Ercolini Danilo, Frisso Giulia, Mauriello Gianluigi, Salvatore Francesco, Coppola Salvatore
School of Biotechnological Sciences, Department of Food Science, University of Naples Federico II, via Università 100, Portici, Italy.
Int J Food Microbiol. 2008 May 31;124(2):164-70. doi: 10.1016/j.ijfoodmicro.2008.03.007. Epub 2008 Mar 27.
The microbial diversity of sixty-three Natural Whey Cultures (NWCs) for the manufacture of Caciocavallo Silano cheese PDO was studied. The NWCs were collected from different dairies covering the whole territory of PDO production including five different regions of southern Italy. The microbial species diversity was determined by direct DNA extraction from NWCs and Polymerase Chain Reaction (PCR) amplification of variable regions of the 16S rRNA gene followed by denaturing gradient gel electrophoresis (DGGE) and denaturing high performance liquid chromatography (DHPLC). DGGE and DHPLC fingerprinting yielded the same results in terms of number of bands/peaks and specific migration/retention time of the amplicons. The DHPLC technique was used in this study for the first time to assess a food-related mixed microbial community by a culture-independent approach and proved to be at least as effective as DGGE in profiling species diversity in NWCs. Cluster analysis of DGGE and DHPLC data revealed that the species-related groups of similarity were not dependent on the geographical origin of the NWCs. The presence of three groups of 10-14 NWCs at 100% of species similarity indicated that some species associations are very commonly occurring in the NWCs for Caciocavallo Silano cheese PDO. A RAPD-PCR analysis of the NWCs was also performed for the members of the above groups and it showed that, though characterized by the same species diversity, most of the identical NWCs included different biotypes. The sequences of DGGE bands and DHPLC peaks revealed the occurrence of mainly thermophilic lactic acid bacteria such as Lactobacillus delbrueckii, L. helveticus and Streptococcus thermophilus even though the mesophilic Lactococcus lactis also occurred in some NWCs. In conclusion, the results of this study indicate that the microbial diversity of NWCs used for the Caciocavallo Silano PDO cheese is not high, it is not dependent on the geographical origin and the same microbial species occur within the territory examined. The microbiota of fermented PDO products and its possible link with territory should be studied case by case in order to have useful evidences for the assessment of product quality and authenticity.
对用于生产法定产区（PDO）西拉诺卡乔卡瓦洛奶酪的63种天然乳清培养物（NWC）的微生物多样性进行了研究。这些NWC取自覆盖PDO生产整个区域的不同乳品厂，包括意大利南部的五个不同地区。通过直接从NWC中提取DNA以及对16S rRNA基因可变区进行聚合酶链反应（PCR）扩增，随后进行变性梯度凝胶电泳（DGGE）和变性高效液相色谱（DHPLC）来确定微生物物种多样性。就条带/峰的数量以及扩增子的特定迁移/保留时间而言，DGGE和DHPLC指纹图谱产生了相同的结果。本研究首次使用DHPLC技术通过非培养方法评估与食品相关的混合微生物群落，并且证明在分析NWC中的物种多样性方面至少与DGGE一样有效。对DGGE和DHPLC数据的聚类分析表明，相似性的物种相关组不依赖于NWC的地理来源。在100%物种相似性水平下存在三组10 - 14个NWC，这表明某些物种组合在用于西拉诺卡乔卡瓦洛奶酪PDO的NWC中非常常见。还对上述组的成员进行了NWC的随机扩增多态性DNA - PCR（RAPD - PCR）分析，结果表明，尽管具有相同的物种多样性，但大多数相同的NWC包含不同的生物型。DGGE条带和DHPLC峰的序列显示，主要存在嗜热乳酸菌，如德氏乳杆菌、瑞士乳杆菌和嗜热链球菌，尽管在一些NWC中也存在嗜温的乳酸乳球菌。总之，本研究结果表明，用于西拉诺卡乔卡瓦洛PDO奶酪的NWC的微生物多样性不高，不依赖于地理来源，并且在所研究的区域内存在相同的微生物物种。对于发酵的PDO产品的微生物群及其与产地的可能联系，应逐案进行研究，以便为评估产品质量和真实性提供有用的证据。
