Laboratorio de Genética y Biología Molecular, CERELA-CONICET, Centro de Referencia para Lactobacilos, Chacabuco 145, San Miguel de Tucumán T4000ILC, Tucumán, Argentina.
Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels, Belgium.
Int J Food Microbiol. 2020 Dec 16;335:108894. doi: 10.1016/j.ijfoodmicro.2020.108894. Epub 2020 Sep 29.
A metagenome-based approach was used to assess the taxonomic affiliation and functional potential for bacteriocin production of the bacterial community in cow's milk artisanal cheeses from Northwestern Argentina. Three different samples were analyzed by high-throughput sequencing of the V4 region of the 16S rRNA gene and shotgun metagenomics. Taxonomic analysis showed that cheese A and C were quite similar whereas cheese B displayed a rather different bacterial composition. Overall, two families, Streptococceae and Enterococceae, dominated the artisanal cheese microbiota, being the former family prevalent in cheese B and the later family the most important in samples A and C. Besides the usual species associated to cheeses, a number of bacterial taxa that have not been previously found in Argentinean artisanal cheeses were reported in the present work such as Macrococcus caseolyticus and Streptococcus macedonicus Functional metagenomics analysis using the bacteriocin mining software BAGEL3, identified 2 ORFs encoding antimicrobial peptides in cheese B and 42 different peptides in sample C. The bacteriocin genes found showed good correlation with taxonomy. Based on the microbial diversity and functional features found through shotgun metagenomic sequencing, a culture-dependent approach was applied aiming to isolate bacteriocin-producing bacteria able to inhibit the growth of the foodborne pathogen Listeria monocytogenes. From 151 bacterial colonies derived from the cheese samples, 10 were associated to high anti-Listeria activity. Based on partial 16S rRNA gene sequencing and RAPD-PCR analysis, all bacteriocinogenic isolates were identified as Enterococcus faecium. Finally, we carried out a pilot experiment with L. monocytogenes-contaminated cheese using one of the enterococcal isolates as a bioprotective adjunct culture. The use of E. faecium CRL1879 during artisanal cheese manufacturing did not alter the main organoleptic properties of the cheese and ensured an efficient control of the foodborne pathogen up to 30 days. This finding supports the use of E. faecium CRL1879 as an adjunct culture in the cheese-making process with a combination of both safety and minimal processing.
采用基于宏基因组学的方法，评估了来自阿根廷西北部的传统奶酪中细菌群落的分类隶属关系和细菌素生产的功能潜力。通过高通量测序分析 V4 区 16S rRNA 基因和鸟枪法宏基因组学对三个不同的样本进行了分析。分类分析表明，奶酪 A 和 C 非常相似，而奶酪 B 则显示出相当不同的细菌组成。总体而言，乳球菌科和肠球菌科两个家族主导了传统奶酪微生物群，前者在奶酪 B 中占优势，后者在样本 A 和 C 中最为重要。除了与奶酪相关的常见物种外，本研究还报道了一些以前未在阿根廷传统奶酪中发现的细菌类群，如 Macrococcus caseolyticus 和 Streptococcus macedonicus。使用细菌素挖掘软件 BAGEL3 进行功能宏基因组学分析，鉴定出在奶酪 B 中编码抗菌肽的 2 个 ORF 和在样本 C 中鉴定出 42 个不同的肽。发现的细菌素基因与分类学具有良好的相关性。基于通过鸟枪法宏基因组测序获得的微生物多样性和功能特征，应用了一种依赖培养的方法，旨在分离能够抑制食源性病原体单核细胞增生李斯特菌生长的产细菌素细菌。从奶酪样本中分离出的 151 个细菌菌落中，有 10 个与高抗李斯特菌活性相关。基于部分 16S rRNA 基因测序和 RAPD-PCR 分析，所有产细菌素的分离株均被鉴定为屎肠球菌。最后，我们使用其中一个肠球菌分离株作为生物保护添加剂培养物，对受单核细胞增生李斯特菌污染的奶酪进行了初步试验。在传统奶酪生产过程中使用屎肠球菌 CRL1879 不会改变奶酪的主要感官特性，并能有效控制食源性病原体长达 30 天。这一发现支持在奶酪生产过程中使用屎肠球菌 CRL1879 作为添加剂培养物，结合安全性和最小加工。
