Kets E P, Galinski E A, de Wit M, de Bont J A, Heipieper H J
Division of Industrial Microbiology, Department of Food Science, Wageningen Agricultural University, The Netherlands.
J Bacteriol. 1996 Dec;178(23):6665-70. doi: 10.1128/jb.178.23.6665-6670.1996.
The aim of this study was to identify the compatible solutes accumulated by Pseudomonas putida S12 subjected to osmotic stress. In response to reduced water activity, P. putida S12 accumulated Nalpha-acetylglutaminylglutamine amide (NAGGN) simultaneously with a novel compatible solute identified as mannitol (using 13C- and 1H-nuclear magnetic resonance, liquid chromatography-mass spectroscopy and high-performance liquid chromatography methods) to maximum concentrations of 74 and 258 micromol g (dry weight) of cells(-1), respectively. The intracellular amounts of each solute varied with both the type and amount of osmolyte applied to induce osmotic stress in the medium. Both solutes were synthesized de novo. Addition of betaine to the medium resulted in accumulation of this compound and depletion of both NAGGN and mannitol. Mannitol and NAGGN were accumulated when sucrose instead of salts was used to reduce the medium water activity. Furthermore, both compatible solutes were accumulated when glucose was substituted by other carbon sources. However, the intracellular quantities of mannitol decreased when fructose, succinate, or lactate were applied as a carbon source. Mannitol was also raised to high intracellular concentrations by other salt-stressed Pseudomonas putida strains. This is the first study demonstrating a principal role for the de novo-synthesized polyol mannitol in osmoadaptation of a heterotrophic eubacterium.
本研究的目的是确定恶臭假单胞菌S12在渗透胁迫下积累的相容性溶质。为响应水分活度降低，恶臭假单胞菌S12积累了Nα-乙酰谷氨酰胺基谷氨酰胺酰胺（NAGGN），同时还积累了一种鉴定为甘露醇的新型相容性溶质（使用13C和1H核磁共振、液相色谱-质谱和高效液相色谱方法），细胞（干重）中最大浓度分别为74和258 μmol g（-1）。每种溶质的细胞内含量随用于在培养基中诱导渗透胁迫的渗透剂类型和用量而变化。两种溶质均从头合成。向培养基中添加甜菜碱导致该化合物积累，同时NAGGN和甘露醇减少。当使用蔗糖而非盐来降低培养基水分活度时，甘露醇和NAGGN会积累。此外，当葡萄糖被其他碳源替代时，两种相容性溶质都会积累。然而，当使用果糖、琥珀酸盐或乳酸盐作为碳源时，细胞内甘露醇的量会减少。其他盐胁迫的恶臭假单胞菌菌株也会将甘露醇提高到较高的细胞内浓度。这是第一项证明从头合成的多元醇甘露醇在异养真细菌渗透适应中起主要作用的研究。
