Abstract：N-acyl-homoserine lactones were typical quorum sensing signal molecules and regulated the expression of many physiological characteristic in Gram-negative bacteria. But the AHL was smaller chemical molecules and the AHL concentration produced by the bacteria was very low, so it was very important to set up the methods of assay for the AHLs. In this paper, the biological methods were established of agar diffusion assays, thin-layer chromatography combination with biosensor analysis andβ-galactosidase activity to detect AHL based on the biosensor Chromobacterium violaceum CVO26 and Agrobacterium tumefaciens A136（pCF218/pCF372）.The powerful manners were developed to research the quorum sensing in Gram-negative bacteria.
