Resumo

Microalgae are unicellular photosynthetic organisms, eukaryotes, can efficiently convert carbon dioxide into biomass and certain bioactive compounds with applications in food, pharmaceutical and cosmetic industries. B. braunii is a microalga capable of synthesizing and storing lipids, including fatty acids, epoxides, ether, and hydrocarbons. Medium components like inorganic carbon, nitrogen, and vitamins are important parameters regulating algal growth, but also a balance between operating parameters such as temperature, light intensity, and pH is required, as well as the alter the salinity of the medium. Aiming to provide information to this subject in cultivation of B. braunii, there were evaluated the influence of different cultivation medium, with different nutrient concentration and salinity, on the growth. Preliminary tests were carried out in a Erlenmeyer flask using different cultivation media; Chu, modified Chu 13, Bold, F⁄2 and modified Bold medium, were then incubated under continuous light on a rotary shaker at 25ºC and 120 min^-1. In one second attempt, they were tested the influence of different concentration of sodium nitrate in Chu medium and light intensity in tubular reactor. The Chu medium resulted in high cell growth compared to the others mediums, due to the minor salinity in Chu medium, what evidence the dependence of the B. braunii by the salinity. So another inoculum was performed with original Chu medium and increasing concentrations of nitrogen and phosphorus. The results from Shapiro-Wilk (p>0.05) and Levene tests (p>0.05) showed that the data be considered parametric, allowing use of ANOVA one-way (p<0.05). The ANOVA test showed that there was not statistically significant difference between growth of B. braunii in the original medium Chu and in the modified one (3N:3P), by increasing three times the concentration of nitrogen and phosphorus. These results, evidence the importance of the nutrients concentration aiming to obtain high cell concentrations in cultivations of B. braunii. Thus, the subsequent experiments in the tubular reactor will be made with original Chu medium and increasing three times the concentration of N and P.