Efeito da temperatura no cultivo unialgal e misto de microalgas (crescimento e composição bioquímica) como subsídio para a aplicação biotecnológica

Abstract

The microalgal biomass has several commercial applications, especially in the pharmaceutical, food, animal feed and, more recently, the biofuels industry. The use of microalgae populations in mixed cultures can provide advantages such as cost reduction with contamination and obtaining biomass rich in lipids, carbohydrates and proteins. This study aimed to evaluate the unialgal and mixed cultivation of Pseudopediastrum boryanum and Scenedesmus obliquus at two different temperatures, in laboratory scale, in terms of biomass and biochemical composition. The experiment was conducted in triplicate, in temperatures set of 20 and 30°C, medium ASM1, photoperiod 12/12h and continuous aeration for 21 days. The inoculum was 1,5 x105 cell/mL to monocultures and 7,5 x104 cell/mL, of each species, in mixed culture. Increased cell density (13.6 x 106 cell/mL) and biomass (55 g/L) were recorded in unialgal S. obliquus culture at 30°C. High protein concentrations (672.6 mg/g) were observed in P20 and S20 treatments and carbohydrates (6.17 mg/g) in P30. There was no significant difference in total lipid content extracted in S20 (95.5 mg/g), P20 (96.3 mg/g) and M20 (105.3 mg/g). FAMEs composition of the microalgae, varied significantly as regards the number of unsaturations, being mostly composed of monounsaturated fatty acids (14 to 41.8%) and tri-unsaturated fatty acids (18.8 to 33.2%). Based on the results, it is concluded that the mixed cultivation of S. obliquus and P. boryanum not shown good results of growth and production of biochemicals. Changes in temperature affect the growth and yield of most biocompounds but, this influence differs between treatments. The FAMEs profile doesn’t fit the rules in force for production of biofuels, however, the biomass rich in protein and essential fatty acids (Omega 3), suggesting a potential use as a supplement in human food and animal feed production