Monitoring L. helveticus strain dynamics in natural whey starters is of great interest at the industrial level due to the key role that this bacterial population plays in Grana Padano cheese production. In this study, we aimed to develop a PCR-denaturing gradient gel electrophoresis (PCR-DGGE) assay based on the slpH locus, in parallel with performing culture-dependent analysis of whey samples using optimized media to maximize the number of isolated strains. We designed new primers targeting the slpH locus to amplify a gene region that would be suitable for PCR-DGGE analysis and discriminating strains. Our results confirmed that the developed PCR-DGGE method was rapid and reliable for monitoring the L. helveticus population in whey starter cultures. All sequences of bands detected in the PCR-DGGE profiles from whey samples showed high similarity to S-layer genes of L. helveticus, and perfectly matched with the slpH locus sequences of dominant strains. Overall, our findings indicated that the target region of the slpH locus was sufficiently heterologous to discriminate L. helveticus strains, and that our PCR-DGGE analysis provided a more accurate picture of the population composition of whey starters compared to culture-dependent techniques that often fail to isolate the most abundant strains.

由于该细菌种群在Grana Padano奶酪生产中所起的关键作用，因此在工业水平上监测天然乳清发酵剂中的瑞士乳杆菌菌株动力学十分重要。在这项研究中，我们旨在开发基于sIpH位点的PCR变性梯度凝胶电泳（PCR-DGGE）分析，同时使用优化的培养基进行乳清样品的培养依赖性分析，以使分离菌株的数量最大化。我们设计了针对sIpH位点的新引物，以扩增适合PCR-DGGE分析和区分菌株的基因区域。我们的结果证实，开发的PCR-DGGE方法可快速可靠地监测瑞士乳杆菌。乳清发酵剂文化中的人口。带的所有序列中从乳清样品显示高相似性的S-层基因PCR-DGGE图谱检测瑞士乳杆菌，并且与完全匹配SLPH优势菌株的基因座序列。总体而言，我们的发现表明，slpH基因座的目标区域具有足够的异源性以区分瑞士乳杆菌菌株，并且与通常依赖于培养物的技术相比，我们的PCR-DGGE分析提供了更准确的乳清发酵剂种群组成图。无法分离出最丰富的菌株。