Erythritol Biosynthesis Research Articles

Mineral Supplementation Increases Erythrose Reductase Activity in Erythritol Biosynthesis from Glycerol by Yarrowia lipolytica

The aim of this study was to examine the impact of divalent copper, iron, manganese, and zinc ions on the production of erythritol from glycerol by Yarrowia lipolytica and their effect on the activity of erythrose reductase. No inhibitory effect of the examined minerals on yeast growth was observed in the study. Supplementation with MnSO4·7H2O (25 mg l−1) increased erythritol production by Y. lipolytica by 14.5 %. In the bioreactor culture with manganese ion addition, 47.1 g l−1 of erythritol was produced from 100.0 g l−1 of glycerol, which corresponded to volumetric productivity of 0.87 g l−1 h−1. The addition of Mn2+ enhanced the intracellular activity of erythrose reductase up to 24.9 U g−1 of dry weight of biomass (DW), hence, about 1.3 times more than in the control.

Erythritol biosynthesis by Yarrowia lipolytica yeast under various culture conditions

Erythritol is a natural compound of great interest in food production because of its very low caloric value, lack of off-taste and lack of side-effects from the gastric system even when consumed with in excess. In the present study, the effect of agitation rates from 500 to 1100 rev/min on biomass and erythritol production on glycerol media by an acetate-negative mutant of Yarrowia lipolytica Wratislavia K1 in batch culture was studied. At a constant aeration rate of 0.36 vvm, the agitation rate between 500 and 900 rev/min wasfound suitable for efficient erythritol production. In the pure glycerol-containing media the erythritol production of 40.7 g/l, corresponding to a 0.28 g/g yield, was achieved at 800 rev/min. The application of crude glycerol at 800 rev/min and 0.6 vvm elicited an increase in erythritol concentration to 58.2 g/l corresponding to a 0.38 g/g yield and a productivity of 0.78 g/lh. Key words: Yarrowia lipolytica, erythritol, glycerol, agitation rate, aeration rate.

Gene expression and function involved in polyol biosynthesis of Trichosporonoides megachiliensis under hyper-osmotic stress

Among three erythritol reductase isogenes (er1, er2, and er3) in Trichosporonoides megachiliensis SN-124A, er1 and er2 each had one stress response element (STRE) approximately 2kbp upstream of their respective initiator codon; in contrast, er3 had two STREs, 148 and 40bp upstream from the initiator codon. Based on intracellular erythritol accumulation and gene expression profiles, er3 seemed to be highly responsive to stress than er1 or er2. Under hyper-osmotic conditions, intracellular glycerol production, increased significantly within 1.5h together with glycerol-3-phosphate dehydrogenase gene (gpd1) expression; in contrast, neither er gene expression nor the corresponding production of intracellular erythritol increased significantly within the first 1.5h of hyper-osmotic culture. However, within 24h of hyper-osmotic culture, erythritol production and er3 gene expression increased significantly and in parallel. Thus, we concluded that, as an initial response to hyper-osmotic growth conditions, T.megachiliensis produces glycerol as an osmoregulatory compatible solute via GPD; however, within 24h, it begins to produce erythritol, mainly via ER3, as the preferred compatible solute. Heterologous expression of ers in a Saccharomyces cerevisiae mutant indicated that any of three ers might not function in S.cerevisiae for erythritol biosynthesis in spite of ers and corresponding ERs expression. Hence, although er is annotated as a galactose-inducible crystalline-like yeast protein gene (gcy1) homolog, er may be functionally different from gcy1 in glycolytic metabolism. Otherwise, S.cerevisiae is not likely to produce erythrose, the substrate of erythrose reductase due to metabolic characteristics.

Production of erythritol and mannitol by Yarrowia lipolytica yeast in media containing glycerol

Glycerol is a by-product generated in large amounts during the production of biofuels. This study presents an alternative means of crude glycerol valorization through the production of erythritol and mannitol. In a shake-flasks experiment in a buffered medium, nine Yarrowia lipolytica strains were examined for polyols production. Three strains (A UV’1, A-15 and Wratislavia K1) were selected as promising producers of erythritol or/and mannitol and used in bioreactor batch cultures and fed-batch mode. Pure and biodiesel-derived crude glycerol media both supplemented (to 2.5 and 3.25 %) and not-supplemented with NaCl were applied. The best results for erythritol biosynthesis were achieved in medium with crude glycerol supplemented with 2.5 % NaCl. Wratislavia K1 strain produced up to 80.0 g l−1 erythritol with 0.49 g g−1 yield and productivity of 1.0 g l−1 h−1. Erythritol biosynthesis by A UV’1 and A-15 strains was accompanied by the simultaneous production of mannitol (up to 27.6 g l−1). Extracellular as well as intracellular erythritol and mannitol ratios depended on the glycerol used and the presence of NaCl in the medium. The results from this study indicate that NaCl addition to the medium improves erythritol biosynthesis, and simultaneously inhibits mannitol formation.

Effect of vitamins source on erythritol biosynthesis by Yarrowia lipolytica Wratislavia K1

Effect of vitamins source on erythritol biosynthesis by Yarrowia lipolytica Wratislavia K1

Polyol accumulation by Aspergillus oryzae at low water activity in solid-state fermentation.

Polyol accumulation and metabolism were examined in Aspergillus oryzae cultured on whole wheat grains or on wheat dough as a model for solid-state culture. In solid-state fermentation (SSF), water activity (a(w)) is typically low resulting in osmotic stress. In addition to a high level of mannitol, which is always present in the cells, A. oryzae accumulated high concentrations of glycerol, erythritol and arabitol at relatively low a(w) (0.96-0.97) in SSF. Accumulation of such a mixture of polyols is rather unusual and might be typical for SSF. A. oryzae mycelium accumulating various polyols at low a(w) contained at least four distinct polyol dehydrogenases with highest activities toward glycerol, erythritol, D-arabitol and mannitol. NADP(+)-dependent glycerol dehydrogenase activity correlated very well with glycerol accumulation. A similar correlation was observed for erythritol and NADP(+)-erythritol dehydrogenase suggesting that NADP(+)-dependent glycerol and erythritol dehydrogenases are involved in biosynthesis of glycerol and erythritol, respectively, and that these enzymes are induced by osmotic stress.