乙醛酸循环维持铜绿假单胞菌在氯胁迫诱导的存活但不可培养状态下的代谢稳态,Microbiological Research

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乙醛酸循环维持铜绿假单胞菌在氯胁迫诱导的存活但不可培养状态下的代谢稳态
Microbiological Research ( IF 6.1 ) Pub Date : 2023-02-22 , DOI: 10.1016/j.micres.2023.127341
Zheng Qi ₁ , Na Sun ₂ , Chunguang Liu ₃

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细菌进入具有低代谢活性的存活但不可培养（VBNC）状态，以应对环境压力（例如氯消毒）。阐明VBNC细菌维持低代谢能力的机制和关键途径，对于实现其有效控制、降低其环境和健康风险具有重要意义。这项研究发现乙醛酸循环是 VBNC 细菌的关键代谢途径，但对于可培养细菌则不然。阻断乙醛酸循环途径会抑制VBNC细菌的重新激活并导致其死亡。主要机制涉及物质和能量代谢以及抗氧化系统的破坏。气相色谱-串联质谱分析表明，阻断乙醛酸循环会导致 VBNC 细菌中碳水化合物代谢和脂肪酸分解代谢的破坏。结果，VBNC细菌的能量代谢系统崩溃，能量代谢物（ATP、NAD和NADP）丰度显着下降。此外，群体感应信号分子（喹啉酮和正丁酰-高丝氨酸内酯）水平的降低抑制了细胞外聚合物（EPS）的合成和生物膜的形成。甘油磷脂代谢能力的下调增加了细胞膜的通透性，导致大量次氯酸（HClO）进入细菌内。此外，核苷酸代谢、谷胱甘肽代谢的下调以及抗氧化酶含量的减少导致无法清除氯胁迫产生的活性氧（ROS）。 ROS的大量产生和抗氧化剂的减少共同导致VBNC细菌抗氧化系统的崩溃。简而言之，乙醛酸循环是VBNC细菌抵抗应激和维持细胞代谢平衡的关键代谢途径，针对乙醛酸循环是开发控制VBNC细菌的新型高效消毒方法的有吸引力的策略。

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Glyoxylate cycle maintains the metabolic homeostasis of Pseudomonas aeruginosa in viable but nonculturable state induced by chlorine stress

Bacteria enter a viable but non-culturable (VBNC) state with low metabolic activity to cope with environmental stress (e.g., chlorine disinfection). Elucidating the mechanism and key pathway of VBNC bacteria maintaining low metabolic competence is of great significance to realize their effective control and reduce their environmental and health risks. This study discovered that the glyoxylate cycle is a key metabolic pathway for VBNC bacteria, but not for culturable bacteria. And blocking the glyoxylate cycle pathway inhibited the reactivation and led to the death of VBNC bacteria. The main mechanisms involved the breakdown of material and energy metabolism and the antioxidant system. Gas chromatography-tandem mass spectrometry analysis showed that blocking the glyoxylate cycle led to a disruption of carbohydrate metabolism and fatty acid catabolism in VBNC bacteria. As a result, the energy metabolism system of VBNC bacteria collapsed and the abundance of energy metabolites (ATP, NAD and NADP) decreased significantly. Moreover, the decrease in the level of quorum sensing signaling molecules (quinolinone and N-Butanoyl--homoserine lactone) inhibited the synthesis of extracellular polymeric substances (EPSs) and biofilm formation. And the downregulation of glycerophospholipid metabolic competence increased the permeability of cell membranes, leading to the entry of large amounts of hypochlorous acid (HClO) into the bacteria. In addition, the down-regulation of nucleotide metabolism, glutathione metabolism, and the reduction of antioxidant enzyme content resulted in the inability to scavenge reactive oxygen species (ROS) generated by chlorine stress. The large production of ROS and the reduction of antioxidants together led to the breakdown of the antioxidant system of VBNC bacteria. In short, the glyoxylate cycle is the key metabolism pathway of VBNC bacteria for stress resistance and maintaining cellular metabolic balance, and targeting the glyoxylate cycle represents an attractive strategy for developing new and efficient disinfection methods for the control of VBNC bacteria.

更新日期：2023-02-22

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