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Effect of ultraviolet light irradiation on viability and aflatoxin production by Aspergillus parasiticus
M A Moreno1, M C Ramos, A González
1Departamento de Microbiologia, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain.
Abstract:
The effect of ultraviolet light irradiation (254 nm) on both the viability and the aflatoxin-producing ability of the fungus Aspergillus parasiticus NRRL 2999, a good aflatoxin-producing strain, was studied. This strain showed noticeable resistance and irradiation for more than 10 min was necessary to reduce survival to under 10%, while the white mutants were more susceptible (5 min of irradiation reduced survival to under 1%). Induction of mutants with complete loss of aflatoxigenicity was rare and only 3 of the 1463 survivors tested were aflatoxinless.
Insights
Ultraviolet light irradiation (254 nm) reduced Aspergillus parasiticus viability, requiring over 10 minutes for significant survival reduction. Complete loss of aflatoxin production in mutants was rare, indicating fungal resistance to UV-induced inactivation.
Area of Science:
- Mycology
- Food Microbiology
- Radiation Biology
Background:
- Aspergillus parasiticus is a significant producer of aflatoxins, which are toxic and carcinogenic compounds contaminating food and feed.
- Ultraviolet (UV) irradiation is explored as a potential method for microbial control and detoxification.
Purpose of the Study:
- To investigate the impact of 254 nm UV irradiation on the viability of Aspergillus parasiticus NRRL 2999.
- To assess the effect of UV irradiation on the aflatoxin-producing capability of Aspergillus parasiticus.
- To determine the susceptibility of wild-type and mutant strains to UV inactivation.
Main Methods:
- Exposure of Aspergillus parasiticus NRRL 2999 cultures to 254 nm UV light for varying durations.
- Viability assessment through colony-forming unit counts.
- Screening of survivors for aflatoxin production.
Main Results:
- The wild-type strain exhibited notable resistance to UV irradiation, with over 10 minutes required to reduce survival below 10%.
- White mutants of Aspergillus parasiticus were more susceptible, with 5 minutes of irradiation reducing survival to under 1%.
- Induction of completely aflatoxinless mutants was infrequent, with only 3 out of 1463 survivors tested showing no aflatoxin production.
Conclusions:
- Aspergillus parasiticus NRRL 2999 demonstrates significant resistance to UV irradiation, necessitating prolonged exposure for substantial viability reduction.
- UV irradiation can induce mutations affecting aflatoxin production, but achieving complete loss of aflatoxigenicity is challenging.
- Further research may explore optimized UV treatment parameters or synergistic methods for effective control of aflatoxin contamination.