We are pursuing a strategy to identify traits important in virulence of Xylella fastidiosa (Xf) through the mutagenesis of “global” regulatory genes, which are known to broadly regulate virulence functions in other microbes. In addition to phenotypic characterization of such mutants, we are using whole-genome microarrays to identify which genes are regulated by these global regulators and exami...

Chronic Pseudomonas aeruginosa lung infection is the major cause of morbidity and mortality in cystic fibrosis (CF) patients. One P. aeruginosa virulence factor unique to CF isolates is overproduction of alginate, phenotypically termed mucoidy. Mucoidy is the result of increased transcription from the algD gene and is activated by the transcriptional regulator AlgR. Mutations in algR result in ...

The present study was undertaken in order to understand more about the interaction occurring between S. maltophilia and P. aeruginosa, which are frequently co-isolated from CF airways. For this purpose, S. maltophilia RR7 and P. aeruginosa RR8 strains, co-isolated from the lung of a chronically infected CF patient during a pulmonary exacerbation episode, were evaluated for reciprocal effect dur...

Mucoid strains of Pseudomonas aeruginosa that overproduce the exopolysaccharide alginate are a frequent cause of chronic respiratory infections in cystic fibrosis (CF) patients. The overproduction of alginate by these strains is often caused by mutations within mucA of the algU mucABCD gene cluster. This gene cluster encodes an extreme stress response system composed of the ECF alternative sigm...

Biofilms exist in a variety of habitats that are routinely or periodically not saturated with water, and residents must integrate cues on water abundance (matric stress) or osmolarity (solute stress) into lifestyle strategies. Here we examine this hypothesis by assessing the extent to which alginate production by Pseudomonas putida strain mt-2 and by other fluorescent pseudomonads occurs in res...