pattern of production of a mycotoxin following the development of fungicide insensitivity in a fungal phytopathogen.

A. M. C. Macdonald

Papers

A review of worldwide contamination of cereal grains and animal feed with Fusarium mycotoxins

Fusarium mycotoxins: a review of global implications for animal health, welfare and productivity

Pesticide Use and Mycotoxin Production in Fusarium and Aspergillus Phytopathogens

Mycotoxin production in a carbendazim-resistant strain of fusarium sporotrichioides.

3-Acetyl deoxynivalenol production in a strain of Fusarium culmorum insensitive to the fungicide difenoconazole