A metabolic trade-off between phosphate and glucose utilization in Escherichia coli.

Getting the most out of available nutrients is a key challenge that all organisms face. Little is known about how they optimize and balance the simultaneous utilization of multiple elemental resources. We investigated the effects of long-term phosphate limitation on carbon metabolism of the model organism Escherichia coli using chemostat cultures.

The mucoid switch in Pseudomonas aeruginosa represses quorum sensing systems and leads to complex changes to stationary phase virulence factor regulation.

The opportunistic pathogen Pseudomonas aeruginosa chronically infects the airways of Cystic Fibrosis (CF) patients during which it adapts and undergoes clonal expansion within the lung. It commonly acquires inactivating mutations of the anti-sigma factor MucA leading to a mucoid phenotype, caused by excessive production of the extracellular polysaccharide alginate that is associated with a decline in lung function. Alginate production is believed to be the key benefit of mucA mutations to the bacterium in the CF lung.

Cyanide measurements in bacterial culture and sputum.

Cyanide is produced by a few bacterial species, including Pseudomonas aeruginosa, and it has a role in the opportunistic infections of this bacterium including in cystic fibrosis lung infections. We describe two methods for determining cyanide in culture and patient sputum samples. One uses an ion-selective electrode to provide a convenient, rapid method of cyanide quantitation in culture or sputum, and the second is a semiquantitative method using Feigl-Anger paper that is useful for screening large numbers of bacterial strains for cyanide production.

The nature of laboratory domestication changes in freshly isolated Escherichia coli strains.

Adaptation of environmental bacteria to laboratory conditions can lead to modification of important traits, what we term domestication. Little is known about the rapidity and reproducibility of domestication changes, the uniformity of these changes within a species or how diverse these are in a single culture. Here, we analysed phenotypic changes in nutrient-rich liquid media or on agar of four Escherichia coli strains newly isolated through minimal steps from different sources.

Sub-lethal concentrations of antibiotics increase mutation frequency in the cystic fibrosis pathogen Pseudomonas aeruginosa.

Approximately 80% of adult patients with cystic fibrosis (CF) become chronically infected with Pseudomonas aeruginosa and consequently require antibiotic therapy at intervals throughout their lives. Achieving lethal concentrations of antibiotics in the lung remains a challenge. Recent evidence from Escherichia coli and Staphylococcus aureus suggests that the generation of hydroxyl radicals by sublethal concentrations of antibiotics may induce mutagenesis and confer bacteria with resistance to a wide range of antimicrobials.