Oral Presentation 2014 International Biophysics Congress

Using wavelength specific photosynthetic responses to improve algal biofuel production (#158)

Peter Ralph 1 , Bojan Tamburic 1 , Milan Szabo 1 , David Suggett 1 , Martin Schliep 1 , Supriya Guruprasad 1 , Unnikrishnan Kuzhiumparambil 2 , Anthony W.D. Larkum 1 , John A. Raven 1 3
  1. Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Australia
  2. Centre for Forensic Science, University of Technology Sydney, Sydney, Australia
  3. Division of Plant Sciences, University of Dundee, James Hutton Institute, Invergowrie, Dundee, UK

Using a novel suite of bio-optical tools and photosynthetic assays we are able to examine how different wavelengths of light alter the primary production, photoprotection and photoinhibition, but more importantly the macromolecular composition of the microalgae Nannochloropsis oculata. As an important biofuel strain, it is important to understand which wavelengths cause greater photodamage and therefore require more repair of the photosynthetic apparatus in Nannochloropsis, leaving reduced energy for biosysnthesis of storage products, especially lipids. 

New insight has been gained through applying a combined light engine (light source able to provide narrow bandwidth excitation), coupled to a fluorometer and an oxygen-sensing optrode, we were able to provide a multi-spectral estimate of optimal photosynthesis (both oxygen and fluorescence proxies of photosynthetic condition). Cells grown at 60 and 300 mol photon m-2 s-1 had similar optical cross sectional area and both became saturated at higher irradiance when exposed to 540 nm, as opposed to 440 nm (highest absorption wavelength). Energy dissipation was strongly induced by 440 nm in comparison to green wavelengths (540 nm) for both HL and LL cells; it appears that different wavelengths induce different photoprotective responses.
The biofuel-producing alga Nannochloropsis oculata has the potential to selectively acclimate to distinct spectral regions of photosynthetically available radiation, with strong preference to blue-green light. These results have particular significance to industry where microalgae are grown under LEDs, rather than full spectrum sunlight.