The expression of a wide variety of physiological functions in many bacterial species is modulated by quorum sensing, a population-dependent signalling mechanism that involves the production and detection of extracellular signalling molecules. The genome sequence of Campylobacter jejuni NCTC 11168 contains a gene encoding an orthologue of LuxS, which is required for autoinducer-2 (AI-2) product...

We have previously demonstrated conjugation of Escherichia coli into vacuoles of the protozoal ciliate (Tetrahymena thermophila). This indicated a possible role of ciliates in evoking bacterial quorum sensing, directly connecting bacterial survival via accumulation in the ciliate vacuoles. We therefore assessed if ciliates promoted bacterial autoinducer (AI)-2 accumulation with vacuole formatio...

Different species of bacteria important in the composition of dental plaque were tested for production of extracellular autoinducer-like activities that stimulate the expression of the luminescence genes in Vibrio harveyi. Several strains of Prevotella intermedia, Fusobacterium nucleatum, and Porphyromonas gingivalis were found to produce such activities. Interestingly, these bacteria belong to...

Defining the metabolic capabilities and regulatory mechanisms controlling gene expression is a valuable step in understanding the pathogenic properties of infectious agents such as Borrelia burgdorferi. The present studies demonstrated that B. burgdorferi encodes functional Pfs and LuxS enzymes for the breakdown of toxic products of methylation reactions. Consistent with those observations, B. ...

Title of Document: INHIBITORS OF AUTOINDUCER-2 QUORUM SENSING AND THEIR EFFECT ON BACTERIAL BIOFILM FORMATION Rebecca Melissa Lennen, Master of Science, 2007 Directed by: Dr. William Bentley, Professor Department of Bioengineering Bacteria utilize small signaling molecules, or autoinducers, to regulate their gene expression in tandem by a process termed quorum sensing. The gene encoding the syn...

Vibrio vulnificus is a causative agent of serious food-borne diseases in humans related to consumption of raw seafoods. This human pathogen secretes a metalloprotease (VVP) that evokes enhancement of the vascular permeability and disruption of the capillaries. Production of microbial proteases is generally induced at early stationary phase of its growth. This cell density dependent regulation o...

Erwinia amylovora is a gram-negative phytopathogen that causes fire blight of pome fruit and related members of the family Rosaceae. We sequenced the putative autoinducer-2 (AI-2) synthase gene luxS from E. amylovora. Diversity analysis indicated that this gene is extremely conserved among E. amylovora strains. Quorum sensing mediated by LuxS has been implicated in coordinated gene expression, ...

Helicobacter pylori possesses a homolog of the luxS gene, initially identified by its role in autoinducer production for the quorum-sensing system 2 in Vibrio harveyi. The genomes of several other species of bacteria, notably Escherichia coli, Salmonella enterica serovar Typhimurium, and Vibrio cholerae, also include luxS homologs. All of these bacteria have been shown to produce active autoind...

Rapid and efficient inactivation of a target gene in Escherichia coli chromosomes is required to investigate metabolic engineering. In the present study, a multiple gene inactivation approach was demonstrated in four strains of enterotoxigenic E. coli (ETEC), which are the predominant pathogenic bacteria causing piglet diarrhea, mediated by λ Red and Xer recombination. The chromosomal genes, lu...

Non-typeable Haemophilus influenzae (NTHi) is a common pathogen associated with diseases such as acute otitis media or exacerbations in patients with chronic obstructive pulmonary disease. The biofilm-forming capability substantially contributes to the persistence of NTHi. However, the regulation of biofilm formation is not completely understood. Quorum sensing regulated by autoinducer-2 produc...