Conversion of light into electricity in a semi-synthetic system based on photosynthetic bacterial chromatophores

• Published in: Biochimica et biophysica acta. Bioenergetics 2023-08, Vol.1864 (3), p.148975-148975, Article 148975
• Main Authors: Vitukhnovskaya, Liya A., Zaspa, Andrey A., Semenov, Alexey Yu, Mamedov, Mahir D.
• Format: Article
• Language: English
• Subjects: Chromatophores; Coenzyme UQ0; Indium tin oxide; Nitrocellulose Millipore filter; Photovoltage; Trehalose
• ISSN: 0005-2728; 1879-2650
• DOI: 10.1016/j.bbabio.2023.148975

Chromatophores (Chr) from photosynthetic nonsulfur purple bacterium Rhodobacter sphaeroides immobilized onto a Millipore membrane filter (MF) and sandwiched between two semiconductor indium tin oxide (ITO) electrodes (termed ITO|Chr – MF|ITO) have been used to measure voltage (ΔV) induced by continuous illumination. The maximum ΔV was detected in the presence of ascorbate / N,N,N’N'-tetramethyl-p-phenylenediamine couple, coenzyme UQ0, disaccaride trehalose and antimycin A, an inhibitor of cytochrome bc1 complex. In doing so, the light-induced electron transfer in the reaction centers was the major source of photovoltages. The stability of the voltage signal upon prolonged irradiation (>1 h) may be due to the maintenance of a conformation that is optimal for the functioning of integral protein complexes and stabilization of lipid bilayer membranes in the presence of trehalose. Retaining ∼70 % of the original photovoltage performance on the 30th day of storage at 23 °C in the dark under air was achieved after re-injection of fresh buffer (∼40 μL) containing redox mediators into the ITO|Chr – MF|ITO system. The approach we use is easy and can be extended to other biological intact systems (cells, thylakoid membranes) capable of converting energy of light. •Immobilization of Chr onto a Millipore nitrocellulose membrane•Direct measurement of photovoltage in Chr vesicles using semiconductors ITO.•Generation of a stable voltage over a 60 min period of irradiation•Preservation of Chr photoactivity after 30 days storage at room temperature in the dark