Univ. Bourgogne Franche-Comté, AgroSupDijon, PAM, UMR A 02.102, F-21000 Dijon, France.
Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
Int J Food Microbiol. 2017 May 2;248:82-89. doi: 10.1016/j.ijfoodmicro.2017.02.010. Epub 2017 Feb 21.
Listeria monocytogenes, a bacterium that is responsible for listeriosis, is a very diverse species. Desiccation resistance has been rarely studied in L. monocytogenes, although it is a stress that is largely encountered by this microorganism in food-processing environments and that could be managed to prevent its presence. The objective of this study was to evaluate the resistance of 30 L. monocytogenes strains to moderate desiccation (75% relative humidity) and evaluate the correlation of such resistance with the strains' virulence, serotype and genotype. The results showed a great heterogeneity of strains regarding their ability to survive (loss of cultivability between 0.4 and 2.0 log). Strains were classified into three groups according to desiccation resistance (sensitive, intermediate, or resistant), and the strain repartition was analyzed relative to serotype, virulence level and environmental origin of the strains. No correlation was found between isolate origin and desiccation resistance. All serotype 1/2b strains were classified into the group of resistant strains. Virulent and hypovirulent strains were distributed among the three groups of desiccation resistance. Finally, a genomic comparison was performed based on 31 genes that were previously identified as being involved in desiccation resistance. The presence of those genes was localized among the genomes of some strains and compared regarding strain-resistance levels. High nucleotide conservation was identified between resistant and desiccation-sensitive strains. In conclusion, the findings regarding the strains of serotype 1/2b indicate potential serotype-specific resistance to desiccation, and thus, to relative humidity fluctuations potentially encountered in food-related environments. The genomic comparison of 31 genes associated to desiccation tolerance did not reveal differences among four strains which have different level of resistance to desiccation.
单增李斯特菌是一种导致李斯特菌病的细菌，它是一个非常多样化的物种。尽管干燥耐受性是这种微生物在食品加工环境中主要面临的压力之一，可以通过管理来防止其存在，但在单增李斯特菌中，对其干燥耐受性的研究很少。本研究的目的是评估 30 株单增李斯特菌对中度干燥（相对湿度 75%）的抗性，并评估这种抗性与菌株的毒力、血清型和基因型的相关性。结果表明，菌株在存活能力方面存在很大的异质性（可培养性损失在 0.4 到 2.0 对数之间）。根据干燥耐受性，将菌株分为三组（敏感、中间或耐受），并根据血清型、毒力水平和菌株的环境来源分析菌株的分布情况。未发现分离株起源与干燥耐受性之间存在相关性。所有血清型 1/2b 菌株均被归类为抗性菌株。毒力和低毒力菌株分布在三组干燥耐受性菌株中。最后，根据先前确定的 31 个与干燥耐受性相关的基因进行基因组比较。这些基因的存在定位在一些菌株的基因组中，并根据菌株的抗性水平进行比较。在抗性和干燥敏感菌株之间发现了高核苷酸保守性。总之，关于血清型 1/2b 的菌株的发现表明其对干燥具有潜在的血清型特异性抗性，因此对食品相关环境中可能遇到的相对湿度波动具有抗性。对与干燥耐受性相关的 31 个基因的基因组比较未显示出对干燥具有不同抗性水平的四株菌株之间的差异。
