蓝藻细胞工厂用于生产高性能生物降解塑料的直接碳捕获,Green Chemistry

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蓝藻细胞工厂用于生产高性能生物降解塑料的直接碳捕获
Green Chemistry ( IF 9.3 ) Pub Date : 2022-04-05 , DOI: 10.1039/d1gc04188f
Chunlin Tan ₁ , Fei Tao ₁ , Ping Xu ₁

Affiliation

由不可生物降解的塑料引起的塑料污染是 21 世纪最广泛讨论和最显着的挑战之一。开发可生物降解的塑料，如聚乳酸 (PLA)，被广泛认为是缓解这一问题的最终方法。然而，目前的PLA生产技术严重依赖玉米等粮食生产材料，导致材料生产与粮食供应之间的资源竞争。过量排放加剧全球变暖的二氧化碳是一种尚未开发的丰富碳资源。在此，我们开发了一种蓝藻细胞工厂，用于直接从 CO ₂从头生物合成 PLA，使用代谢工程和高密度培养（HDC）的组合策略。PLA生产的异源途径，包括工程化的D-乳酸脱氢酶、丙酸CoA-转移酶和聚羟基链烷酸合酶，被引入细长聚球藻PCC7942。随后，系统地应用了各种代谢工程策略，包括启动子优化、乙酰辅酶 A 自循环和碳通量重定向，导致 PLA 增加约 19 倍，达到 15.0 mg g ^-1细胞干重 (DCW)与对照相比。最后，PLA滴度为108.0 mg L ^-1使用 HDC 策略后获得的 , 比最初构建的菌株高出约 270 倍。令人惊讶的是，我们的蓝藻 PLA 的分子量（M _w , 62.5 kDa; M _n , 32.8 kDa）是报道的最高水平之一，非常适合商业化。这项研究揭示了使用蓝藻细胞工厂从 CO _{2生产自养塑料的前景。}

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Direct carbon capture for the production of high-performance biodegradable plastics by cyanobacterial cell factories

Plastic pollution caused by non-biodegradable plastics is one of the most widely discussed and notable challenges of the 21st century. Developing biodegradable plastics, such as polylactic acid (PLA), is broadly accepted as the ultimate way of alleviating this problem. However, current PLA production technology relies heavily on food-producible materials such as corn, which leads to competition for resources between material production and food supply. Carbon dioxide whose excessive emission aggravates global warming is an abundant underexplored carbon resource. Herein, we developed a cyanobacterial cell factory for the de novo biosynthesis of PLA directly from CO₂, using combinational strategies of metabolic engineering and high-density cultivation (HDC). The heterologous pathway for PLA production, which involves engineered D-lactic dehydrogenase, propionate CoA-transferase, and polyhydroxyalkanoate synthase, was introduced into Synechococcus elongatus PCC7942. Subsequently, various metabolic engineering strategies, including promoter optimization, acetyl–CoA self-circulation, and carbon-flux redirection, were systematically applied, resulting in an approximately 19-fold increase of PLA to 15.0 mg g⁻¹ dry cell weight (DCW) compared to the control. Finally, the PLA titer of 108.0 mg L⁻¹ was obtained after using the HDC strategy, approximately 270 times higher than that obtained from the initially constructed strain. Surprisingly, the molecular weight (M_w, 62.5 kDa; M_n, 32.8 kDa) of our cyanobacterial PLA is among the highest reported levels, which is superior for commercialization. This study sheds light on the prospects of autotrophic plastic production from CO₂ using cyanobacterial cell factories.

更新日期：2022-04-05

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