In a groundbreaking study published in Environmental Science and Ecotechnology, researchers have advanced our understanding of biophotovoltaic (BPV) systems—innovative devices that merge photosynthetic microbes with electrochemical systems to convert sunlight into electricity. Using the cyanobacterium Synechocystis sp. PCC 6803, the study provides critical insights into the molecular mechanisms driving this green energy technology. Central to BPV systems is the process of extracellular electron transfer (EET), where electrons generated during photosynthesis are harvested by an electrode via mediators such as ferricyanide. The research reveals that EET does not significantly affect cell growth, carbon fixation, or oxygen evolution. However, it competes with natural photoprotective mechanisms known as Mehler-like reactions, redirecting electrons downstream of photosystem I. This sheds light on the electron source for ferricyanide-mediated EET, a key step in optimizing BPV efficiency. Additionally, the study highlights that high ferricyanide concentrations can alter the electron transport chain independently of EET, mimicking the effects of trace cyanide. This finding underscores the need to carefully balance mediator concentrations to enhance efficiency while minimizing potential biotoxic effects.

Full report : Biophotovoltaics: Advancing Sustainable Energy Tech.