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Mycotoxin formation/fungal growth
| Fungal colonization and growth and/or mycotoxin production are generally influenced by a variety of factors. Therefore it is not possible to describe a single set of conditions that are favorable for fungal growth and mycotoxin production. The most important conditions are temperature and water activity (available water content to a mold in a substrate). Generally, the optimal temperature for mycotoxin production by many molds range between 20 to 30°C. |
The most important factors can be categorized in three groups:
- plant and environmental factors, including substrate characteristics (e.g. composition, pH, water activity, oxygen content)
- possible competitive actions (e.g. associated growth of other fungi or microbes)
- climatic conditions (e.g. temperature, atmospheric humidity) |
Aspergillus flavus
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Generally, in warm (tropical and subtropical) regions aflatoxins are of major concern, while fusariotoxins, such as zearalenone or trichothecenes mainly occur in more moderate climatic regions.
Furthermore, stress factors such as drought, poor fertilization, high crop densities, weed competition, insect or mechanical damage can weaken the plant’s natural defenses and promote colonization by mycotoxin-producing fungi as well as toxin-formation.
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The tables outline the available data about temperature for fungal growth and mycotoxins formation as well as water activity for fungal growth and mycotoxins formation: |
| Fungus species |
Temperature range for fungal growth [°C] |
| Minimum |
Optimum |
Maximum |
| Aspergillus flavus |
10-12 |
25-35 |
42-43 |
| A. parasiticus |
10-12 |
32-35 |
42-43 |
| A. ochraceus |
8 |
24-37 |
37 |
| Penicillium verrucosum |
0 |
20 |
31-35 |
| Fusarium verticilliodes |
2-5 |
22.5-30 |
32-37 |
| F. proliferatum |
4 |
30 |
37 |
| F. culmorum |
0–10 |
20–25 |
31-35 |
| F. poae |
5–10 |
20–25 |
35 |
| F. avenacum |
5–10 |
20–25 |
35 |
| F. tricinctum |
5–10 |
20–25 |
35 |
| F. graminearum |
- |
24-26 |
- |
| F. sporotrichioides |
-2 |
21-27.5 |
35 |
| Fungus species |
Temperature range for mycotoxins formation [°C] |
| Minimum |
Optimum |
Maximum |
| Aspergillus flavus |
12-15 |
30-33 |
37-40 |
| A. parasiticus |
12 |
33 |
40 |
| A. ochraceus |
12-15 |
25-31 |
37 |
| Penicillium verrucosum |
4 |
20-25 |
- |
| Fusarium verticilliodes |
10 |
15-30 |
37 |
| F. proliferatum |
10 |
15-30 |
37 |
| F. culmorum |
11 |
29-30 |
- |
| F. graminearum |
11 |
29-30 |
- |
| Fungus species |
Water activity (aw) for fungal growth |
| Minimum |
Optimum |
Maximum |
| Aspergillus flavus |
0.80 |
0.95-0.99 |
- |
| A. parasiticus |
0.83-0.84 |
0.95- 0.99 |
- |
| A. ochraceus |
0.77-0.79 |
0.95-0.99 |
- |
| Penicillium verrucosum |
0.80 |
0.95 |
- |
| Fusarium verticilliodes |
0.87-0.9 |
- |
0.99 |
| F. proliferatum |
0.9 |
- |
- |
| F. culmorum |
0.90-0.91 |
0.98-0.995 |
- |
| F. poae |
0.90-0.91 |
0.98-0.995 |
- |
| F. avenacum |
0.90-0.91 |
0.98-0.995 |
- |
| F. tricinctum |
0.90-0.91 |
0.98-0.995 |
- |
| F. graminearum |
0.9 |
- |
0.99 |
| F. sporotrichioides |
0.88 |
- |
0.99 |
| Fungus species |
Water activity (aw) for mycotoxins formation |
| Minimum |
Optimum |
Maximum |
| Aspergillus flavus |
0.82 |
0.99-0.996 |
0.998 |
| A. parasiticus |
0.87 |
0.99 |
- |
| A. ochraceus |
0.80-0.85 |
0.98 |
- |
| Penicillium verrucosum |
0.83-0.86 |
0.90-0.95 |
- |
| Fusarium verticilliodes |
0.92-0.93 |
- |
- |
| F. proliferatum |
0.93 |
- |
- |
| F. graminearum |
0.9-0.91 |
0.98 |
- |
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