我們研究趨磁螺菌 AMB-1局限在 100微米厚的空間內的運動，細菌濃度約為每立方厘米 10⁹個。整個過程以一台安裝在顯微鏡上的攝像機，以暗場摸式觀察及拍攝。在地球磁場下，我們可以觀察到細菌聚集成環紋，並開始擴大。擴大的初始速度與細菌的游泳速度接近。半小時後，環紋擴大至離液滴邊緣毫米左右，然後停止擴大。環寬約 130微米，比大腸桿菌的趨化環結構小 100倍。我們對這個現象作出了一系列的實驗，研究其特性。 / 我們測試了不同化學成份的實驗緩衝液對環紋的影響。發現當緩衝液缺少琥珀酸時，環紋不會出現；另一方面，當使用琥珀酸作為緩衝液的唯一化學成份時，環紋能清楚地被觀測。這表明琥珀酸是環紋形成的關鍵成份。 / 實驗環境的氧氣含量能按不同比例混合氮和氧來控制。當環境改變為純氮時，環紋進一步擴大；當環境氧氣含量提高時，環紋縮小。實驗結果與微好氧細菌的特性相同。 / 在施加外加的磁場後，環紋被拉成長橢球形，證明細菌的擴散在環紋的形中有重要的作用。在更大的外加磁場下（ 0.3mT，十倍地球磁場），細胞聚集在液滴的兩端，隨後在這些位置長出環紋。該現象證明了環紋會在高細菌濃度的條件下形成， AMB-1有可能存在群體感應機制。 / We study the motion of Magnetospirillum magneticum strain AMB-1 in solution of concentration around 10⁹ cells cm⁻³, which was conned between two glasses with separation 100 μm. The motion was imaged with a EMCCD camera attached to a microscope in darkeld mode and growing ring pattern was observed. Under the earth magnetic eld, the ring migrated under the velocity close to the bacteria swimming velocity. After about half an hour, the ring had expanded to around 1 mm from the edge of droplet. The ring width is about 130 μm, which is 2 orders of magnitude smaller than that of similar ring structure found in E. Coli. A series of experiments were conducted to study the properties of such ring. / In studying the chemical composition of the buffer uid, different compositions were tested. No ring was obseved when succinic acid was absent; on the other hand, ring pattern was observed when using succinic acid alone as a buffer, which suggests that succinic acid is one of the key components of ring formation. / Oxygen level was controlled by mixing nitrogen and oxygen in dierent ratios. Ring further expanded to the edge of droplet when pure nitrogen was pumped in; and shrank when oxygen level was high. The results are consistent with the property of micro-aerophilic band in all micro-aerophilic bacteria. / With an applied magnetic eld, the swarm ring elongated to ellip¬soidal shape, which suggests that the diusion of bacteria plays an important role in the formation of ring. Under even larger magnetic eld (10 times earth magnetic eld), cells aggregated at opposite ends of the droplet, and rings formed at these positions afterwards, which suggests that ring grows at high cell concentrations. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Siu Kit = 趨磁螺菌AMB-1的環紋觀測 / 陳兆傑. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 48-50). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Chan, Siu Kit = Qu ci luo jun AMB-1 de huan wen guan ce / Chen Zhaojie. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- History --- p.1 / Chapter 1.2 --- General Properties of MTB --- p.1 / Chapter 1.2.1 --- Microaerophilic --- p.2 / Chapter 1.2.2 --- Magnetotaxis and Magnetosome --- p.2 / Chapter 1.3 --- Motivation --- p.6 / Chapter 1.3.1 --- Observation of Ring Pattern --- p.6 / Chapter 2 --- Experimental Setup --- p.8 / Chapter 2.1 --- Cell Culturing --- p.8 / Chapter 2.1.1 --- Incubation --- p.9 / Chapter 2.1.2 --- Culture Characterization --- p.11 / Chapter 2.1.3 --- Storage --- p.11 / Chapter 2.1.4 --- Strain Maintenance --- p.11 / Chapter 2.2 --- Bacteria Tracking --- p.14 / Chapter 2.2.1 --- Darkfield microscopy --- p.14 / Chapter 2.2.2 --- Concentration Measurement --- p.17 / Chapter 2.2.3 --- Darkfield image and cell density --- p.18 / Chapter 2.3 --- Design of Experiment --- p.19 / Chapter 2.3.1 --- Magnetic Field --- p.19 / Chapter 2.3.2 --- Chemicals --- p.20 / Chapter 2.3.3 --- Air Chamber --- p.20 / Chapter 3 --- Experimental Result and Analysis --- p.22 / Chapter 3.1 --- Ring properties --- p.22 / Chapter 3.2 --- Chemotactic Property --- p.24 / Chapter 3.3 --- Oxygen Concentration Control --- p.27 / Chapter 3.3.1 --- Micro-aerophilic property --- p.27 / Chapter 3.4 --- Response to Magnetic Field --- p.28 / Chapter 3.4.1 --- Ring under constant magnetic field --- p.32 / Chapter 3.4.2 --- Analysis on the change of shape --- p.35 / Chapter 4 --- Conclusion and Discussion --- p.41 / Chapter 4.1 --- Discussion --- p.41 / Chapter 4.1.1 --- Formation of ring --- p.41 / Chapter 4.1.2 --- Band Property --- p.43 / Chapter 4.2 --- Suggested Focus --- p.44 / Chapter A --- MSGM Content --- p.45 / Chapter B --- Shrinking of Ring --- p.47 / Bibliography --- p.48
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328293 |
| Date | January 2012 |
| Contributors | Chan, Siu Kit., Chinese University of Hong Kong Graduate School. Division of Physics. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (viii, 50 leaves) : ill. (some col.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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