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Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism

Fatty acid ethyl esters are important flavor chemicals in strong-flavor baijiu. Microorganisms are the main contributors to ester synthesis during baijiu manufacture. However, the ester synthesis was unstable between batches. This was owing to a limited knowledge of the mechanisms for ester synthesi...

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Autores principales: Xu, Youqiang, Huang, Huiqin, Lu, Hongyun, Wu, Mengqin, Lin, Mengwei, Zhang, Chunsheng, Zhao, Zhigang, Li, Weiwei, Zhang, Chengnan, Li, Xiuting, Sun, Baoguo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8899536/
https://www.ncbi.nlm.nih.gov/pubmed/35265050
http://dx.doi.org/10.3389/fmicb.2021.820380
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author Xu, Youqiang
Huang, Huiqin
Lu, Hongyun
Wu, Mengqin
Lin, Mengwei
Zhang, Chunsheng
Zhao, Zhigang
Li, Weiwei
Zhang, Chengnan
Li, Xiuting
Sun, Baoguo
author_facet Xu, Youqiang
Huang, Huiqin
Lu, Hongyun
Wu, Mengqin
Lin, Mengwei
Zhang, Chunsheng
Zhao, Zhigang
Li, Weiwei
Zhang, Chengnan
Li, Xiuting
Sun, Baoguo
author_sort Xu, Youqiang
collection PubMed
description Fatty acid ethyl esters are important flavor chemicals in strong-flavor baijiu. Microorganisms are the main contributors to ester synthesis during baijiu manufacture. However, the ester synthesis was unstable between batches. This was owing to a limited knowledge of the mechanisms for ester synthesis by microorganisms. In this work, a fatty acid ethyl ester synthesizing Aspergillus niger strain CGMCC (China General Microbiological Culture Collection) 3.4309 was identified. The conversion ratios of ethyl valerate, ethyl caproate, ethyl caprylate, and ethyl caprate were 7.87, 29.20, 94.80, and 85.20%, respectively, under the optimized conditions. A comparison of transcriptomes under the initial and optimized ester synthetic conditions indicated that 23 genes were upregulated in transcription level and encoded enzymes with potential abilities for ester synthesis. Eleven of the enzymes were expressed, and three of them, numbered An605, An1097, and An3131, showed the ability to catalyze fatty acid ethyl ester synthesis under aqueous phase, with capric acid as the preferred substrate. The possible enzymatic catalytic mechanism was proposed based on homology modeling and molecular docking. This study reported for the first time that A. niger showed the ability to efficiently catalyze the synthesis of short- and medium-chain fatty acid ethyl esters in aqueous phase, identified the key enzymes, and analyzed the basic enzymatic properties. This is helpful to promote the application of related microorganisms and enzyme resources in the baijiu industry.
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spelling pubmed-88995362022-03-08 Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism Xu, Youqiang Huang, Huiqin Lu, Hongyun Wu, Mengqin Lin, Mengwei Zhang, Chunsheng Zhao, Zhigang Li, Weiwei Zhang, Chengnan Li, Xiuting Sun, Baoguo Front Microbiol Microbiology Fatty acid ethyl esters are important flavor chemicals in strong-flavor baijiu. Microorganisms are the main contributors to ester synthesis during baijiu manufacture. However, the ester synthesis was unstable between batches. This was owing to a limited knowledge of the mechanisms for ester synthesis by microorganisms. In this work, a fatty acid ethyl ester synthesizing Aspergillus niger strain CGMCC (China General Microbiological Culture Collection) 3.4309 was identified. The conversion ratios of ethyl valerate, ethyl caproate, ethyl caprylate, and ethyl caprate were 7.87, 29.20, 94.80, and 85.20%, respectively, under the optimized conditions. A comparison of transcriptomes under the initial and optimized ester synthetic conditions indicated that 23 genes were upregulated in transcription level and encoded enzymes with potential abilities for ester synthesis. Eleven of the enzymes were expressed, and three of them, numbered An605, An1097, and An3131, showed the ability to catalyze fatty acid ethyl ester synthesis under aqueous phase, with capric acid as the preferred substrate. The possible enzymatic catalytic mechanism was proposed based on homology modeling and molecular docking. This study reported for the first time that A. niger showed the ability to efficiently catalyze the synthesis of short- and medium-chain fatty acid ethyl esters in aqueous phase, identified the key enzymes, and analyzed the basic enzymatic properties. This is helpful to promote the application of related microorganisms and enzyme resources in the baijiu industry. Frontiers Media S.A. 2022-02-21 /pmc/articles/PMC8899536/ /pubmed/35265050 http://dx.doi.org/10.3389/fmicb.2021.820380 Text en Copyright © 2022 Xu, Huang, Lu, Wu, Lin, Zhang, Zhao, Li, Zhang, Li and Sun. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Microbiology
Xu, Youqiang
Huang, Huiqin
Lu, Hongyun
Wu, Mengqin
Lin, Mengwei
Zhang, Chunsheng
Zhao, Zhigang
Li, Weiwei
Zhang, Chengnan
Li, Xiuting
Sun, Baoguo
Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism
title Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism
title_full Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism
title_fullStr Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism
title_full_unstemmed Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism
title_short Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism
title_sort characterization of an aspergillus niger for efficient fatty acid ethyl ester synthesis in aqueous phase and the molecular mechanism
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8899536/
https://www.ncbi.nlm.nih.gov/pubmed/35265050
http://dx.doi.org/10.3389/fmicb.2021.820380
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