초록
The effect of different vitamins and nitrogen sources on the yield, productivity and selectivity of erythritol production from glycerol in batch and fed-batch cultures by Yarrowia lipolytica Wratislavia K1 strain was examined in the study. Thiamine was a vitamin necessary for efficient erythritol production and the yeast extract (YE) turned out to be its best source. The YE was additionally a very good source of nitrogen in this process. Erythritol production may be efficient in the media containing only yeast extract and crude glycerol. The application of a high substrate concentration (325 kg m<SUP>-3</SUP>) in the fed-batch system with pulsed addition of glycerol resulted in erythritol production of 201.2 kg m<SUP>-3</SUP> after 168 h of cultivation. The mass fraction of by-products, such as other polyols and organic acids, did not exceed 10%. The study showed that by-products formation could be significantly reduced by the addition of a nitrogen source after glycerol depletion from the media. Wratislavia K1 strain does not utilize erythritol in the presence of other carbon sources and this feature was used in order to increase product selectivity up to 99.7% and protein content in yeast biomass up to 28.7%. The factors determining the use of biomass as animal feed, i.e. protein concentration and presence of metal ions, were discussed as well.