蓝藻-曲霉共培养合成聚酮化合物研究及藻菌互作机制的解析

新兴的人工光驱共生合成体系是藻类与异养微生物共培养形成的合成微生物群落，可实现二氧化碳向高附加值生物质产品的转化。其中藻菌的组成及藻菌互作机制对该体系的稳定和高效有重要影响，但迄今仍缺乏系统和深入的研究。我们已发表文章报道，①蓝藻与酵母真菌共培养，可形成稳定的共生合成体系；②蓝藻与真菌的互作可增强蓝藻的生理鲁棒性。近期预实验我们发现，蓝藻与丝状真菌构巢曲霉显示出互利共生的共培养特征。本项目计划模拟地衣菌藻共生体，创新性地采用与地衣真菌具有高度同源性的构巢曲霉，利用其较强的抗逆性、广泛的底物利用能力等优势，与盐胁迫产蔗糖的蓝藻共培养；进而研究“类地衣”光驱共生体系的构建及聚酮化合物的合成。同时，设置藻菌各自的纯培养和彼此菌体直接与非直接接触的共培养，系统地比较蓝藻与曲霉菌体的生理状态、代谢途径和代谢物交换的变化，阐明共培养中藻菌的互作机制，为人工光驱共生合成体系的优化和控制提供理论依据。

Synthetic light-driven consortia composed of a photoautotroph (algae or cyanobacteria) and a heterotroph, has the capability to transform carbon dioxide into high value-added bioproducts. This symbiotic synthesis system represents an emerging frontier of synthetic microbial communities. Photoautotroph in these consortia harvests light energy and converts it to organic substrate that is provided to a heterotrophic partner, which then converts the organic compounds into biomass and products. As important factors affecting the establishment of a stable and efficient symbiotic synthesis system, the composition of consortia and the mutualistic interaction between partners involved in the consortia are less studied. In our previous studies, mimicking the symbiosis of cyanobacteria and fungi in lichens, incorporating yeast strains together with sucrose-secreting cyanobacteria built a mutualistic co-culture consortia; the mutualistic interaction between cyanobacteria and fungi significantly enhanced the robustness of cyanobacteria. .Recently, in preliminary experiments, we found that sucrose-secreting cyanobacteria can form partnerships with filamentous fungi Aspergillus that promote the growth and physical association of both species. Interestingly, many of the ascomycete fungal species present in lichens such as Aspergillus evolved originally as lichen partners before becoming independent free-living organisms. Furthermore, Aspergillus has the advantage of tolerating salt stress that required for sucrose secreting by cyanobacteria, and utilizing a wide range of substrates, such as extra-polysaccharides, and other organic carbon from cyanobacteria. .Therefore, one goal of this proposal is using sucrose-secreting cyanobacteria and polyketide-producing Aspergillus, to create synthetic lichen partnerships that can achieve high biomass levels using CO2 and sunlight while simultaneously generating valuable bioproducts such as polyketide with immunosuppressive activities. A second goal is to decipher how each species is benefitting from cyanobacteria-Aspergillus interactions. This will be ascertained by performing SEM, CLSM, photosynthesis regulation of cyanobacteria, transcriptomic, proteomics and major metabolites analysis. The physiological state, metabolic pathway and metabolite exchange of cyanobacteria and Aspergillus in axenic culture and co-culture will be systematically compared to examine how physiology changes as part of these partnerships. Our study will help to understand relationships in the phototroph-heterotroph community, and will provide theoretical surpport for the optimization and control of a synthetic light-driven consortia which represents a novel bioproduction platform for the sustainable future.