Avaliação da produção da microalga Limnospira platensis em reatores tipo bags indoor e outdoor

Abstract

Limnospira platensis (formerly known as Spirulina or Arthrospira platensis) is a filamentous cyanobacterium with a spiral-shaped morphology, commonly classified as a microalga. Its use in human nutrition dates back to ancient civilizations, having been consumed by peoples living near alkaline lakes in Africa and Mexico. Currently, this species is widely cultivated on an industrial scale and is considered a promising alternative for diversifying aquaculture and agro-industrial production systems. Its applications include use as a dietary supplement, an ingredient in animal feed formulations, and a source of bioactive compounds of interest in the pharmaceutical, nutraceutical, and cosmetic industries. This study aimed to evaluate the production of the microalga L. platensis in bag cultivation systems under two distinct conditions: indoor and outdoor environments. The cultivation was carried out in 50 L plastic bags using the standard Jourdan culture medium at a salinity of 20. The experiment lasted 25 days, with daily monitoring of physicochemical parameters (temperature, pH, salinity, light intensity, and optical density), followed by quantification of dry biomass and chlorophyll a content. Data were analyzed using one-way ANOVA and Tukey's test (p < 0.05). The results showed that outdoor cultivation performed significantly better in terms of cell growth, biomass yield (40 mg·L⁻¹), and chlorophyll a concentration (13.573 ± 0.501 μg·L⁻¹) compared to indoor cultivation (8 mg·L⁻¹ and 3.807 ± 0.991 μg·L⁻¹, respectively). Higher light intensity and temperature in outdoor cultivation were the main factors associated with the better performance of the outdoor system. In conclusion, the use of bags as photobioreactors is feasible and promising for L. platensis production under outdoor conditions, offering a low-cost alternative for obtaining biomass with potential applications in food, aquaculture, and biotechnological industries