Sensitive Whole-Cell Biosensor Suitable for Detecting a Variety of N -Acyl Homoserine Lactones in Intact Rhizosphere Microbial Communities

Abstract

To investigate quorum sensing in rhizosphere soil, a whole-cell biosensor, Agrobacterium tumefaciens (pAHL-Ice), was constructed. The biosensor responded to all N -acyl homoserine lactones (AHLs) tested, except C ₄ homoserine lactone, with a minimum detection limit of 10 ⁻¹² M, as well as to both exogenously added AHLs and AHL-producing bacterial strains in soil. This highly sensitive biosensor reveals for the first time the increased AHL availability in intact rhizosphere microbial communities compared to that in bulk soil.