Investigating photosynthetic efficiency and nutrient use in marine microalgae (provisional- for admin. purposes only)

Given the role of CO2 in climate change, development of carbon-efficient biomanufacturing solutions is important. Microalgae (including cyanobacteria) are an important part of the global food chain as major primary producers, and are unique in their ability to perform oxygenic photosynthesis and CO2 fixation. However, low photosynthetic efficiency, specifically carbon fixation per nutrient used, is limiting under industrial settings. CyanoCapture seeks to engineer a Synechococcus elongatus, PCC11901 (Syn11901) with maximum carbon fixation for minimum nutrient input, with a view to scale up as a point-source carbon capture technology. Pathways for maximising photosynthetic efficiency include improving Rubisco activity for carbon fixation, CO2 concentrating mechanism (CCM), and reduction of other metabolic burdens including respiration rates. However, these incur significant barriers, so we look to evolutionary history in search of novel avenues for manipulation.

This iCASE focuses on characterising nutrient use efficiency (NUE) across cyanobacteria, coccolithophores and prasinophytes, with implications for industrial application of carbon fixation and in understanding the emergence of the oligotrophic ocean in Earth's history. The primary nutrient of interest is phosphorus, as inorganic phosphorous stores have rapidly depleted with the advent of modern agriculture and industry. The project fits into a large-scale attempt to understand the global shift from a nitrogen- to phosphorous-limited planet, and what this will mean for the composition and carbon fixing power of primary productivity.

The project aims to: (1) identify the most photosynthetically efficient coccolithophore and prasinophytes; (2) investigate growth rate and elemental stoichiometry of these strains in comparison to Syn11901 (WT and engineered strains of interest provided by CyanoCapture); (3) place the strains into their evolutionary contexts; (4) engineer a photosynthetically 'streamlined' cyanobacterium with maximum carbon fixation for minimum energy loss, under minimal nutrient conditions and; (5) use metabolomics and fluxomics to elucidate carbon flux in these organisms.

BBSRC theme: Bioscience for renewable resources and clean growth.