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- Lipid and carotenoid production by a Rhodosporidium toruloides and Tetradesmus obliquus mixed culture using primary brewery wastewater supplemented with sugarcane molasses and ureaPublication . Dias, Carla; Nobre, B. P.; Santos, J. A. L.; Reis, Alberto; Silva, Teresa Lopes daABSTRACT: In this study, Rhodosporidium toruloides and Tetradesmus obliquus were used for lipid and carotenoid production in mixed cultures using primary brewery wastewater (PBWW) as a culture medium, supplemented with sugarcane molasses (SCM) as a carbon source and urea as a nitrogen source. To improve biomass, lipid, and carotenoid production by R. toruloides and T obliquus mixed cultures, initial SCM concentrations ranging from 10 to 280 g L-1 were tested. The medium that allowed higher lipid content (26.2% w/w dry cell weight (DCW)) and higher carotenoid productivity (10.47 mu g L-1 h(-1)) was the PBWW medium supplemented with 100 g L-1 of SCM and 2 g L-1 of urea, which was further used in the fed-batch mixed cultivation performed in a 7-L bioreactor. A maximum biomass concentration of 58.6 g L-1 and maximum lipid content of 31.2% w/w DCW were obtained in the fed-batch cultivation. PBWW supplemented with SCM was successfully used as a low-cost medium to produce lipids and carotenoids in a R. toruloides and T obliquus mixed culture, with higher productivities than in pure cultures, which can significantly reduce the cost of the biofuels obtained.
- Direct lipid and carotenoid extraction from Rhodosporidium toruloides broth culture after high pressure homogenization cell disruption: Strategies, methodologies, and yieldsPublication . Dias, Carla; Nobre, B. P.; Santos, J. A. L.; Silva, Teresa Lopes da; Reis, AlbertoABSTRACT: Biodiesel produced from oleaginous microorganisms is considered an appealing option since oleaginous yeasts and microalgae can accumulate between 20 % and 80 % lipids of their dry cell weight. However, it is still not economically sustainable since production costs are still high. This work developed a new mild protocol using hexane or sunflower oil as extraction solvents to simultaneously extract lipids and carotenoids from Rhodosporidium toruloides biomass directly from the broth culture without using any harvesting technique after performing high pressure homogenization to disrupt the yeast cells. The highest results were obtained for the hexane extractions attaining 55.9 % of total lipids (w/w) and 111.5 mu g g-1 (eq. torulene) of carotenoids, which are higher values than the ones obtained using lipid extraction traditional methods. The process here presented is an easy, simple, inexpensive and environmentally friendly methodology which involves the simultaneous extraction of carotenoids and lipids directly from R. toruloides broth culture which has never been reported before and can greatly improve the economics of the biodiesel production process.