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Browsing by Author "Fonseca, Ana Rita da Conceição Ferreira da"

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  • Harnessing the biomedical potential of bacterial pigments to develop antimicrobial solutions against multidrug resistant pathogens
    Publication . Fonseca, Ana Rita da Conceição Ferreira da; Ribeiro, Edna; Castro, Pedro; Gonçalves, Sónia
    There is an urgent need to have alternatives to the existing antibiotics. This happens because microorganisms become multi-resistant to available antibiotics. To possibly combat this global health problem, investigations have pointed out that some bacteria produce bioactive pigments with interesting antimicrobial properties. One of these pigments is prodigiosin, which has been investigated because of its broad biomedical potential. In this work, the heterologous production of prodigiosin was optimized in Pseudomonas strains, corresponding to the best condition tested for the cultivation of the strain in a minimal medium supplemented with 0.4% (v/v) lactate and 2.5% (v/v) glycerol, producing 2.0 ± 0.5 mg/mL which is more than in the existing literature for Pseudomonas spp. The results obtained showed that prodigiosin extract in dimethyl sulfoxide (DMSO) was not capable of inhibiting the growth of Gram-negative bacteria tested. However, the same prodigiosin extract showed antimicrobial activity against Staphylococcus epidermidis. The colony formation units (CFU) count method showed an inhibitory growth of that strain at a prodigiosin extract concentration of 25 µg/mL and a Minimum Bactericidal Concentration (MBC) value of 200 µg/mL. To improve the antimicrobial activity of prodigiosin a few attempts by conjugation with silver nanoparticles and silver star-shaped nanoparticles were tried. The effect of parameters such as agitation, time of reaction, reducing agents with silver nitrate (AgNO3), and different concentrations of prodigiosin were also studied. The obtained results suggest the search for new synthesis methodologies to improve the conjugation of prodigiosin with silver nanoparticles.
    2023-10Master thesis Restricted access Show more