Loos H, Krämer R, Sahm H, Sprenger G A
Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, Germany.
J Bacteriol. 1994 Dec;176(24):7688-93. doi: 10.1128/jb.176.24.7688-7693.1994.
The gram-negative ethanologenic bacterium Zymomonas mobilis is able to grow in media containing high concentrations of glucose or other sugars. A novel compatible solute for bacteria, sorbitol, which enhances growth of Z. mobilis at glucose concentrations exceeding 0.83 M (15%), is described. Added sorbitol was accumulated intracellularly up to 1 M to counteract high external glucose concentrations (up to 1.66 M or 30%). Accumulation of sorbitol was triggered by a glucose upshift (e.g., from 0.33 to 1.27 M or 6 to 23%) and was prevented by the uncoupler CCCP (carbonyl cyanide m-chlorophenylhydrazone; 100 microM). The sorbitol transport system followed Michaelis-Menten kinetics, with an apparent Km of 34 mM and a Vmax of 11.2 nmol.min-1.mg-1 (dry mass). Sorbitol was produced by the cells themselves and was accumulated when growing on sucrose (1 M or 36%) by the action of the periplasmic enzyme glucose-fructose oxidoreductase, which converts glucose and fructose to gluconolactone and sorbitol. Thus, Z. mobilis can form and accumulate the compatible solute sorbitol from a natural carbon source, sucrose, in order to overcome osmotic stress in high-sugar media. No other major compatible solute (betaine, proline, glutamate, or trehalose) was detected.
革兰氏阴性产乙醇细菌运动发酵单胞菌能够在含有高浓度葡萄糖或其他糖类的培养基中生长。本文描述了一种新型的细菌相容性溶质——山梨醇，它能在葡萄糖浓度超过0.83 M（15%）时促进运动发酵单胞菌的生长。添加的山梨醇在细胞内积累至1 M，以应对高浓度的外部葡萄糖（高达1.66 M或30%）。山梨醇的积累由葡萄糖浓度升高（例如，从0.33 M升至1.27 M或从6%升至23%）触发，并被解偶联剂CCCP（羰基氰化物间氯苯腙；100 μM）抑制。山梨醇转运系统遵循米氏动力学，表观Km为34 mM，Vmax为11.2 nmol·min⁻¹·mg⁻¹（干重）。山梨醇由细胞自身产生，当在蔗糖（1 M或36%）上生长时，通过周质酶葡萄糖 - 果糖氧化还原酶的作用积累，该酶将葡萄糖和果糖转化为葡萄糖酸内酯和山梨醇。因此，运动发酵单胞菌可以从天然碳源蔗糖中形成并积累相容性溶质山梨醇，以克服高糖培养基中的渗透胁迫。未检测到其他主要的相容性溶质（甜菜碱、脯氨酸、谷氨酸或海藻糖）。
