Delhalle L, Korsak N, Taminiau B, Nezer C, Burteau S, Delcenserie V, Poullet J B, Daube G
University of Lìege, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, Department of Food Science, Sart-Tilman, B43bis, 4000 Liege, Belgium; Quality Partner, Belgium, Rue Hayeneux 62, 4040 Herstal, Belgium.
University of Lìege, Fundamental and Applied Research for Animals & Health (FARAH), Faculty of Veterinary Medicine, Department of Food Science, Sart-Tilman, B43bis, 4000 Liege, Belgium.
J Food Prot. 2016 Feb;79(2):220-9. doi: 10.4315/0362-028X.JFP-15-185.
Steak tartare is a popular meat dish in Belgium. It is prepared with raw minced beef and is eaten with sauce, vegetables, and spices. Because it contains raw meat, steak tartare is highly prone to bacterial spoilage. The objective of this study was to explore the diversity of bacterial flora in steak tartare in Belgium according to the source and to determine which bacteria are able to grow during shelf life. A total of 58 samples from butchers' shops, restaurants, sandwich shops, and supermarkets were collected. These samples were analyzed using 16S rDNA metagenetics, a classical microbiological technique, and quantitative real-time PCR (qPCR) targeting the Lactobacillus genus. Samples were analyzed at the beginning and at the end of their shelf life, except for those from restaurants and sandwich shops, which were analyzed only on the purchase date. Metagenetic analysis identified up to 180 bacterial species and 90 genera in some samples. But only seven bacterial species were predominant in the samples, depending on the source: Brochothrix thermosphacta, Lactobacillus algidus, Lactococcus piscium, Leuconostoc gelidum, Photobacterium kishitani, Pseudomonas spp., and Xanthomonas oryzae. With this work, an alternative method is proposed to evaluate the total flora in food samples based on the number of reads from metagenetic analysis and the results of qPCR. The degree of underestimation of aerobic plate counts at 30°C estimated with the classical microbiology method was demonstrated in comparison with the proposed culture-independent method. Compared with culture-based methods, metagenetic analysis combined with qPCR targeting Lactobacillus provides valuable information for characterizing the bacterial flora of raw meat.
鞑靼牛排是比利时一种受欢迎的肉类菜肴。它由生牛肉末制成，搭配酱汁、蔬菜和香料食用。由于含有生肉，鞑靼牛排极易受到细菌腐败的影响。本研究的目的是根据来源探究比利时鞑靼牛排中细菌菌群的多样性，并确定哪些细菌能够在保质期内生长。总共从肉店、餐馆、三明治店和超市收集了58个样本。这些样本采用16S rDNA宏基因组学（一种经典的微生物技术）以及针对乳酸杆菌属的定量实时PCR（qPCR）进行分析。除了来自餐馆和三明治店的样本仅在购买日期进行分析外，其他样本在保质期开始和结束时进行分析。宏基因组分析在一些样本中鉴定出多达180种细菌和90个属。但根据来源不同，样本中只有7种细菌占主导地位：嗜热栖热放线菌、冷栖乳酸杆菌、鱼乳球菌、嗜冷明串珠菌、岸田发光杆菌、假单胞菌属和稻黄单胞菌。通过这项工作，提出了一种基于宏基因组分析读数数量和qPCR结果来评估食品样本中总菌群的替代方法。与所提出的非培养方法相比，证明了用经典微生物学方法估计的30°C需氧平板计数的低估程度。与基于培养的方法相比，宏基因组分析结合针对乳酸杆菌的qPCR为表征生肉中的细菌菌群提供了有价值的信息。
