Detection and characterization of quorum sensing signal molecules in Acinetobacter strains

Quorum sensing is a widespread regulatory mechanism among Gram-negative bac teria. In this study, Acinetobacter strains were assayed for the presence o f quorum sensing signal molecules capable of activating N-acylhomoserine la ctone biosensors. By using an Agrobacterium tumefaciens reporter strain it was shown that all the cultures produced two to four detectable signal mole cules with different chromatographic patterns. In A. calcoaceticus BD413 su pernatants four compounds were detected in a time-dependent manner, and max imal activity was reached at stationary phase. The number of signal molecul es was dependent on medium composition; typically, cultures in minimal medi um displayed one or two more signals, as compared to complex medium. None o f the Acinetobacter supernatants showed autoinduction activity with an Chro mobacterium violaceum reporter strain, neither in direct or competition ass ays.