Fig. 5. Periplasmic semiconductor biointerface may couple with electron transport chain for semi-artificial photosynthesis.

(A) A heatmap from transcriptomic analysis indicates that CdS biomineralization up-regulates genes related to the electron transport chain, including dehydrogenases, terminal reductases and oxidases, and ATP synthases. (B) Schematic showing the electron transport chain with up-regulated genes highlighted in red letters. The red arrow indicates the direction of electron transport, while the purple arrow indicates proton transport. (C) Production of ATP in E. coli cells with biomineralized CdS nanoclusters under light is 8.1 times of the ATP production in cells in the dark. The data points represent means ± SD (n = 4). P values (<0.001) are determined by unpaired two-tailed t test. White light intensity, 6.25 mW/cm²; duration, 24 hours. (D) Schematic of an artificial power system derived from biohybrids to assist ATP production and speed up the production of high-value biochemicals (e.g., malate). PPS, phosphoenolpyruvate synthase; PEPC, PEP carboxylase; PC, pyruvate carboxylase; MDH, malate dehydrogenase. (E) Production of malate in E. coli with CdS nanoclusters increases from 1.9 mg/liter (in the dark) to 12.1 mg/liter (under light). The data points represent means ± SD (n = 5). P values (<0.001) are determined by unpaired two-tailed t test. Notably, E. coli without CdS nanoclusters produces no significant difference in malate production in light or in the dark. P values (0.3121) are determined by unpaired two-tailed t test. The data points represent means ± SD (n = 4). White light intensity, 6.25 mW/cm²; duration, 24 hours.