Autolysis of Bacterial Cells Leads to Formation of Empty Sheaths by Leptothrix spp.
Autolysis of Bacterial Cells Leads to Formation of Empty Sheaths by Leptothrix spp.
复制标题
DOI：
10.3390/min3020247
复制
发表时间：
2013-06-01
期刊：
影响因子：
2.5
通讯作者：
Takada, Jun
中科院分区：
文献类型：
--
作者：
Suzuki, Tomoko;Ishihara, Hiromichi;Takada, Jun
水生的铁氧化细菌细螺旋体产生独特形状的细胞外鞘，由有机细菌聚合物和来自其水生环境的无机元素组成。在鞘形成的初始阶段，细菌细胞在鞘内排列，但后来大多数鞘变成空的。本研究通过钩螺旋体OUMS1分离株在人工培养基和天然地下水中培养，研究了鞘空化的机制。在培养基中放置3天后，大多数初始阶段的鞘围绕着一排活细胞，而这排细胞中的一些细胞无论在鞘中的位置如何都已死亡。在细胞和/或其残余物几乎无法通过差示干涉对比显微镜（DIC）区分的鞘中，重要染色剂和核酸特异性染色剂偶尔会显示死细胞和/或核酸残余物，而对这些试剂缺乏阳性反应的鞘在DIC下看起来是透明的。在培养基中培养7天的标本中，死细胞数量增加，与它们在鞘中的位置无关。在天然地下水中培养到第7天的标本也出现了几乎相同的现象。透射电镜（TEM）显示细胞退化，导致鞘内细菌细胞自溶。这些观察结果使我们得出结论，细菌细胞的自溶可能是鞘空化的主要原因。
The aquatic, Fe-oxidizing bacteria Leptothrix spp. produce uniquely shaped extracellular sheaths composed of organic bacterial polymers encrusted with inorganic elements from its aquatic environments. At the initial stage of sheath formation, bacterial cells were aligned in the sheath, but later most sheaths became empty. Here, we studied the mechanism of sheath hollowing by examining an isolate of Leptothrix sp. strain OUMS1 cultured in either artificial medium or natural groundwater. After 3 days in the medium, most sheaths at the initial stage surrounded a line of live cells, while some cells in the line were dead regardless of their position in a sheath. In sheaths where cells and/or their remnants were barely distinguishable by differential interference contrast microscopy (DIC), a vital stain and a stain specific for nucleic acids occasionally revealed dead cells and/or nucleic acid remnants, while sheaths that lacked a positive response to these reagents looked transparent when viewed with DIC. In specimens cultured in the medium for 7 days, dead cells increased in number regardless of their position in the sheath. Almost the same phenomena occurred in specimens cultured in natural groundwater until day 7. Transmission electron microscopy (TEM) showed that cells degenerated, leading to autolysis of bacterial cells in the sheath. These observations led us to conclude that autolysis of bacterial cells could be a major cause of sheath hollowing.