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Sargassum muticum and Osmundea pinnatifida enzymatic extracts: chemical, structural, and cytotoxic characterization

Publication . Rodrigues, Dina; Costa-Pinto, Ana R.; Sousa, Sérgio; Vasconcelos, Marta W.; Pintado, Manuela M.; Pereira, Leonel; Rocha-Santos, Teresa A. P.; Costa, João P. da; Silva, Artur M. S.; Duarte, Armando C.; Gomes, Ana M. P.; Freitas, Ana C.

Seaweeds, which have been widely used for human consumption, are considered a potential source of biological compounds, where enzyme-assisted extraction can be an efficient method to obtain multifunctional extracts. Chemical characterization of Sargassum muticum and Osmundea pinnatifida extracts obtained by Alcalase and Viscozyme assisted extraction, respectively, showed an increment of macro/micro elements in comparison to the corresponding dry seaweeds, while the ratio of Na/K decreased in both extracts. Galactose, mannose, xylose, fucose, and glucuronic acid were the main monosaccharides (3.2–27.3 mg/glyophilized extract) present in variable molar ratios, whereas low free amino acids content and diversity (1.4–2.7 g/100gprotein) characterized both extracts. FTIR-ATR and 1H NMR spectra confirmed the presence of important polysaccharide structures in the extracts, namely fucoidans from S. muticum or agarans as sulfated polysaccharides from O. pinnatifida. No cytotoxicity against normal mammalian cells was observed from 0 to 4 mglyophilized extract/mL for both extracts. The comprehensive characterization of the composition and safety of these two extracts fulfils an important step towards their authorized application for nutritional and/or nutraceutical purposes.

2019Journal article

Open access

Salinity induced effects on the growth rates and mycelia composition of basidiomycete and zygomycete fungi

Publication . Venâncio, C.; Pereira, R.; Freitas, A. C.; Rocha-Santos, T. A. P.; Costa, J. P. da; Duarte, A. C.; Lopes, I.

Soil salinization, as the combination of primary and secondary events, can adversely affect organisms inhabiting this compartment. In the present study, the effects of increased salinity were assessed in four species of terrestrial fungi: Lentinus sajor caju, Phanerochaete chrysosporium, Rhizopus oryzae and Trametes versicolor. The mycelial growth and biochemical composition of the four fungi were determined under three exposure scenarios: 1) exposure to serial dilutions of natural seawater (SW), 2) exposure to serial concentrations of NaCl (potential surrogate of SW); and 3) exposure to serial concentrations of NaCl after a period of pre-exposure to low levels of NaCl. The toxicity of NaCl was slightly higher than that of SW, for all fungi species: the conductivities causing 50% of growth inhibition (EC50) were within 14.9 and 22.0 mScm−1 for NaCl and within 20.2 and 34.1 mScm−1 for SW. Phanerochaete chrysosporium showed to be the less sensitive species, both for NaCl and SW. Exposure to NaCl caused changes in the biochemical composition of fungi, mainly increasing the production of polysaccharides. When fungi were exposed to SW this pattern of biochemical response was not observed. Fungi pre-exposed to low levels of salinity presented higher EC50 than fungi non-pre-exposed, though 95% confidence limits overlapped, with the exception of P. chrysosporium. Pre-exposure to low levels of NaCl also induced changes in the biochemical composition of the mycelia of L. sajor caju and R. oryzae, relatively to the respective control. These results suggest that some terrestrial fungi may acquire an increased tolerance to NaCl after being pre-exposed to low levels of this salt, thus, suggesting their capacity to persist in environments that will undergo salinization. Furthermore, NaCl could be used as a protective surrogate of SW to derive safe salinity levels for soils, since it induced toxicity similar or higher than that of SW.

2017Journal article

Restricted access

Pedobacter lusitanus sp. nov., isolated from sludge of a deactivated uranium mine

Publication . Covas, Cláudia; Caetano, Tânia; Cruz, Andreia; Santos, Tiago; Dias, Liliana; Klein, Guenter; Abdulmawjood, Amir; Rodriguez-Alcala, Luis M.; Pimentel, Ligia L.; Gomes, Ana; Freitas, Ana Cristina; Garcia-Serrano, Alba; Fontecha, Javier; Mendo, Sonia

Strain NL19(T) is a Gram-stain-negative, aerobic bacterium that was isolated from sludge of a deactivated uranium mine in Portugal. 16S rRNA gene sequence analysis revealed that strain NL19(T) is a member of the genus Pedobacter and closely related to the strains Pedobacter himalayensis MTCC 6384(T), Pedobacter cryoconitis DSM 14825(T), Pedobacter westerhofensis DSM 19036 (T) and Pedobacter hartonius DSM 19033(T). It had a DNA G+C content of 40.8 mol%, which agreed with the genus description. The main fatty acids included C-16 : 1 omega 7c, C-14 : 1 omega 5c, C-4 : 0, iso-C-17 : 0, iso-C-17 : 0 3-OH, C-16 : 0, anteiso-C-15 : 0 and isoC(15 : 0) 3-OH. The main lipids present were phospholipids (60 %) and sphingolipids (35 %). The most abundant phospholipids included phosphatidylethanolamine, phosphatidylinositol and phosphatidylcholine. Menaquinone-7 (MK-7) was the only isoprenoid quinone detected. DNA-DNA hybridization similarities between strain NL19(T) and Pedobacter himalayensis MTCC 6384(T), Pedobacter cryoconitis DSM 14825(T), Pedobacter westerhofensis DSM 19036(T) and Pedobacter hartonius DSM 19033(T) were 15.3, 16.2, 11.5 and 16.0 %, respectively. Strain NL19(T) can also be distinguished from these four species based on gyrB and intergenic transcribed spacers (ITS) sequences and by some phenotypic traits such as NaCl tolerance, pH, growth temperature and carbon source utilization. Strain NL19(T) represents a novel species of the genus Pedobacter, for which the name Pedobacter lusitanus sp. nov. is proposed. The type strain is NL19(T) (= LMG 29220(T) = CECT 9028(T)). An amended description of Pedobacter himalayensis is also included.

2017Journal article

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Carbon nanotube field effect transistor biosensor for the detection of toxins in seawater

Publication . Marques, Inês; Costa, João Pinto da; Justino, Celine; Santos, Patrícia; Duarte, Kátia; Freitas, Ana; Cardoso, Susana; Duarte, Armando; Rocha-Santos, Teresa

Disposable field effect transistors (FET) biosensors (bio-FET) based on carbon nanotubes were fabricated for detection of domoic acid (DA), which belongs to the group of biotoxins associated with the amnesic shellfish poisoning. The analytical results obtained with the bio-FET were compared with those obtained with a traditional methodology (enzyme-linked immunosorbent assay) in order to validate the bio-FET for DA detection. Standard solutions of DA with concentrations between 10 and 500 ng L−1 were tested in order to construct the calibration curve, where five bio-FET were used for reproducibility estimation and two analytical measurements were performed for each bio-FET for repeatability estimation. Ten spiked artificial seawater samples were used to validate the bio-FET. The obtained reproducibility (0.52–1.43%), repeatability (0.57–1.27%), limit of detection (10 ng L−1) and recovery range (92.3–100.3%) reveal an adequate analytical performance of the bio-FET for the detection of DA in environmental samples such as seawater samples.

2017Journal article

Restricted access

Chemical and structural characterization of Pholiota nameko extracts with biological properties

Publication . Rodrigues, Dina; Freitas, Ana C.; Sousa, Sérgio; Amorim, Manuela; Vasconcelos, Marta W.; Costa, João P. da; Silva, Artur M. S.; Rocha-Santos, Teresa A. P.; Duarte, Armando C.; Gomes, Ana M. P.

Edible mushrooms including Pholiota nameko are excellent sources of extractable bioactive compounds with much to explore. Enzymatic extractions with Cellulase and Viscozyme were responsible for highest extraction yields (67-77%). No strong antioxidant activity was observed although extracts were able to scavenge ABTS(+) and OH(+). Potential prebiotic activity was observed in all extracts, some increasing 1.4-2 Log cycles of Lactobacillus acidophilus La-5 and Bifidobacterium animalis BB12. 30-50% α-glucosidase inhibition was observed in ultrasound, Flavourzyme and Cellulase extracts. Flavourzyme and Cellulase extracts are richer in macro (Mg, K and P) and micro elements (Zn, Mn and Fe) in comparison to mushroom. Monosaccharides content and profile varied slightly among both extracts with predominance of glucose, galactose and mannose with no uronic acids detection; Flavourzyme extract reported higher free amino acids content. Presence of α and β-glycosidic structures such as glucans and glucan-protein complexes are among the polysaccharides found in both extracts.

2017Journal article

Restricted access