The Mechanism Of Polymyxin E Oxidative Stress To Paenibacillus Polymyxa

Polymyxin E is a polypeptide antibiotic produced by Paenibacillus Polymyxa,mainly for the treatment of multi-drug resistant gram-negative infection.In this dissertation,the mechanism of polymyxin E oxidative stress to P.polymyxa,and the related stress effect to P.polymyxa and its response to polymyxin E were studied.The stress effect of Polymyxin E on P.polymyxa was studied.The result showed that the damages of cell growth,surface morphology,DNA,and lipid peroxidation were observed in P.polymyxa after polymyxin E treatment,which was consistent with the stress effect caused by oxidative stress.It demonstrated that polymyxin E induced rapid P.polymyxa damage even death through oxidative stress.Further study indicated that ROS was found to display a statistically significant increase?a 3.94-fold increase?after polymyxin E treatment and ROS scavengers played a significant role in relieving rapid cell death of P.polymyxa.The transcription levels of Mn-SOD and Fe-SOD increased,which were aimed at clearing ROS caused by polymyxin E while the transcript levels of DHAD decreased.Extracellular Fe³⁺was introduced to cell together with the increase of transcription level of Fur-like protein after polymyxin E treatment,indicating that Fe³⁺was introduced to repair Fe-S cluster.In addition,the transcription level of Dps also increased to sequester Fe²⁺so as to decrease the formation of.OH.In conclusion,polymyxin E can induce the formation of ROS,leading to the damage of P.polymyxa and cellular response to defend oxidative stress.