A synthetic biology platform for sustainable, climate-friendly conversion of CO2 to products using cyanobacteria

一个合成生物学平台，利用蓝藻将二氧化碳可持续、气候友好地转化为产品

• 批准号: 2746407
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2746407
• 关键词: synthetic; biology; platform; sustainable; climate

Cyanobacteria are the simplest and most genetically-tractable organisms capable of oxygenic photosynthesis, using CO2 and sunlight as sole carbon and energy sources. Their photosynthetic yield and growth rate are similar to the fastest-growing microalgae, and greater than terrestrial plants. Consequently, cyanobacteria have great potential as whole-cell biocatalysts in light-driven, carbon-negative bioprocesses converting atmospheric or waste CO2 to products of interest, while avoiding competition with the food chain. Cyanobacteria have been genetically modified to synthesise a wide range of non-native compounds from commodity chemicals and biofuels to high-value products.CHALLENGE:Production using cyanobacteria is not yet commercially competitive with production by conventional approaches due to the current low economic cost of using fossil carbon and emitting CO2. It is also difficult to rationally design DNA encoding an optimal metabolic pathway. If expression is too high, too low, or poorly 'balanced', then low productivity and/or genetic instability results.SOLUTION:Modern DNA assembly allows construction of large libraries of many pathway-encoding construct variants, varying the expression of each enzyme combinatorially. High-performance variants can be identified by screening. This approach has been well proven, but in only a few model organisms. We recently developed a platform for combinatorial construction and optimisation of metabolic pathway-encoding constructs in cyanobacteria, applied it to production of lycopene from CO2 in Synechocystis sp. PCC 6803, and successfully obtained strains with pathways that were both productive and genetically stable, overcoming this key problem.AIM:The new combinatorial metabolic pathway construction platform will be applied and developed to generate photoautotrophic cell factories with highly-productive, genetically stable engineered metabolic pathways, using key strains.APPROACH:Using DNA synthesis, coding sequences for foreign pathway enzymes and native 'bottleneck' enzymes, as well as host-appropriate expression control parts (promoters, ribosome-binding sites, terminators, etc) will be formatted for Start-Stop Assembly, our recently-published DNA assembly system optimised for metabolic engineering. Hierarchical multi-part assembly with controlled part mixtures will generate combinatorial pathway libraries for insertion into host cells and screening using analytical methods e.g. GC/LC/MS/NMR.A) HOSTS:The platform is already validated for the standard strain Synechocystis sp. PCC 6803, allowing work to start quickly and focus entirely on pathways, without need for platform development. The newly-described, fast-growing, high-producing, but little-studied strain Synechococcus sp. PCC 11901 has great potential, and will first require the development of expression control parts. Similarly, the platform will be transferred to Spirulina, a safe, food-grade strain suitable for nutraceutical and medical products.B) PRODUCTS:A wide range of natural and non-natural products could be biosynthesised including alcohols, organic acids, fatty acids, fatty alcohols, alkanes, terpenoids, alkaloids, peptides, sugars, flavours, fragrances, specialised metabolites, pharmaceutical precursors, nutraceuticals, drugs and vaccines. The high-throughput assembly allows multiple different products to be targeted in parallel.C) INTEGRATION WITH OTHER APPROACHES & TECHNIQUES:Combinatorial pathway optimisation will be combined with classical metabolic engineering, knocking out competing pathways, guided by physiological understanding and/or metabolic modelling, subject to the student's interests. Finally, our new, patented, high-throughput enzyme evolution system can be applied to problematic enzymes in important pathways, such as alkane biosynthesis.

蓝藻是最简单和最易遗传的生物，能够利用二氧化碳和阳光作为唯一的碳和能源进行氧合光合作用。它们的光合作用产量和生长速度与生长最快的微藻相似，比陆地植物更大。因此，蓝藻在光驱动的、碳负的生物过程中作为全细胞生物催化剂具有巨大的潜力，将大气或废物二氧化碳转化为感兴趣的产品，同时避免与食物链竞争。蓝藻已经经过基因改造，可以合成从商品化学品和生物燃料到高价值产品的各种非本地化合物。查伦格：由于目前使用化石碳和排放二氧化碳的经济成本较低，使用蓝藻生产与传统方法生产相比，在商业上尚不具竞争力。要合理地设计编码最佳代谢途径的DNA也是很困难的。如果表达太高、太低或不平衡，那么就会导致生产率低下和/或遗传不稳定。解决方案：现代DNA组装允许构建许多编码途径的结构变体的大型文库，从而组合改变每个酶的表达。高性能的变种可以通过筛选来识别。这种方法已经得到了很好的证明，但只在少数几个模式生物中得到了验证。我们最近开发了一个蓝藻代谢途径编码结构的组合构建和优化平台，并将其应用于集胞藻CO2合成番茄红素的研究。目的：应用和开发新的组合代谢途径构建平台，利用关键菌株产生高效、遗传稳定的工程代谢途径的光自养细胞工厂。APPROACH：利用DNA合成，外源途径酶和天然的瓶颈酶的编码序列，以及宿主适当的表达调控部分(启动子、核糖体结合位点、终止子等)将被形成用于起止组装，我们最近发表的DNA组装系统针对代谢工程进行了优化。带有受控部分混合物的分层多部分组装将生成组合途径文库，用于插入宿主细胞并使用分析方法(如GC/LC/MS/NMR)进行筛选。PCC 6803，允许工作快速启动并完全专注于路径，而不需要平台开发。新发现的一株快速生长、高产但鲜有研究的聚球藻。PCC11901有很大的潜力，首先需要开发表达调控部分。同样，该平台将转移到螺旋藻，这是一种安全的食品级菌株，适合于营养食品和医疗产品。b)产品：广泛的天然和非天然产品可以被生物合成，包括醇、有机酸、脂肪酸、脂肪醇、烷烃、萜类、生物碱、多肽、糖、香料、香料、特殊代谢物、药物前体、营养食品、药物和疫苗。C)与其他方法和技术的集成：组合途径优化将与经典代谢工程相结合，根据学生的兴趣，在生理理解和/或代谢模型的指导下，敲除相互竞争的途径。最后，我们新的、获得专利的高通量酶进化系统可以应用于重要途径中的问题酶，如烷烃生物合成。