Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Via Delpino 1, 80137 Napoli, Italy.
Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Via Delpino 1, 80137 Napoli, Italy.
Int J Food Microbiol. 2019 Feb 2;290:27-35. doi: 10.1016/j.ijfoodmicro.2018.09.025. Epub 2018 Oct 2.
Routine evaluation of bacterial contamination in minced pork is still mainly performed by the enumeration of indicator bacteria, including total aerobic colony count and E. coli, using standardized isolation methods. However, the bacterial community structure as well as the effect of the storage time and temperature on the aerobic plate count are largely unknown for this matrix. The aim of the study was to characterize the microbial community in minced pork by 16S rRNA amplicon sequencing compared to classical isolation methods combined with identification by Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF MS) and 16S rRNA gene sequencing. Analysis of 14 unrelated samples showed that total aerobic counts determined at 30 °C and 7 °C showed no significant difference, but the richness was higher on PCA at 30 °C for 7 samples, equal in 5, and higher at 7 °C for 2 samples. Members of the genus Pseudomonas, along with the genera Brochothrix and Carnobacterium were commonly identified among both the mesophilic and psychrotrophic population. Comparing to 16S rRNA amplicon sequencing, some contrasting data were obtained. Except for Brochothrix spp. and Pseudomonas spp., that were abundant and always detected, genera obtained with the two methods in the same sample were not always the same. Comparison of different sample preparation techniques and DNA extraction methods demonstrated also in this matrix that different results on the microbial composition and complexity are obtained. Present data illustrate that the combined isolation and identification of isolates using MALDI TOF MS and 16S gene sequencing and overall community profiling using 16S rRNA amplicon sequencing provides complementary results and yields important insights into the complex relationship between microorganisms in a food.
常规评估绞碎猪肉中的细菌污染仍然主要通过指示菌的计数来进行，包括使用标准化分离方法的总需氧菌落计数和大肠杆菌。然而，对于这种基质，细菌群落结构以及储存时间和温度对需氧平板计数的影响在很大程度上是未知的。本研究的目的是通过 16S rRNA 扩增子测序对绞碎猪肉中的微生物群落进行表征，与结合 MALDI TOF MS 鉴定的经典分离方法和 16S rRNA 基因测序进行比较。对 14 个无关样本的分析表明，在 30°C 和 7°C 下确定的总需氧计数没有显著差异，但在 PCA 上，7 个样本在 30°C 时的丰富度更高，5 个样本相等，2 个样本在 7°C 时更高。假单胞菌属的成员，以及 Br ochothrix 和 Carnobacterium 属，在嗜温和嗜冷种群中都被普遍鉴定出来。与 16S rRNA 扩增子测序相比，得到了一些对比数据。除了丰度高且始终检测到的 Br ochothrix spp. 和 Pseudomonas spp. 之外，用两种方法在同一样本中获得的属并不总是相同的。对不同的样品制备技术和 DNA 提取方法的比较也表明，在这种基质中，微生物组成和复杂性的结果不同。目前的数据表明，使用 MALDI TOF MS 和 16S 基因测序对分离物进行联合分离和鉴定，以及使用 16S rRNA 扩增子测序对整个群落进行分析，提供了互补的结果，并对食品中微生物之间的复杂关系有了重要的了解。
