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Toxicity of ochratoxin A in aBrevibacillus brevis - Growth inhibition assay
1Department of Environmental Biotechnology, IFA-Tulln, Konrad Lorenzstr. 20, A-3430, Tulln, Austria.
Abstract:
Ochratoxin A (OTA) is a nephrotoxic, carcinogenic and immunosuppressive mycotoxin. It can be detoxified by various microorganisms, e.g. different yeast strains, via metabolisation into ochratoxin α (OTα). Within this study a growth inhibition assay was developed to compare the toxicity of OTA and its degradation product OTα. As an indicator organismBrevibacillus brevis was used. The assay was performed in microtiterplates. Growth inhibition was determined by comparing the optical density values ofBrevibacillus brevis cultures grown in medium supplemented with OTA/OTα and OTA/OTα-free medium, respectively.It could be shown thatB. brevis is sensitive to OTA (EC100=0.5 mg/L±0.03 mg/L), which is not the case for its metabolite OTα. Therefore this bioassay is a useful tool to show the detoxification of OTA to OTα by microbial degradation.
Insights
This study developed a bioassay to measure Ochratoxin A (OTA) toxicity. The assay confirmed that the mycotoxin OTA is toxic to Brevibacillus brevis, but its metabolite ochratoxin α (OTα) is not.
Area of Science:
- Mycology
- Microbiology
- Toxicology
Background:
- Ochratoxin A (OTA) is a harmful mycotoxin with nephrotoxic, carcinogenic, and immunosuppressive properties.
- Microorganisms, such as yeast, can detoxify OTA by metabolizing it into ochratoxin α (OTα).
Purpose of the Study:
- To develop and validate a growth inhibition bioassay for comparing the toxicity of OTA and its degradation product, OTα.
- To utilize Brevibacillus brevis as an indicator organism to assess OTA and OTα toxicity.
Main Methods:
- A microtiter plate-based growth inhibition assay was designed.
- Brevibacillus brevis growth was monitored by measuring optical density.
- Cultures were compared between those exposed to OTA/OTα and control media.
Main Results:
- Brevibacillus brevis demonstrated sensitivity to OTA, with an EC100 value of 0.5 mg/L ± 0.03 mg/L.
- The metabolite OTα did not exhibit toxicity to B. brevis under the tested conditions.
- The bioassay effectively distinguished the toxicity of OTA from its non-toxic metabolite OTα.
Conclusions:
- The developed bioassay is a reliable tool for detecting and quantifying OTA detoxification by microbial action.
- This method can confirm the conversion of toxic OTA to non-toxic OTα by microorganisms.
- The findings support the use of microbial detoxification strategies for mitigating OTA contamination.
