Siragusa Sonya, Di Cagno Raffaella, Ercolini Danilo, Minervini Fabio, Gobbetti Marco, De Angelis Maria
Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi di Bari, Bari, Italy.
Appl Environ Microbiol. 2009 Feb;75(4):1099-109. doi: 10.1128/AEM.01524-08. Epub 2008 Dec 16.
The structure and stability of the dominant lactic acid bacterium population were assessed during wheat flour sourdough type I propagation by using singly nine strains of Lactobacillus sanfranciscensis. Under back-slopping propagation with wheat flour type 0 F114, cell numbers of presumptive lactic acid bacteria varied slightly between and within starters. As determined by randomly amplified polymorphic DNA-PCR and restriction endonuclease analysis-pulsed-field gel electrophoresis analyses, only three (LS8, LS14, and LS44) starters dominated throughout 10 days of propagation. The others progressively decreased to less than 3 log CFU g(-1). Partial sequence analysis of the 16S rRNA and recA genes and PCR-denaturating gradient gel electrophoresis analysis using the rpoB gene allowed identification of Weissella confusa, Lactobacillus sanfranciscensis, Lactobacillus plantarum, Lactobacillus rossiae, Lactobacillus brevis, Lactococcus lactis subsp. lactis, Pediococcus pentosaceus, and Lactobacillus spp. as the dominant species of the raw wheat flour. At the end of propagation, one autochthonous strain of L. sanfranciscensis was found in all the sourdoughs. Except for L. brevis, strains of the above species were variously found in the mature sourdoughs. Persistent starters were found in association with other biotypes of L. sanfranciscensis and with W. confusa or L. plantarum. Sourdoughs were characterized for acidification, quotient of fermentation, free amino acids, and community-level catabolic profiles by USING Biolog 96-well Eco microplates. In particular, catabolic profiles of sourdoughs containing persistent starters behaved similarly and were clearly differentiated from the others. The three persistent starters were further used for the production of sourdoughs and propagated by using another wheat flour whose lactic acid bacterium population in part differed from the previous one. Also, in this case all three starter strains persisted during propagation.
通过单独使用9株旧金山乳杆菌，评估了I型小麦粉酸面团发酵过程中优势乳酸菌种群的结构和稳定性。在使用0型F114小麦粉进行回接发酵时，推定乳酸菌的细胞数量在发酵剂之间和内部略有变化。通过随机扩增多态性DNA-PCR和限制性内切酶分析-脉冲场凝胶电泳分析确定，在整个10天的发酵过程中，只有3个（LS8、LS14和LS44）发酵剂占主导地位。其他发酵剂逐渐减少至低于3 log CFU g(-1)。对16S rRNA和recA基因进行部分序列分析，并使用rpoB基因进行PCR-变性梯度凝胶电泳分析，从而鉴定出了混淆魏斯氏菌、旧金山乳杆菌、植物乳杆菌、罗西亚乳杆菌、短乳杆菌、乳酸乳球菌乳酸亚种、戊糖片球菌和乳杆菌属作为生小麦粉中的优势菌种。在发酵结束时，在所有酸面团中都发现了一株本地的旧金山乳杆菌。除了短乳杆菌外，上述菌种的菌株在成熟酸面团中也有不同程度的发现。持久性发酵剂与旧金山乳杆菌的其他生物型以及混淆魏斯氏菌或植物乳杆菌有关。使用Biolog 96孔Eco微孔板对酸面团的酸化、发酵商、游离氨基酸和群落水平的分解代谢谱进行了表征。特别是，含有持久性发酵剂的酸面团的分解代谢谱表现相似，并且与其他酸面团明显不同。这3个持久性发酵剂进一步用于酸面团的生产，并使用另一种乳酸菌种群部分不同于前一种的小麦粉进行发酵。同样，在这种情况下，所有3种发酵剂菌株在发酵过程中都持续存在。
