Centre for Geometric Biology, School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
J Mol Evol. 2018 Feb;86(2):111-117. doi: 10.1007/s00239-018-9829-9. Epub 2018 Jan 18.
A major goal of evolutionary biology is to understand how beneficial mutations translate into increased fitness. Here, we study beneficial mutations that arise in experimental populations of yeast evolved in glucose-rich media. We find that fitness increases are caused by enhanced maximum growth rate (R) that come at the cost of reduced yield (K). We show that for some of these mutants, high R coincides with higher rates of ethanol secretion, suggesting that higher growth rates are due to an increased preference to utilize glucose through the fermentation pathway, instead of respiration. We examine the performance of mutants across gradients of glucose and nitrogen concentrations and show that the preference for fermentation over respiration is influenced by the availability of glucose and nitrogen. Overall, our data show that selection for high growth rates can lead to an enhanced Crabtree phenotype by the way of beneficial mutations that permit aerobic fermentation at a greater range of glucose concentrations.
进化生物学的主要目标之一是理解有益突变如何转化为适应性的提高。在这里，我们研究了在富含葡萄糖的培养基中进化的酵母实验种群中出现的有益突变。我们发现，适应性的提高是由最大生长率（R）的提高引起的，而这是以产率（K）的降低为代价的。我们表明，对于其中一些突变体，高 R 与更高的乙醇分泌率相关，这表明更高的生长速率是由于通过发酵途径而不是呼吸作用来增加利用葡萄糖的偏好。我们在葡萄糖和氮浓度的梯度上检查了突变体的性能，并表明发酵对呼吸作用的偏好受葡萄糖和氮的可用性的影响。总的来说，我们的数据表明，对高生长速率的选择可以通过允许在更大范围的葡萄糖浓度下进行有氧发酵的有益突变来导致增强的 Crabtree 表型。
