Abstract—Changes in the activity of antioxidant systems in Escherichia coli during phosphate starvation have been studied. It is shown that starvation was accompanied by a decrease in the intensity of respiration, an increase in the rate of superoxide production, and a decrease in the level of ATP. Simultaneously, there was a decrease in H₂O₂ in the medium and a significant increase in the expression of the katG and katE genes which encode the HPI and HPII catalases, respectively. At the same time, there was no drop in the membrane potential, which may indicate the retention of normal membrane activity in starving cells. It has been shown for the first time that the transition of E. coli to phosphate starvation is accompanied by significant changes in the status of glutathione. The most important of these are associated with a decrease in the level of reduced glutathione in the medium (GSH_out) and with a simultaneous increase in its content in the cytoplasm (GSH_in), as well as a shift in the GSH_in to oxidized glutathione form (GSSG_in) ratio towards reductive values, and GSH_out/GSSG_out towards oxidative values. Among the mutants used in the work, the gor trxB double mutant, which is deficient in the synthesis of glutathione reductase and thioredoxin reductase, showed the most pronounced distinctive features. Compared to the parental strain, this mutant showed a multiple higher expression of katG::lacZ, the highest level of oxidized intra- and extracellular glutathione, and, accordingly, the lowest GSH/GSSG ratio in both compartments. In general, the data we obtained indicate that during phosphate starvation the interaction of the glutathione redox-system and regulons that control protection against reactive oxygen species creates conditions that allow maintaining the concentration of ROS below the toxic level. As a result, phosphate-starved E. coli cells can maintain high viability for a long period of time, which allows them to quickly resume growth after the addition of phosphate.

摘要：研究了磷酸盐饥饿期间大肠杆菌抗氧化系统活性的变化。结果表明，饥饿伴随着呼吸强度的降低、超氧化物产生速率的增加以及ATP水平的降低。同时，培养基中的H ₂ O ₂减少，并且分别编码HPI和HPII过氧化氢酶的katG和katE基因的表达显着增加。同时，膜电位没有下降，这可能表明饥饿细胞中保留了正常的膜活性。首次表明，大肠杆菌向磷酸盐饥饿的转变伴随着谷胱甘肽状态的显着变化。其中最重要的是与培养基中还原型谷胱甘肽水平的降低 (GSH _out ) 和细胞质中其含量的同时增加 (GSH _in ) 以及 GSH _in向氧化型谷胱甘肽的转变有关。谷胱甘肽形式 (GSSG _in ) 与还原值的比率，以及 GSH_输出/GSSG_输出与氧化值的比率。在工作中使用的突变体中，gor trxB双突变体表现出最明显的独特特征，该突变体缺乏谷胱甘肽还原酶和硫氧还蛋白还原酶的合成。与亲本菌株相比，该突变体表现出更高的katG :: lacZ表达、最高水平的细胞内和细胞外氧化谷胱甘肽，以及相应的两个区室中最低的 GSH/GSSG 比率。一般来说，我们获得的数据表明，在磷酸盐饥饿期间，谷胱甘肽氧化还原系统和控制活性氧保护的调节子之间的相互作用创造了使活性氧浓度保持在毒性水平以下的条件。结果，磷酸盐饥饿的大肠杆菌细胞可以长时间保持高活力，这使得它们在添加磷酸盐后能够快速恢复生长。