窄食单胞菌对微藻在高浓度甲酸条件下光合生长的促进作用

Promotion of Stenotrophomonas sp. on the photosynthetic growth of microalgae exposed to high concentrations of formate

摘要:

甲酸是一种重要的太阳燃料，具有很高的生物转化应用前景，尤其是与光合微藻相结合，理论上能最大化人工与生物光合成的优势。然而甲酸对微藻光合电子传递具有明显的抑制，限制了其应用，常规的改造和定向进化策略耗时且普适性不高。本文介绍了一条新的甲酸在光合微藻培养过程中的应用路线，通过将一株分离自微藻高甲酸进化过程的窄食单胞菌或其发酵产物与微藻进行共培养，解除了50 mmol/L甲酸根对莱茵衣藻光合活性的抑制，促进其光合生长，极大提升了胞内蛋白含量(约50%)。初步测试表明，这一策略也同样适用于小球藻和集胞藻，具有普适性。这一策略的提出有望打破甲酸介导的人工-生物杂化光合成技术瓶颈，建立更普适和高效的太阳光能驱动二氧化碳还原制备蛋白质的大宗生物质工艺。

关键词:太阳燃料;甲酸;蛋白质;食品供给安全;藻菌互作

Abstract:

Formate is an important solar fuel, with large application potential in bioconversion. Especially, the win-win collaboration is achieved when formate is applied to the cultivation of microalgae, which combines the advantages from both artificial and natural photosynthesis. However, the inhibition of formate on the photosynthetic electron transport hinders the application of formate at high concentrations. The engineering or directed evolution of the regulation pathway is a case-by-case and time-consuming strategy. Here, we developed a new strategy by introducing a Stenotrophomonas sp. strain which was isolated and identified from the long-term self-evolution process of Chlamydomonas reinhardtii for adapting to high concentrations of formate. The co-culture with the strain or the fermentation broth relieved the inhibition of formate (50 mmol/L) on C. reinhardtii and promoted the growth of the microalga. Especially, the protein content increased significantly to nearly 50% of the dried weight. In addition, the co-culture also benefited the growth of both Chlorella pyrenoidesa and Synechocystis sp. PCC 6803 exposed to formate, which indicated broader applicability of this strategy. This strategy provides the opportunity to overcome the bottleneck in the formate-mediated artificial-natural hybrid photosynthesis and to aid the development of technologies for solar energy-driven production of bulk biomass, including proteins, by carbon dioxide reduction.

Key words:solar fuels;formate;protein;security of food supply;bacterium-microalga interaction