Osmotaxis in Escherichia coli.
Osmotaxis in Escherichia coli.
复制标题
大肠杆菌中的渗透性。
DOI：
10.1101/sqb.1988.053.01.005
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Kung,C
中科院分区：
文献类型：
--
作者：
Adler,J;Li,C;Boileau,AJ;Qi,Y;Kung,C
通过毛细管测定法测量渗透性。将在池塘中游动的细菌暴露于含有待测化学品的毛细管中（Adler 1973）。(The池和毛细管均含有0.01 MK §磷酸盐[pH 7.0]和0.0001 M EDTA，这是最佳运动性所需的。）在毛细管中，加入渗透剂核糖醇或蔗糖至0.8 M。这两种化学物质以前已被发现既不是引诱剂，也不是驱避剂。当在低于0.1 M的浓度下检测时，大肠杆菌（Adler et al. 1973; Tso and Adler 1974）。图1显示细菌寻求最佳渗透压，毛细管中约0.2 M化学品（较低浓度扩散出毛细管以在那里活跃）。当浓度高于0.2 M时，吸引力下降;这表明细菌避免如此高的浓度。当毛细管中只含有水时，细菌也会避开水（见图1）;这表明细菌会远离纯水。图1所示的吸引力似乎是由趋化性而不是趋化性引起的。这是通过在每种已知的化学感受器突变体中发现对核糖醇和蔗糖的野生型应答来确定的：tsr（MCPI-）菌株AW518、tar（MCPII-）菌株AW539、trg（MCPIII-）菌株AW701、tap（MCPIV-）菌株RP 3525和ptsl（酶I-）菌株AW509。
Osmotaxis measured by capillary assays. Bacteria swimming in a pond were exposed to capillaries containing the chemical to be tested (Adler 1973).(The pond and the capillary both contained 0.01 MK § phosphate [pH 7.0] and 0.0001 M EDTA, needed for optimum motility.) In the capillary, the osmotic agent, ribitol or sucrose, was added up to 0.8 M. Both of these chemicals had been found previously to be neither attractants nor repellents for E. coli when tested below 0.1 M (Adler et al. 1973; Tso and Adler 1974). Figure 1 shows that the bacteria seek an optimum osmolarity, about 0.2 M chemical in the capillary (lower concentrations diffuse out of the capillary to be active there.) At concentrations higher than 0.2 M, the attraction fell off; this suggests that the bacteria avoid such high concentrations. When the capillary contained only water, the bacteria also avoided it (see Fig. 1); this indicates osmotaxis away from pure water. The attraction shown in Figure 1 appears to result from osmotaxis, rather than from chemotaxis. This was determined by finding a wild-type response to ribitol and sucrose in each of the known chemoreceptor mutants: tsr (MCPI-) strain AW518, tar (MCPII-) strain AW539, trg (MCPIII-) strain AW701, tap (MCPIV-) strain RP3525 and ptsl (enzyme I-) strain AW509.