A Combined Proteomic and Metabolomic Strategy for Allergens Characterization in Natural and Fermented Brassica napus Bee Pollen
Shuting Yin, Yuxiao Tao, Yusuo Jiang, Lifeng Meng, Liuwei Zhao, Xiaofeng Xue, Qiangqiang Li, Liming Wu
近日，中国农业科学院蜜蜂研究所蜂产品质量与风险评估团队研究揭示油菜蜂花粉的潜在致敏机制和酵母菌发酵的降敏机制。相关成果发表在《营养学前沿》（Frontiers in Nutrition）上。
蜂花粉是蜜蜂将花蜜及唾液腺分泌物加入其所采集的花粉粒中形成的团状物。蜂花粉营养成分十分丰富，具有极高的食用与药用价值。但同时也存在尚未确定的致敏风险与过敏原，这在一定程度上制约了蜂花粉的开发与利用。
该研究利用基于质谱的蛋白质组学分析方法，在甘蓝型油菜蜂花粉中发现了两种潜在的过敏原glutaredoxin和oleosin-B2，并利用生物信息学方法预测了它们的抗原表位。
对油菜蜂花粉的代谢组学分析显示，相较于未发酵样品，经酿酒酵母发酵后的蜂花粉样品中两种潜在致敏蛋白glutaredoxin和oleosin-B2的含量显著降低，且主成分中寡肽和氨基酸含量显著提高。
免疫印迹实验结果表明，发酵后提取的蜂花粉蛋白与特异性IgE结合能力也显著降低，表明发酵后的油菜蜂花粉过敏原性显著降低。此外，发酵对L-缬氨酸、L-异亮氨酸、L -色氨酸和L -苯丙氨酸等人体必需氨基酸及其前体或中间体的生物合成有明显的促进作用。
该实验证明，酵母菌发酵可以潜在地缓解甘蓝型油菜蜂花粉的过敏性，同时对其营养特性也有更积极的影响，为提高蜂花粉产品的安全性，促进其更广泛的应用提供科学依据。在未来的研究中，对蜂花粉致敏原分离鉴定及其致敏机制的探究，以及建立发酵降解蜂花粉致敏原的方法，将会对蜂花粉的安全利用发挥重要的作用。
该研究得到国家自然科学基金、中国农业科学院科技创新工程项目资助。
来源：中国科学报 李晨
Abstract
Bee pollen is consumed for its nutritional and pharmacological benefits, but it also contains hazardous allergens which have not been identified. Here, we identified two potential allergens, glutaredoxin and oleosin-B2, in Brassica napus bee pollen using mass spectrometry-based proteomics analyses, and used bioinformatics to predict their antigenic epitopes. Comparison of fermented (by Saccharomyces cerevisiae) and unfermented bee pollen samples indicated that glutaredoxin and oleosin-B2 contents were significantly decreased following fermentation, while the contents of their major constituent oligopeptides and amino acids were significantly increased based on metabolomics analyses. Immunoblot analysis indicated that the IgE-binding affinity with extracted bee pollen proteins was also significantly decreased after fermentation, suggesting a reduction in the allergenicity of fermented bee pollen. Furthermore, fermentation apparently promoted the biosynthesis of L-valine, L-isoleucine, L-tryptophan, and L-phenylalanine, as well as their precursors or intermediates. Thus, fermentation could potentially alleviate allergenicity, while also positively affecting nutritional properties of B. napus bee pollen. Our findings might provide a scientific foundation for improving the safety of bee pollen products to facilitate its wider application.
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