Evaluation of land use and water quality in an agricultural watershed in the USA indicates multiple sources of bacterial impairment.

Pathogens are the number one cause of impairments of assessed rivers and streams in the USA and pose a significant human health hazard. The Dry Run Creek Watershed in Northeast Iowa has been designated as impaired by the State of Iowa because of high levels of Escherichia coli bacteria. To investigate the nature of this impairment, land use and stream bank assessments were coupled with comprehensive water quality monitoring.

OmpR regulation of the uropathogenic Escherichia coli fimB gene in an acidic/high osmolality environment.

Uropathogenic Escherichia coli (UPEC) causes more than 90 % of all human urinary tract infections through type 1 piliated UPEC cells binding to bladder epithelial cells. The FimB and FimE site-specific recombinases orient the fimS element containing the fimA structural gene promoter. Regulation of fimB and fimE depends on environmental pH and osmolality.

Genetic determinants of biofilm development of opaque and translucent Vibrio parahaemolyticus.

Vibrio parahaemolyticus isolates display variation in colony morphology, alternating between opaque (OP) and translucent (TR) cell types. Phase variation is the consequence of genetic alterations in the locus encoding the quorum sensing output regulator OpaR. Here, we show that both cell types form stable, but distinguishable biofilms that differ with respect to attachment and detachment profiles to polystyrene, pellicle formation and stability at the air/medium interface, and submerged biofilm architecture and dispersion at a solid/liquid interface.

Relation of capsular polysaccharide production and colonial cell organization to colony morphology in Vibrio parahaemolyticus.

Vibrio parahaemolyticus is a ubiquitous, gram-negative marine bacterium that undergoes phase variation between opaque and translucent colony morphologies. The purpose of this study was to determine the factor(s) responsible for the opaque and translucent phenotypes and to examine cell organization within both colony types. Examination of thin sections of ruthenium red-stained bacterial cells by electron microscopy revealed a thick, electron-dense layer surrounding the opaque cells that was absent in preparations from translucent strains.

Biosynthesis of the pyrimidine moiety of thiamine independent of the PurF enzyme (Phosphoribosylpyrophosphate amidotransferase) in Salmonella typhimurium: incorporation of stable isotope-labeled glycine and formate.

Genetic analyses have suggested that the pyrimidine moiety of thiamine can be synthesized independently of the first enzyme of de novo purine synthesis, phosphoribosylpyrophosphate amidotransferase (PurF), in Salmonella typhimurium. To obtain biochemical evidence for and to further define this proposed synthesis, stable isotope labeling experiments were performed with two compounds, [2-13C]glycine and [13C]formate. These compounds are normally incorporated into thiamine pyrophosphate (TPP) via steps in the purine pathway subsequent to PurF.