Nature's biocatalytic processes are driven by photosynthesis, whereby photosystems I and II are connected in series for light-stimulated generation of fuel products or electricity. Externally supplying electricity directly to the photosynthetic electron transfer chain (PETC) has numerous potential benefits, although strategies for achieving this goal have remained elusive. Here we report an integrated photo-electrochemical architecture which shuttles electrons directly to PETC in living cyanobacteria. The cathode of this architecture electrochemically interfaces with cyanobacterial cells that have a lack of photosystem II activity and cannot perform photosynthesis independently. Illumination of the cathode channels electrons from an external circuit to intracellular PETC through photosystem I, ultimately fueling cyanobacterial conversion of CO₂ into acetate. We observed acetate formation when supplying both illumination and exogenous electrons under intermittent conditions (e.g., in a 30 s supply plus 30 min interval condition of both light and exogenous electrons). The energy conversion efficiency for acetate production under programmed intermittent LED illumination (400–700 nm) and exogenous electron supply reached ca. 9%, when taking into account the number of photons and electrons received by the biotic system, and ca. 3% for total photons and electrons supplied to the cyanobacteria. This approach is applicable for generating various CO₂ reduction products by using engineered cyanobacteria, one of which has enabled electrophototrophic production of ethylene, a broadly used hydrocarbon in the chemical industry. The resulting bio-electrochemical hybrid has the potential to produce fuel chemicals with numerous potential advantages over standalone natural and artificial photosynthetic approaches.

中文翻译：

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流经蓝藻光系统 I 的外源电力以高能效驱动 CO2 增值

大自然的生物催化过程由光合作用驱动，其中光系统 I 和 II 串联连接以光刺激产生燃料产品或电力。从外部直接向光合电子转移链 (PETC) 供电具有许多潜在的好处，尽管实现这一目标的策略仍然难以捉摸。在这里，我们报告了一种集成的光电化学结构，该结构将电子直接穿梭到活蓝藻中的 PETC。这种结构的阴极与缺乏光系统 II 活性且不能独立进行光合作用的蓝藻细胞进行电化学接口。阴极的照明通过光系统 I 将电子从外部电路引导至细胞内 PETC，最终促进 CO 的蓝藻转化₂成醋酸盐。我们在间歇条件下（例如，在 30 秒的供应加上 30 分钟的光和外源电子的间隔条件下）同时提供照明和外源电子时，我们观察到醋酸盐的形成。在程序化的间歇 LED 照明（400-700 nm）和外源电子供应下，醋酸盐生产的能量转换效率达到了大约。9%，当考虑到生物系统接收的光子和电子数量时，大约为 9%。提供给蓝藻的总光子和电子为 3%。这种方法适用于产生各种 CO ₂通过使用工程蓝藻还原产物，其中一种已经能够通过电光养生法生产乙烯，这是一种在化学工业中广泛使用的碳氢化合物。由此产生的生物电化学混合物有可能生产燃料化学品，与独立的自然和人工光合作用方法相比具有许多潜在优势。