RAPISARDA Viviana Andrea
congresos y reuniones científicas
Production and characterization of a pigment synthesized by Escherichia coli cells exposed to high copper concentrations
RINTOUL, M. R.; SCARAVAGLIO, O. R.; CERIONI, L.; VOLENTINI, S. I.; RAPISARDA, V. A.; RODRÍGUEZ-MONTELONGO, L.
Congreso; X PABMB Congress, XLI Reunión anual de SAIB y XX Reunión anual SAN; 2005
Studies carried out in our laboratory showed that different Escherichia coli strains produce a pink-brownish pigment when they were grown, aerobically or anaerobically, with high copper concentrations. The pigment was present either in cells or in the growth media (liquid or solid).Its production was detected during the whole growth curve, increasing in stationary phase. All strains tested produced the pigment, except for the ubiA- strain, which is defective in ubiquinone synthesis. Addition of p-hydroxibenzoate to the growth medium, which allowed mutants to synthesize ubiquinone, restores the pigment production. On the other hand, we partially purified the coloured compound by gel filtration chromatography (Sephadex G25) as a high molecular weigh fraction, which was chromatographied by strong anionic exchange chromatography (Q Sepharose fast flow). The pigments fraction is negatively charged at pH7 and it shows an absorption peak at 370nm, and a luminescence at 475nm when it was excited at 370nm. It seemed to be associated to proteins and Cu1+. The pigment could have a protective effect in cells under oxidative stress conditions caused by high copper level.