Abstract：
Peanut-based products have been associated with Salmonella foodborne outbreaks and/or recalls worldwide. The ability of Salmonella to persist for a long time in a low moisture environment can contribute to this kind of contamination. The objective of this study was to analyse the genome of five S. enterica enterica strains isolated from the peanut supply chain in Brazil, as well as to identify genetic determinants for survival under desiccation and validate these findings by phenotypic test of desiccation stress. The strains were in silico serotyped using the platform SeqSero2 as Miami (M2851), Javiana (M2973), Oranienburg (M2976), Muenster (M624), and Glostrup/Chomedey (M7864); with phylogenomic analysis support. Based on Multilocus Sequence Typing (MLST) the strains were assigned to STs 140, 1674, 321, 174, and 2519. In addition, eight pathogenicity islands were found in all the genomes using the SPIFinder 2.0 (SPI-1, SPI-2, SPI-3, SPI-5, SPI-9, SPI-13, SPI-14). The absence of a SPI-4 may indicate a loss of this island in the surveyed genomes. For the pangenomic analysis, 49 S. enterica genomes were input into the Roary pipeline. The majority of the stress related genes were considered as soft-core genes and were located on the chromosome. A desiccation stress phenotypic test was performed in trypticase soy broth (TSB) with four different water activity (aw) values. M2976 and M7864, both isolated from the peanut samples with the lowest aw, showed the highest OD570nm in TSB aw 0.964 and were statistically different (p < 0.05) from the strain isolated from the peanut sample with the highest aw (0.997). In conclusion, genome analyses have revealed signatures of desiccation adaptation in Salmonella strains, but phenotypic analyses suggested the environment influences the adaptive ability of Salmonella to overcome desiccation stress.
摘要：
以花生为基础的产品与全球食源性沙门氏菌爆发和/或召回有关。沙门氏菌在低水分环境中长时间持续存在的能力可能导致这种污染。这项研究的目的是分析从巴西花生供应链中分离出的五种肠球菌菌株的基因组，以及确定在干燥下生存的遗传决定因素，并通过干燥胁迫的表型测试验证这些发现。使用平台SeqSero2作为迈阿密（M2851）对菌株进行了计算机血清分型，Javiana(M2973),奥兰宁堡(M2976),明斯特(M624),和Glostrup/Chomedey（M7864）；具有系统基因组分析支持。基于多位点序列分型(MLST),将菌株分配给ST140、1674、321、174和2519。此外,使用SPIFinder2.0在所有基因组中发现了八个致病性岛（SPI-1，SPI-2，SPI-3，SPI-5，SPI-9，SPI-13，SPI-14）。SPI-4的缺失可能表明该岛在所调查的基因组中丢失。对于全基因组分析，49个肠道基因组被输入到Roary管道中。大多数胁迫相关基因被认为是软核基因，位于染色体上。在具有四种不同水活度（aw）值的胰蛋白酶大豆肉汤（TSB）中进行干燥胁迫表型测试。M2976和M7864，均从aw最低的花生样品中分离出来，在TSBaw0.964中显示出最高的OD570nm，并且与从具有最高aw（0.997）的花生样品中分离的菌株有统计学差异（p<0.05）。总之,基因组分析揭示了沙门氏菌菌株的干燥适应特征，但是表型分析表明，环境会影响沙门氏菌克服干燥胁迫的适应能力。
