title: Detection of quorum sensing signal molecules and mutation of luxS gene in Vibrio ichthyoenteri.
abstract: Some pathogenic species belonging to the Vibrionaceae family have been shown to regulate virulence through a complicated network of quorum sensing systems. In this study, three kinds of N-acylhomoserine lactone (AHL) signal molecules were detected in Vibrio ichthyoenteri DA3, a pathogen of cultured turbot (Scophthalmus maximus), with the Agrobacterium tumefaciens reporter strain KYC55 (pJZ372)(pJZ384)(pJZ410). DA3 produced AHLs during the entire growth phase, and the level of AHLs increased, accompanied by an increase in cell population density. DA3 was also shown to have autoinducer 2 (AI-2) activities. The level of AI-2 activity in DA3 increased rapidly during the exponential phase of growth and maintained a high level up until the stationary phase. The coding sequence for a luxS-like gene of DA3 was obtained showing maximum similarity of 99.6% with that of Vibrio scophthalmi. A mutation in luxS produced no detectable AI-2 activity, but did not result in noticeable changes in growth rate, biofilm formation or virulence of V. ichthyoenteri to turbot, implying that luxS may not play a significant role in regulating virulence gene expression in this bacterium, or that different signal systems need to be inactivated at once in order to decrease virulence. Neither V. ichthyoenteri DA3 nor type strain LMG19664(T) produced any cholerae autoinducer 1 (CAI-1) activity.
authors.affiliation: Department of Marine Biology, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
authors.forename: Yin
authors.initials: Y
authors.lastname: Han
authors.forename: Qian
authors.initials: Q
authors.lastname: Yang
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Zhang
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism*; D016960:Agrobacterium tumefaciens / Q000235:genetics; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D018441:Biofilms / Q000254:growth & development; D013437:Carbon-Sulfur Lyases / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005393:Fish Diseases / Q000382:microbiology*; D005412:Flatfishes / Q000382:microbiology; D017353:Gene Deletion; D006714:Homoserine / Q000031:analogs & derivatives / Q000378:metabolism; D007783:Lactones / Q000378:metabolism; D008969:Molecular Sequence Data; D053038:Quorum Sensing; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014733:Vibrio / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology*; D014735:Vibrio Infections / Q000382:microbiology / Q000662:veterinary*; D014774:Virulence
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria