Protocolo de cultivo e identificação de compostos bioativos na microalga Scenedesmus Obtusus

Abstract

Microalgae, as photosynthetic organisms, possess the ability to produce a variety of high-valuecompounds. Like any living organism, they respond to stimuli and changes in their environment by adjusting their metabolic processes to promote growth, development, and the production of secondary metabolites. The compounds produced by microalgae exhibit biological activities and have garnered commercial interest across various industries, including nutraceuticals, food, aquaculture, biofuels, bioremediation, and cosmetics. Through their photosynthetic apparatus, these microorganisms contribute to CO2 fixation and O2 production, mitigating the impacts of human activities, such as the greenhouse effect, and serving as a renewable resource. The objective of this study was to establish a cultivation protocol for the microalgae genus Scenedesmus to accumulate biomass and investigate the classes of compounds present within it. The study was structured into two chapters. The first chapter focused on developing a cultivation protocol for Scenedesmus obtusus (Chlorophyceae) to optimize biomass accumulation and compound production. The second chapter investigated the classes of components present in the biomass of the studied microalgae. A Fed-Batch cultivation system using BG11 medium, with controlled temperature and photoperiod, was employed. Cultivation monitoring was conducted through optical density measurements and cell counting. Initial population peaks occurred within the first 10 days of cultivation; however, to accumulate additional biomass, the biomass was centrifuged and subsequently dried, with an average cultivation time of 55 days (SD=36.4) and a cell density of 4.72 x 10^7 individuals/mL. The investigated algae yielded a biomass production of 1.70 g/L. Centrifugation and drying were themethods used for biomass harvesting and subsequent analysis. Qualitative tests were performedon the dried biomass to identify the classes of compounds present, with alkaloids andflavonoids being the suggested classes in this analysis. A chromatogram was generated to assessthe profile of metabolites synthesized by the microalgae. Three spectra from the microalgaebiomass were similar to the spectra of analytical standards used for comparison: resveratrol,quercetin, and kaempferol. Future studies may explore the optimization of cultivation and thepurification of these compounds for specific commercial applications.