An Alkaliphilic Cyanobacterial Consortium for Air-Capture and Conversion of Carbon dioxide
Creators: name: Ataeian, Maryam
Publisher: name: Science
Year: 2022
Subjects: subject: Cyanobacteria
subject: Biofuels
subject: Carbon Capture
subject: Metagenomics
subject: Metaproteomics
subject: Soda lakes
subject: Bioproducts
subject: Direct Air Capture
subject: Renewable Energy
subject: Photosynthesis
subject: Algae
subject: Biotechnology
subject: Education--Sciences
subject: Biology
subject: Bioinformatics
subject: FOS: Computer and information sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Genetics
subject: Microbiology
subject: Biology--Molecular
subject: Environmental Sciences
subject: Energy

description: Cyanobacteria encompass a diverse group of photosynthetic Bacteria with important roles in nature and biotechnology. The ability of cyanobacteria to fix carbon dioxide (CO2) through oxygenic photosynthesis, with minimal nutritional requirements and non-potable water, has led to their adoption for bio-production of high-value nutraceuticals. While cyanobacteria-based biotechnologies hold much potential for the production of bio-products, there remain several challenges for efficient and cost-effective implementation of this technology at scale. This thesis explores multiple innovative approaches to overcome those challenges using a cyanobacterial consortium, enriched from phototrophic microbial mats of alkaline soda lakes in British Columbia, Canada. First, the cyanobacterial consortium was investigated as an alkaline capture and conversion system (chapter 2). This study demonstrated successful cyanobacterial growth at a pH above 11, with high and robust biomass productivity. And for the first time, feasibility of direct capture of CO2 from the atmosphere into the spent medium was shown. In chapter 3, a combination of Nanopore and Illumina sequencing was used to obtain a complete genome of the abundant cyanobacterium of the consortium, provisionally named Candidatus “Phormidium alkaliphilum”. Evolutionary changes in the genome during three years of laboratory cultivation were investigated and differences in gene content between alkaliphilic and neutral pH Phormidium species were studied. Favourable genomic factors contributing to the ecological success of this genus in both alkaline soda lakes and in photobioreactors were discussed. Lastly, in chapter 4, the community composition of the consortium’s heterotrophic members and their ecological interactions with Ca P. alkaliphilum were analyzed using metagenomics, metaproteomics, and stable isotope probing/proteomics. Adaptation to different photobioreactors (tubular and stirred) at different pH and with different nitrogen sources (ammonium, urea, and nitrate) was explored. Genome information from each heterotrophic population was investigated for six ecological niches created by cyanobacterial metabolism and one niche for phototrophy, explaining the robustness of the system. In conclusion, this work explored innovative solutions based on biological and chemical mechanisms to improve the feasibility of cyanobacterial biotechnology and expanded current knowledge on ecological interactions of the genus Phormidium in its natural environment.