A hysteresis model for bacterial growth patterns
A hysteresis model for bacterial growth patterns
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细菌生长模式的滞后模型
DOI：
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发表时间：
1984
期刊：
影响因子：
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通讯作者：
C. Pöppe
中科院分区：
文献类型：
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作者：
F. Hoppensteadt;W. Jäger;C. Pöppe
几位科学家已经观察和研究了细菌培养物的生长模式。1978年，Hoppensteadt、Jager、Roth和Schmid在组氨酸营养缺陷型鼠伤寒沙门氏菌培养物中观察到环状结构。与化学沉淀中的Liesegang现象的经典实验类似，同心生长环的形成是对组氨酸从培养皿中心扩散到其边界的扩散前沿的响应。在细胞群生长模式的许多例子中，细胞是移动的;系统可以通过显示扩散不稳定性的反应扩散方程来建模（参见本卷中的论文[1]，[9]，[11]）。然而，在这种情况下，不可能观察到种群的流动性：细菌被固定在含有生长所需的所有化学物质的琼脂凝胶上，除了缺失的氨基酸。因此，空间相互作用仅由营养物的扩散和由作为细胞生长副产物产生的酸中和的缓冲液引起。在不假设pH值的生长抑制变化的情况下，不可能找到解释环结构的数学模型。这一假设在实验上是合理的。有些盐藻需要其他氨基酸来生长，例如脯氨酸或组氨酸和脯氨酸。在两种缺失物质和两个扩散中心的情况下，实验显示出透镜状的生长结构，这可以用相同的机制来解释。
Growth patterns in bacterial cultures have been observed and studied by several scientists. In 1978, Hoppensteadt, Jager, Roth and Schmid observed ring structures in cultures of histidine auxotrophic salmonella typhimurium. Similar to the classical experiment for Liesegang phenomena in chemical precipitation, concentrical growth rings are formed in response to a diffusing front of histidine spreading from the center of a Petri dish to its boundary. In many examples for growth patterns in cell populations the cells are mobile; the systems can be modelled by reaction diffusion equations showing diffusive instabilities (see e.g. the papers [1], [9], [11] in this volume). However, in this case it is impossible to observe mobility of the population: the bacteria are fixed on an agar gel containing all chemicals necessary for growth except the missing amino acid. Therefore, the spatial interaction is caused only by the diffusion of the nutrients and the buffer neutralized by acids produced as by-products of the cell growth. It has been impossible to find a mathematical model explaining the ring structures without assuming a growth inhibiting change of the pH-value. This assumption was justified experimentally. There are strains of salmonella needing other amino acids for growth, e.g. proline or histidine and proline. The experiments in case of two missing substances and two diffusion centers show lens shaped growth structures which can be explained by the same mechanisms.