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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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Advisor(s)
Abstract(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.
Description
Keywords
Gloeocapsa gelatinosa Extracellular polymeric substances Physicochemical characterization Functional properties Antioxidant activity Extremophilic Cyanobacteria . Faculdade de Ciências Exatas e da Engenharia
Citation
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.
Publisher
MDPI