Neubauer P, Ahman M, Törnkvist M, Larsson G, Enfors S O
Royal Institute of Technology (KTH), Department of Biochemistry and Biotechnology, Stockholm, Sweden.
J Biotechnol. 1995 Dec 15;43(3):195-204. doi: 10.1016/0168-1656(95)00130-1.
A rapid transient increase of guanosine 3'-diphosphate 5'-diphosphate (ppGpp) in Escherichia coli was found in response to short-term glucose fluctuations that may occur in large-scale fed-batch cultivations. The concentration of ppGpp was measured in laboratory-scale glucose limited fed-batch cultivations. Starvation zones were imitated by using an intermittent feeding scheme or a two-compartment reactor system. The cellular concentration of ppGpp per biomass increased from 80 nmol to 300-600 nmol per g cell dry weight within only 1 min after consumption of the residual glucose in dependence on the test system, which is much faster than earlier described in literature. Readdition of glucose caused immediate reduction of the ppGpp to the basic level which did not differ in cultivations with simulated starvation zones from control cultivations. Possible physiological consequences by an enhanced stringent response in cultivations with limited mass transfer have to be considered.
在大肠杆菌中发现，鸟苷3'-二磷酸5'-二磷酸（ppGpp）会迅速短暂增加，以响应大规模补料分批培养中可能出现的短期葡萄糖波动。在实验室规模的葡萄糖限制补料分批培养中测量了ppGpp的浓度。通过使用间歇补料方案或双隔室反应器系统来模拟饥饿区。根据测试系统的不同，在残余葡萄糖消耗后仅1分钟内，每克细胞干重的细胞内ppGpp浓度就从80 nmol增加到300 - 600 nmol，这比文献中先前描述的要快得多。重新添加葡萄糖会使ppGpp立即降至基础水平，在有模拟饥饿区的培养中，该基础水平与对照培养没有差异。必须考虑在传质受限的培养中增强的严格反应可能产生的生理后果。
