Interactions between food-borne pathogens and protozoa isolated from lettuce and spinach
Interactions between food-borne pathogens and protozoa isolated from lettuce and spinach
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DOI：
10.1128/aem.02709-07
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发表时间：
2008-04-01
影响因子：
4.4
通讯作者：
Berk, Sharon G.
中科院分区：
文献类型：
--
作者：
Gourabathini, Poornima;Brandl, Maria T.;Berk, Sharon G.
最近发现，当细菌被隔离在四膜虫排出的食物液泡（囊泡）中时，肠道沙门氏菌的存活率会增加。由于新鲜农产品与肠道疾病的爆发越来越相关，本研究旨在确定菠菜和生菜上原生动物的流行情况，并检查它们与肠沙门氏菌、大肠杆菌 O157:117 和单核细胞增生李斯特氏菌的相互作用。青光眼属、Colpoda steinii 和巴勒斯坦棘阿米巴是从商店购买的菠菜和生菜中培养出来的，并用于我们的研究。先前从菠菜中分离出的梨形四膜虫菌株和土传四膜虫属 sp。也被使用。让洗涤后的原生动物吃绿色荧光蛋白或红色荧光蛋白标记的肠道病原体。观察到各种原生生物-肠道病原体组合之间的相互作用存在显着差异。青光眼所有细菌菌株均产生囊泡，但单核细胞增生利斯特氏菌在纤毛虫中产生的囊泡数量最少。在四膜虫放牧大肠杆菌 O157:117 和肠沙门氏菌期间也观察到了囊泡的产生，但在体外和叶子上放牧单核细胞增生利斯特氏菌期间没有观察到囊泡产生。所有囊泡均含有完整的荧光细菌。相比之下，斯坦氏梭菌和变形虫不会从任何肠道病原体中产生囊泡，病原体也不会被困在它们的包囊内。对排出囊泡中大肠杆菌 O157:117 命运的研究表明，添加菠菜提取物后 4 小时，细菌繁殖并逃离囊泡。叶类蔬菜上原生动物的存在及其在囊泡中对肠道细菌的隔离表明，它们可能在人类病原体对农产品的生态学中发挥着重要作用。
The survival of Salmonella enterica was recently shown to increase when the bacteria were sequestered in expelled food vacuoles (vesicles) of Tetrahymena. Because fresh produce is increasingly linked to outbreaks of enteric illness, the present investigation aimed to determine the prevalence of protozoa on spinach and lettuce and to examine their interactions with S. enterica, Escherichia coli O157:117, and Listeria monocytogenes. Glaucoma sp., Colpoda steinii, and Acanthamoeba palestinensis were cultured from store-bought spinach and lettuce and used in our study. A strain of Tetrahymena pyriformis previously isolated from spinach and a soil-borne Tetrahymena sp. were also used. Washed protozoa were allowed to graze on green fluorescent protein-or red fluorescent protein-labeled enteric pathogens. Significant differences in interactions among the various protist-enteric pathogen combinations were observed. Vesicles were produced by Glaucoma with all of the bacterial strains, although L. monocytogenes resulted in the smallest number per ciliate. Vesicle production was observed also during grazing of Tetrahymena on E. coli O157:117 and S. enterica but not during grazing on L. monocytogenes, in vitro and on leaves. All vesicles contained intact fluorescing bacteria. In contrast, C. steinii and the amoeba did not produce vesicles from any of the enteric pathogens, nor were pathogens trapped within their cysts. Studies of the fate of E. coli O157:117 in expelled vesicles revealed that by 4 It after addition of spinach extract, the bacteria multiplied and escaped the vesicles. The presence of protozoa on leafy vegetables and their sequestration of enteric bacteria in vesicles indicate that they may play an important role in the ecology of human pathogens on produce.