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Cyanobacterial extracellular carbohydrate polymers are particularly attractive for biotechnological applications. Previously, we determined the monosaccharidic composition of the polymer of a Synechocystis Δ sigF overproducing mutant. Here, we further characterized this polymer, demonstrated that it is possible to recover it in high yields, and successfully use it for biomedical research. This amorphous polymer is formed by a mesh of fibrils/lamellar structures with high porosity, is constituted by high molecular mass fractions, is highly sulfated and displays low viscosity, even in highly concentrated aqueous solutions. FTIR analysis confirmed the presence of several functional groups. We demonstrated that the Δ sigF polymer has strong biological activity, decreasing the viability of melanoma, thyroid and ovary carcinoma cells by inducing high levels of apoptosis, through p53 and caspase-3 activation. Therefore, the Δ sigF Synechocystis mutant is a promising platform for the sustainable production of biological active carbohydrate polymer(s) with the desired characteristics for biomedical applications. • The Synechocystis Δ sigF polymer (SP) yield is 4-fold higher than wild-type. • SP is formed by fibrils/lamellae with high porosity and molecular mass fractions. • SP is sulphated, has several functional groups and non-Newtonian fluid behaviour. • SP strongly reduces the viability of different human tumor cell lines. • SP induces apoptosis in the human melanoma cell line Mewo via p53 and caspase-3. [ABSTRACT FROM AUTHOR]

Medical device-associated infections are a major health threat, representing about half of all hospital-acquired infections. Current strategies to prevent this problem based on device coatings with antimicrobial compounds (antibiotics or antiseptics) have proven to be insufficient, often toxic, and even promoting bacterial resistance. Herein, we report the development of an infection-preventive coating (CyanoCoating) produced with an extracellular polymer released by the marine cyanobacterium Cyanothece sp. CCY 0110. CyanoCoating was prepared by spin-coating and its bacterial anti-adhesive efficiency was evaluated against relevant etiological agents (Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa and Escherichia coli) and platelets, both in the presence or absence of human plasma proteins. CyanoCoating cytotoxicity was assessed using the L929 fibroblasts cell line. CyanoCoating exhibited a smooth topography, low thickness and high hydrophilic properties with mild negative charge. The non-cytotoxic CyanoCoating prevented adhesion of all the bacteria tested (≤80%) and platelets (

Cyanobacterium aponinum is a thermotolerant cyanobacterium species isolated from different thermal springs and showing potential therapeutic application thanks to the synthesis and release of exopolysaccharides with anti-inflammatory and immunomodulating properties. This work investigates the effects of temperature and light on growth rate, biomass yield, and released polysaccharides (RPS) synthesis in C. aponinum cultures. The highest biomass productivity was obtained at 40 °C (about 92 mg L d), while the highest RPS synthesis rate (about 10 mg L d) was detected at 35 °C. At this temperature, the influence of light intensities, between 15 and 650 μmol photons m s, was also evaluated. C. aponinum showed the highest productivity in biomass (about 280 mg L d) and RPS (about 20 mg L d) at 500 μmol photons m s. Interestingly, this strain also had the ability to accumulate other high-value compounds such as phycocyanin, zeaxanthin, and β-carotene suggesting that C. aponinum can be used for the industrial production of multiple molecules of biotechnological interest. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPS) acting as cementing substance (chelator) of biological soil crusts (BSCs) are a considerable amount of metabolic investment for cyanobacteria. However, their partition mechanism has long been overlooked. In this paper, we investigated the effects of light intensity on production, distribution pattern, carbohydrate and protein contents, monosaccharide composition, and topographical structures of EPS from Microcoleus vaginatus, the first dominant cyanobacterium of BSCs. The results showed that the amounts of released Polysaccharides (RPS). capsular Polysaccharides (CPS), and total EPS increased with enhanced light intensity. The weaker the light, the higher the ratio of CPS to EPS and the lower the ratio of RPS to EPS. Although the highest light intensity significantly reduced the Charge distribution in RPS, it had no effect on the Charge distribution of CPS. For monosaccharide composition, although light intensity did not influence either RPS or CPS, the proportions of main components were still different. Carbohydrate, glucose, galactose, and arabinose were most abundant in RPS; whereas, glucose and galactose were highest in CPS. Comparison with protein content in RPS, carbohydrate was dominant in water eluates under 40 μE m-2s-1 , whereas protein was dominant in 1.0 M NaCl eluates. Carbohydrate was dominant in both eluates under 80 μE m-2s-1. Protein content of the same fraction in CPS generally decreased with increasing light intensity. The images from atomic force microscopy showed that light intensity significantly affected the molecular weight of EPS, as well as the topographical structures, namely, long chains only found in RPS at 80 μE m-2s-1 and CPS at 4 μE m-2s-1. Short chains and irregular lumps occurred under all test light intensities. The above results strongly suggested that light intensity not only affects the EPS yield but also its partition pattern, component, and spatial structure. Therefore, light intensity also likely influences BSCs gluing cohesion. [ABSTRACT FROM AUTHOR]

Abstract: Cyanobacterial extracellular polymeric substances (EPS) are heteropolysaccharides that possess characteristics suitable for industrial applications, notably a high number of different monomers, strong anionic nature and high hydrophobicity. However, systematic studies that unveil the conditions influencing EPS synthesis and/or its characteristics are mandatory. In this work, Cyanothece sp. CCY 0110 was used as model organism. Our results revealed that this strain is among the most efficient EPS producers, and that the amount of RPS (released polysaccharides) is mainly related to the number of cells, rather than to the amount produced by each cell. Light was the key parameter, with high light intensity enhancing significantly RPS production (reaching 1.8gL−1), especially in the presence of combined nitrogen. The data showed that RPS are composed by nine different monosaccharides (including two uronic acids), the presence of sulfate groups and peptides, and that the polymer is remarkably thermostable and amorphous in nature. [Copyright &y& Elsevier]

Medical device-associated infections are a major health threat, representing about half of all hospital-acquired infections. Current strategies to prevent this problem based on device coatings with antimicrobial compounds (antibiotics or antiseptics) have proven to be insufficient, often toxic, and even promoting bacterial resistance. Herein, we report the development of an infection-preventive coating (CyanoCoating) produced with an extracellular polymer released by the marine cyanobacterium Cyanothece sp. CCY 0110. CyanoCoating was prepared by spin-coating and its bacterial anti-adhesive efficiency was evaluated against relevant etiological agents (Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa and Escherichia coli) and platelets, both in the presence or absence of human plasma proteins. CyanoCoating cytotoxicity was assessed using the L929 fibroblasts cell line. CyanoCoating exhibited a smooth topography, low thickness and high hydrophilic properties with mild negative charge. The non-cytotoxic CyanoCoating prevented adhesion of all the bacteria tested (≤80%) and platelets (<87%), without inducing platelet activation (even in the presence of plasma proteins). The significant reduction in protein adsorption (<77%) confirmed its anti-adhesive properties. The development of this anti-adhesive coating is an important step towards the establishment of a new technological platform capable of preventing medical device-associated infections, without inducing thrombus formation in blood-contacting applications. [ABSTRACT FROM AUTHOR]