郫县豆瓣发酵过程的微生物多样性及溯源分析

目的] 解析郫县豆瓣及其酿造半成品-蚕豆醅与辣椒醅微生物多样性和来源，探究郫县豆瓣酿造过程风味化合物特征。方法] 采用高通量测序法测定蚕豆醅、辣椒醅与混合醅（蚕豆醅-辣椒醅混合物，发酵成熟形成郫县豆瓣）在酿造过程中的微生物群落结构；利用高效气相质谱与高效液相色谱高通量检测蚕豆醅及辣椒醅中基础理化指标及挥发性、非挥发性风味化合物浓度；利用多种生物信息学分析方法对混合醅酿造微生物及风味化合物进行溯源。结果] 微生物方面：44%–59%的混合醅细菌来源于辣椒醅，5%–22%的混合醅细菌来源于蚕豆醅，其他混合醅细菌来源未知。同时，42%–77%的混合醅真菌来源于辣椒醅，2%–18%的混合醅真菌来源于蚕豆醅，其他混合醅真菌来源未知。另外，16个细菌属由辣椒醅特异性贡献；2个细菌属及2个真菌属由蚕豆醅特异性贡献。化合物方面：1-辛烯-3醇（1-octen-3-ol）、苯乙醛（phenylacetaldehyde）、异丁醛（isobutyraldehyde）、苹果酸（malic acid）与糠醛（furfural）仅由蚕豆醅贡献。辣椒素（capsaicin）、3-甲基-1-丁醇（3-methyl-1-butanol）、已醇（hexanol）与异丁醇（isobutanol）仅由辣椒醅贡献。结论] 郫县豆瓣发酵中大部分微生物来源于辣椒醅，大部分发酵底物（氨基酸及葡萄糖）来源于蚕豆醅。两种发酵半成品均特异性贡献微生物及风味化合物，形成郫县豆瓣的独特风味密码。

Diversity and source tracking of microbial community in Pixian broad bean paste

Objective] We studied the diversity and traced the source of microbial community in Pixian broad bean paste and its two semi-fermented products, including broad bean meju and chili moromi. In addition, we also characterized the flavor compounds in Pixian broad bean paste. Methods] High throughput sequencing was used to explore the microbial community structure and succession. Meanwhile, high throughput liquid chromatography and gas chromatography-mass spectrometry were used to determine the concentrations of nonvolatile and volatile flavor compounds. Multiple bioinformatic methods were used to trace the microbes and flavor compounds in Pixian broad bean paste. Results] Chili moromi contributes 44% to 59% bacterial communities and 42% to 77% fungal communities to Pixian broad bean paste fermentation. Broad bean meju contributes 5% to 22% bacterial communities and 2% to 18% fungal communities to Pixian broad bean paste fermentation. In addition, 16 bacterial genera were only contributed by chili moromi. Two bacterial genus and two fungal genera are only contributed by broad bean meju. In addition, 1-octen-3-ol, phenylacetaldehyde, isobutyraldehyde, malic acid and furfural were only traced from broad bean meju. Capsaicin, 3-methyl-1-butanol, hexanol and isobutanol were only traced from chili moromi. Conclusion] Chili moromi contributes the main microbial communities to Pixian broad bean paste, while broad bean meju contributes the main substrates (including amino acids and glucose). Two semi-fermented products, including chili moromi and broad bean meju, contributed their unique microbes and flavor compounds to Pixian broad bean paste, which might be the reason why Pixian broad bean paste has the characteristic aroma and taste.