Wang Zixuan, Luo Du, Xu Wenjing, Liu Haoqun, Pang Mei, Chen Gong
Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205, People's Republic of China.
Bioprocess Biosyst Eng. 2025 Feb;48(2):287-299. doi: 10.1007/s00449-024-03109-x. Epub 2024 Dec 20.
Microbial fermentation is an effective method to improve the functional activity of oats (Avena sativa L.), while there are some limitations to the advantages of single microbial fermentation. In this study, a microbial co-culture fermentation system with Monascus anka, Saccharomyces cerevisiae and Bacillus subtilis to release and conversion oat phenolics was established. Results showed that the optimal microbial co-fermentation system was obtained by adding Saccharomyces cerevisiae on the fourth day and Bacillus subtilis on the eighth day during Monascus anka fermentation (MF + 4S + 8B). The phenolic content was reached 26.93 mg GAE/g DW, which increased 41.08 times compared to un-fermented oats (UF). In the process of co-fermentation systems, cellulase and β-glucosidase (r = 0.97, p < 0.01) had a positive correlation with the release of phenolics. SEM combined with HPLC showed that the complex enzyme system produced by microbial co-fermentation enhanced the disruption of oat cell structure, as well as altered the phenolics fractions and facilitated the conversion of bound phenolics to free phenolics, especially the content of chlorogenic acid and vanillic acid in the free forms was increased 31.42 and 14.15 times, respectively. Additionally, the phenolic contents were increased and the components were changed with the microbial co-fermentation of crude enzyme solution further added, which validated the positive influence of complex enzyme system of MF + 4S + 8B in the phenolic release and transformation of oats. Therefore, this study systematically investigated the phenolic mobilization in oats during the co-fermentation period, which provides a viable option for improving the functional properties of cereal products, as well as the application of microbial cell factories.
微生物发酵是提高燕麦（ Avena sativa L.）功能活性的有效方法，然而单一微生物发酵的优势存在一定局限性。本研究建立了红曲霉菌、酿酒酵母和枯草芽孢杆菌的微生物共培养发酵体系，用于燕麦酚类物质的释放与转化。结果表明，在红曲霉发酵期间，于第4天添加酿酒酵母、第8天添加枯草芽孢杆菌，可获得最佳微生物共发酵体系（MF + 4S + 8B）。酚类物质含量达到26.93 mg GAE/g DW，相较于未发酵燕麦（UF）增加了41.08倍。在共发酵体系过程中，纤维素酶和β-葡萄糖苷酶（r = 0.97，p < 0.01）与酚类物质的释放呈正相关。扫描电子显微镜（SEM）结合高效液相色谱（HPLC）表明，微生物共发酵产生的复合酶系统增强了燕麦细胞结构的破坏，同时改变了酚类组分，促进了结合态酚类向游离态酚类的转化，尤其是游离态绿原酸和香草酸的含量分别增加了31.42倍和14.15倍。此外，进一步添加粗酶液进行微生物共发酵，酚类物质含量增加且组分发生变化，这验证了MF + 4S + 8B复合酶系统对燕麦酚类释放和转化的积极影响。因此，本研究系统地研究了共发酵期间燕麦中酚类物质的迁移，为改善谷物产品的功能特性以及微生物细胞工厂的应用提供了可行的选择。
