Welsh D T, Reed R H, Herbert R A
Department of Biological Sciences, University of Dundee, UK.
J Gen Microbiol. 1991 Apr;137(4):745-50. doi: 10.1099/00221287-137-4-745.
Natural abundance 13C nuclear magnetic resonance spectroscopy identified the disaccharide trehalose as the major organic osmolyte synthesized by Escherichia coli grown in continuous culture under nitrogen limitation in the presence of 0.5 M-NaCl. Trehalose accumulation was dependent on both the growth phase of the culture and the osmolality of the growth medium, but independent of the solute used to increase the osmolality as long as the solute was non-penetrant. The penetrant solute glycerol did not induce trehalose synthesis indicating that the loss of cell turgor rather than increasing medium osmolality per se was the mechanism stimulating trehalose synthesis. Under conditions of either carbon or nitrogen limitation osmoadaptation was distinctly biphasic. The initial response consisted of a rapid (within 30 min) accumulation of K+ and a concurrent synthesis of the amino acid glutamate; trehalose synthesis occurred during the second slower phase of osmoadaption. Chloramphenicol severely inhibited trehalose accumulation indicating that the enzyme(s) involved in trehalose synthesis were inducible.
天然丰度13C核磁共振光谱法鉴定出，海藻糖这种二糖是在0.5M氯化钠存在的情况下，于氮限制条件下连续培养的大肠杆菌合成的主要有机渗透溶质。海藻糖的积累既取决于培养物的生长阶段，也取决于生长培养基的渗透压，但只要溶质是非渗透性的，就与用于提高渗透压的溶质无关。渗透性溶质甘油不会诱导海藻糖合成，这表明细胞膨压的丧失而非培养基渗透压本身的增加是刺激海藻糖合成的机制。在碳或氮限制条件下，渗透适应明显呈双相性。初始反应包括K+的快速（30分钟内）积累以及氨基酸谷氨酸的同时合成；海藻糖合成发生在渗透适应的第二个较慢阶段。氯霉素严重抑制海藻糖积累，表明参与海藻糖合成的酶是可诱导的。
