Pantoea Sp. Strain A4, a New Plant-Associated Bacterium Exhibiting Quorum Sensing Activity

Quorum sensing (QS) is a method of bacterial cell-tocell communication to coordinate adaptive behaviour. N-Acyl homoserine lactone (AHL) is the most studied signalling molecule among proteobacteria. In the present study, we characterize QS activity in Pantoea sp. A4, a new Rafflesia-associated bacterium. Results show the production of purple violacein by reporter bioassay Chromobacterium violaceum CV026 and bioluminescence activation in Escherichia coli [pSB401], indicating AHL production. Using liquid chromatography- mass spectrometry, Pantoea sp. was found to excrete four types of AHL, namely N-hexanoylhomoserine lactone, 3-oxo-N-hexanoylhomoserine lactone, N-octanoylhomoserine lactone and N-dodecanoylhomoserine lactone. To our knowledge, there is no previous documentation of Rafflesia-associated bacterium that produces long chain AHL.