Attfield P V, Kletsas S, Veal D A, van Rooijen R, Bell P J
Centre for Fluorimetric Applications in Biotechnology, Department of Biological Sciences, Macquarie University, Sydney, Australia.
J Appl Microbiol. 2000 Aug;89(2):207-14. doi: 10.1046/j.1365-2672.2000.01100.x.
Viable dried yeast is used as an inoculum for many fermentations in the baking and wine industries. The fermentative activity of yeast in bread dough or grape must is a critical parameter of process efficiency. Here, it is shown that fluorescent stains and flow cytometry can be used in concert to predict the abilities of populations of dried bakers' and wine yeasts to ferment after rehydration. Fluorescent dyes that stain cells only if they have damaged membrane potential (oxonol) or have increased membrane permeability (propidium iodide) were used to analyse, by flow cytometry, populations of rehydrated yeasts. A strong relationship (r2 = 0.99) was found between the percentages of populations staining with the oxonol and the degree of cell membrane damage as measured by the more traditional method of leakage of intracellular compounds. There were also were good negative relationships (r2 > or = 0.83) between fermentation by rehydrated bakers' or wine dry yeasts and percentage of populations staining with either oxonol or propidium iodide. Fluorescent staining with flow cytometry confirmed that factors such as vigour of dried yeast mixing in water, soaking before stirring, rehydration in water or fermentation medium and temperature of rehydration have profound effects on subsequent yeast vitality. These experiments indicate the potential of flow cytometry as a rapid means of predicting the fermentation performance of dried bakers' and wine yeasts.
活的干酵母被用作烘焙和酿酒行业许多发酵过程的接种物。酵母在面包面团或葡萄汁中的发酵活性是工艺效率的关键参数。在此表明，荧光染色和流式细胞术可协同用于预测干面包酵母和葡萄酒酵母群体复水后发酵的能力。使用仅在细胞膜电位受损（氧杂萘邻酮）或膜通透性增加（碘化丙啶）时才对细胞染色的荧光染料，通过流式细胞术分析复水酵母群体。在使用氧杂萘邻酮染色的群体百分比与通过更传统的细胞内化合物泄漏方法测量的细胞膜损伤程度之间发现了很强的相关性（r2 = 0.99）。复水的面包酵母或葡萄酒干酵母的发酵与用氧杂萘邻酮或碘化丙啶染色的群体百分比之间也存在良好的负相关（r2≥0.83）。流式细胞术的荧光染色证实，诸如干酵母在水中混合的活力、搅拌前浸泡、在水或发酵培养基中复水以及复水温度等因素对随后的酵母活力有深远影响。这些实验表明流式细胞术作为预测干面包酵母和葡萄酒酵母发酵性能的快速方法的潜力。
