Systems and Synthetic Biology, Department of Chemical and Biological Engineering, Chalmers University of Technology, Kemivagen 10, Gothenburg, Sweden.
Biotechnol J. 2012 May;7(5):594-601. doi: 10.1002/biot.201000386. Epub 2011 Sep 20.
There is increasing interest in bioengineering of lipids for use in functional foods, pharmaceuticals, and biofuels. Saccharomyces cerevisiae is a widely utilized cell factory for biotechnological production, thus a tempting alternative. Herein, we show how its neutral lipid accumulation varies throughout metabolic phases under nutritional conditions relevant for large-scale fermentation. Population-averaged metabolic data were correlated with lipid storage at the single-cell level monitored at submicron resolution by label-free coherent anti-Stokes Raman scattering (CARS) microscopy. While lipid droplet sizes are fairly constant, the number of droplets is a dynamic parameter determined by glucose and ethanol levels. The lowest number of lipid droplets is observed in the transition phase between glucose and ethanol fermentation. It is followed by a buildup during the ethanol phase. The surplus of accumulated lipids is then mobilized at concurrent glucose and ethanol starvation in the subsequent stationary phase. Thus, the highest amount of lipids is found in the ethanol phase, which is about 0.3 fL/cell. Our results indicate that the budding yeast, S. cerevisiae, can be used for the biosynthesis of lipids and demonstrate the strength of CARS microscopy for monitoring the dynamics of lipid metabolism at the single-cell level of importance for optimized lipid production.
人们对用于功能性食品、药物和生物燃料的脂质的生物工程越来越感兴趣。酿酒酵母是生物技术生产中广泛使用的细胞工厂，因此是一个诱人的选择。在此，我们展示了在与大规模发酵相关的营养条件下，其中性脂质积累如何在整个代谢阶段发生变化。通过无标记相干反斯托克斯拉曼散射（CARS）显微镜以亚微米分辨率监测单细胞水平的脂质储存，将群体平均代谢数据与脂质储存相关联。虽然油滴大小相当稳定，但油滴数量是一个动态参数，由葡萄糖和乙醇水平决定。在葡萄糖和乙醇发酵之间的过渡阶段观察到的油滴数量最少。随后，在随后的静止阶段同时葡萄糖和乙醇饥饿时，会积累更多的脂质。因此，在乙醇阶段可以发现最多的脂质，约为 0.3 fL/细胞。我们的结果表明，出芽酵母酿酒酵母可用于脂质的生物合成，并证明了 CARS 显微镜在监测脂质代谢动力学方面的优势，这对于优化脂质生产非常重要。
