Estudos de atividade biológica do exopolissacarídeo e da biomassa da microalga porphydium cruentum

  • Helena Patrícia Sousa de Vasconcelos (Student)

Student thesis: Master's Thesis


Porphyridium sp. is a microalgia, which is encapsulated inside a gel of sulfated exopolysaccharides (EPS). EPS’s have behaviors of dynamic fluid with production of highly viscous solutions and high molecular weight. It is known that these polysaccharides have relevant biological activity in various applications, from cosmetics and medicines to food.With this work, it was intended to optimize parameters of culture and production of the marine microalga Porphyridium cruentum, namely for its EPS. For this purpose, the microalga was cultivated NTIP medium and then studied with the supplementation of magnesium sulfate (NTIP-MgSO4) and magnesium chloride (NTIP-MgCl2). With this an extension of the exponential phase with the type NTIP-MgSO4 when compared to control (NTIP) and NTIP-MgCl2 was observed.The aim was also to verify the action of EPS concerning potential human pathogens. For that, several profiles of biological activity were carried out, namely antibacterial capacity, antifungal and bacterial antibiofilm.The EPS revealed antimicrobial activity dependente on concentration. At 4% EPS, MRSA showed the highest percentage of inhibition (~11%), followed by S. enteritidis (~ 9%), E. coli (~ 7%) and C. albicans (~ 6%). P. aeruginosa was the only microorganism that showed no inhibition in any of the concentrations tested. The EPS was also tested for M. canisand T. rubrum, but the results did not show antifungal activity for the tested method.The prebiotic profile EPS for 9 lactic bacteria has been studied. When cultured in theMRS médium with glucose and EPS, L. plantarum, L. acidophilus La-5 (aerobiose) and L. acidophylus Ki, have shown the highest stimulation, ~5%, ~19% and ~22%, respectively.Regarding the study of the capacity of bacterial antibiofilm of EPS, it was tested for P.aeruginosa, The results obtained did not show any antibiofilm activity of the EPS. The fraction of biomass of P. cruentum was also studyand it was analysed for its antibacterian performance in extracts of chloroform, hexane and ethanol. The inhibition of S. enteritidis and MSSA was observed, obtaining a bigger percentage of inhibition with ethanol extract.Thus, Porphyyridium cruentum demonstrated a selective antimicrobial effect, with potential prebiotic effect, thus assuring a high interest in applications, cosmetic or biomedical.
Date of Award27 Apr 2018
Original languagePortuguese
Awarding Institution
  • Universidade Católica Portuguesa
SupervisorRui M.S.C. Morais (Supervisor) & Maria Manuela Pintado (Co-Supervisor)


  • Mestrado em Microbiologia Aplicada

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