Department of Food Biotechnology and Microbiology, Institute of Food Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159 C, 02-776, Warsaw, Poland.
Unit of Microbiology, Division of Genetics, Cell and Developmental Biology, Department of Biology, University of Patras, 26504, Patras, Greece.
Biol Trace Elem Res. 2021 Apr;199(4):1611-1622. doi: 10.1007/s12011-020-02266-w. Epub 2020 Jul 6.
Nowadays, there is an increase attention on the effect of selenium (Se) on metabolic processes of microorganisms. Strains belonging to the genus of Yarrowia are of great biotechnological interest for various industries. In this study, we evaluated the effect of 10 mg/L of Se on the growth and lipid production of two Yarrowia lipolytica strains: the ACA DC 50109 and one more with increased oleagenicity, derived after ALE methodology (referred here as Y. lipolytica ALE_70). The presence of Se in the growth medium negatively affected both cell mass production and total lipid accumulation, for both Y. lipolytica strains. Fractionation of total lipids showed an inhibition on neutral lipid (NL) synthesis and consequently, an increase of polar lipids (glycolipids plus sphingolipids, and phospholipids) on the lipids of the Se-enriched ACA DC 50109 strain; however, the NL/polar ratio of the Se-enriched ALE_70 indicated that Se, apart from the inhibition of NL synthesis, provoked also the accumulation of polar lipids in this strain. In addition, the fatty acid (FA) composition was differently affected by Se. Se-enriched total lipids of the ALE_70 strain were enriched in linoleic acid (C18:2 n-6), which resulted in increase of the unsaturated index. On the other hand, Se-enriched lipids of the ACA DC 50109 strain were more saturated, as the percentage of palmitic (C16:0) and stearic (C18:0) acids increased in the total FAs. Moreover, it seems that Se influenced the activity or the expression of desaturases and elongase in both strains. Finally, the supplementation of growth medium with Se affected cell morphology, as well as the size and distribution of lipid droplets inside the yeast cells. According to our opinion, Se caused stress conditions and the consequence of that was the occurrence of metabolic disorders that affected cell mass, lipid content, and/or morphological structures. The results of the present study suggest that further research should be carried out to understand the background of the lipogenesis process in yeast cells cultured under stress conditions.
如今，人们越来越关注硒 (Se) 对微生物代谢过程的影响。属于 Yarrowia 属的菌株对各个行业都具有巨大的生物技术兴趣。在这项研究中，我们评估了 10mg/L 的 Se 对两种 Yarrowia lipolytica 菌株（ACA DC 50109 和通过 ALE 方法获得的具有更高油脂生成能力的菌株，这里称为 Y. lipolytica ALE_70）的生长和脂质生产的影响。在生长培养基中存在 Se 会对两种 Yarrowia lipolytica 菌株的细胞质量生产和总脂质积累产生负面影响。总脂质的分级分离显示对中性脂质 (NL) 合成的抑制作用，因此，富含 Se 的 ACA DC 50109 菌株的脂质中极性脂质（糖脂加神经酰胺和磷脂）增加；然而，富含 Se 的 ALE_70 菌株的 NL/极性比率表明，除了 NL 合成的抑制作用外，Se 还导致了该菌株中极性脂质的积累。此外，脂肪酸 (FA) 组成受到 Se 的不同影响。富含 Se 的 ALE_70 菌株的总脂质富含亚油酸 (C18:2 n-6)，这导致不饱和指数增加。另一方面，富含 Se 的 ACA DC 50109 菌株的脂质更饱和，因为棕榈酸 (C16:0) 和硬脂酸 (C18:0) 的百分比在总 FA 中增加。此外，似乎 Se 影响了两种菌株中去饱和酶和延伸酶的活性或表达。最后，生长培养基中 Se 的补充影响细胞形态以及酵母细胞内脂质滴的大小和分布。根据我们的观点，Se 引起了应激条件，其结果是发生了代谢紊乱，影响了细胞质量、脂质含量和/或形态结构。本研究的结果表明，应该进行进一步的研究以了解在应激条件下培养的酵母细胞中的脂生成过程的背景。
