AHL signal assay
The isolation and purification of AHLs were performed as described by
Kim et al . (2004). The culture supernatants from time course
cultures of P. ananatis PA13 and mutants were extracted with
ethyl acetate (1:1). The ethyl acetate layer was dried, and the residue
was dissolved in methanol. The ethyl acetate extracts were applied to
C18 reversed-phase TLC plates (Merck) and developed with
60% methanol. The TLC plates were dried in a fume hood and overlaid
with soft agar containing Chromobacterium violaceum CV026 cells
cultured overnight. The plates were incubated at 28°C overnight.