Virus inhibition of oceanic CO2 fixation

ongoing

Around half of the carbon dioxide (CO2) fixation on Earth occurs in marine systems, environments dominated by the cyanobacterial genera Synechococcus and Prochlorococcus. Viruses infecting these organisms (cyanophages) divert the flow of an estimated 20% of globally fixed CO2. Intriguingly, my lab has recently shown that cyanophage can directly inhibit host CO2 fixation capacity whilst at the same time carry genes essential for the light-driven reactions of photosynthesis. VirFix will elucidate the molecular basis of how viruses inhibit host CO2 fixation, which I hypothesise involves a novel protein based mechanism, and directly assess CO2 fixation rates in viral infected cells requiring the development of innovative approaches to both manipulate cyanophage genomes and enumerate viral infected cells in natural seawater samples. By focusing on how viral infection controls CO2 fixation under environmentally relevant light and nutrient conditions, Virfix will tackle novel concepts associated with elemental stoichiometry and pseudolysogeny and provide host mortality estimates which will directly inform and refine global primary production ecosystem models. In so doing, I will contribute new biological theory into how CO2 fixation is controlled at the global scale. Thus, I will be able to determine how viruses modulate primary production in organisms that are the most abundant phototrophs on the planet and whose abundance is expected to increase by 15-30% at the end of the 21st century due to global warming. By building innovative research directions on a solid foundation of host physiology and genomics I will contribute new understanding of photosynthesis and metabolism as subverted by cyanophage. Together, the proposed work has crucial implications for our understanding of marine carbon cycling and ultimately the planet’s climate and will provide novel genetic approaches for manipulating photosynthesis allowing for their potential exploitation in energy generation.