title: Lead precipitation by Vibrio harveyi: evidence for novel quorum-sensing interactions.
abstract: Three pleiotropic, quorum sensing-defective Vibrio harveyi mutants were observed to precipitate soluble Pb2+ as an insoluble compound. The compound was purified and subjected to X-ray diffraction and elemental analyses. These assays identified the precipitated compound as Pb9(PO4)6, an unusual and complex lead phosphate salt that is produced synthetically at temperatures of ca. 200 degrees C. Regulation of the precipitation phenotype was also examined. Introduction of a luxO::kan allele into one of the mutants abolished lead precipitation, indicating that the well-characterized autoinducer 1 (AI1)-AI2 quorum-sensing system can block lead precipitation in dense cell populations. Interestingly, the V. harveyi D1 mutant, a strain defective for secretion of both AI1 and AI2, was shown to be an effective trans inhibitor of lead precipitation. This suggests that a previously undescribed V. harveyi autoinducer, referred to as AI3, can also negatively regulate lead precipitation. Experiments with heterologous bacterial populations demonstrated that many different species are capable of trans regulating the V. harveyi lead precipitation phenotype. Moreover, one of the V. harveyi mutants in this study exhibited little or no response to intercellular signals from other V. harveyi inocula but was quite responsive to some of the heterologous bacteria. Based on these observations, we propose that V. harveyi carries at least one quorum sensor that is specifically dedicated to receiving cross-species communication.
authors.affiliation: Department of Biological Sciences, Rowan University, Glassboro, New Jersey 08028, USA.
authors.forename: Chad E
authors.initials: CE
authors.lastname: Mire
authors.forename: Jeanette A
authors.initials: JA
authors.lastname: Tourjee
authors.forename: William F
authors.initials: WF
authors.lastname: O'Brien
authors.forename: Kandalam V
authors.initials: KV
authors.lastname: Ramanujachary
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Hecht
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D011232:Chemical Precipitation; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D007854:Lead / Q000737:chemistry / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014733:Vibrio / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; C088907:LuxO protein, Vibrio harveyi; D012097:Repressor Proteins; D014157:Transcription Factors; D007854:Lead; C036682:lead phosphate