GUIMARÃES, B. S.; http://lattes.cnpq.br/8917611742350918; GUIMARÃES, Bruna da Silveira.
Résumé:
Microalgae are unicellular microorganisms that can grow in both freshwater and
saltwater. They are chlorophyll and are practically in all kinds of water on the planet.
Its cultivation is increasingly attracting interest since the applicability has been
observed in several segments, such as in the treatment of water, nutrition and energy
generation. The microalgae Scenedesmus sp. is chlorophyllated, unicellular and
uninucleate and belongs to Scenedesmaceae family, genus Scenedesmus. This
microalgae is more common in fresh water and can be found less frequently in
brackish water with salinity between 0.05 and 3% salts (500-30000 ppm). It has
ellipsoidal shape, linear colonies and grouped in numbers 4, 8, 16 or 32. This study
aimed growth kinetics study of microalgae Scenedesmus sp. in brackish means, by
producing two synthetic culture media with the addition of NaCl and MgCl2 salts, with
a view to possible subsequent utilizations of brackish water for the production of
microalgae. It has been found that the presence of salts influences the growth of
such microorganisms. Analyzing the microbial growth curves of the microalgae
Scenedesmus sp., it was noted that, in the means containing magnesium chloride,
the Lag phase or latency hardly occurred, with the exception of media with
concentration of 8000 mg.L-1, indicating that the microalgae took less time to adapt to
the medium with addition of MgCl2, compared with media containing NaCl. It was
also found that the influence of chloride ion in the growth of microalgae was
decreased due to the presence of sodium and magnesium ions, nutrients that are
important in cellular metabolism. By analyzing the calculated kinetic parameters
(maximum growth rate, productivity of biomass and generation time), it was observed
that the best results were obtained in media containing magnesium chloride,
indicating a better growth kinetics in these media compared to those containing NaCl.
This was due to the fact that Mg is classified as a macronutrient or essential nutrient,
important for cell metabolism of microalgae, and sodium is classified as a
micronutrient (required in smaller amounts). The influence of that ion (Mg) in
microalgae growing has been more observed than sodium ions influence. Based on
the kinetic results, the possibility of the microalga Scenedesmus sp growth. in
brackish means has been verified.