Abstract

DELGADILLO RODRIGUEZ, Ibeth Paola; MONTENEGRO RUIZ, Luis Carlos; PINILLA AGUDELO, Gabriel Antonio  and  MELGAREJO, Luz MARINA. Measuring of the Chlorophyll a Fluorescence in Calcium Alginate-Encapsulated Algae. Acta biol.Colomb. [online]. 2017, vol.22, n.2, pp.199-208. ISSN 0120-548X.  https://doi.org/10.15446/abc.v22n2.60741.

ABSTRACT Immobilization of algae has many applications, such as water bioremediation and production of metabolites. One of the variables that can be determined in the immobilized algae is chlorophyll a fluorescence, because this parameter is related to the physiological response ofthese organisms. Therefore, the objective ofthis study was to explore a method for measuring the chlorophyll a fluorescence in calcium alginate-encapsulated algae. To do this, two species of microalgae (Scenedesmus ovalternus LAUN 001 and Parachlorella kessleri LAUN 002) were grown in monocultures in both free culture conditions (10 mL of algae preparation in 250 mL of Basal Bold Medium) and encapsulated (250 spheres in 250 mL of Basal Bold Medium). Different measurement protocols of chlorophyll a fluorescence of photosystem II (PSII) were performed by varying a) the preadaptation time to darkness (10, 15 and 30 min), b) the light intensity of the non-modulated fluorometer (between 1000 and 3500 Llmoles m^-2s^-1), and c) the time of exposure to actinic light (1, 2 and 5 s). The optimal conditions for the measurement of the maximum quantum yield ofPSII (F_v/F_m) in encapsulated algae were established as follow: a) 30 min of preadaptation time; b) 3000 Llmoles m^-2s^-1 of the fluorometer light intensity; and c) 1 to 2 s of exposure to actinic light. The following values in the photochemical activity of algae in non-stressful conditions were found: 0.760 - 0.764 for S. ovalternus, and 0.732 - 0.748 for P. kessleri. This methodology allows to observe some changes in the photochemical activity related with variations in the factors under which are the immobilized algae.

Keywords : immobilized algae; maximum quantum yield of PSII; microalgae; Parachlorella kessleri; Scenedesmus ovalternus.

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