Rules Of Policing Quorum Sensing And Mechanisms Of Self-protection In Pseudomonas Aeruginosa

Quorum sensing(QS)is a communication mechanism for bacteria to regulate group behavior through the secretion,diffusion,and recognition of signal molecules.To prevent group cooperation from being invaded by deceivers,bacteria have evolved a variety of mechanisms to stably suppress deceivers,including careful metabolism,kin selection,metabolic restriction,and toxin regulation.Although some progress has been made in the study of the toxin regulatory mechanism,the issues of its regulatory role and how partners can protect themselves while releasing toxins have not yet been explored.Based on this,this article conducts research on the above issues and achieves the following main results:(1)Through the evolutionary experiments of wild strains and?rhl R mutants,it was found that?rhl R mutants collapsed rapidly due to lack of supervision;wild strains were relatively stable,and only two groups collapsed at the end of the evolution experiment..Compared with the wild strain,the C₄-HSL signal molecule,Rhamnolipid,Pyocyanin,and Hydrogen cyanide secretion of the?rhl R mutant decreased by about 40?M,40 mg/L,1 mg/L,and 40?M,respectively.In the wild strain parallel,the two groups with the lowest Pyocyanin secretion(0.32 mg/L and 0.48 mg/L)quickly collapsed;and when the cheaters appeared,the Hydrogen cyanide secretion increased,and the collapsed group changed from 79.61±2.48?M increased to 103.31±8.40?M.(2)Both hydrogen cyanide and pyocyanin have regulatory roles.In the short-term competition experiments of regulatory restructuring and material replenishment,the lack of a regulatory system is more likely to collapse than a complete regulatory system.In the absence of supervision system,supplementation with 50?M C4-HSL can accelerate population collapse;50 mg/L or 100 mg/L rhamnolipid supplementation has no significant effect on population stability;supplementation with 2 mg/L Or 4 mg/L psaldin,the population collapse rate was reduced by 20%;50?M cyanide ion supplementation could significantly inhibit the generation of population deceivers,and the population collapse rate was reduced by nearly 80%.(3)In the process of quorum sensing,Hydrogen cyanide-insensitive terminal oxidase plays a vital role in self-protection of partners.There was no difference in pa4133 and rhd A gene expression between the wild strain and the deceiver,and the expression of cio A in the deceiver was only 1/4 of that of the wild strain.Under 100?M KCN treatment,?cio A hydrogen cyanide tolerance decreased significantly,and its survival rate was only two orders of magnitude lower than that of wild strains.Using mutant strains to conduct competition experiments,the?cio A collaborator-cheater competition system had collapsed on the 5th day;in the?pa4133 collaborator-cheater competition system and the?rhd A collaborator-cheater competition system,the population did not collapse,deceiving The sub-ratio remains below 40%.This result proved that the?cio A collaborators lost the ability to detoxify hydrogen cyanide,causing the population to collapse rapidly.Hydrogen cyanide-terminal insensitive enzymes help wild strains achieve self-protection in regulation.