High pressure processing (HPP; i.e. 100–600 MPa pressure depending on product) is a non-thermal preservation technique adopted by the food industry to decrease significantly foodborne pathogens, including Listeria monocytogenes, from food. However, susceptibility towards pressure differs among diverse strains of L. monocytogenes and it is unclear if this is due to their intrinsic characteristics related to genomic content. Here, we tested the barotolerance of 10 different L. monocytogenes strains, from food and food processing environments and widely used reference strains including clinical isolate, to pressure treatments with 400 and 600 MPa. Genome sequencing and genome comparison of the tested L. monocytogenes strains were performed to investigate the relation between genomic profile and pressure tolerance. None of the tested strains were tolerant to 600 MPa. A reduction of more than 5 log10 was observed for all strains after 1 min 600 MPa pressure treatment. L. monocytogenes strain RO15 showed no significant reduction in viable cell counts after 400 MPa for 1 min and was therefore defined as barotolerant. Genome analysis of so far unsequenced L. monocytogenes strain RO15, 2HF33, MB5, AB199, AB120, C7, and RO4 allowed us to compare the gene content of all strains tested. This revealed that the three most pressure tolerant strains had more than one CRISPR system with self-targeting spacers. Furthermore, several anti-CRISPR genes were detected in these strains. Pan-genome analysis showed that 10 prophage genes were significantly associated with the three most barotolerant strains. L. monocytogenes strain RO15 was the most pressure tolerant among the selected strains. Genome comparison suggests that there might be a relationship between prophages and pressure tolerance in L. monocytogenes.

中文翻译：

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与用于评估食品高压加工的参考菌株相比，最耐单核细胞增生性李斯特菌RO15菌株的基因组表征。

高压加工（HPP；即取决于产品的100-600 MPa压力）是食品工业采用的一种非保温技术，可从食品中大量减少食源性病原体，包括单核细胞增生李斯特菌。然而，对单核细胞增生李斯特氏菌的不同菌株之间对压力的敏感性不同，尚不清楚这是否是由于它们与基因组含量有关的内在特性。在这里，我们测试了10种不同的单核细胞增生李斯特氏菌菌株的耐压性，这些菌株从食品和食品加工环境以及广泛使用的参考菌株（包括临床分离株）到400和600 MPa的压力处理。进行了测试的单核细胞增生李斯特氏菌菌株的基因组测序和基因组比较，以研究基因组图谱与耐压性之间的关系。所测试的菌株均不耐受600MPa。在600 MPa压力处理1分钟后，所有应变均降低了5 log10以上。单核细胞增生李斯特氏菌菌株RO15在400 MPa处理1分钟后未显示活细胞计数的显着减少，因此被定义为耐压性。迄今为止未测序的单核细胞增生李斯特菌菌株RO15、2HF33，MB5，AB199，AB120，C7和RO4的基因组分析使我们能够比较所有测试菌株的基因含量。这揭示了三个最耐压力的菌株具有不止一个具有自靶向间隔子的CRISPR系统。此外，在这些菌株中检测到了几种抗CRISPR基因。泛基因组分析表明，10个噬菌体基因与三种最耐高压的菌株显着相关。L. 在所选菌株中，单核细胞增生李斯特菌RO15的耐压性最高。基因组比较表明，单核细胞增生李斯特氏菌的原噬菌体和压力耐受性之间可能存在关系。