Exploiting Underutilised Regions of the Solar Spectrum

Anoxygenic phototrophs use bacteriochlorophylls to harvest light outside of the visible range, relying on wavelengths unused by chlorophyll-containing oxygenic organisms typically found above in their ecological niche. Augmentation of oxygenic organisms with near-infrared absorbing complexes from anoxygenic phototrophic bacteria has been suggested as a means to increase the efficiency of photosynthesis in crops^1,2. Current understanding of photosynthetic apparatus assembly and regulation, and the complexity of extending the chlorophyll pathway towards bacteriochlorophyll biosynthesis, are hindering progress towards this goal. I will present recent work detailing the successful transfer of a bacterial light-harvesting complex between purple bacteria, allowing the transgenic strain to access wavelengths that were previously unavailable. I will also discuss methods we have used for the modification of the (bacterio)chlorophyll biosynthesis pathway in phototrophic bacteria, yielding strains producing non-native pigments that permit photosynthesis in underutilised regions of the near-infrared. These approaches serve as first steps in the engineering of oxygenic organisms to capture light outside of the visible range.

1. Blankenship RE et al. 2011. Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement. Science 332:805-809
2. Ort DR et al. 2015. Redesigning photosynthesis to sustainably meet global food and bioenergy demand. PNAS 112:8529-8536