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Application of the Food Fermenting Fungus Aspergillus oryzae to Control Aflatoxin Contamination and Foodborne Pathogens
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Application of the Food Fermenting Fungus Aspergillus oryzae to Control Aflatoxin Contamination and Foodborne Pathogens. |
| 개인저자 | Alshannaq, Ahmad F. |
| 단체저자명 | The University of Wisconsin - Madison. Food Science. |
| 발행사항 | [S.l.]: The University of Wisconsin - Madison., 2018. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2018. |
| 형태사항 | 122 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781687972910 |
| 학위논문주기 | Thesis (Ph.D.)--The University of Wisconsin - Madison, 2018. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Yu, Jae-Hyuk. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Fungi of the genus Aspergillus are widespread in the environment and have both beneficial and detrimental effects on humankind. Aspergillus oryzae has a long history of extensive use in food fermentation and biotechnological applications, which prompted it to be listed as Generally Recognized as Safe (GRAS) by the Food and Drug Administration (FDA) of the United States and World Health Organization (WHO). Thus far, applications of this GRAS fungal species have been largely limited to food fermentation and enzyme production, and its potential in controlling fungal toxin contaminations and various foodborne pathogens has been overlooked. Aflatoxin is an unavoidable chemical contaminant of worldwide concern due to its stability in the food and feed, and potent carcinogenic effects in mammals. In this study, based on the observation that various soy-based foods fermented with A. oryzae are rarely contaminated with fungal toxins, we first demonstrated that live cells of the soy-fermenting strain A. oryzae M2040 can effectively inhibit aflatoxin B1 (AFB1) production and proliferation of toxigenic Aspergillus flavus. Moreover, cell-free culture filtrate of A. oryzae effectively inhibited AFB1 production and A. flavus growth, indicating a potential secretion of (unknown) inhibitory compounds. Whole genome sequencing and comparative analyses indicate that the A. oryzae M2040 genomes are 37.9 Mbp. Our studies demonstrate the possible use of A. oryzae and its cell-free culture fermentate as a biocontrol agent to control A. flavus propagation and AF contamination in fields, and food and feed. While testing AFB1 inhibition by A. oryzae culture filtrate, we found its activity against foodborne pathogenic bacteria and yeasts. We further tested several culture conditions and found a special food grade medium that maximized the antimicrobial activity of the cell-free culture filtrate against major foodborne and human pathogens. Briefly, the ethyl acetate extract of this fermentate displayed significant anti-bacterial activity against Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli with minimum inhibitory concentration (MIC) of 0.78%, 1.56%, 12.5% and 25% (v/v), respectively, suggesting its strong activity against Gram positive bacteria. Importantly, the extract showed substantial activity against Methicillin-resistant S. aureus (MRSA) (MIC=3.125%) and the human pathogenic yeast Candida albicans (MIC=6.25%) (v/v). Crude fermentate displayed anti-fungal activity against Aspergillus fumigatus, A. flavus, and Penicillium roqueforti. The extract is heat stable and non-enzymatic. Overall, this study revealed that the GRAS fungus A. oryzae has antifungal and antimicrobial activity, opening up the possibility of using A. oryzae to control foodborne and human pathogens, and reducing aflatoxin contamination in food and feed. |
| 일반주제명 | Food science. Microbiology. |
| 언어 | 영어 |
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