Direct Visualization of Nano-Spinning Process of Cellulose Produced by Acetobacter Xyliman

本文试图直接观察木醋杆菌生产纤维素的纳米纺丝过程。所得结果如下.通过视频显微镜系统观察了由活细菌产生的宽度约为50 nm的带状纤维素组装体的纳米纺丝过程。该系统由微分干涉显微镜、CCD摄像机、图像处理器、视频监视器和录像机组成。从粗糙菌落中测得的细菌的旋转速度为3.4 μm/min，而从光滑菌落中测得的细菌的旋转速度为2.4 μm/min，这种旋转速度的差异可能是两种菌落产生的纤维素的高级结构不同的原因之一.从木醋杆菌ATCC 23769中分离的光滑菌落在4 ℃下产生由许多股组成的密集和粗糙的带状纤维素组装体，而相同的菌落在28 ℃下产生带状组装体。在选区电子衍射（艾德）实验中，致密组装体给出了对应于纤维素II型晶体的结晶反射，而在相同的艾德条件下，粗糙组装体没有给出结晶反射.将未干燥的带组件在液态丙烷（-179 ℃）中快速淬火，并通过低温转移引入TEM柱中。我们尝试用低温TEM（在400 kV下操作的JEOL JEM-4000 SFX）拍摄带组件的图像。然而，包埋组件的玻璃冰太厚，电子束无法穿透样品。有必要尽量减少样品中的水含量。进一步调查仍在进行中。

In this paper we tried to directly observe nano-spinning process of cellulose produced by Acetobacter xylinum. The results obtained are as given below.1. Nano-spinning process of the ribbon-like cellulose assembly with a width of about 50 nm produced by a living bacterium was visualized by a video microscopy system. This system is composed of a differential interference contrast microscope, a CCD camera, an image processor, a video monitor, and a videocassette recorder. The spinning speed measured for a bacterium from rough colony was 3.4 μm/min, and that from smooth colony was 2.4 μm/min. This difference in spinning speed may be one of the reasons why high-order structures of cellulose produced by two types of colonies are different.2. Dense and coarse band-like cellulose assemblies which consist of many strands were produced at 4 ℃, using smooth colonies isolated from Acetobacter xylinum ATCC 23769, whereas ribbon assemblies were produced by the same colonies at 28 ℃. The dense assembly gave crystalline reflections corresponding to the cellulose II type crystal in the selected-area electron diffraction (ED) experiment, while the coarse assembly did not give crystalline reflections under the same ED condition.3. Never-dried ribbon assemblies were rapidly quenched in liquid propane (-179 ℃) and introduced into a TEM column by cryo-transfer. We tried to take images of ribbon assemblies with a cryo-TEM (JEOL JEM-4000SFX operated at 400kV). However, the vitreous ice embedding the assemblies was so thick that electron beams did not penetrate the samples. It is necessary to minimize the content of water in the samples. Further investigation is in progress.