Protective effect against gastric mucosa injury of a sulfated agaran from Acanthophora spicifera.

In this study, a polysaccharide from marine alga Acanthophora spicifera (PAs) was isolated and structurally characterized. Its protective potential against chemically-induced gastric mucosa injury was evaluated. The gel permeation chromatography experiments and spectroscopy spectrum showed that PAs is a sulfated polysaccharide with a high molecular mass (6.98 × 105g/mol) and degree of sulfation of 1.23, exhibiting structural characteristic typical of an agar-type polysaccharide. Experimental results demonstrated that PAs reduced the hemorrhagic gastric injury, in a dose-dependent manner. Additionally, PAs reduced the intense gastric oxidative stress, measured by glutathione (GSH) and malondialdehyde (MDA) levels. PAs also prevented the reduction of mucus levels adhered to the gastric mucosa, promoted by the aggressive effect of ethanol. In summary, the sulfated polysaccharide from A. spicifera protected the gastric mucosa through the prevention of lipid peroxidation and enhanced the defense mechanisms of the gastric mucosa, suggesting as a promising functional food as gastroprotective agent.

Extraction of sulfated agar from Gracilaria lemaneiformis using hydrogen peroxide-assisted enzymatic method.

In this study, an eco-friendly extraction method was explored to obtain high sulfate content agar and repair the deficiency of enzymatic extraction by taking full advantage of H2O2. The sulfate content of EHA (H2O2-assisted enzymatic extracted agar) reached 3.56 %, which is significantly higher than that of traditional alkali-extracted agar (AA, 1.8 %). Moreover, EHA exhibited lower viscosity (9.4 cP), which improved 26.6 % and 14 % of filtration and gel dehydration rates than EA (enzymatic extracted agar), respectively. Additionally, the physicochemical properties of the agars were evaluated and compared. Among these agars, EHA showed some favorable properties, such as high yield (16.08 %) and low dissolution temperature (88.9 °C). The surface of algae became smoother after treatment with H2O2 due to effective degradation of cellulose. Besides, mass spectrometry analysis revealed that EHA preserved a great amount of sulfate, while thermogravimetric analysis suggested that the thermal stability of EA and EHA both decreased.

Evaluación de una pauta de detección de colonización vaginorrectal por Streptococcus agalactiae usando medio de cultivo GBS modified / Evaluation of a pattern of culture for detecting Streptococcus agalactiae carriage using GBS modified médium

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Successful Approaches for a Red Seaweed Biorefinery.

Macroalgae have been commercially exploited as food and for the production of phycocolloids, but they also contain compounds with potential in pharmaceutical, nutraceutical, cosmetic, chemical and energetic applications. The biorefinery concept applied to seaweed facilitates the extraction of different constituents ensuring full utilization of resources and generating few residues through a succession of steps. Seaweed biorefineries are less advanced than those based on terrestrial biomass and the design of efficient processes requires further study. This review presents practical successful examples to obtain two or more commercially valuable components from red seaweeds. The selected processes consist on cascading stages of both conventional and alternative techniques to illustrate different possible valorization strategies.

Integral Utilization of Red Seaweed for Bioactive Production.

The hydrocolloids carrageenan and agar are the major fraction industrially extracted and commercialized from red seaweeds. However, this type of macroalgae also contains a variety of components with nutritional, functional and biological properties. In the context of sustainability and bioeconomy, where the integral utilization of the natural resources is incentivized, the sequential separation and valorization of seaweed components with biological properties of interest for food, nutraceuticals, cosmeceuticals and pharmaceuticals is proposed. In this work, a review of the available conventional and alternative greener and efficient extraction for obtaining red seaweed bioactives is presented. The potential of emerging technologies for the production of valuable oligomers from carrageenan and agar is also commented, and finally, the sequential extraction of the constituent fractions is discussed.

Gracilariopsis hommersandii, a red seaweed, source of agar and sulfated polysaccharides with unusual structures.

Red seaweed Gracilariopsis hommersandii produces important amounts of non-gelling galactans, which were extracted with hot water (GrC, yield, 37%, viscosity average molecular weight, Mv 109 kDa), comprising agarose and sulfated galactan structures. The alkali modified derivative, GrCTr (Mv 95 kDa), gave a galactose:3,6-anhydrogalactose molar ratio of 1.0:0.9, and a more regular structure, favouring gelation (melting and gelling temperatures 64 and 14 °C, respectively). The rheological properties of this product suggest possible applications as hydrocolloid. G. hommersandii also biosynthesizes non gelling sulfated galactan fractions with diads constituted by ß-d-galactose and partially cyclized α-l-galactose units or non-cyclized α-d-galactose residues. Sulfation was mainly detected on C6 or C4 of the ß-d-galactose units, and on C6 and, in minor amounts, on C3 of the α-l-galactose units. The presence of ß-apiuronic acid was demonstrated for these fractions as side chains of the galactan backbone. Carrageenan structures were found for the first time in an agarophyte of the Gracilariales.

Oligosaccharides Derived from Red Seaweed: Production, Properties, and Potential Health and Cosmetic Applications.

Because of their potential use as functional ingredients in human nutrition, oligosaccharides derived from natural sources are receiving paramount consideration. Red seaweed, a proven rich source of agar and carrageenan, is one of the most abundantly present sources of such oligosaccharides. Agaro-oligosaccharides (AOS) and carrageenan-oligosaccharides (COS) are produced from agar and carrageenan, respectively, through chemical and enzymatic hydrolyses. Enzymatic hydrolysis of agar and carrageenan into oligosaccharides is preferred in industrial production because of certain problems associated with chemical hydrolysis, including the release of high amounts of monosaccharides and undesirable toxic products, such as furfural. AOS and COS possess many biological activities, including prebiotic, immuno-modulatory, anti-oxidant, and anti-tumor activities. These activities are related to their chemical structure, molecular weight, degree of polymerization, and the flexibility of the glycosidic linkages. Therefore, the structure⁻function relationship and the mechanisms occurring during the specific biological applications of AOS and COS are discussed herein. Moreover, the chromatographic separation, purification, and characterization of AOS and COS are also part of this review. This piece of writing strives to create a new perspective on the potential applications of AOS and COS in the functional food and pharmaceutical industry.

Fluconazole-containing agar Sabouraud dextrose plates are not useful when screening for susceptibility in Candida albicans / Las placas de agar dextrosado de Sabouraud con fluconazol no son útiles para la detección de resistencia en Candida albicans

Introduction. Fluconazole is an alternative for candidemic patients who are not critically ill. Fluconazole is mainly fungistatic and does not completely inhibit visual Candida albicans growth. We studied the usefulness of fluconazolecontaining Sabouraud dextrose agar plates for detecting susceptibility to fluconazole in C. albicans. Material and methods. Adjusted inocula of 19 isolates were transferred directly onto fluconazole-containing Sabouraud dextrose plates (concentrations ranging from 0.125 mg/L to 128 mg/L). The fluconazole MIC in fresh isolates and after growth on the fluconazole-containing plate at 128 mg/L was recorded following the EUCAST EDef 7.2 guidelines. Then isolates were classified according to their degree of trailing production, based on microdilution procedure. Results. All isolates were able to grow on all fluconazolecontaining plates, even those isolates susceptible to fluconazole. In fact, we selected isolates with different degrees of trailing based on microdilution procedures. 50% of isolates classified as heavy trailers, 35.71% as moderate trailers, and 14.28% as slight trailers. Conclusions. The use of fluconazole-containing Sabouraud dextrose agar plates was not a reliable method to detect fluconazole susceptibility in C. albicans isolates; growth of the isolates was a trailing effect rather than true resistance (AU)

Introducción. Fluconazol es el antifúngico de elección en pacientes con candidemia que no están en estado crítico. Fluconazol es un fármaco fungistático y no inhibe por completo el crecimiento de Candida albicans. En este estudio se evalúa la posibilidad de emplear placas de agar dextrosado de Sabouraud con diferentes concentraciones de fluconazol como método para evaluar la sensibilidad a este fármaco de aislados de C. albicans. Material y métodos. El inóculo ajustado procedente de 19 aislados de C. albicans se transfirió directamente a placas que contenían concentraciones de fluconazol comprendidas entre 0,125 mg/L y 128 mg/L. La CMI de fluconazol se calculó en los aislados originales y en los aislados crecidos en la placa de fluconazol de 128 mg/L, según el protocolo de EUCAST EDef 7.2. Los aislados se clasificaron según su grado de producción de efecto de arrastre, siguiendo el procedimiento de microdilución. Resultados. Todos los aislados fueron capaces de crecer en todas las placas con diferentes concentraciones de fluconazol, incluso las cepas sensibles. Los aislados mostraron diferentes grados de efecto de arrastre. El 50% de los aislados se clasificaron como altamente productores, el 35,71% como moderadamente productores y el 14,28% como poco productores de efecto de arrastre. Conclusión. El uso de placas de agar dextrosado de Sabouraud con fluconazol no demostró ser un método útil para el estudio de la sensibilidad de C. albicans a este fármaco ya que el crecimiento de los aislados fue interpretado como efecto de arrastre y no como una verdadera resistencia (AU)

A simple process for recovery of a stream of products from marine macroalgal biomass.

The present study describes a simple process for recovering a stream of products sequentially including bioethanol from the fresh biomass of the red seaweed Gracilaria corticata. From processing of 100g fresh biomass (∼12.2 g dry), 166 ± 3 µg/g R-phycoerythrin, 126±4µg/g R-phycocyanin can be realized on fresh weight basis, and 1.41 ± 0.03% crude lipid, 22.45 ± 0.53% agar, 12.39 ± 0.85% soil conditioner, 2.89 ± 0.04% bioethanol on dry weight basis along with 318 ± 3 ml of mineral rich liquid with possible fertilizer applications. The advantages of this process are complete utilization of feedstock without compromising the yield and quality of products, reusability of solvents and no solid waste. Further, the products recovered from one ton fresh biomass were found to have an estimated market value of USD 1051 while processing cost including raw material as 241 USD, a fourfold value addition of feedstock.

Seaweed hydrocolloid production: an update on enzyme assisted extraction and modification technologies.

Agar, alginate, and carrageenans are high-value seaweed hydrocolloids, which are used as gelation and thickening agents in different food, pharmaceutical, and biotechnological applications. The annual global production of these hydrocolloids has recently reached 100,000 tons with a gross market value just above US$ 1.1 billion. The techno-functional properties of the seaweed polysaccharides depend strictly on their unique structural make-up, notably degree and position of sulfation and presence of anhydro-bridges. Classical extraction techniques include hot alkali treatments, but recent research has shown promising results with enzymes. Current methods mainly involve use of commercially available enzyme mixtures developed for terrestrial plant material processing. Application of seaweed polysaccharide targeted enzymes allows for selective extraction at mild conditions as well as tailor-made modifications of the hydrocolloids to obtain specific functionalities. This review provides an update of the detailed structural features of κ-, ι-, λ-carrageenans, agars, and alginate, and a thorough discussion of enzyme assisted extraction and processing techniques for these hydrocolloids.

RT-PCR testing of allograft musculoskeletal tissue: is it time for culture-based methods to move over?

Allograft musculoskeletal tissue samples are assessed for microbial bioburden to reduce the risk of post-transplant infection. Traditionally, solid agar and broth culture media have been used however, nucleic acid testing, such as real-time (RT) polymerase chain reaction (PCR), has been described as more sensitive. This study evaluated the recovery of low numbers of challenge organisms from inoculated swab and musculoskeletal biopsy samples using solid agar culture, cooked meat medium, blood culture bottles and a RT-PCR assay. It was found that broth culture methods were the most sensitive with RT-PCR unable to detect low numbers of bacteria from these samples. Investigation of other non-culture methods may be worthwhile.

Extraction of agar from Gelidium sesquipedale (Rhodopyta) and surface characterization of agar based films.

The chemical structure of the agar obtained from Gelidium sesquipedale (Rhodophyta) has been determined by (13)C nuclear magnetic resonance ((13)C NMR) and Fourier transform infrared spectroscopy (FTIR). Agar (AG) films with different amounts of soy protein isolate (SPI) were prepared using a thermo-moulding method, and transparent and hydrophobic films were obtained and characterized. FTIR analysis provided a detailed description of the binding groups present in the films, such as carboxylic, hydroxyl and sulfonate groups, while the surface composition was examined using X-ray photoelectron spectroscopy (XPS). The changes observed by FTIR and XPS spectra suggested interactions between functional groups of agar and SPI. This is a novel approach to the characterization of agar-based films and provides knowledge about the compatibility of agar and soy protein for further investigation of the functional properties of biodegradable films based on these biopolymers.

Natural porous agar materials from macroalgae.

Porous agar materials have been prepared from marine macroalgae species using a simple microwave-assisted extraction/drying methodology, providing a new family of polysaccharide derived porous solids. The microwave-assisted extraction allows a more efficient and less time-consuming extraction of the polysaccharide compared to conventional extraction protocols based on conventional heating. DRIFT and (13)C NMR results indicated that the internal agar structure (based on d-galactose and 3,6-anhydro-l-galactose linked units) was preserved after the extraction methodology, which opens a wide range of future possibilities and applications for this new family of porous polysaccharides. The extracted agar materials, which have already applications per se due to their high purities, could be subsequently transformed into a novel family of attractive mesoporous agar materials that could be used as natural templates for the production of nanocrystals of metal oxides.

Discordancia en los resultados de sensibilidad mediante método de difusión en agar de aislados de Pseudomonas aeruginosa en pacientes con fibrosis quística tras pre-incubación anaerobia y su potencial relevancia clínica / Discrepancy in the disk diffusion susceptibility test of Pseudomonas aeruginosa strains isolated from cystic fibrosis patients after anaerobic preincubation and its potential clinical relevance

Introducción. En la fibrosis quística las células de Pseudomonas aeruginosa crecen en el interior de la espesa mucosidad, y pese a ser un organismo aerobio estricto, se desarrolla en un ambiente donde la presión de oxígeno es muy limitada. Posibles movimientos de la masa mucosa podrían dejar expuestas de forma súbita a las células de P. aeruginosa a concentraciones altas de oxígeno. El objetivo del estudio fue determinar cómo afecta a la sensibilidad antibiótica de P. aeruginosa un período de incubación anaerobia. Material y métodos. Se emplearon 4 cepas de P. aeruginosa (NTCC 23389 y 3 aislados clínicos). Para la determinación de la sensibilidad antibiótica se empleó el método de difusión en agar. Resultados. La preincubación anaerobia produce cambios en la sensibilidad en todas las cepas estudiadas. Todas las cepas sensibles en aerobiosis resultaron también sensibles tras la incubación anaerobia a excepción de la cepa 2 para los betalactámicos. El tipo de respuesta resulta dependiente de cada cepa, siendo especialmente significativo el incremento en la sensibilidad observado en el caso de ciprofloxacino para dos de los tres aislados clínicos. Conclusiones. La sensibilidad de cepas P. aeruginosa varía si han sido previamente expuestas a condiciones de anaerobiosis. Tratamientos que favorezcan la fluidificación de la mucosidad podrían contribuir aumentando el éxito del tratamiento con ciertos antibióticos(AU)

Introduction. In cystic fibrosis, the Pseudomonas aeruginosa cells grow inside the thick mucus layer. In spite of being an obligate aerobe, P. aeruginosa is able to grow in a limited oxygen environment. Bacterial cells could be suddenly exposed to high oxygen levels due to the movements of the mucus mass. The aim of study was to determine the impact of a previous anaerobic incubation on the antimicrobial susceptibility of P. aeruginosa strains isolated from patients with cystic fibrosis. Materials and Methods. Four P. aeruginosa strains were used in this study (ATCC 23389 and 3 clinical isolates). The disk diffusion method was used to determine the antimicrobial susceptibility. Results. The anaerobic pre-incubation produced changes on the susceptibility in all studied strains. All susceptible strains after an aerobic incubation remained susceptible after an anaerobic incubation except one clinical strain, which became resistant to betalactams. The response was strain-dependent and the most significant increase in susceptibility was observed in two of the three clinical isolates when ciprofloxacin was used. Conclusions. The antimicrobial susceptibility of P. aeruginosa strains varies after their exposure to anaerobic conditions. Treatments promoting mucus fluidization could contribute to increase the antimicrobial efficacy(AU)

Complexation of WPI and microwave-assisted extracted agars with different physicochemical properties.

The complex formation between whey protein isolate (WPI) and agar has been investigated and their interactions were monitored as a function of the physicochemical properties of agar, the pH and the ionic strength of the medium. Agars from Gracilaria vermiculophylla were extracted under different MAE conditions and characterized according to their physicochemical properties. By using microwave irradiation a wide variety of agars was obtained, as different MAE conditions results in polyelectrolytes with distinct properties. UV-vis (in optical dispersion (O.D.) model) spectroscopy and isothermal titration calorimetry (ITC) have been used to study the formation of insoluble (coacervate) complexes. MAE agars revealed excellent properties for complex formation with WPI. The binding of WPI to MAE agar samples has been shown to be the result of different contributions. O.D. and ITC results showed that the molecular mass and the sulfate content of different agars had a determinant effect on coacervate formation.

Characterization of free nitrogen fixing bacteria of the genus Azotobacter in organic vegetable-grown Colombian soils

With the purpose of isolating and characterizing free nitrogen fixing bacteria (FNFB) of the genus Azotobacter, soil samples were collected randomly from different vegetable organic cultures with neutral pH in different zones of Boyacá-Colombia. Isolations were done in selective free nitrogen Ashby-Sucrose agar obtaining a recovery of 40 percent. Twenty four isolates were evaluated for colony and cellular morphology, pigment production and metabolic activities. Molecular characterization was carried out using amplified ribosomal DNA restriction analysis (ARDRA). After digestion of 16S rDNA Y1-Y3 PCR products (1487pb) with AluI, HpaII and RsaI endonucleases, a polymorphism of 16 percent was obtained. Cluster analysis showed three main groups based on DNA fingerprints. Comparison between ribotypes generated by isolates and in silico restriction of 16S rDNA partial sequences with same restriction enzymes was done with Gen Workbench v.2.2.4 software. Nevertheless, Y1-Y2 PCR products were analysed using BLASTn. Isolate C5T from tomato (Lycopersicon esculentum) grown soils presented the same in silico restriction patterns with A. chroococcum (AY353708) and 99 percent of similarity with the same sequence. Isolate C5CO from cauliflower (Brassica oleracea var. botrytis) grown soils showed black pigmentation in Ashby-Benzoate agar and high similarity (91 percent) with A. nigricans (AB175651) sequence. In this work we demonstrated the utility of molecular techniques and bioinformatics tools as a support to conventional techniques in characterization of the genus Azotobacter from vegetable-grown soils.

Agar extraction from integrated multitrophic aquacultured Gracilaria vermiculophylla: evaluation of a microwave-assisted process using response surface methodology.

Microwave-assisted extraction (MAE) of agar from Gracilaria vermiculophylla, produced in an integrated multitrophic aquaculture (IMTA) system, from Ria de Aveiro (northwestern Portugal), was tested and optimized using response surface methodology. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the physical and chemical properties of agar (yield, gel strength, gelling and melting temperatures, as well as, sulphate and 3,6-anhydro-L-galactose contents) was evaluated in a 2(4) orthogonal composite design. The quality of the extracted agar compared favorably with the attained using traditional extraction (2 h at 85 degrees Celsius) while reducing drastically extraction time, solvent consumption and waste disposal requirements. Agar MAE optimum results were: an yield of 14.4 + or - 0.4%, a gel strength of 1331 + or - 51 g/cm(2), 40.7 + or - 0.2 degrees Celsius gelling temperature, 93.1 + or - 0.5 degrees Celsius melting temperature, 1.73 + or - 0.13% sulfate content and 39.4 + or - 0.3% 3,6-anhydro-L-galactose content. Furthermore, this study suggests the feasibility of the exploitation of G. vermiculophylla grew in IMTA systems for agar production.

Agar from Gracilaria gracilis (Gracilariales, Rhodophyta) of the Patagonic coast of Argentina--content, structure and physical properties.

Milled summer thalli of Gracilaria gracilis from Argentina were sequentially extracted with water at room temperature (RTW1-3), 70 degrees C (W701-3) and 90 degrees C (W901-2). Both W701 and W901 consisted of high molecular weight polysaccharides (ca. 540,000Da), but polydispersity was higher for the major product W701 (yield, 72% of the recovered). Structural analyzes by methylation and (13)C NMR spectroscopy revealed that W701 was mainly agarose. Alkaline treatment, together with structural analyzes, indicated a negligible proportion of precursor l-galactose 6-sulfate residues in this product, while they were clearly detected in the (13)C NMR spectra of RTW2-3. The presence of floridean starch in W901 had an antagonistic effect on its gel strength, which resulted nearly three times lower than that of fraction W701. Ultrastructural observation by transmission electron microscopy showed that, after extraction with hot water, a partial loss of cell wall stratification and disorganization of the cuticle had occurred. Final cellular debris exhibited swelling in the microfibrillar component. After this first thorough study of the chemical composition and physical properties of the products of G. gracilis from Bahía Bustamante we conclude that a good quality agarose is obtained in high yield after extraction with water at 70 degrees C without the requirement of alkaline pretreatment, which usually produces degradation of the polysaccharide.

Stability of agar in the seaweed Gracilaria eucheumatoides (Gracilariales, Rhodophyta) during postharvest storage.

The status of the cell-wall polysaccharide of the red seaweed, Gracilaria eucheumatoides upon postharvest storage was assessed in this study. The yield, chemical composition, physical and textural properties of alkali-treated agar extract was determined at different time intervals within 31 months of storage at dried state after harvest. Minimal fluctuation in agar yield was observed, ranging from 22.9% to 29.0%. The gel strength of agar extracts averaged 318gcm(-2) until the third month of storage but decreased considerably thereafter. The relative viscosity and molecular weight of the extracts varied inversely with storage time. Results indicated that both physical and textural parameters of agar generally decreased with storage time, likely due to depolymerization as indicated by decrease in molecular weight. Agar extracted from seaweeds up to 3 months of storage could be considered to exhibit gel quality suitable for food applications. Prolonged storage of the seaweed harvest is not recommended.