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

本文试图直接观察木醋酸菌产生的纤维素的纳米纺丝过程。得到的结果如下所示。利用视频显微镜系统对由活细菌产生的宽度约为50 nm的带状纤维集合体的纳米纺丝过程进行了可视化。该系统由差动干涉显微镜、CCD摄像机、图像处理器、视频监视器和盒式录像机组成。粗菌落测得的旋转速度为3.4min/μ，光滑菌落测得的旋转速度为2.4min/μ。这种纺丝速度的差异可能是两种类型的菌落产生的纤维素的高阶结构不同的原因之一。从木醋杆菌ATCC 23769分离的光滑菌落在4℃时产生致密而粗大的条带状纤维素组装体，而在28℃时同样的菌落产生带状集合体。在选区电子衍射(ED)实验中，致密的组装产生了与纤维素II型晶体相对应的结晶反射，而在相同的选区电子衍射条件下，粗组装没有得到结晶反射。未干燥的带状组件在液体丙烷(-179℃)中快速淬火，并通过低温转移引入TEM柱。我们试图用低温透射电子显微镜(JEOL JEM-4000SFX，工作电压为400千伏)拍摄带状组件的图像。然而，嵌入组件的玻璃冰太厚了，电子束无法穿透样品。有必要将样品中的水分含量降至最低。进一步的调查正在进行中。

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.