Enzymatic Biodiesel Synthesis From Yeast Oil Using Immobilized Recombinant Rhizopus Oryzae Lipase.

The recombinant Rhizopus oryzae lipase (1-3 positional selective), immobilized on Relizyme OD403, has been applied to the production of biodiesel using single cell oil from Candida sp. LEB-M3 growing on glycerol from biodiesel process. The composition of microbial oil is quite similar in terms of saponifiable lipids than olive oil, although with a higher amount of saturated fatty acids. The reaction was carried out in a solvent system, and n-hexane showed the best performance in terms of yield and easy recovery. The strategy selected for acyl acceptor addition was a stepwise methanol addition using crude and neutralized single cell oil, olive oil and oleic acid as substrates. A FAMEs yield of 40.6% was obtained with microbial oils lower than olive oil 54.3%. Finally in terms of stability, only a lost about 30% after 6 reutilizations were achieved.

Microbial Lipid Production: Screening With Yeasts Grown On Brazilian Molasses.

Rhodotorula glutinis CCT 2182, Rhodosporidium toruloides CCT 0783, Rhodotorula minuta CCT 1751 and Lipomyces starkeyi DSM 70296 were evaluated for the conversion of sugars from Brazilian molasses into single-cell oil (SCO) feedstock for biodiesel. Pulsed fed-batch fermentations were performed in 1.65 l working volume bioreactors. The maximum specific growth rate (µmax), lipid productivity (Pr) and cellular lipid content were, respectively, 0.23 h(-1), 0.41 g l(-1) h(-1), and 41% for Rsp. toruloides; 0.20 h(-1), 0.27 g l(-1) h(-1), and 36% for Rta. glutinis; 0.115 h(-1), 0.135 g l(-1) h(-1), and 27 % for Rta. minuta; and 0.11 h(-1), 0.13 g l(-1) h(-1), and 32% for L. starkeyi. Based on their microbial lipid productivity, content, and profile, Rsp. toruloides and Rta. glutinis are promising candidates for biodiesel production from Brazilian molasses. All the oils from the yeasts were similar to the composition of plant oils (rapeseed and soybean) and could be used as raw material for biofuels, as well as in food and nutraceutical products.

Nitrogen Starvation For Lipid Accumulation In The Microalga Species Desmodesmus Sp.

Recently, to obtain lipids from microalgae has been the object of extensive research, since it is viewed as a promising feedstock for biodiesel production, especially when compared with crops such as soybean and sunflower, in terms of theoretical performance. The reduction of nutrient availability in culture media, especially nitrogen, stresses the microorganisms and affects cell growth, thus inducing lipid accumulation. This is an interesting step in biodiesel feedstock obtention from microalgae and should be better understood. In this study, four levels of nitrogen concentration in the BG-11 culture medium were evaluated in the growth of the chlorophycean microalga Desmodesmus sp. Both cell growth and lipid content were monitored over 7 days of cultivation, which yielded a final cell density of 33 × 10(6) cells mL(-1) with an initial NaNO3 concentration of 750 mg L(-1) in the medium and a maximum lipid content of 23 % with total nitrogen starvation. It was observed that the microalgae presented high lipid accumulation in the fourth day of cultivation with nitrogen starvation, although with moderate cell growth.