Department of Chemical and Biological Engineering, Montana State Universitygrid.41891.35, Bozeman, Montana, USA.
Department of Biological and Environmental Sciences, Carroll Collegegrid.253718.a, Helena, Montana, USA.
mSystems. 2022 Aug 30;7(4):e0005122. doi: 10.1128/msystems.00051-22. Epub 2022 Jun 28.
Fitness benefits from division of labor are well documented in microbial consortia, but the dependency of the benefits on environmental context is poorly understood. Two synthetic Escherichia coli consortia were built to test the relationships between exchanged organic acid, local environment, and opportunity costs of different metabolic strategies. Opportunity costs quantify benefits not realized due to selecting one phenotype over another. The consortia catabolized glucose and exchanged either acetic or lactic acid to create producer-consumer food webs. The organic acids had different inhibitory properties and different opportunity costs associated with their positions in central metabolism. The exchanged metabolites modulated different consortial dynamics. The acetic acid-exchanging (AAE) consortium had a "push" interaction motif where acetic acid was secreted faster by the producer than the consumer imported it, while the lactic acid-exchanging (LAE) consortium had a "pull" interaction motif where the consumer imported lactic acid at a comparable rate to its production. The LAE consortium outperformed wild-type (WT) batch cultures under the environmental context of weakly buffered conditions, achieving a 55% increase in biomass titer, a 51% increase in biomass per proton yield, an 86% increase in substrate conversion, and the complete elimination of by-product accumulation all relative to the WT. However, the LAE consortium had the trade-off of a 42% lower specific growth rate. The AAE consortium did not outperform the WT in any considered performance metric. Performance advantages of the LAE consortium were sensitive to environment; increasing the medium buffering capacity negated the performance advantages compared to WT. Most naturally occurring microorganisms persist in consortia where metabolic interactions are common and often essential to ecosystem function. This study uses synthetic ecology to test how different cellular interaction motifs influence performance properties of consortia. Environmental context ultimately controlled the division of labor performance as shifts from weakly buffered to highly buffered conditions negated the benefits of the strategy. Understanding the limits of division of labor advances our understanding of natural community functioning, which is central to nutrient cycling and provides design rules for assembling consortia used in applied bioprocessing.
分工带来的健身益处在微生物共生体中已有充分记录,但对这些益处对环境背景的依赖性却知之甚少。构建了两个合成大肠杆菌共生体来测试交换有机酸、局部环境和不同代谢策略机会成本之间的关系。机会成本量化了由于选择一种表型而未实现的收益。这些共生体代谢葡萄糖并交换乙酸或乳酸,以创建生产者-消费者食物网。有机酸具有不同的抑制特性和与它们在中心代谢中的位置相关的不同机会成本。交换的代谢物调节了不同的共生体动力学。交换乙酸的(AAE)共生体具有“推动”相互作用模式,其中生产者分泌的乙酸比消费者导入的乙酸快,而交换乳酸的(LAE)共生体具有“拉动”相互作用模式,其中消费者以与生产相当的速度导入乳酸。在缓冲能力较弱的环境条件下,LAE 共生体的性能优于野生型(WT)批次培养物,生物量滴度提高了 55%,生物量每质子产率提高了 51%,底物转化率提高了 86%,副产物积累完全消除,与 WT 相比均有所提高。然而,LAE 共生体的比生长速率降低了 42%。在任何考虑的性能指标中,AAE 共生体都没有优于 WT。LAE 共生体的性能优势对环境敏感;与 WT 相比,增加培养基缓冲能力会否定其性能优势。大多数自然存在的微生物在共生体中生存,在共生体中,代谢相互作用很常见,而且通常对生态系统功能至关重要。本研究使用合成生态学来测试不同的细胞相互作用模式如何影响共生体的性能特性。环境背景最终控制了分工绩效,因为从弱缓冲到强缓冲条件的转变否定了该策略的收益。了解分工的局限性有助于我们了解自然群落的功能,这对于养分循环至关重要,并为组装用于应用生物加工的共生体提供了设计规则。