嗜盐紫色硫细菌283-1的耐盐机制

Osmotolerant Mechanism of a Halophilic Purple Sulfur Bacterium 283-1

菌株283-1是一株中度嗜盐紫色硫细菌,对其耐盐特性和机理进行了初步研究。结果表明,菌株283-1在改良的Pfennig紫色硫细菌培养基中最大能耐受2.3mol·L-1 NaCl,其生长对Na+有专一依赖性,对Cl-依赖性较弱;它主要通过在胞内积累相容性溶质甜菜碱来对抗胞外渗透压力,胞内甜菜碱的含量随培养基中NaCl浓度增加而增加,2.0mol·L-1 NaCl时浓度可达到156.4mg·g-1干重。外源添加甜菜碱可以明显提高该菌株耐盐生长的能力。

Purple sulfur bacterium 283-1 was a moderate halophilic photosynthetic purple sulfur bacterium and its os- motolerant property and mechanism were studied. The results showed that strain 283-1 could maximally tolerate 2. 3 mol · L-1 NaCl in improved Pfennig purple sulfur bacterium medium. The growth of 283-1 specifically depended on an- ion Na＋ and anion C1- was more suitable provide intracellular osmotic pressure than anion Br-. 283-1 accumulated be taine to equilibrate extracellulary osmotic pressure. While betaine, which was most important compatible solutes, in- creased with increasing of the NaCI concentration, reaching 156.4 mg·g-1 by dry weight under a 2.0 mol · L-1 NaCl concentration. Exogenous betaine was sufficient to promote the growth of 283-1 under high salinities and enhance its salinity tolerance.