Bacterial strains used in characterization

Chromobacterium violaceum CV026

Chromobacterium violaceum is a Gram-negative bacterium commonly found in soil and water which produces violacein a characteristic purple coloured pigment under the induction of some sort of AHLs. C. violaceum strain CV026, is a mutant strain who has lost its capability of synthesizing lactones because of an interrupted version from endogenous LuxI analogous gene. In this strain violacein is inducible by AHLs and AHTs with N-acyl side chains from C4 to C8 in length, with varying degrees of sensitivity. For this reason CV026 can be used as a biosensor in a pool of simple bioassays with the ability to detect a wide spectrum of AHL signal molecules.

Rhizobium leguminosarum wild type

Rhizobium leguminosarum is a nitrogen fixing symbiont who synthesizes a number of different AHLs. Some of them, as N-hexanoyl homoserine lactone (C6HSL), can induce the expression of violacein in C. violaceum strain CV026. For this reason R. leguminosarum can be used as a positive control in AHLs detecting assays with CV026.