Impact of osmotic stress on volume regulation, cytoplasmic solute composition and lysine production in Corynebacterium glutamicum MH20-22B
Impact of osmotic stress on volume regulation, cytoplasmic solute composition and lysine production in Corynebacterium glutamicum MH20-22B
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DOI：
10.1016/s0168-1656(03)00166-4
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发表时间：
2003-09-04
影响因子：
4.1
通讯作者：
Morbach, S
中科院分区：
文献类型：
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作者：
Rönsch, H;Krämer, R;Morbach, S
在间歇培养条件下，研究了L赖氨酸产生菌MH20-22B对渗透胁迫的响应。为了模拟发酵过程中的条件，研究了细胞在1.0OSM至2.5OSM恒定渗透胁迫下的长期适应。谷氨酰胺细胞的细胞质水分含量和体积与生长阶段、渗透胁迫程度和甜菜碱的可利用性有关。最大细胞质体积在最大生长速率时最大，与渗透胁迫呈线性相关，而在静止细胞中没有观察到主动的体积调节。在严重渗透胁迫下，生长细胞中的主要亲和性溶质是脯氨酸。甜菜碱的吸收，如果在介质中存在，将Pro的浓度从750 mM降低到300 mM，这表明吸收相容的溶质比合成更受欢迎。此外，甜菜碱被证明有更高的效率来抵消渗透胁迫，因为总的浓度相容。甜菜碱存在时，溶质含量较低。在严重渗透胁迫下，甜菜碱的添加使L赖氨酸的发酵时间提前，提高了这两个阶段的产物浓度和产量，但并没有提高最终的L赖氨酸产量。(C)2003爱思唯尔B.V.保留所有权利。
The response of the L-lysine producing Corynebacterium glutamicum strain MH20-22B to osmotic stress was studied in batch cultures. To mimic the conditions during a fermentation process the long term adaptation of cells subjected to a constant osmotic stress between 1.0 and 2.5 osM was investigated. Cytoplasmic water content and volume of C. glutamicum cells were found to depend on growth phase, extent of osmotic stress and availability of betaine. The maximal cytoplasmic volumes, which were highest at maximal growth rate, were linearily related to osmotic stress, whereas in stationary cells no active volume regulation was observed. Under severe osmotic stress proline was the prominent compatible solute in growing cells. Uptake of betaine, if available in the medium, reduced the concentration of proline from 750 to 300 mM, indicating that uptake of compatible solutes is preferred to synthesis. Furthermore, betaine was shown to have a higher efficiency to counteract osmotic stress, since the overall concentration of compatible. solutes was lower in the presence of betaine. Under severe osmotic stress, the addition of betaine shifted L-lysine production in MH20-22B to earlier fermentation times and increased both product concentration and yield in these phases, but did not improve the final L-lysine yield. (C) 2003 Elsevier B.V. All rights reserved.