CHEMOTAXIS IN BACTERIA
CHEMOTAXIS IN BACTERIA
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DOI：
10.1126/science.153.3737.708
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发表时间：
1966-01-01
期刊：
影响因子：
56.9
通讯作者：
ADLER, J
中科院分区：
文献类型：
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作者：
ADLER, J
放置在含有能量源和O2的毛细管一端的运动大肠杆菌以1或2条带迁移到管中，这些带肉眼清晰可见，并且可以通过摄影、显微镜和光密度测定以及通过测定整个管中的细菌来证明。2条条带的形成不是由于细菌之间的异质性，因为每条条带中的细菌在重复使用时将形成2条以上的条带。如果可厌氧利用的能量源如半乳糖以超过O2的量存在，则第一条带消耗所有O2和一部分糖，而第二条带厌氧地使用残留的糖。如果O2过量存在于糖中，则第一条带氧化所有糖并留下未使用的O2，并且第二条带耗尽剩余的O2以氧化内源性能源。问题的本质是，细菌创造了一个氧气或能源的梯度，然后它们优先向化学物质浓度较高的方向移动。结果，细菌条带（或琼脂平板中的细菌环）形成并移出。结果表明，E.大肠杆菌对O2和能量源如半乳糖、葡萄糖、天冬氨酸、苏氨酸或丝氨酸具有趋化性。E.大肠杆菌的数量无疑比这个要多，一个更完整的列表还有待编制。这里报道的研究表明，趋化性允许细菌找到为它们提供最大能量供应的环境。对于细菌来说，能够进行趋化性显然是一个优势，因为通过这种方式，它们可以避免不利的条件并寻求最佳环境。最后，有必要承认Englemann，Pfeffer和其他19世纪后期发现细菌趋化性的生物学家的开创性工作，并指出，本文报道的研究充分证实了Beijerinck（4）和Sherris及其合作者（5，6）关于细菌对O2的趋化性条带的早期报道。通过使用化学成分确定的培养基而不是复杂的肉汤，可以更仔细地研究该条带，并另外证明细菌对能量源的趋化性的第二条带的出现。Beijerinck（4）确实，事实上，有时观察到第二带，但他没有提供解释。
Motile Escherichia coli placed at 1 end of a capillary tube containing an energy source and O2 migrate out into the tube in 1 or 2 bands, which are clearly visible to the naked eye and can be demonstrated by photography, microscopy and densitometry and by assaying for bacteria throughout the tube. The formation of 2 bands is not due to heterogeneity among the bacteria since the bacteria in each band will form 2 more bands when reused. If an anaerobically utilizable energy source such as galactose is present in excess over the O2, the first band consumes all the O2 and a part of the sugar and the 2nd band uses the residual sugar anaerobically. If O2 is present in excess over the sugar, the 1st band oxidizes all the sugar and leaves behind unused O2, and the 2nd band uses up the residual O2 to oxidize an endogenous energy source. The essence of the matter is that the bacteria create a gradient of O2 or of an energy source, and then they move preferentially in the direction of the higher concentration of the chemical. As a consequence, bands of bacteria (or rings of bacteria in the case of agar plates) form and move out. These results show that E. coli is chemotactic toward O2 and energy sources such as galactose, glucose, aspartic acid, threonine, or serine. The full repertoire of chemotactic responses by E. coli is no doubt greater than this, and a more complete list remains to be compiled. The studies reported here demonstrate the chemotaxis allows bacteria to find that environment which provides them with the greatest supply of energy. It is clearly an advantage for bacteria to be able to carry out chemotaxis, since by this means they can avoid unfavorable conditions and seek optimum surroundings Finally, it is necessary to acknowledge the pioneering work of Englemann, Pfeffer, and the other late-19th-century biologists who discovered chemotaxis in bacteria, and to point out that the studies reported here fully confirm the earlier reports of Beijerinck (4) and Sherris and his collaborators (5, 6) on a band of bacteria chemotactic toward O2. By using a chemically defined medium instead of a complex broth, it has been possible to study this band more closely and to demonstrate in addition the occurrence of a 2nd band of bacteria chemotactic toward an energy source. Beijerinck (4) did, in fact, sometimes observe a 2nd band, but he did not offer an explanation for it.