Beta-1,3-glucomannanase assisted lipid extraction from Rhodosporidium toruloides / 生物工程学报

To evaluate the effectiveness of enzymatic assisted extraction (EAE) of lipid from the oleaginous yeast Rhodosporidium toruloides in the presence of beta-1,3-glucomannanase at a larger scale, we investigated the effects of enzymatic treatment and extraction conditions on lipid extraction yields at 10-L scale by using the broth of R. toruloides Y4 as the feed and ethyl acetate as the solvent. When it was treated for 0.5 h, the lipid extraction yield reached 71.1%, indicating that the enzymatic treatment process reached similar efficiency to that obtained at 10-mL scale. The inhibitory effect of emulsification was greatly reduced by repeated extraction. After extracted for three times, yields of lipid extraction, solvent recovery and total material recovery reached 92.9%, 87.0% and 94.2% respectively. As it can use the lipid production slurry with good extraction efficiency, EAE technology is promising for industrial production of microbial lipids.

Effects of dilution rate and carbon-to-nitrogen ratio on lipid accumulation by Rhodosporidium toruloides under chemostat conditions / 生物工程学报

The objective of this work is to investigate how dilution rate and carbon-to-nitrogen (C/N) ratio affects lipid accumulation by Rhodosporidium toruloides AS 2.138 9 in continuous culture. Under steady-state conditions, the increase in dilution rate led to the decrease in lipid content and lipid yield. The highest lipid yield and lipid content at D = 0.02 h(-1) were 0.18 g lipid/g sugar and 57.1%, respectively, while the highest lipid productivity and biomass productivity were obtained at D = 0.14 h(-1). The increase in C/N ratio led to the increase in lipid content. The highest lipid content of 38% was obtained at C/N = 237. The highest lipid yield of 0.12 g lipid/g sugar was obtained at C/N = 92. However, the highest lipid productivity of 0.12 g/(L x h) was obtained at C/N = 32. No significant changes were observed in terms of fatty acid composition of the lipid produced under different C/N ratios, and these three fatty acids, palmitic acid, stearic acid and oleic acid, took over 85% in all samples.

Microbial lipid production by Rhodosporidium toruloides in a two-stage culture mode / 生物工程学报

To shorten the cultivation time and reduce the consumption of raw materials for microbial lipid production, oleaginous yeast Rhodosporidium toruloides AS 2.1389 was cultivated using a two-stage culture mode, in which the cell propagation and lipid accumulation were separated. The yeast cells recovered from the propagation culture were re-suspended in glucose solution for lipid accumulation, through which lipid content over 55% of the dry cell weight was achieved, the longer the propagation stage was, the higher the lipid content. Analysis of the lipid indicated that the long-chain fatty acids with 16 and 18 carbon atoms were major components, suggesting that the lipid can be an alternative feedstock for biodiesel production.