Microbial mutualism dynamics governed by dose-dependent toxicity of cross-fed nutrients
Microbial mutualism dynamics governed by dose-dependent toxicity of cross-fed nutrients
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DOI：
10.1038/ismej.2016.141
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发表时间：
2017-02-01
期刊：
影响因子：
11
通讯作者：
McKinlay, James B.
中科院分区：
文献类型：
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作者：
LaSarre, Breah;McCully, Alexandra L.;McKinlay, James B.
微生物之间的相互作用，包括互惠营养交换（交叉喂养），是所有生态系统中能量和物质流动的基础。代谢交换在自然系统中很难评估。因此，交换水平对生态系统动态和功能的影响仍不清楚。为了评估交叉喂养水平如何管理互惠行为，我们开发了一种适合建模和实验操作的细菌共培养物。在这种类似于厌氧食物网的共培养物中，发酵大肠杆菌和光异养沼泽红球藻专性交叉喂养碳（有机酸）和氮（铵）。这种互惠的交换促进了立即稳定的共存和耦合的物种生长。R. palustris增加铵态氮的交叉取食引起了E.大肠杆菌，导致培养酸化。因此，有机酸的功能从营养物质的抑制剂，最终偏置物种比例和降低碳转化效率的社会，尽管如此，稳定共存持续在一个新的平衡。因此，破坏养分交换的对称性可以放大交换资源的替代作用，从而改变群落功能。这些结果对我们理解互惠互利的相互作用和利用微生物财团作为生物技术的影响。
Microbial interactions, including mutualistic nutrient exchange (cross-feeding), underpin the flow of energy and materials in all ecosystems. Metabolic exchanges are difficult to assess within natural systems. As such, the impact of exchange levels on ecosystem dynamics and function remains unclear. To assess how cross-feeding levels govern mutualism behavior, we developed a bacterial coculture amenable to both modeling and experimental manipulation. In this coculture, which resembles an anaerobic food web, fermentative Escherichia coli and photoheterotrophic Rhodopseudomonas palustris obligately cross-feed carbon (organic acids) and nitrogen (ammonium). This reciprocal exchange enforced immediate stable coexistence and coupled species growth. Genetic engineering of R. palustris to increase ammonium cross-feeding elicited increased reciprocal organic acid production from E. coli, resulting in culture acidification. Consequently, organic acid function shifted from that of a nutrient to an inhibitor, ultimately biasing species ratios and decreasing carbon transformation efficiency by the community; nonetheless, stable coexistence persisted at a new equilibrium. Thus, disrupting the symmetry of nutrient exchange can amplify alternative roles of an exchanged resource and thereby alter community function. These results have implications for our understanding of mutualistic interactions and the use of microbial consortia as biotechnology.