Metabolism of acyl-homoserine lactone quorum-sensing signals by Variovoraxparadoxus

Acyl-homoserine lactones (acyl-HSLs) serve as dedicated cell-to-cell signal ing molecules in many species of the class Proteobacteria. We have addresse d the question of whether these compounds can be degraded biologically. A m otile, rod-shaped bacterium was isolated from soil based upon its ability t o utilize N-(3-oxohexanoyl)-L-homoserine lactone as the sole source of ener gy and nitrogen. The bacterium was classified as a strain of Variovorax par adoxus, The V, paradoxus isolate was capable of growth on all of the acyl-H SLs tested. The molar growth yields correlated with the length of the acyl group. HSL, a product of acyl-HSL metabolism, was used as a nitrogen source , but not as an energy source. Cleavage and partial mineralization of the H SL ring were demonstrated by using radiolabeled substrate, This study indic ates that some strains of V. paradoxus degrade and grow on acyl-HSL signals as the sole energy and nitrogen sources. This study provides dues about th e metabolic pathway of acyl-HSL degradation by V. paradoxus.