Walker G M
Department of Molecular and Life Sciences, University of Abertay Dundee, Scotland.
Crit Rev Biotechnol. 1994;14(4):311-54. doi: 10.3109/07388559409063643.
This review highlights the important roles played by magnesium in the growth and metabolic functions of microbial and animal cells, and therefore assigns a key role for magnesium ions in biotechnology. The fundamental biochemical and physiological actions of magnesium as a regulatory cation are outlined. Such actions are deemed to be relevant in an applied sense, because Mg2+ availability in cell culture and fermentation media can dramatically influence growth and metabolism of cells. Manipulation of extracellular and intracellular magnesium ions can thus be envisaged as a relatively simplistic, but nevertheless versatile, means of physiological cell engineering. In addition, biological antagonism between calcium and magnesium at the molecular level may have profound consequences for the optimization of biotechnological processes that exploit cells. In fermentation, for example, it is argued that the efficiency of microbial conversion of substrate to product may be improved by altering Mg:Ca concentration ratios in industrial feedstocks in a way that makes more magnesium available to the cells. With particular respect to yeast-based biotechnologies, magnesium availability is seen as being crucially important in governing central pathways of carbohydrate catabolism, especially ethanolic fermentation. It is proposed that such influences of magnesium ions are expressed at the combined levels of key enzyme activation and cell membrane stabilization. The former ensures optimum flow of substrate to ethanol and the latter acts to protect yeasts from physical and chemical stress.
本综述强调了镁在微生物和动物细胞生长及代谢功能中所起的重要作用，因此赋予镁离子在生物技术中关键角色。概述了镁作为调节阳离子的基本生化和生理作用。这些作用在应用层面被认为是相关的，因为细胞培养和发酵培养基中镁离子的可利用性会显著影响细胞的生长和代谢。因此，对细胞外和细胞内镁离子的调控可被设想为一种相对简单但却通用的生理细胞工程手段。此外，钙和镁在分子水平上的生物拮抗作用可能对利用细胞的生物技术过程的优化产生深远影响。例如，在发酵过程中，有人认为通过改变工业原料中镁与钙的浓度比，使细胞能获得更多的镁，可提高微生物将底物转化为产物的效率。特别是对于基于酵母的生物技术，镁的可利用性在控制碳水化合物分解代谢的中心途径，尤其是乙醇发酵方面被视为至关重要。有人提出，镁离子的这种影响在关键酶激活和细胞膜稳定的综合层面得以体现。前者确保底物向乙醇的最佳流动，后者则起到保护酵母免受物理和化学应激的作用。
