Produção de proteína da microalga Haematococcus pluvialis cultivada em diferentes meios de cultura

Abstract

Haematococcus pluvialis is a freshwater microalgae of high biotechnological potential, with the ability to accumulate proteins being highlighted, whose growth and accumulation of this biocomposite becomes variable according to the growing conditions, highlighting the availability of nutrients, mainly nitrogen and phosphorus. Therefore, the present study aimed to evaluate the influence of different culture media on the protein synthesis and growth of H. pluvialis. The cultivation was carried out in 2 liter flasks, enriched with four culture media: BBM, RM, BG11 and KM2 and addition of B complex vitamins, in triplicate. It was inoculated at 10 x 104 cells mL-1, temperature of 24 ± 1 ° C, full photoperiod and light intensity of 40 μmol photons m-2 s-1. Daily samples (2 mL) fixed in formaldehyde (2%) were collected for cell count and determination of growth variables: doubling time (TD), growth rate (K), specific growth rate (μ), maximum cell density (DCM) and development of growth curves. At the end of cultivation, the volume produced in each unit was collected and centrifuged at 3.500 x g for 10 minutes. Then, the samples were frozen and lyophilized to obtain dry biomass. For protein analysis, total protein content (PT,%), protein production (g L-1) and yield (g L-1 day-1) were evaluated. Based on the composition of the culture media, stoichiometric calculations were performed to analyze the influence of nitrogen (N), phosphorus (P) and N: P ratio. There was a statistical difference (p <0.05) regarding DCM, whose maximum concentration was verified in BG11 (142.13 ± 29.52 .104 cell mL-1) and the lowest in KM2 (56.67 ± 9.09. 104 cells mL-1). For K, TD and μ, statistical difference was observed only for BG11, indicating a gradual growth in this culture medium, as observed in the growth curves. Regarding PT, there was a statistical difference (p <0.05), with similarity between RM, BG11 and KM2, of 55.08 ± 5.6, 49.33 ± 3.64 and 58.37 ± 2.8% , respectively, differing from BBM, which had the lowest content, of 31, 11 ± 2.93%. As for protein production, there was a statistical difference (p <0.05), in which the highest index was obtained in BG11 (0.31 g L-1), followed by RM (0.25 g L-1), which it was similar to BG11 and KM2 (0.22 g L-1), being smaller in BBM (0.13 g L-1). The highest cell density, duration of the vegetative phase and biomass production were achieved where there was a greater availability of nitrogen, in high N: P, which also stimulated high levels of total protein. It is concluded that the culture media influence the growth and protein synthesis of H. pluvialis, in which the growth, higher cell density, biomass production and microalgae protein was significantly higher in BG11 medium, which had higher nitrogen content and greater N: P ratio compared to other evaluated media. The results of this study suggest that H. pluvialis is a potential species for obtaining proteins and BG11 medium is the most suitable for greater production in biomass and proteins for microalgae.