Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for outbreaks of bloody diarrhea and hemolytic-uremic syndrome in many countries. EHEC virulence mechanisms include the production of Shiga toxins (Stx) and formation of attaching and effacing (AE) lesions on intestinal epithelial cells. We recently reported that genes involved in the formation of the AE lesion were regulated by q...

The interbacterial communication system known as quorum sensing (QS) utilizes hormone-like compounds referred to as autoinducers to regulate bacterial gene expression. Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is the agent responsible for outbreaks of bloody diarrhea in several countries. We previously proposed that EHEC uses a QS regulatory system to "sense" that it is within ...

The establishment of Borrelia burgdorferi infection involves numerous interactions between the bacteria and a variety of vertebrate host and arthropod vector tissues. This complex process requires regulated synthesis of many bacterial proteins. We now demonstrate that these spirochetes utilize a LuxS/autoinducer-2 (AI-2)-based quorum-sensing mechanism to regulate protein expression, the first s...

Bacillus subtilis is an attractive host for production of recombinant proteins. Promoters and expression plasmid backbones have direct impacts on the efficiency of gene expression. To screen and isolate strong promoters, a promoter trap vector pShuttleF was developed in this study. Using the vector, approximately 1000 colonies containing likely promoters from Bacillus licheniformis genomic DNA ...

Title of dissertation: AUTOINDUCER-2 (AI-2) MEDIATED QUORUM SENSING IN ESCHERICHIA COLI Liang Wang, Doctor of Philosophy, 2004 Dissertation directed by: Professor William E. Bentley, Department of Chemical Engineering & Professor Steven W. Hutcheson, Department of Cell Biology and Molecular Genetics Bacteria have evolved complex genetic circuits to regulate their physiological activities and be...

The periodontal pathogen Porphyromonas gingivalis employs a variety of mechanisms for the uptake of hemin and inorganic iron. Previous work demonstrated that hemin uptake in P. gingivalis may be controlled by LuxS-mediated signaling. In the present study, the expression of genes involved in hemin and iron uptake was determined in parent and luxS mutant strains by quantitative real-time reverse ...

Furanone metabolites called AI-2 (autoinducer 2), used by some bacterial species for signaling and cell density-regulated changes in gene expression, are made while regenerating S-adenosyl methionine (SAM) after its use as a methyl donor. The luxS-encoded enzyme, in particular, participates in this activated methyl cycle by generating both a pentanedione, which is transformed chemically into th...

The moderately halophilic bacterium Halobacillus halophilus carries a homologue of LuxS, a protein involved in the activated methyl cycle and the production of autoinducer-2, which mediates quorum sensing between certain species. luxS of H. halophilus is part of an operon that encodes an S-adenosylmethionine-dependent methyltransferase, a cysteine synthase, and a beta-cystathionine lyase. Expre...

To investigate the effects of subminimum inhibitory concentrations of cephalosporins on bacterial biofilm formation, the biofilm production of 52 Escherichia (E.) coli strains was examined following treatment with cephalosporin compounds at 1/4 minimum inhibitory concentrations (MICs). Ceftazidime (CAZ) inhibited biofilm formation in seven isolates, while cefoperazone (CFP) enhanced biofilm for...

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...