Effect of initial pH on aflatoxin production

Area of Science:

• Mycology
• Food Microbiology
• Toxicology

Background:

• Aflatoxins are toxic secondary metabolites produced by Aspergillus species.
• Aspergillus parasiticus is a significant producer of aflatoxins, posing risks to food safety.
• Environmental factors, such as pH, can influence fungal growth and toxin production.

Purpose of the Study:

• To investigate the influence of initial pH on the growth and aflatoxin production of Aspergillus parasiticus NRRL 2999.
• To determine the optimal initial pH for maximal fungal growth and aflatoxin yield.
• To analyze the effect of pH on the specific types of aflatoxins (B and G) produced.

Main Methods:

• Culturing Aspergillus parasiticus NRRL 2999 in a semisynthetic medium with varying initial pH levels.
• Measuring fungal biomass to assess growth.
• Quantifying total aflatoxin production using analytical methods.
• Differentiating and quantifying B and G aflatoxin types.

Main Results:

• Maximal fungal growth occurred at an initial pH of 5.0.
• Maximal total aflatoxin production was observed at an initial pH of 6.0.
• The highest aflatoxin production per unit of growth was recorded at an initial pH of 7.0.
• Initial pH levels below 6.0 favored the production of aflatoxin B toxins.
• Initial pH levels above 6.0 favored the production of aflatoxin G toxins.

Conclusions:

• Initial pH is a critical factor regulating both the quantity and type of aflatoxins produced by Aspergillus parasiticus.
• Understanding pH-dependent production is crucial for developing strategies to control aflatoxin contamination in food and feed.
• Specific pH ranges can be targeted to either minimize overall aflatoxin accumulation or shift the toxin profile towards less prevalent types.