Changes in Gene Expression during Adaptation of Listeria monocytogenes to the Soil Environment

Listeria monocytogenes is a ubiquitous opportunistic pathogen responsible for listeriosis. In order to study the processes underlying its ability to adapt to the soil environment, whole-genome arrays were used to analyse transcriptome modifications 15 minutes, 30 minutes and 18 h after inoculation of L. monocytogenes EGD-e in soil extracts. Growth was observed within the first day of incubation and large numbers were still detected in soil extract and soil microcosms one year after the start of the experiment. Major transcriptional reprofiling was observed. Nutrient acquisition mechanisms (phosphoenolpyruvate-dependent phosphotransferase systems and ABC transporters) and enzymes involved in catabolism of specific carbohydrates (β-glucosidases; chitinases) were prevalent. This is consistent with the overrepresentation of the CodY regulon that suggests that in a nutrient depleted environment, L. monocytogenes recruits its extensive repertoire of transporters to acquire a range of substrates for energy production.单核细胞增生李斯特菌（Listeria monocytogenes）是一种广泛存在的机会致病菌，可引发李斯特菌病（listeriosis）。为研究其适应土壤环境的分子机制，本研究采用全基因组阵列（whole-genome arrays），对土壤提取液中接种单核细胞增生李斯特菌EGD-e株后15分钟、30分钟及18小时的转录组变化进行分析。培养首日即可观察到菌体生长，且实验启动一年后，仍可在土壤提取液与土壤微宇宙（soil microcosms）中检测到大量活菌。研究观察到显著的转录重编程现象。营养获取机制（包括磷酸烯醇式丙酮酸依赖性磷酸转移酶系统（phosphoenolpyruvate-dependent phosphotransferase systems）与ATP结合盒转运蛋白（ABC transporters））以及参与特定碳水化合物分解代谢的酶类（β-葡萄糖苷酶（β-glucosidases）、几丁质酶（chitinases））占主导地位。这与CodY调节子（CodY regulon）的富集现象相一致，表明在营养匮乏的环境中，单核细胞增生李斯特菌会调动其全套转运蛋白，以获取多种底物用于能量产生。