Physicochemical Factors in Growth
Physicochemical Factors in Growth
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DOI：
10.1128/9781555817497.ch14
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
J. Breznak;R. N. Costilow
中科院分区：
文献类型：
--
作者：
J. Breznak;R. N. Costilow
影响微生物生长的一些理化因素受培养基成分（氢离子活度、水活度、渗透压和粘度）的控制。其他则受外部环境（温度、氧气、光、静水压力和磁场强度）的控制。本章讨论物理化学因素的应用和控制的实际方面。连续的pH控制可以通过自动添加酸或碱来实现。讨论了静水压力对细菌生理代谢的影响。许多假单胞菌和芽孢杆菌在低基质培养基中生长时也表现出嗜微气表型。氧化还原电位（Eh）为测量厌氧程度提供了一个有用的尺度。一些具有含磁小体的磁铁矿或灰长岩的活动细菌，例如，磁螺菌（以前的Aquaspirillum）磁致细菌，与地球的地磁场对齐，其强度约为1g，因此，它们表现出偏向游动的行为，并且有寻北和寻南两种形式。这种行为被称为趋磁性，并被认为在一定程度上帮助这些细菌（其中许多是微嗜气的）朝向溶解氧浓度低于地表水的水生沉积物。
Some physicochemical factors affecting microbial growth are controlled by the constituents of the culture medium (hydrogen ion activity, water activity, osmotic pressure, and viscosity). Others are controlled by the external environment (temperature, oxygen, light, hydrostatic pressure, and magnetic-field strength). This chapter addresses practical aspects of application and control of physicochemical factors. Continuous pH control may be achieved by the automatic addition of acid or base. The effects of hydrostatic pressure on the physiology and metabolism of bacteria are discussed. A number of Pseudomonas and Bacillus species also exhibit a microaerophilic phenotype when growing in low-substrate media. The oxidation-reduction (redox) potential (Eh ) provides a useful scale for measuring the degree of anaerobiosis. Some motile bacteria that possess magnetite- or greigite containing magnetosomes, e.g., Magnetospirillum (formerly Aquaspirillum) magnetotacticum, align with the Earth geomagnetic field, which has strength of about 1 G. As a consequence, they show a biased swimming behavior, and both north-seeking and south-seeking forms are known. This behavior has been termed magnetotaxis and is thought, in part, to help these bacteria (many of which are microaerophilic) orient toward aquatic sediments where dissolved-oxygen concentrations are lower than in surface waters.