Analysis of molecular mechanisms of baicalin in inhibiting Pseudomonas aeruginosa biofilm based on RNA-seq technique
OBJECTIVE To explore the molecular mechanisms of baicalin in inhibiting the biofilm of Pseudomonas aeruginosa so as to provide theoretical basis and data support for adjuvant treatment of P.aeruginosa infection with baicalin.METHODS The effect of sub-inhibitory concentration of baicalin on P.aeruginosa PAO1 biofilm was observed by using crystal violet staining,light microscope and fluorescence microscope.The expression of PAO1 gene analyzed by transcriptome sequencing(RNA-seq)technique,the differentially expressed genes were subjected to functional enrichment and signaling pathway analysis,and the key genes involved in multiple biologi-cal processes and metabolic pathways were validated through qPCR and phenotype trial.RESULTS The result of RNA-seq indicated that under the effect of baicalin,totally 1 821 differentially expressed genes were identified,in-cluding 1 054 down-regulated genes and 767 up-regulated genes.These genes were predominantly enriched in sig-naling pathways associated with biofilm formation,production of phenazine compounds,regulation of quorum sensing system and two-component system.Baicalin had inhibiting effect on the PAO1 biofilm that was formed within 72 hours;the findings from the qPCR and phenotypic validation experiments suggested that baicalin presen-ted a significant potential to decrease the expression of biofilm-related components such as extracellular polysac-charides and proteins,as well as their regulating genes(pelA,pslA,algR,algD,pilA and filC).Further-more,Las A,LasB and phzM which were responsible for producing Las A,LasB,and pyocyanin respectively,as well as the transcription levels of quorum sensing systems(lasR,rhlR and pqsR)and type Ⅵ secretion systems(hcp1,hcp2 and hcp3),were all downregulated when exposed to baicalin.CONCLUSION Baicalin inhibits the formation of P.aeruginosa biofilm by downregulating the expression and transcription of quorum sensing systems and type Ⅵ secretion systems to regulate the biofilm-related components,which acts in a muti-target and multi-pathway manner.
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