哈氏噬纤维菌生活史中形态的变化

Morphologic changes in the life cycle of Cytophaga hutchinsonii

摘要:

【目的】研究哈氏噬纤维菌Cytophaga hutchinsonii 在生活史中细胞形态的变化。【方法】利用光学显微镜、荧光显微镜和电子扫描显微镜对哈氏噬纤维菌生活状态进行详细观察。【结果】发现在饥饿状态下，长杆状菌体开始逐渐弯曲，菌体两端靠近成环形，环形菌体又进一步盘绕收缩成微小球形体，微小球形体在一定条件下能像生孢噬纤维菌的小孢囊一样萌发形成长杆状菌。另外还观察到哈氏噬纤维菌特殊的类核分裂现象。【结论】首次对哈氏噬纤维形成环形菌体和类似小孢囊的微小球形体的过程进行详细描述，为进一步揭示其形态变化与纤维素降解能力之间的关系提供依据。

Abstract:

[Objective] To study the morphological changes of Cytophaga hutchinsonii cell during its life circle. [Methods] Cytophaga hutchinsonii cell was observed under light microscope, fluorescence microscope and scanning electron microscope. The nucleoids in the cell were stained with fluorescent dye Hoechst33342 and examined by fluorescence microscopy. [Results] We discovered that under starvation conditions, the long, flexible rod cell of Cytophaga hutchinsonii would bend and turn into circular cell. The circular cell failed to produce carboxymethyl cellulase. Some of the circular cells might further wind around and turn into tiny spherical cells. The tiny spherical cell similar to the microcyst of sporocytophaga could germ into long flexible rods again under certain circumstances. When growing cultures to logarithmic phase of cell growth, Cytophaga hutchinsonii cell with three nucleoids in it was occasionally observed, which indicated that the two strands of DNA might act differently in the initiation of DNA replication. [Conclusion] This is the first detailed description of the formation process of circular cell and tiny spherical cell in the life circle of Cytophaga hutchinsonii. The result will help to further reveal the relation between morphologic change and cellulose degradation ability of the strain.