Members of the Cytophaga-Flavobacterium-Bacteroides phylum as intracellular bacteria of acanthamoebae:: proposal of 'Candidatus Amoebophilus asiaticus'
Members of the Cytophaga-Flavobacterium-Bacteroides phylum as intracellular bacteria of acanthamoebae:: proposal of 'Candidatus Amoebophilus asiaticus'
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DOI：
10.1046/j.1462-2920.2001.00210.x
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发表时间：
2001-07-01
影响因子：
5.1
通讯作者：
Wagner, M
中科院分区：
文献类型：
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作者：
Horn, M;Harzenetter, MD;Wagner, M
在两种环境和一种临床棘阿米巴中发现了三种革兰氏阴性杆状细菌。对分离的菌株进行了分析。两种表现寄生行为的内生生物被成功地繁殖到它们的阿米巴宿主细胞外，随后通过16S rRNA序列比较分析，证实它们与琥珀黄杆菌(16S rRNA序列相似性为99%)或约翰氏黄杆菌(16S rRNA序列相似性为98%)最接近。有一种内生生物不能在其原始宿主棘阿米巴(Acanthamoeba sp.)外培养。TUMSJ-321)，也没有转入其他阿米巴。电子显微镜显示阿米巴滋养体和包囊几乎完全充满了这种内共生体的细胞，这些细胞被宿主衍生的膜所包围。根据16S rRNA序列分析，该内共生菌也可归属于细胞吞噬-黄杆菌-类杆菌(CFB)门，但与该系统发育类群中的任何已知物种没有密切联系(16S rRNA序列相似性低于82%)。通过应用荧光标记的16S rRNA靶向探针，确认了该内共生菌的身份和细胞内的定位。基于这些发现，我们建议将该专性棘阿米巴内共生菌归类为‘亚洲假丝酵母菌’。对亚洲假丝酵母菌寄主的18S rRNA序列的比较分析表明，它属于棘阿米巴18S rDNA序列类型T4型，构成了所有棘阿米巴分离物的大部分。
Three Gram-negative, rod-shaped bacteria that were found intracellularly in two environmental and one clinical Acanthamoeba sp. isolates were analysed. Two endocytobionts showing a parasitic behaviour were propagated successfully outside their amoebal host cells and were identified subsequently by comparative 16S rRNA sequence analysis as being most closely affiliated with Flavobacterium succinicans (99% 16S rRNA sequence similarity) or Flavobacterium johnsoniae (98% 16S rRNA sequence similarity). One endocytobiont could neither be cultivated outside its original Acanthamoeba host (Acanthamoeba sp. TUMSJ-321) nor transferred into other amoebae. Electron microscopy revealed that the amoebal trophozoites and cysts were almost completely filled with cells of this endosymbiont which are surrounded by a host-derived membrane. According to 16S rRNA sequence analysis, this endosymbiont could also be assigned to the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum, but was not closely affiliated to any recognized species within this phylogenetic group (less than 82% 16S rRNA sequence similarity). Identity and intracellular localization of this endosymbiont were confirmed by application of a specific fluorescently labelled 16S rRNA-targeted probe. Based on these findings, we propose classification of this obligate Acanthamoeba endosymbiont as 'Candidatus Amoebophilus asiaticus'. Comparative 18S rRNA sequence analysis of the host of 'Candidatus Amoebophilus asiaticus' revealed its membership with Acanthamoeba 18S rDNA sequence type T4 that comprises the majority of all Acanthamoeba isolates.