Avaliação de meios de cultura no cultivo de microalgas Chlorella vulgaris para a produção de carboidratos

Abstract

Biomass is, by definition, any organic substance of plant or animal origin capable of being used for energy production. Its energy potential depends on its origin, or the process used to obtain it. Thus, the use of biomass for carbohydrate production has become a good and sustainable alternative. In this context, the use of microorganisms like microalgae for carbohydrate production has been gaining prominence because their production process is alternative compared to conventional methods. Therefore, varying concentrations of biomass and carbohydrates can be obtained, influenced by the composition of the culture media. The study aimed to analyze three culture media: Bold's Basal Medium (BBM), Blue Green 11 (BG11), and CHU, and evaluate their influence on carbohydrate production by the microalga Chlorella vulgaris. Fermentations were conducted using these three-culture media in triplicate in Erlenmeyer flasks, under a light intensity of 5000 lux, agitation at 140 rpm, at 25 ± 2ºC. Microalgae cultivation for fermentation followed a light-dark photoperiod of 12:12 hours over a period of 7 days. Calibration curves were constructed to correlate absorbance with biomass and absorbance with carbohydrates, allowing the determination of biomass and carbohydrate concentrations during the microalgae fermentation processes in the three studied culture media. Results showed that all three culture media were suitable for carbohydrate production and microalgae growth. BBM medium exhibited a growth of 18.5% yielding 0.1602 ± 0.0063 g.L-1 of reducing sugars; BG11 medium showed a growth of 9.4% yielding 0.1821 ± 0.0570 g.L-1; and, CHU medium showed a growth of 14.9% yielding 0.1250 ± 0.0183 g.L-1. However, the obtained values did not show statistically significant differences by ANOVA analysis, suggesting that the similarity in the composition of the media studied prevented the identification of differences in carbohydrate production by microalgae. It is suggested that na approach involving nutritional stress on the microalgae may be more effective in optimizing carbohydrate productivity.