Comparison of microbial communities in marinated and unmainated broiler meat by metagenomics. Microbial metagenomics in broiler meat

Most raw poultry sold in Finland at the retail level is mixed with marinades containing oil, sugar, spices and acetic acid and packaged under modified atmosphere. Growth of Leuconostoc spp. has been observed to cause premature spoilage of marinated broiler meat packages. In this study we investigated whether marinating enriched Leuconostoc spp. in meat microbiota. To obtain a complete view of the microbiota, we sequenced total DNA and 16S rRNA gene amplicons from the microbial communities. In addition, the lactic acid bacterial communities were characterized by identification of colonies. The results showed that marinade increased the proportions of the spoilage-associated Leuconostoc gasicomitatum in the communities as well as the proportions of L. gelidum and Lactobacillus spp.. The proportions of Carnobacterium, Vagococcus, Brochothrix thrermosphacta, Clostridium, Enterobacteriaceae and Vibrio were diminished. Analysis of 16S rRNA gene amplicons resulted in 312 and 284 operational taxonomical units (dissimilarity 0.03) in unmarinated and marinated meat, respectively, indicating that the meat communities were more diverse than hitherto shown. A number of bacterial taxa that have not been associated with late shelf-life meat before were detected, including Vagococcus and Vibrio that belonged to the predominating part of the microbial community in unmarinated meat. According to the functional analysis of the metagenomes, both communities were characterized by high proportions (15.6% or 17.9%) of genes involved in carbohydrate metabolism.

芬兰零售市场销售的多数生鲜禽肉，均经添加含油脂、蔗糖、香辛料及乙酸的腌渍液处理，并采用气调包装（modified atmosphere）。明串珠菌属（Leuconostoc spp.）的生长已被证实会导致腌渍禽肉包装出现过早变质现象。本研究旨在探究腌渍处理是否会提升肉源微生物群落中明串珠菌属的丰度。为全面解析该微生物群落，我们对菌群总DNA及16S rRNA基因扩增子（16S rRNA gene amplicons）进行了测序分析；此外，通过菌落鉴定手段对乳酸菌群落进行了表征。研究结果显示，腌渍液提升了群落中与变质相关的食酸明串珠菌（Leuconostoc gasicomitatum）的相对丰度，同时也提高了冷明串珠菌（L. gelidum）及乳杆菌属（Lactobacillus spp.）的相对占比；而肉杆菌属（Carnobacterium）、漫游球菌属（Vagococcus）、热死环丝菌（Brochothrix thermosphacta）、梭菌属（Clostridium）、肠杆菌科（Enterobacteriaceae）及弧菌属（Vibrio）的相对占比则有所下降。对16S rRNA基因扩增子的分析显示，未腌渍组与腌渍组肉样中分别得到312个及284个操作分类单元（operational taxonomic unit, OTU，序列相似度阈值为0.03），表明肉源微生物群落的多样性较此前报道更为丰富。本研究还检测到多种此前未被关联至货架期后期肉品的细菌类群，其中漫游球菌属与弧菌属为未腌渍肉样中微生物群落的优势类群。宏基因组（metagenomes）功能分析结果显示，两组微生物群落均以参与碳水化合物代谢的基因占比偏高为特征，其占比分别为15.6%及17.9%。