Anticoagulant and antibacterial activities of polysaccharides fraction from Nostoc muscorum and Arthrospira platensis cultivated under abiotic stress conditions

BackgroundCyanobacteria are very old phylogenetic group of prokaryotic phototrophicmicroorganisms. With repeated quick adaptations to different environmental circumstances in different ecosystems, their presence in the biosphere from the early Precambrian and extensive diversity up to the present witness to with theiramazingandcontinuousphysiologicallyandenvironmentallyimportantlifestrategies.Polysaccharides have recently attracted a lot of attention their efficiency in various biological activities, including immunomodulatory, antibacterial, anticoagulant, antimutagenic, radioprotective, anti-oxidative, and anticancer. So, this researchdemonstrates the role of algal polysaccharides, produced under abiotic stress condition, in some of these biological activities.ObjectiveThe aim of this study was selectedNostoc muscorum and Arthrospira platensis ascyanobacteria species for studying the effect of some abiotic stress conditions (light intensity & sulfate concentrations and aeration rate) on polysaccharide production(intracellular and extracellular). Evaluate the ability of the different algal extracts asanticoagulants and antibacterial.Materials and methodsN. muscorum was cultivated on BG-110medium andA. platensis was cultivated on Zarrouk medium. Algal species were grown and incubated in controlled photo period of, 16-8 l/D cycles, light intensity of 40 mu E/m2/s and temperature at 25 degrees C +/- 2 degrees C with continuous aeration supplied with air (60 bubbles/min.). Cultivation of algae under a biotic stress conditions and the growth rate of both investigated species was determined by optical density and dry cell weight. Extraction of polysaccharides by different methods and determination of total hydrolysable carbohydrates. Determination of sulfate contents. Protein molecular weight determination in algal species were determined by SDS-page. Determination of bacterial activity of different algal extracts, was tested in vitro against G+ and G-bacterial strains using the filter paper disk diffusion method, The Gram-positive bacterial strains, Staphylococcus aureus and the gram-negative strains, Pseudomonas aeruginosa, Also the anticoagulating activity of promising algal extracts was investigated using the method of US pharmacopeia.Results and conclusionThere was positive correlation between light intensity, MgSO(4)concentrations and aeration, on algal growth and polysaccharide production. Ethanol was found to behighly efficient for polysaccharide extraction. Intracellular polysaccharide content was higher than extracellularly released one in both the studied cyano bacteriaspecies. Intracellular polysaccharides of A. platensis exhibited antibacterial activity higher than those of N. muscorum. Anticoagulation efficiency of sulfated polysaccharides in both investigated stressed cyanobacteria species was highly pronounced (>30min). Chemically active groups showed by FT-IR of the produced polysaccharides under stressed conditions are variable depending on both the type of stress and the method of extraction.