Differences Between Aspergillus flavus Strains in Growth and Aflatoxin B1 Production in Relation to Water Activity
M D Northolt1, H P van Egmond1, W E Paulsch1
1Laboratorium voor Zoönosen en Levensmiddelenmicrobiologie and Laboratorium voor Chemisch Levenmiddelenonderzoek Rijksinstituut voor de Volksgezondheid, Bilthoven, The Netherlands.
Journal of Food Protection
|February 10, 2019
Summary
This study investigated Aspergillus flavus growth and aflatoxin B1 production under varying water activity and temperature conditions. Results show that reduced water activity and moderate temperatures inhibit toxin production more than fungal growth.
Area of Science:
- Food Microbiology
- Mycology
- Food Safety
Background:
- Aspergillus flavus is a significant fungal pathogen.
- Aflatoxin B1 is a potent mycotoxin produced by Aspergillus flavus.
- Understanding growth and toxin production conditions is crucial for food safety.
Purpose of the Study:
- Determine optimal and limiting conditions for Aspergillus flavus growth.
- Investigate factors affecting aflatoxin B1 production by Aspergillus flavus strains.
- Analyze the influence of water activity and temperature on fungal growth and mycotoxin synthesis.
Main Methods:
- Cultured Aspergillus flavus strains on agar media with adjusted water activity (using sucrose or glycerine).
- Monitored fungal growth and aflatoxin B1 production at various temperatures.
- Assessed the impact of reduced water activity (≤0.95) and different temperatures on toxinogenesis.
Main Results:
- Optimal temperatures for aflatoxin B1 production varied by strain (13-16°C, 16-24°C, or 31°C) at high water activity.
- Some strains exhibited rapid growth at 37°C without aflatoxin B1 production.
- Reduced water activity (≤0.95) combined with moderate/low temperatures inhibited toxin production more than growth.
- One strain showed increased aflatoxin B1 production at reduced water activity on glycerine medium at high temperatures.
- No significant differences in growth were observed between aflatoxin-positive and negative strains under tested conditions.
Conclusions:
- Water activity and temperature are critical regulators of Aspergillus flavus growth and aflatoxin B1 production.
- Environmental conditions can differentially affect fungal growth and mycotoxin synthesis.
- Strain-specific responses to environmental factors influence aflatoxin B1 production dynamics.
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