Instituto de las Ciencias de la Vid y del Vino, Logroño, Spain.
FEMS Yeast Res. 2012 Jun;12(4):477-85. doi: 10.1111/j.1567-1364.2012.00802.x. Epub 2012 Apr 10.
Nitrogen limitation is one of the most common causes for stuck or sluggish fermentation. A broad range of values have been reported as the minimum nitrogen concentration necessary for the completion of alcoholic fermentation. We have analyzed the minimum nitrogen concentration required to yield the maximum biomass (nitrogen reference value) using a microwell plate reader to monitor fermentation with different nitrogen sources and sugar concentrations. The biomass yield was dependent on the amount of available nitrogen, the nature of nitrogen source, and the sugar concentration in the medium. Nevertheless, achieving the maximum biomass was not sufficient to ensure the completion of the alcoholic fermentation, because the fermentation of 280 g sugar L(-1) stuck, regardless of the nature and concentration of nitrogen source. However, a mixture of five amino acids (Leu, Ile, Val, Phe and Thr) as the nitrogen source allowed for maximum sugar consumption. Analysis of cell vitality by impedance showed a significant improvement in the vitality for cells fermenting using this amino acid combination.
氮限制是发酵停滞或缓慢的最常见原因之一。已经报道了广泛的数值作为完成酒精发酵所需的最低氮浓度。我们使用微孔板读数器分析了在不同氮源和糖浓度下产生最大生物量所需的最低氮浓度（氮参考值）。生物量的产量取决于可用氮的量、氮源的性质和培养基中的糖浓度。然而，达到最大生物量不足以确保酒精发酵的完成，因为无论氮源的性质和浓度如何，280g/L 糖的发酵都停滞了。然而，作为氮源的五种氨基酸（亮氨酸、异亮氨酸、缬氨酸、苯丙氨酸和苏氨酸）的混合物允许最大的糖消耗。通过阻抗分析细胞活力显示，使用这种氨基酸组合发酵的细胞活力显著提高。
