Super life - how and why 'cell selection' leads to the fastest-growing eukaryote
Super life - how and why 'cell selection' leads to the fastest-growing eukaryote
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DOI：
10.1111/j.1742-4658.2008.06778.x
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发表时间：
2009-01-01
期刊：
影响因子：
5.4
通讯作者：
Westerhoff, Hans V.
中科院分区：
文献类型：
--
作者：
Groeneveld, Philip;Stouthamer, Adriaan H.;Westerhoff, Hans V.
生物体可能的最高复制率是多少？细胞的生长速度受各种过程的控制。因此，还不清楚应该激活哪一种代谢过程或哪一组代谢过程来提高生长速度。一个已经快速生长的有机体可能已经通过进化优化了所有可以轻易优化的过程，但可能面临着更普遍的限制。在这里，我们介绍了一种被称为“细胞选择”的方法来选择最高的生长速度，并展示了这样一个“生长控制”的细胞位置是如何被识别的。通过对已经快速生长的酵母Kluyvermyces marxianus进行足够长的时间的恒定pH培养，我们选择了一株生长速度提高了30%的菌株，其细胞周期时间减少到52min，远远低于迄今报道的任何真核生物。在细胞体积相当恒定的情况下，细胞生长速度的增加伴随着细胞表面的40%的增加。我们展示了生长速度的提高可以用一组膜过程(比生长速度增加0.7%到膜表面积增加1%)的显性(80%)生长限制来解释。膜过程的同时激活可能是加速生长最快的真核生物的生长速度到更快的生长速度所必需的，并可能对工业化的白色生物技术过程中的单细胞蛋白质生产产生潜在的兴趣。
What is the highest possible replication rate for living organisms? The cellular growth rate is controlled by a variety of processes. Therefore, it is unclear which metabolic process or group of processes should be activated to increase growth rate. An organism that is already growing fast may already have optimized through evolution all processes that could be optimized readily, but may be confronted with a more generic limitation. Here we introduce a method called 'cell selection' to select for highest growth rate, and show how such a cellular site of 'growth control' was identified. By applying pH-auxostat cultivation to the already fast-growing yeast Kluyveromyces marxianus for a sufficiently long time, we selected a strain with a 30% increased growth rate; its cell-cycle time decreased to 52 min, much below that reported to date for any eukaryote. The increase in growth rate was accompanied by a 40% increase in cell surface at a fairly constant cell volume. We show how the increase in growth rate can be explained by a dominant (80%) limitation of growth by the group of membrane processes (a 0.7% increase of specific growth rate to a 1% increase in membrane surface area). Simultaneous activation of membrane processes may be what is required to accelerate growth of the fastest-growing form of eukaryotic life to growth rates that are even faster, and may be of potential interest for single-cell protein production in industrial 'White' biotechnology processes.