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Growth and biosynthesis of aflatoxin by Aspergillus parasiticus in cultures containing nisin
Abstract:
Nisin, 200 or 5000 Reading units/ml, was added to Aspergillus parasiticus cultures. The cultures were incubated at 28 degrees C for 3, 7 or 10 days and analyzed for mycelial dry weight, pH and accumulation of aflatoxin B1 and G1. During the first 3 days of incubation, dry weight, pH decrease and aflatoxin accumulation were suppressed by nisin, when compared with similar values for the nisin-free control. After longer incubation, differences in dry weight nd pH values decreased, whereas accumulation of aflatoxin in the nisin-containing cultures surpassed that of the control.
Insights
Nisin initially suppressed Aspergillus parasiticus growth and aflatoxin production. However, prolonged exposure to nisin led to increased aflatoxin accumulation compared to controls.
Area of Science:
- Food microbiology
- Mycology
- Antimicrobial agents
Background:
- Aspergillus parasiticus is a significant producer of aflatoxins, which are toxic and carcinogenic compounds.
- Nisin is a bacteriocin with known antimicrobial properties, but its effect on aflatoxin production is not fully understood.
Purpose of the Study:
- To investigate the impact of nisin on the growth and aflatoxin B1 and G1 production of Aspergillus parasiticus.
- To determine the effect of different nisin concentrations and incubation times on fungal development and mycotoxin accumulation.
Main Methods:
- Aspergillus parasiticus cultures were treated with nisin (200 or 5000 IU/ml) and incubated at 28°C for 3, 7, or 10 days.
- Mycelial dry weight, pH, and accumulation of aflatoxin B1 and G1 were measured.
Main Results:
- Nisin at both concentrations initially suppressed mycelial dry weight, pH decrease, and aflatoxin accumulation within the first 3 days.
- After longer incubation periods (7 and 10 days), the differences in dry weight and pH diminished.
- Aflatoxin accumulation in nisin-treated cultures eventually surpassed that of the nisin-free control.
Conclusions:
- Nisin exhibits a biphasic effect on Aspergillus parasiticus, initially inhibiting growth and aflatoxin production.
- Prolonged exposure to nisin can lead to enhanced aflatoxin accumulation, suggesting a potential for increased risk under certain conditions.
- The findings highlight the complex interaction between nisin and fungal metabolism, necessitating careful consideration for its application in food preservation.