Sauer T, Galinski E A
Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Meckenheimer Allee 168, D-53115 Bonn, Germany.
Biotechnol Bioeng. 1998 Feb 5;57(3):306-13.
A novel biotechnological process called "bacterial milking" has been established for the production of compatible solutes using the Gram-negative bacterium Halomonas elongata. Following a high-cell-density fermentation which provided biomass up to 48 g cell dry weight per liter, we applied alternating osmotic shocks in combination with crossflow filtration techniques to harvest the compatible solutes ectoine and hydroxyectoine. H. elongata, like other halophilic or halotolerant microorganisms, produces compatible solutes in response to the salinity of the medium. When transferred to a low salinity medium (osmotic downshock), H. elongata cells rapidly released their solutes to achieve osmotic equilibrium. Subsequent reincubation in a medium of higher salt concentration resulted in resynthesis of these compatible solutes and-after a defined regeneration time-the procedure could be repeated. By repeatedly performing this "bacterial milking" process (at least nine times) we were able to produce large amounts of ectoines with a biomass productivity of 155 mg of ectoine per cycle per gram cell dry weight. Further purification of the products was achieved by a simple two-step procedure based on cation exchange chromatography and crystallization. The principles described in this article may also be useful for the production of other low-molecular-weight compounds.
一种名为“细菌挤奶”的新型生物技术工艺已被确立，用于利用革兰氏阴性菌嗜盐栖热袍菌生产相容性溶质。在进行了高细胞密度发酵（每升可提供高达48克细胞干重的生物量）之后，我们应用交替渗透冲击并结合错流过滤技术来收获相容性溶质四氢嘧啶和羟基四氢嘧啶。嗜盐栖热袍菌与其他嗜盐或耐盐微生物一样，会根据培养基的盐度产生相容性溶质。当转移到低盐度培养基（渗透降冲击）中时，嗜盐栖热袍菌细胞会迅速释放其溶质以实现渗透平衡。随后在盐浓度更高的培养基中再培养会导致这些相容性溶质重新合成，并且在经过确定的再生时间后，该过程可以重复。通过反复进行这种“细菌挤奶”过程（至少九次），我们能够以每克细胞干重每循环155毫克四氢嘧啶的生物量生产率生产大量的四氢嘧啶。通过基于阳离子交换色谱和结晶的简单两步法实现了产物的进一步纯化。本文所述原理可能也有助于生产其他低分子量化合物。
