Abstract
A study of the influence of different laboratory growth conditions on the biomass and EPS production by Nostoc minutum, a diazothophic cyanobacterium locally isolated, was carried out. Two culture media were tested, with or without NaNO3 addition, and three luminous intensities: low (4530 lux), intermediate (7300 lux) and high (9860 lux). BW3 medium was better than BG11 for N. minutum growth, with maximal values of biomass concentration (4.98 DO) and the highest growth rate (0.019 h-1) at 9860 lux of light intensity. A progressive increase in culture viscosity of N. minutum cultures was observed, for stirred condition and non-diazotrophic growth in BG11 medium, together with the production of maximal EPS concentration (2.485 g/L). On the other hand, the EPS production in BW3 medium was maximal in diazotrophic conditions, both for still (1.66 g/L) and stirred (2.56 g/L) cultures. The different yields of EPS reported for each condition, results in the requirement of a species-specific optimization of the cultivation conditions for the exploitation of an efficient technology for the production of N. minutum EPS.
Highlights
Cyanobacteria are photosynthetic microorganisms with morphological diversity and metabolic versatility
The aim of this work was to study the influence of different laboratory growth conditions on the biomass and Extracellular Polymeric Substance (EPS) production by Nostoc minutum, a diazothophic cyanobacterium locally isolated
Stock cyanobacterial cultures were maintained in the BW3 medium with the following composition (g/L): K2HPO4 0.25; NaHCO3 0.5; MgSO4 0.7 H2O 0.375; CaCl2 0.4; NaCl 4; NaNO3 0.5; FeCl3∙6H2O 0.024; EDTA.2H2O 0.0625; micronutrients 6.25 ml [14] and BG11 medium with the following composition (g/L): NaNO3 1.5; K2HPO4∙3H2O 0.04; MgSO4∙7H2O 0.075; CaCl2∙2H2O 0.036; C6H8O7 0.06; C6H5+4yFexNyO7 0.06; Na2EDTA 0.0005; Na2CO3∙(H2O) 0.010; micronutrients 1 ml [15]
Summary
Cyanobacteria are photosynthetic microorganisms with morphological diversity and metabolic versatility. They are included in a wide range of microorganisms that are able to synthesize and secrete extracellular polymeric. How to cite this paper: Pereyra, D.S.V. and Ferrari, S.G. (2016) Extracellular Polymeric Substance (EPS) Production by Nostoc minutum under Different Laboratory Conditions. G. Ferrari substances (EPS) mainly of polysaccharidic nature, which can remain covalently linked or loosely bound to the cell surface, or be liberated to the surrounding medium [1]
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