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Extracellular polymeric substances produced by the Thermophilic Cyanobacterium Gloeocapsa gelatinosa: characterization and assessment of their antioxidant and metal-chelating activities
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Orientador(es)
Resumo(s)
Cyanobacteria, particularly thermophilic strains, represent an important potential source of
EPSs, harboring structural complexity that predicts diverse and specific bioactive potential. The ther mophilic cyanobacteria Gloeocapsa gelatinosa, isolated from a natural hot source in Ain Echfa (Tunisia),
was cultivated in a cylindrical reactor, and the production of biomass and EPSs was investigated.
Results revealed that the strain is amongst the most efficient EPSs producers (0.89 g L−1
) and that
EPSs production was not correlated with the growth phase. EPSs were sulfated heteropolysaccharides
containing carbohydrates (70%) based on nine different monosaccharides, mainly mannose (22%), and
with the presence of two uronic acids. EPSs were formed by two polymers moieties with a molecular
weight of 598.3 ± 7.2 and 67.2 ± 4.4 kDa. They are thermostable in temperatures exceeding 100 ◦C
and have an anionic nature (zeta potential of −40 ± 2 mV). Atomic force microscopy showed that
EPSs formed multimodal lumps with 88 nm maximum height. EPSs presented high water holding
capacity (70.29 ± 2.36%) and solubility index (97.43 ± 1.24%), and a strong bivalent metal sorption
capacity especially for Cu2+ (91.20 ± 1.25%) and Fe2+ (75.51 ± 0.71%). The antioxidant activity of
G. gelatinosa EPSs was investigated using four methods: the β-carotene-bleaching activity, DPPH
assays, iron-reducing activity, and metal-chelating activity. EPS has shown high potential as free
radicals’ scavenger, with an IC50 on DPPH (0.2 g L−1
) three-fold lower than ascorbic acid (0.6 g L −1
)
and as a metal chelating activity (IC50 = 0.4 g L−1
) significantly lower than EDTA. The obtained
results allow further exploration of the thermophilic G. gelatinosa for several biotechnological and
industrial applications.
Descrição
Palavras-chave
Gloeocapsa gelatinosa Extracellular polymeric substances Physicochemical characterization Functional properties Antioxidant activity Extremophilic Cyanobacteria . Faculdade de Ciências Exatas e da Engenharia
Contexto Educativo
Citação
Gongi, W., Gomez Pinchetti, J. L., Cordeiro, N., & Ouada, H. B. (2022). Extracellular polymeric substances produced by the Thermophilic Cyanobacterium Gloeocapsa gelatinosa: characterization and assessment of their antioxidant and metal-chelating activities. Marine Drugs, 20(4), 227.
Editora
MDPI