Molecular characterization of mycotoxin producing moulds from grains and legumes and their susceptibility to plant extracts
| dc.contributor.author | Ohabughiro, Ndidi Blessing | |
| dc.date.accessioned | 2025-04-15T10:13:58Z | |
| dc.date.available | 2025-04-15T10:13:58Z | |
| dc.date.issued | 2021-11 | |
| dc.description | Doctoral thesis on mycotoxin producing moulds from grains and legumes. It also contains pictures and tables | |
| dc.description.abstract | Molecular characterization of mycotoxin producing moulds from grains and legumes and their susceptibility to plant extracts was studied. Grains and legumes were stored for a period of two and four months. They were analysed for the presence of moulds and mycotoxin producing moulds. They were also analysed for the production of different mycotoxins. Sabouraud dextrose agar, Sabouraud dextrose broth, potato dextrose agar and malt extract agar were used in this study. The methods of isolation used were direct physical examination and direct plate count method. Moulds were identified based on their colony morphology, cultural characteristics and molecular characterization. Mycotoxin analysis was done using Liquid chromatography tandem mass spectrometry. Antifungal susceptibility test was done using the Clinical Laboratory and Standards Institute approved methods for testing of moulds using disk diffusion method. The following four oxoid antifungal agents were used: Amphotericin B, fluconazole, ketoconazole and voriconazole. The following medicinal plants: Ocimum gratissimum (scent leaves), Vemonia amygdalina (bitter leaves), Gongronema latifolium (utazi leaves) and Piper guineense (uziza leaves) were assessed for their phytochemical properties and antifungal susceptibility profile against various moulds. The organic solvents used for antifungal susceptibility profile were methanol and hot water. One way analysis of variance, Duncan tests and descriptive statistics were used for statistical analysis. The moulds isolated and identified culturally were Aspergillus sp. Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus, Penicillium chrysogenum, Fusarium sp, Rhizopus stolonifer, Rhizopus nigricans and Mucor sp. while those identified molecularly were Aspergillus flavus, Aspergillus tamarii, Aspergillus niger, Aspergillus brunneoviolaceus, and Penicillium chrysogenum. The genus Aspergillus was the most prevalent mould. Groundnut had the highest number of isolates followed by maize, beans, rice while wheat had the least number of isolates. The numbers of colony forming units were more in Potato dextrose agar, Sabouraud dextrose agar and least on malt extract agar. Potato dextrose agar recovered the highest number of isolates from both unstored and stored samples followed by sabouraud dextrose agar then malt extract agar. The following mycotoxins were detected Aflatoxin B1, Aflatoxin B2, Aflatoxin G1, Aflatoxin G2, Ochratoxin A, Citrinin, Dihydrocitrinone, Fumonisin B1, Fumonisin B2, Fumonisin B3, Fumonisin B4, Zearalenone, Deoxynivalenol and Nivalenol. Aflatoxin was the most frequent mycotoxin detected. Rice (1286.3 ± 29.689 µg/kg) had the highest rate of recovery of mycotoxins followed by wheat (1166.8 ± 0.901 µg/kg) and groundnuts (1142.9 ± 10.488 µg/kg) while maize (1111.6 ± 9.810 µg/kg) had the least concentration of mycotoxins. Ketoconazole (39 ±1.000 mm) had the highest minimum inhibitory concentration among different anti-fungal agents, followed by voriconazole (36 ± 2.000 mm), Amphotericin B (30 ±2.000 mm) and then Fluconazole (21 ± 12.124 mm). Susceptibility profile using only tetrazolium gave no zone of inhibition. Antifungal agents alone gave a better zone of inhibition than the combination of antifungal agents with tetrazolium. The medicinal plants such as scent leaves, bitter leaves, uziza leaves and utazi leaves analysed contained the following phytochemicals tannin, alkaloid, steroid, saponin and flavonoid. Percentage growth inhibition of moulds by methanol and hot water xiii extract of scent leaf gave the highest inhibition followed by bitter leaf, utazi and uziza gave the least growth inhibition. Methanol extract gave a better inhibition than hot water extract at 100 mg/ml and 50 mg/ml. One-way analysis of variance and Duncan tests showed that there was a significant difference (P < 0.05) between the isolates found in stored and unstored grains and legume. There was also a significant difference (P < 0.05) between the antifungal agents and media used. Potato dextrose agar should be used frequently since it gave the highest rate of mould recovery. Ketoconazole remains the best drug of choice among other antifungal agents against moulds. Medicinal plants like scent leaves, bitter leaves, utazi leaves and uziza leaves gave varying levels of growth inhibition against various isolates and should be used both at home and clinical settings. The grains and legumes studied were contaminated with various species of moulds and contained many mycotoxins of public health importance. | |
| dc.identifier.citation | Ohabughiro, N. B. (2021). Molecular characterization of mycotoxin producing moulds from grains and legumes and their susceptibility to plant extracts. (Unpublished Doctoral Thesis). Federal University of Technology, Owerri, Nigerai . | |
| dc.identifier.uri | https://repository.futo.edu.ng/handle/20.500.14562/1770 | |
| dc.language.iso | en | |
| dc.publisher | Federal University of Technology, Owerri | |
| dc.rights | Attribution-NonCommercial-NoDerivatives 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | |
| dc.subject | Grains and legumes | |
| dc.subject | moulds | |
| dc.subject | 18S rRNA sequencing | |
| dc.subject | mycotoxins | |
| dc.subject | Department of Microbiology | |
| dc.subject | antifungal agents | |
| dc.subject | medicinal plants | |
| dc.title | Molecular characterization of mycotoxin producing moulds from grains and legumes and their susceptibility to plant extracts | |
| dc.type | Doctoral Thesis |