Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Appl Environ Microbiol. 2013 Oct;79(20):6407-13. doi: 10.1128/AEM.01915-13. Epub 2013 Aug 9.
Free-living protozoa play an important role in the ecology and epidemiology of human-pathogenic bacteria. In the present study, the interaction between Yersinia enterocolitica, an important food-borne pathogen, and the free-living amoeba Acanthamoeba castellanii was studied. Several cocultivation assays were set up to assess the resistance of Y. enterocolitica to A. castellanii predation and the impact of environmental factors and bacterial strain-specific characteristics. Results showed that all Y. enterocolitica strains persist in association with A. castellanii for at least 14 days, and associations with A. castellanii enhanced survival of Yersinia under nutrient-rich conditions at 25°C and under nutrient-poor conditions at 37°C. Amoebae cultivated in the supernatant of one Yersinia strain showed temperature- and time-dependent permeabilization. Intraprotozoan survival of Y. enterocolitica depended on nutrient availability and temperature, with up to 2.8 log CFU/ml bacteria displaying intracellular survival at 7°C for at least 4 days in nutrient-rich medium. Transmission electron microscopy was performed to locate the Yersinia cells inside the amoebae. As Yersinia and Acanthamoeba share similar ecological niches, this interaction identifies a role of free-living protozoa in the ecology and epidemiology of Y. enterocolitica.
自由生活的原生动物在人类致病菌的生态学和流行病学中起着重要作用。在本研究中，研究了重要的食源性病原体耶尔森氏菌与自由生活的变形虫棘阿米巴之间的相互作用。设置了几种共培养实验来评估耶尔森氏菌对棘阿米巴捕食的抵抗力以及环境因素和细菌株特异性特征的影响。结果表明，所有的耶尔森氏菌菌株都至少与棘阿米巴共生 14 天，并且与棘阿米巴的共生关系增强了在 25°C 下营养丰富条件下和在 37°C 下营养缺乏条件下生存的耶尔森氏菌的生存能力。在一种耶尔森氏菌菌株的上清液中培养的变形虫表现出温度和时间依赖性的通透性。肠耶尔森氏菌在原生动物体内的存活取决于营养物质的可用性和温度，在营养丰富的培养基中，在 7°C 下至少有 4 天，多达 2.8 log CFU/ml 的细菌可在细胞内存活。进行了透射电子显微镜检查以定位在变形虫内的耶尔森氏菌细胞。由于耶尔森氏菌和棘阿米巴具有相似的生态位，这种相互作用确定了自由生活的原生动物在肠耶尔森氏菌的生态学和流行病学中的作用。
