To explore that if the Enterococcus durans SQ-3-2 produces the quorum-sensing signal autoinducer-2 by utilizing a biological assay and optimize the test condition at the same time.The experiment employed a bioluminescent bacterial reporter strain called Vibrio harveyi BB170,which produces light in response to AI-2.We collected the cell-free culture fluids and added them to the V.harveyi BB170 reporter strain.The resulting light production was measured using a luminometer or scintillation counter.AI-2 activity was deduced according to the induction of luminescence of V.harveyi BB170.The fluorescence of the V.harveyi increased after adding the cell-free culture fluids of E.durans SQ-3-2 and based on the fluorescence intensity of different sample experiment condition was optimized.We found that the E.durans SQ-3-2 produces the quorum-sensing signal AI-2.With the increase of cell density,concentration of signaling molecule AI-2 increased and the maximum value was reached in logarithmic period.Optimal testing condition was sample pH=7 and sample ratio of 1∶ 100.Experiment lays the foundation to further study of function of AI-2 from E.durans SQ-3-2.At the same time,the optimized experimental conditions for detection of quorum-sensing signal AI-2 of various kinds of lactic acid bacteria is the experimental foundation.