AKINYELE, Ayomide Faith and Covenant University, Theses Masters (2024) BIODEGRADATION OF OCHRATOXIN A IN SELECTED FOOD SPICES USING LACCASE OBTAINED FROM FUNGI ISOLATED IN OTA COVER. Masters thesis, Covenant University.
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Abstract
The carcinogenicity, hepatotoxicity, and nephrotoxicity associated with the ingestion of ochratoxin A (OTA)-contaminated food spices demand an effective biodegradation approach that ensures food safety and sustainability. The aim of this research was to produce and characterise laccase from selected fungal specie and to determine its effectiveness in degrading OTA present in selected food spices. Fungal species were isolated from soil samples and screened for laccase production. Selected laccase-producing fungi was induced for quantitative laccase production by solid-state fermentation using a laccase basal medium supplemented with pre-treated corncobs. The produced laccase was extracted, characterised and enzyme activity analysed. The OTA in the selected food spices was detected and quantified using High- Performance Liquid Chromatography (HPLC). Using computational tools, insights were also provided on the mechanisms of biodegradation of OTA using obtained laccase. Eight fungi species were isolated from the soil sample, of which three screened positive for laccase production. The most efficient laccase-producing fungi (identified by intensity of the brown colouration on the screening medium) was selected and identified as Pleurotus sp. The laccase obtained from the selected fungi isolate had an activity of 51.93±1.8 U/mL. Following characterization, the optimum condition of temperature and pH were 70oC and 7 respectively. HPLC chromatogram showed the presence of OTA at peak area of 132.55 and 132.16 for both chilli and turmeric respectively. There was a 29.5% and 29.9% reduction in OTA extracted from the selected chilli and turmeric spices respectively after incubation with the obtained laccase. Statistically, there were significant differences between the levels of detected OTA in the spices before and after incubation with laccase (p<0.05). The laccase was computationally predicted to bind to the phenol of the OTA which bears the chlorine atom responsible for the toxicity of the OTA. This binding results in a cleavage of the phenol group resulting in the breakdown of the OTA into OTα and L-β-phenylalanine. Therefore, treatment with laccase serves as an effective method for the degradation of OTA in food spices.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Biodegradation, Computational Analysis, Laccase, Ochratoxin A, Spices |
| Subjects: | Q Science > QH Natural history Q Science > QR Microbiology R Medicine > R Medicine (General) |
| Divisions: | Faculty of Medicine, Health and Life Sciences > School of Biological Sciences |
| Depositing User: | Patricia Nwokealisi |
| Date Deposited: | 30 Sep 2024 09:16 |
| Last Modified: | 30 Sep 2024 09:16 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/18465 |
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