Diversity and Stability of Lactic Acid Bacteria in Rye Sourdoughs of Four Bakeries with Different Propagation Parameters

We identified the lactic acid bacteria within rye sourdoughs and starters from four bakeries with different propagation parameters and tracked their dynamics for between 5–28 months after renewal. Evaluation of bacterial communities was performed using plating, denaturing gradient gel electrophoresis, and pyrosequencing of 16S rRNA gene amplicons. Lactobacillus amylovorus and Lactobacillus frumenti or Lactobacillus helveticus, Lactobacillus pontis and Lactobacillus panis prevailed in sourdoughs propagated at higher temperature, while ambient temperature combined with a short fermentation cycle selected for Lactobacillus sanfranciscensis, Lactobacillus pontis, and Lactobacillus zymae or Lactobacillus helveticus, Lactobacillus pontis and Lactobacillus zymae. The ratio of species in bakeries employing room-temperature propagation displayed a seasonal dependence. Introduction of different and controlled propagation parameters at one bakery (higher fermentation temperature, reduced inoculum size, and extended fermentation time) resulted in stabilization of the microbial community with an increased proportion of L. helveticus and L. pontis. Despite these new propagation parameters no new species were detected.

我们对4家采用不同发酵传代参数的面包店的黑麦酸面团及发酵种中的乳酸菌进行了鉴定，并追踪了其在菌种更新后5至28个月内的群落动态。本研究采用平板培养计数法、变性梯度凝胶电泳（denaturing gradient gel electrophoresis，DGGE）以及16S rRNA基因扩增子焦磷酸测序，对细菌群落组成进行了分析。在较高温度下发酵的酸面团中，优势菌群为淀粉液化乳杆菌（Lactobacillus amylovorus）、谷物乳杆菌（Lactobacillus frumenti）或瑞士乳杆菌（Lactobacillus helveticus）、庞蒂乳杆菌（Lactobacillus pontis）与面包乳杆菌（Lactobacillus panis）；而采用室温结合短发酵周期工艺的面包店，其优势菌群则为旧金山乳杆菌（Lactobacillus sanfranciscensis）、庞蒂乳杆菌与产酶乳杆菌（Lactobacillus zymae），或是瑞士乳杆菌、庞蒂乳杆菌与产酶乳杆菌。采用室温发酵工艺的面包店中，菌种比例呈现出季节性变化规律。在其中一家面包店调整并控制发酵传代参数（提高发酵温度、降低接种量、延长发酵时间）后，微生物群落趋于稳定，瑞士乳杆菌与庞蒂乳杆菌的占比均有所提升。尽管调整了发酵参数，并未检测到新的菌种。