An oligonucleotide-based DNA microarray was developed to evaluate expression of genes for efflux pumps in Acinetobacter baumannii and to detect acquired antibiotic resistance determinants. The microarray contained probes for 205 genes, including those for 47 efflux systems, 55 resistance determinants, and 35 housekeeping genes. The microarray was validated by comparative analysis of mutants overexpressing or deficient in the pumps relative to the parental strain. The performance of the microarra ...[more]
Project description:Hybridisation of reference strains to the VirEp Staphylococcus aureus microarray, and characterisation of different S. aureus isolates from different locations and associated with different diseases.
Project description:Comparative genome hybridization of transconjugants of E. faecalis OG1RF mated with V583. The total DNA of transconjugants was compared with wildtype strains to ascertain the amount of DNA that was transferred from E. faecalis V583 to E. faecalis OG1RF.
Project description:Clinical isolates of the porcine pathogen Actinobacillus pleuropneumoniae often form adherent colonies on agar plates due to expression of an operon, pgaABCD, encoding a poly-N-acetylglucosamine (PGA) extracellular matrix. The adherent colony phenotype, which correlates with the ability to form a biofilm on the surface of polystyrene plates, is lost following serial passage in broth culture, and repeated passage of the non-adherent variants on solid media does not result in reversion to the adherent colony phenotype. In order to investigate the regulation of PGA expression and biofilm formation in A. pleuropneumoniae, we screened a bank of transposon mutants of the non-adherent serovar 1 strain, S4074T, and identified mutations in two genes, rseA and hns, which resulted in formation of the adherent colony phenotype. In other bacteria, including the Enterobacteriaceae, H-NS acts as a global gene regulator, and RseA is a negative regulator of the extracytoplasmic stress response sigma factor, ?E. Transcription profiling of A. pleuropneumoniae rseA and hns mutants revealed that both ?E and H-NS independently regulate expression of the pga operon. Transcription of the pga operon is initiated from a ?E promoter site in the absence of H-NS, and up-regulation of ?E is sufficient to displace H-NS, allowing transcription to proceed. In A. pleuropneumoniae, H-NS does not act as a global gene regulator, but rather specifically regulates biofilm formation via repression of the pga operon. Positive regulation of the pga operon by ?E indicates that biofilm formation in is part of the extracytoplasmic stress response in A. pleuropneumoniae.