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The growing world food demand has led to the search for new sources of highly nutritious biomass. Cyanobacteria can be used not only as a source of compounds of biotechnological interest, but also as food for animals and humans, because of their high nutritional quality. The aim of this study was to evaluate the biomass production of nitrogen fixing filamentous cyanobacteria Nostoc LAUN0015 and Anabaena MOF015 outdoors at two culture volumes: 50 and 100 L using BG11 with no nitrogen as culture medium without nitrogen. Growth was followed by turbidity and determination of pigments until reaching stationary phase of growth. The Biomass was harvested, dried and used for the determination of dry mass of protein, carbohydrates and phycohiliprotrin total lipids. Anabaena MOF015 produced the highest values of dry mass, chlorophyll, phycocyanin, phycoerythrin, proteins and lipids with 3.85 ±0.41 g L-1, 3.76 ±0.51, 6.16 ±0.85, 2.79 ±0.25, 250.31 ±10.01 and 20.11 ±1.01 μg mL-1 respectively in a volume of 50 L culture. Nostoc LAUN0015 reached the maximum production of carbohydrates of 754.17 ±79.86 μg mL-1. Anabaena MOF015 is prominent for further growth and production of dry biomass and metabolites (p<0.05) in diazotrophic conditions, which means more economical culture systems with great biotechnological value. [ABSTRACT FROM AUTHOR]

Nitrogen concentration is an essential parameter in cyanobacterial cultures to produce enriched biomass with biotechnological purposes. Growth and biochemical composition of Nostoc LAUN0015, Nostoc UAM206, Anabaena sp.1 and Anabaena sp.2 were compared at 0, 4.25, 8.5 and 17 mM NaNO3. Cultures under laboratory conditions were maintained for 30 days at a volume of 500 mL. Anabaena sp.1 yielded the highest value of dry mass of 0.26 ± 2.49 mg mL-1 at 8.5 mM NaNO3. For chlorophyll, phycocyanin and phycoerythrin, maximum values were achieved at 17 mM NaNO3 with 18.09 ± 1.74, 102.90 ± 6.73 and 53.47 ± 2.40 μg mL-1, respectively. Nostoc LAUN0015 produced its maximum value of protein 644.86 ± 19.77 μg mL-1, and 890 mg mL-1 of carbohydrates in the absence of nitrogen. This comparative study shows that the most efficient strain for the production of protein, carbohydrates and lipids in diazotrophic conditions corresponded to Nostoc LAUN0015. However, Anabaena sp.1 and Anabaena sp.2 required high nitrogen concentrations to achieve higher values of metabolites, comparing with Nostoc strains. Nitrogen dependence for the production of pigments and high protein production in strains of Anabaena and in diazotrophic conditions for Nostoc was demonstrated. Nostoc can be cultured under nitrogen deficiency and Anabaena in sufficiency, for biomass production enriched with proteins and carbohydrates. [ABSTRACT FROM AUTHOR]

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Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria from saline environments. Cyanobacteria from these environments have biotechnological potential for the production of metabolites with pharmaceutical and industrial interest. We studied the growth, dry mass and metabolite production of the cyanobacterium Synechococcus sp. MOF-03 in function of irradiance (78, 156 and 234 μmol q m-2 s-1). All batch cultures were maintained by triplicate in constant aeration, 12:12 h photoperiod, 30 ±2°C and 35‰. Maximum values of protein, carbohydrates and lipids, of 530.19 ±11.16, 408.94 ±4.27 and 56.20 ±1.17 μg ml-1, respectively, were achieved at 78 μmol q m-2 s-1. Pigments, analyzed by HPLC, showed maximum values at 78 μmol q m-2 s-1 for chlorophyll a with 7.72 ±0.16 μg ml-1, and at 234 μmol q m-2 s-1 for β-carotene and zeaxanthin with 0.70 ±0.01 and 0.67 ±0.05 μg ml-1. Chlorophyll a:β-carotene ratio decreased from 17.15 to 6.91 at 78 and 234 μmol q m-2 s-1; whereas β-carotene:zeaxanthin ratio showed no changes between 78 and 156 μmol q m-2 s-1, around 1.21, and decreased at 234 μmol q m-2 s-1, to 1.04. Also, this cyanobacterium produced the greatest cell density and dry mass at 156 μmol q m-2 s-1, with 406.13 ±21.74 x106 cell ml-1 and 1.49 ±0.11 mg ml-1, respectively. Exopolysaccharide production was stable between 156 y 234 μmol q m-2 s-1, around 110 μg ml-1. This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites. [ABSTRACT FROM AUTHOR]