Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC 27695-7624, USA.
J Appl Microbiol. 2013 Jan;114(1):161-72. doi: 10.1111/jam.12022. Epub 2012 Nov 6.
To evaluate the interaction between selected yeasts and bacteria and associate their metabolic activity with secondary cucumber fermentation.
Selected yeast and bacteria, isolated from cucumber secondary fermentations, were inoculated as single and mixed cultures in a cucumber juice model system. Our results confirmed that during storage of fermented cucumbers and in the presence of oxygen, spoilage yeasts are able to grow and utilize the lactic and acetic acids present in the medium, which results in increased brine pH and the chemical reduction in the environment. These conditions favour opportunistic bacteria that continue the degradation of lactic acid. Lactobacillus buchneri, Clostridium bifermentans and Enterobacter cloacae were able to produce acetic, butyric and propionic acids, respectively, when inoculated in the experimental medium at pH 4.6. Yeast and bacteria interactions favoured the survival of Cl. bifermentans and E. cloacae at the acidic pH typical of fermented cucumbers (3.2), but only E. cloacae was able to produce a secondary product.
The methodology used in this study confirmed that a complex microbiota is responsible for the changes observed during fermented cucumber secondary fermentation and that certain microbial interactions may be essential for the production of propionic and butyric acids.
Understanding the dynamics of the development of secondary cucumber fermentation aids in the identification of strategies to prevent its occurrence and economic losses for the pickling industry.
评估选定酵母和细菌之间的相互作用，并将其代谢活性与黄瓜二次发酵相关联。
从黄瓜二次发酵中分离出的选定酵母和细菌，作为单一和混合培养物接种到黄瓜汁模型系统中。我们的结果证实，在发酵黄瓜的储存过程中，在氧气存在的情况下，腐败酵母能够生长并利用培养基中存在的乳酸和乙酸，这导致盐水 pH 值升高，环境中的化学还原。这些条件有利于继续降解乳酸的机会细菌。当在 pH 值为 4.6 的实验培养基中接种时，Lactobacillus buchneri、Clostridium bifermentans 和 Enterobacter cloacae 分别能够产生乙酸、丁酸和丙酸。酵母和细菌的相互作用有利于 Clostridium bifermentans 和 Enterobacter cloacae 在发酵黄瓜（3.2）典型的酸性 pH 值下存活，但只有 Enterobacter cloacae 能够产生次级产物。
本研究中使用的方法学证实，复杂的微生物群是导致发酵黄瓜二次发酵过程中观察到的变化的原因，并且某些微生物相互作用可能对于丙酸和丁酸的产生是必不可少的。
了解二次黄瓜发酵的发展动态有助于确定防止其发生和为腌制工业造成经济损失的策略。
