show Abstracthide AbstractLactobacillus as a probiotic has been verified to inhibit pathogenesis in P. aeruginosa via quenching QS. The objective of this study was to investigate mechanism of the QS quenching function of Lactobacillus via analyzing the gene expression by transcriptome. We previously isolated a Lactobacillus brevis strain 3M004 from an aquafeed and identified the strain has the function of degrading QS molecular AHL (OC12-HSL). The result showed that 3M004 cells/lysate inhibited biofilm and pyocyanin production of Pseudomonas aeruginosa PA002. Transcriptomic analysis showed that down-regulation of genes in PA002 was essential in regulating the QS system. The biofilm decrease of PA002 seems not only resulted from gene biosynthesizing of polysaccharides but also from other genes regulating components biosynthesis.