Abstract

With an increasing energy demand in the world, other potential sources of energy are needed to be secured and developed. Solar technologies are attractive, though to harvest this energy cheaply and efficiently is technically challenging. Bio-photovoltaic (BPV) devices have been developed as a way of harvesting the solar energy. These devices use photosynthetic material to generate electron that can generate power output. Whilst it is believed that the source of electron is from chloroplasts (Bombelli et al., 2011; Energy Environ. Sci., 2011, 4, 4690), the mechanism on how electrons leave the cell is largely unknown.

It is hypothesised that NADPH oxidase is a potential candidate protein responsible for electrons extrusion across the cell plasma membrane (PM). Using a specific assay to detect extracellular superoxide anion (O2-) generated by NADPH oxidase, we have shown that diatoms can generate extracellular O2-. This production differs depending on the growth phase of the diatoms. Furthermore, increasing production of extracellular O2- is positively correlated with increasing power output, as measured by the BPV devices and rotating disc electrode (RDE) electrochemistry. This paves the way to manipulate cells to increase efficiency of BPV devices.