Enhanced nutrient uptake is sufficient to drive emergent cross-feeding between bacteria in a synthetic community
Enhanced nutrient uptake is sufficient to drive emergent cross-feeding between bacteria in a synthetic community
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DOI：
10.1038/s41396-020-00737-5
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发表时间：
2020-08-12
期刊：
影响因子：
11
通讯作者：
McKinlay, James B.
中科院分区：
文献类型：
--
作者：
Fritts, Ryan K.;Bird, Jordan T.;McKinlay, James B.
相互作用的微生物群落无处不在，影响生态地球化学循环和宿主健康。一种广泛的相互作用是营养交换或交叉喂养，其中代谢物在微生物之间转移。一些交叉喂养的代谢物，如维生素，氨基酸和铵（NH 4+），是共同有价值的，并强加给生产者的成本。强制交叉喂养的共同有价值的代谢物的机制还没有完全理解。以前，我们设计了一个交叉喂养的共培养之间的N-2-固定红球藻沼泽和发酵大肠杆菌。工程河沼泽湿地必需氮以NH（4）（+）→ E的形式存在。coli，而E.大肠杆菌以发酵产物的形式排出必需的碳。沼泽在这里，我们试图确定一个互惠的交叉喂养的关系是否会自发地在与野生型R的共培养。palustris，这是不知道排泄NH 4+。事实上，我们观察到NH（4）（+）交叉喂养的出现，但由E的适应驱动。大肠杆菌酮。E. coliNtrC是一种氮清除调节因子，导致NH（4）（+）转运蛋白的组成性激活。这种活动可能允许。大肠杆菌依靠少量泄漏的NH（4）（+）生存，并通过从较大的大肠杆菌中增加发酵产物的排泄而更好地进行往复运动。大肠菌群我们的研究结果表明，增强营养吸收的收件人，而不是增加排泄的生产者，是一个未得到充分重视，但可能普遍的机制，交叉喂养可以出现。
Interactive microbial communities are ubiquitous, influencing biogeochemical cycles and host health. One widespread interaction is nutrient exchange, or cross-feeding, wherein metabolites are transferred between microbes. Some cross-fed metabolites, such as vitamins, amino acids, and ammonium (NH4+), are communally valuable and impose a cost on the producer. The mechanisms that enforce cross-feeding of communally valuable metabolites are not fully understood. Previously we engineered a cross-feeding coculture between N-2-fixingRhodopseudomonas palustrisand fermentativeEscherichia coli. EngineeredR. palustrisexcretes essential nitrogen as NH(4)(+)toE. coli, whileE. coliexcretes essential carbon as fermentation products toR. palustris. Here, we sought to determine whether a reciprocal cross-feeding relationship would evolve spontaneously in cocultures with wild-typeR. palustris, which is not known to excrete NH4+. Indeed, we observed the emergence of NH(4)(+)cross-feeding, but driven by adaptation ofE. colialone. A missense mutation inE. coliNtrC, a regulator of nitrogen scavenging, resulted in constitutive activation of an NH(4)(+)transporter. This activity likely allowedE. colito subsist on the small amount of leaked NH(4)(+)and better reciprocate through elevated excretion of fermentation products from a largerE. colipopulation. Our results indicate that enhanced nutrient uptake by recipients, rather than increased excretion by producers, is an underappreciated yet possibly prevalent mechanism by which cross-feeding can emerge.