Onraedt A, De Mey M, Walcarius B, Soetaert W, Vandamme E J
Laboratory of Industrial Microbiology and Biocatalysis, Department of Biochemical and Microbial Technology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Biotechnol Lett. 2006 Nov;28(21):1741-7. doi: 10.1007/s10529-006-9149-9. Epub 2006 Aug 10.
Brevibacterium epidermis DSM 20659 is a halotolerant Gram-positive bacterium which can synthesize the osmolyte, ectoine, but prefers to take it up from its environment. The present study revealed that B. epidermis is equipped with at least one transport system for ectoine, with a maximal transport velocity of 15.7 +/- 4.3 nmol/g CDW.min. The transport requires energy (ATP) and is completely inhibited by the proton uncoupler, CCCP. The ectoine uptake system is constitutively expressed at a basal level of activity and its activity is immediately 10-fold increased by hyper-osmotic stress. Initial uptake rates are not influenced by the intensity of the hyper-osmotic shock but the duration of the increased activity of the uptake system could be directly related to the osmotic strength of the assay solution. Competition assays indicate that betaine, but not proline, is also transported by the ectoine uptake system.
表皮短杆菌DSM 20659是一种耐盐革兰氏阳性菌，它能够合成渗透调节物质四氢嘧啶，但更倾向于从周围环境中摄取该物质。本研究表明，表皮短杆菌至少拥有一种转运四氢嘧啶的系统，其最大转运速度为15.7±4.3 nmol/g CDW·min。该转运过程需要能量（ATP），并且会被质子解偶联剂CCCP完全抑制。四氢嘧啶摄取系统以基础活性水平组成性表达，其活性在高渗胁迫下会立即增加10倍。初始摄取速率不受高渗休克强度的影响，但摄取系统活性增加的持续时间可能与测定溶液的渗透压强度直接相关。竞争试验表明，甜菜碱也可通过四氢嘧啶摄取系统进行转运，而脯氨酸则不能。
