东北酸菜传统自然发酵过程中的真核微生物多样性

Eukaryotic microorganism diversity during traditional natural fermented Northeast pickled cabbage

文章为调查东北酸菜传统自然发酵过程中的真核微生物多样性,监测酸菜发酵体系生理生化动态变化,了解真核微生物在酸菜发酵过程中的作用。分析酸菜体系p H、可溶性糖、亚硝酸盐、乳酸、乙酸、乙醇和26S r DNA片段多样性。结果表明,发酵12 d时,酸菜体系p H从发酵初始值7.3下降到4.3后维持在4.1。可溶性糖发酵18 d时,由初始15.1%DM下降到4.5%DM。亚硝酸盐第6天时达到最大,随后下降。发酵体系中检测到的挥发性产物包括乳酸、乙酸和乙醇。发酵结束时,相应浓度分别达到6.8、0.78和32.2 g·L-1。26S r DNA D1/D2区变性梯度凝胶电泳结果显示发酵过程中真核微生物种类丰富。克隆文库揭示发酵第12天时,真核微生物主要为未培养的Stramenopile和土壤真菌,发酵30 d时,除上述两类微生物外还包括Candida sake,Cystofilobasidium infirmominiatum,未培养Claclosporium和Tilletiopsis washingtonensis。土壤真菌(41%)、Candida sake(29%)、未培养Stramenopile(17%)占所有检测真核微生物的86%。研究表明,Candida sake和Cystofilobasidium infirmominiatum对发酵体系中乙醇产生起一定作用。为研究酸菜发酵机制和控制酸菜发酵质量提供技术参考。

In this study, eukaryoUc diversity during Northeast pickled cabbage fermentation was investigated, and biochemical indices and microbial succession were measured. The pH decreased to 4.3 after 12 days of Northeast pickled cabbage fermentation from the initial 7.3, and then remained at approximately 4.1. Water-soluble carbohydrate content decreased from 15.1% to 4.5% of dry matter at 18 days of fermentation. At 6 days, nitrite content was the maximum, and then decreased dramatically. Lactic acid, acetic acid and ethanol were the main volatile products identified. At the end of fermentation, the concentrations of lactic acid and acetic acid were 6.8 and 0.78 g. L^-1, respectively. The ethanol concentration was 32.2 g. L^-1. The results of 26S rDNA D1/D2 region DGGE and clone library analysis showed that eukaryotic diversity was rich during fermentation. The results from the cloning libraries revealed that the eukaryotic microorganisms detected included uncultured Stramenopile and uncultured soil fungus at 12 days fermentation. Candida sake, Cystofilo basidium infirmominiatum,uncultured Claclosporium and Tilletiopsis washingtonensis were also detected un- til 30 days of fermentation, in addition to the two species mentioned above. Uncultured soil fungus （41%）, Candida sake （29%） and uncultured Stramenopile （17%） accounted for 86% of the eukaryotic microorganisms detected. The results indicated that Candida sake and Cystofilobasidium infirmominiatum （yeasts） contributed to ethanol production during the Northeast pickled cabbage fermentation. These results provided a comprehensive understanding of the traditional Northeast pickled cabbage fermentation process and a foundation for controlling Northeast pickled cabbage fermentation and quality.