Mycotoxin formation/fungal growth

Fungal colonization and growth and/or mycotoxin production are generally influenced by a variety of factors 1 2. 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


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 3 4 .

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.


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: 1 2 5 6 7 8 9 10

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 -



References:

1 Richard, J.L., & Payne, G. A. (2003). Mycotoxins: Risks in Plant, Animal and Human Systems. CAST The Science Source for Food, Agriculture and Environmental Issues, 139, 20-35.

2 Sanchis, V. (2004). Environmental conditions affecting mycotoxins. In: Magan N. and Olsen M. (Eds.), Mycotoxins in food. CRC Press, Boca Raton Bosten New York, Washington, DC, pp.174- 189.

3 Magan, N., Medina, A., & Aldred, D. (2011). Possible climate-change effects on mycotoxin contamination of food crops pre- and postharvest. Plant Pathology, 60(1), 150-163.

4 Paterson, R. R. M., & Lima, N. (2011). Further mycotoxin effects from climate change. Food Research International, 44(9), 2555-2566.

5 Sweeney, M. J., & Dobson, A. D. W. (1998). Mycotoxin production by aspergillus, fusarium and penicillium species. International Journal of Food Microbiology, 43(3), 141-158.

6 Hussein, H. S., & Brasel, J. M. (2001). Toxicity, metabolism, and impact of mycotoxins on humans and animals. Toxicology, 167(2), 101-134.

7 Manual on the application of the HACCP system in Mycotoxin prevention and control. Food and Agriculture Organization of the United Nations; Rome, 2001.

8 Marth, E.H. (1992). Mycotoxin: Production and control. Food Laboratory News, 35-51.

9 Ramos, A.J., Laberniaa, N., Marina, S., Sanchisa, V., Maganb, N. (1998). Effect of water activity and temperature on growth and ochratoxin production by three strains of Aspergillus ochraceus on a barley extract medium and on barley grains. International Journal of Food Microbiology, 44, 133–140.

10 Ribeiro, J.M.M., Cavaglieri, L.R., Fraga, M.E., Direito, G.M., Dalcero, A.M., Rosa, C.A.R. (2006). Influence of water activity, temperature and time on mycotoxins production on barley rootlets. Letters in Applied Microbiology. 42(2), 179-184.



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