Availability of public goods shapes the evolution of competing metabolic strategies
Availability of public goods shapes the evolution of competing metabolic strategies
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DOI：
10.1073/pnas.1308523110
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发表时间：
2013-08-27
影响因子：
11.1
通讯作者：
Teusink, Bas
中科院分区：
文献类型：
--
作者：
Bachmann, Herwig;Fischlechner, Martin;Teusink, Bas
权衡为自然选择的结果提供了理论依据。一个突出的例子是在单细胞生物中生长速率和生物量产量之间的负相关。这种权衡导致了一个困境，其中生长速率的优化对于个体是有利的，而生物质产量的优化对于群体是有利的。在大肠杆菌、酵母和癌细胞等多种生物体中观察到高速率策略。悬浮培养有利于快速生长的生物体的生长，而空间结构对于高产策略的进化具有重要意义。尽管认识到这一点，但缺乏直接选择增加产量的实验方法。我们在这里表明，在油包水乳液中的微生物种群的连续繁殖允许选择具有增加的生物质产量的菌株。乳液中的繁殖创造了一个空间结构化的环境，其中生长限制基质被私有化为由单个细胞建立的群体。几个同基因乳酸乳球菌菌株的实验进化证明了生长速率和生物量产量之间存在一个权衡，作为一个明显的帕累托前沿。潜在的突变改变了葡萄糖转运，并导致同型发酵和异型发酵代谢之间的重大转变，解释了代谢效率的变化。结果表明，公共产品私有化对竞争代谢策略之间的进化结果的影响。所提出的方法允许在生物学中的基本问题，如合作，细胞-细胞相互作用的演变，以及环境和代谢约束之间的关系的调查。
Tradeoffs provide a rationale for the outcome of natural selection. A prominent example is the negative correlation between the growth rate and the biomass yield in unicellular organisms. This tradeoff leads to a dilemma, where the optimization of growth rate is advantageous for an individual, whereas the optimization of the biomass yield would be advantageous for a population. High-rate strategies are observed in a broad variety of organisms such as Escherichia coli, yeast, and cancer cells. Growth in suspension cultures favors fast-growing organisms, whereas spatial structure is of importance for the evolution of high-yield strategies. Despite this realization, experimental methods to directly select for increased yield are lacking. We here show that the serial propagation of a microbial population in a water-in-oil emulsion allows selection of strains with increased biomass yield. The propagation in emulsion creates a spatially structured environment where the growth-limiting substrate is privatized for populations founded by individual cells. Experimental evolution of several isogenic Lactococcus lactis strains demonstrated the existence of a tradeoff between growth rate and biomass yield as an apparent Pareto front. The underlying mutations altered glucose transport and led to major shifts between homofermentative and heterofermentative metabolism, accounting for the changes in metabolic efficiency. The results demonstrated the impact of privatizing a public good on the evolutionary outcome between competing metabolic strategies. The presented approach allows the investigation of fundamental questions in biology such as the evolution of cooperation, cell-cell interactions, and the relationships between environmental and metabolic constraints.