Australian scientists have helped visualise a complex and critical part of photosynthesis.

The experts behind the finding say it could help guide the development of next-generation solar biotechnologies.

Over three billion years, plants, algae, and blue-green bacteria have evolved elaborate nano-machinery that enables them to perform photosynthesis, in which solar energy is captured and stored in the form of chemical energy.

Researchers from The University of Queensland, (UQ) the University of Münster, the Universities of Basel, Okayama and New South Wales, have purified and visualised a big part of this process - the ‘Cyclic Electron Flow’ (CEF).

Photosynthesis has two modes: linear electron flow (LEF) and cyclic electron flow (CEF).

To work efficiently under changing light conditions, a photosynthetic organism balances the light that it absorbs with the energy that it needs. It does this by continuously fine-tuning the levels of these two modes in relation to one another.

There had been some evidence that the cyclic electron flow (CEF) plays a critical role in this fine-tuning process, but due to its dynamic nature it has been difficult to purify so that its structure could be determined.

The team used sophisticated methods to purify and characterise the CEF supercomplex from micro-algae, and then analysed its structure using electron microscopy.

This involved painstakingly imaging about half a million protein complexes extracted from microalgae in search for the supercomplex. Only about one thousand of these turned out to be the CEF supercomplex.

The analysis revealed how the light harvesting arrangement enables the connection and disconnection needed to perform different functions, allowing the organism to adapt to varying light conditions and energy requirements.

The researchers say that understanding photosynthesis at the molecular level is crucial for the development of solar biotechnologies – using natural systems to harvest electricity.

“By the year 2050, we will need 50 per cent more fuel, 70 per cent more food, and 50 per cent more clean water. Technologies based on photosynthetic microalgae have the potential to play an important role in meeting these needs,” says Professor Ben Hankamer from UQ’s Institute for Molecular Bioscience and directs the Centre for Solar Biotechnology.