Development of Anabaena 33047, a Fast-Growing N2-Fixing Cyanobacterium, as a Carbon Neutral Bioproduction Platform
Cyanobacteria, oxygenic photosynthetic prokaryotes, are emerging as promising platforms for cost effective conversion of sunlight and CO2 into high value end products. Anabaena sp. ATCC 33047, a heterocystous cyanobacterium, stands out in this category of fast-growing cyanobacteria for its ability to utilize atmospheric N2 in addition to CO2 and generate biomass at unprecedented rates. Developing such a strain as a chassis can eliminate the need for fixed nitrogen in bioproduction systems, a significant step towards replacement of petroleum derived products. Our work aimed to develop Anabaena 33047 into such a bioproduction platform. Despite its many appealing traits, Anabaena 33047 remained largely unexplored due to its recalcitrance to any genetic manipulation. During this project, we have developed a method that has enabled targeted genome modification of this strain. We also constructed a genome scale metabolic model iAnC892, which captures the diazotrophic life cycle of Anabaena 33047 by accounting for both vegetative and heterocyst cell types. The model provided insight into the importance of light dependent electron transport in the heterocyst and revealed pathway combinations that can supply reducing equivalents and ATP in the appropriate ratio for optimal N2 fixation. To validate the existing metabolic models and to have a better understanding of the metabolism of Anabaena 33047 under different growth conditions, we performed a series of stable-isotope tracing experiments and quantified metabolic fluxes using state-of-the-art tools for 13C-metabolic flux analysis. Using our novel engineering strategy and based on our model predictions, we performed targeted deletion in the strain and generated a mutant with modified light harvesting properties in heterocysts. The mutant exhibited better light utilization and increased rates of nitrogen fixation. Overall, this project has laid the foundation for developing the non-model cyanobacterium Anabaena 33047 into a highly efficient chassis for conversion of solar energy, atmospheric CO2 and N2 into high value bio products.
- Research Organization:
- Washington Univ., St. Louis, MO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- DOE Contract Number:
- SC0019386
- OSTI ID:
- 1961394
- Report Number(s):
- DOE-WUSTL-9386
- Country of Publication:
- United States
- Language:
- English
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