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Quorum sensing (QS) coordinates the expression of virulence factors and allows bacteria to counteract the immune response, partly by increasing their tolerance to the oxidative stress generated by immune cells. Despite the recognized role of QS in enhancing the oxidative stress response, the consequences of this relationship for the bacterial ecology remain(More)
Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric) for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted(More)
The facultative protist Euglena gracilis, a heavy metal hyper-accumulator, was grown under photo-heterotrophic and extreme conditions (acidic pH, anaerobiosis and with Cd(2+)) and biochemically characterized. High biomass (8.5×10(6)cellsmL(-1)) was reached after 10 days of culture. Under anaerobiosis, photosynthetic activity built up a microaerophilic(More)
The synthesis of ATP in the human parasite Entamoeba histolytica is carried out solely by the glycolytic pathway. Little kinetic and structural information is available for most of the pathway enzymes. We report here the gene cloning, overexpression and purification of hexokinase, hexose-6-phosphate isomerase, inorganic pyrophosphate-dependent(More)
A kinetic model of trypanothione [T(SH)(2)] metabolism in Trypanosoma cruzi was constructed based on enzyme kinetic parameters determined under near-physiological conditions (including glutathione synthetase), and the enzyme activities, metabolite concentrations and fluxes determined in the parasite under control and oxidizing conditions. The pathway(More)
The activity of the pyridine nucleotide-independent lactate dehydrogenase (iLDH) was characterized in mitochondria isolated from the protist Euglena gracilis. The dissociation constants for L- and D-lactate were similar, but the V(max) was higher with the d isomer. A ping-pong kinetic mechanism was displayed with 2,4-dichlorophenol-indolphenol (DCPIP), or(More)
Pseudomonas aeruginosa PA14 cells resistant to the novel antimicrobial gallium nitrate (Ga) were developed using transposon mutagenesis and by selecting spontaneous mutants. The mutants showing the highest growth in the presence of Ga were selected for further characterization. These mutants showed 4- to 12-fold higher Ga minimal inhibitory growth(More)
The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by(More)
The role of the multisubunit sodium/proton antiporter (Mrp) of Methanosarcina acetivorans was investigated with a mutant deleted for the gene encoding the MrpA subunit. Antiporter activity was 5-fold greater in acetate-grown versus methanol-grown wild-type cells, consistent with the previously published relative levels of mrp transcript. The rate, final(More)
To assess the toxic effect of Cr on energy metabolism, heterotrophic Euglena gracilis was grown in a medium that prompts high yield biomass and in the presence of different Cr(VI) or Cr(III) concentrations. The cell growth IC₅₀ value was 12 and >250μM for Cr(VI) and Cr(III), respectively; in these cells chromium was accumulated and a fraction(More)