Müller Volker, Oren Aharon
Section Microbiology, Department Biology I, LMU München, Maria-Ward-Strasse 1a, 80638 München, Germany.
Extremophiles. 2003 Aug;7(4):261-6. doi: 10.1007/s00792-003-0332-9. Epub 2003 May 1.
While much understanding has been achieved on the intracellular sodium and potassium concentrations of halophilic and halotolerant microorganisms and on their regulation, we know little on the metabolism of anions. Archaea of the family Halobacteriaceae contain molar concentrations of chloride, which is pumped into the cells by cotransport with sodium ions and/or using the light-driven primary chloride pump halorhodopsin. Most halophilic and halotolerant representatives of the bacterial domain contain low intracellular ion concentrations, with organic osmotic solutes providing osmotic balance. However, some species show a specific requirement for chloride. In Halobacillus halophilus certain functions, such as growth, endospore germination, motility and flagellar synthesis, and glycine betaine transport are chloride dependent. In this organism the expression of a large number of proteins is chloride regulated. Other moderately halophilic Bacteria such as Halomonas elongata do not show a specific demand for chloride. A very high requirement for chloride was demonstrated in two groups of Bacteria that accumulate inorganic salts intracellularly rather than using organic osmotic solutes: the anaerobic Halanaerobiales and the aerobic extremely halophilic Salinibacter ruber. It is thus becoming increasingly clear that chloride has specific functions in haloadaptation in different groups of halophilic microorganisms.
虽然我们对嗜盐和耐盐微生物细胞内的钠和钾浓度及其调节机制已经有了很多了解，但对于阴离子的代谢却知之甚少。盐杆菌科的古菌含有摩尔浓度的氯化物，它通过与钠离子共转运和/或利用光驱动的初级氯化物泵视紫红质被泵入细胞。细菌域中的大多数嗜盐和耐盐代表菌细胞内离子浓度较低，并利用有机渗透溶质来维持渗透平衡。然而，一些物种对氯化物有特定需求。在嗜盐嗜碱芽孢杆菌中，某些功能，如生长、芽孢萌发、运动性和鞭毛合成以及甘氨酸甜菜碱转运都依赖于氯化物。在这种生物体中，大量蛋白质的表达受氯化物调节。其他中度嗜盐细菌，如伸长盐单胞菌，对氯化物没有特定需求。在两组通过在细胞内积累无机盐而非利用有机渗透溶质来适应高盐环境的细菌中，即厌氧的嗜盐厌氧菌和需氧的极端嗜盐红杆菌，对氯化物的需求非常高。因此，越来越清楚的是，氯化物在不同嗜盐微生物群体的嗜盐适应中具有特定功能。
