Collaborative Research: Creating Synthetic Lichen to Elucidate how Morphology Impacts Mutualistic Exchanges in Microbial Communities.

复杂的微生物群落定居在地球上的大多数表面，包括岩石、树叶和我们的器官。它们在这些表面上的活动和相互作用对人类、植物、动物和生态系统的健康都有重大影响。然而，这些微生物群落的三维结构对它们交换资源的能力的影响仍然知之甚少。这限制了预测自然微生物在不断变化的环境中的生长速度和弹性的能力，以及为工业应用设计合成微生物的能力。这项工作使用合成生物学来改造工业微生物，以概括地衣共生的各个方面，其中结构在微生物交换中起着核心作用。这种方法有助于对形态对共生的贡献产生新的见解，并为设计微生物之间的生长和交流提供强大的新工具。通过这项工作创造的合成地衣是研究共生的一个强大的新平台，也是一个新的光合作用生物制造平台。此外，这个项目使用合成地衣作为工具和隐喻来创造艺术，可以将支撑这项工作的想法传达给本科生和更广泛的公众。在这个项目中，由自由生活的蓝藻作为光生物体和丝状真菌作为真菌生物体创造了一个合成的地衣，以探索形态所产生的物理耦合如何影响代谢交换的生理结果。真菌的形态模式是通过先前验证的合成细胞-细胞信号系统实现的，该信号系统包括吲哚3-乙酸(生长素)生物合成途径和具有一系列敏感性的生长素诱导的基于Cas9的转录因子(HACR)文库。蓝藻被设计成产生基于生长素的图案线索，HACR被用来将这些信号与真菌中调节形态的基因的表达联系起来，以产生地衣样的形态。同时，蓝藻的形态特征是通过利用丝状或单细胞菌株来调节的，或者利用已经建立的将杆状单细胞蓝藻转化为不同长度的细丝的途径。这些微生物还被设计成执行利他代谢行为，即光生物体和真菌生物体分别分泌蔗糖和胞外多糖，导致共生体模仿地衣中观察到的关系。该项目阐明了微生物之间形态产生的不同程度的物理耦合如何影响推动联合体水平生理学的新陈代谢交换。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Complex communities of microbes colonize most surfaces on the planet including rocks, leaves, and our organs. Their activities and interactions on these surfaces have major impacts on human, plant, animal, and ecosystem health. However, the impact of the 3D structure of these microbial communities on their capacity to exchange resources remains poorly understood. This has limited the capacity both to predict the growth rate and resilience of natural microbes in changing environments, as well as to engineer synthetic microbiomes for industrial applications. This work uses synthetic biology to engineer industrial microbes to recapitulate aspects of lichen symbiosis, where structure plays a central role in microbial exchange. This approach facilitates generating novel insights into the contribution of morphology to symbiosis and powerful new tools for engineering the growth and communication between microbes. The synthetic lichen created through this work is a powerful new platform to study symbiosis, as well as a novel photosynthetic biomanufacturing platform. Additionally, this project uses synthetic lichen as both a tool and a metaphor to create art that can communicate the ideas underpinning this work to undergraduate students and the broader public. In this project a synthetic lichen is created from free living cyanobacteria as photobiont and filamentous fungi as mycobiont, to explore how the physical coupling created by morphology impacts the physiological outcomes of metabolic exchanges. The morphological patterning of the fungi is implemented using a previously validated synthetic cell-cell signaling system consisting of an Indole 3-Acetic Acid (auxin) biosynthesis pathway and a library of auxin-inducible Cas9-based transcription factors (HACRs) with a range of sensitivities. The cyanobacteria is engineered to generate auxin-based patterning cues and HACRs are used to connect these signals to the expression of genes regulating morphology in the fungus, to generate a lichen-like morphology. In parallel, morphological features of the cyanobacterium are modulated by utilizing either a filamentous or single-celled strain, or established pathways for converting rod-shaped unicellular cyanobacteria into elongated filaments of varying lengths. These microbes are also engineered to perform altruistic metabolic behaviors, namely the secretion of sucrose and extracellular polysaccharide by the photobiont and mycobiont respectively, resulting in symbioses that mimic the relationship observed in lichens. This project elucidates how the different degrees of physical coupling that morphology generates between microbes impact the metabolic exchanges which drive consortia-level physiology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.