Certain microalgal species can grow under high CO2 conditions and they hold the potential for tackling climate change by sequestering CO2 produced by power plants and other industries. Here we show how to select suitable algal species or strains for carbon sequestration and understand their responses to the high CO2 level (10%) at the molecular level. A community-based approach was used to enrich CO2-tolerant microalgae from a local water source. During the incubation process, changes in bacterio- and phytoplankton communities were monitored. At the end of CO2 enrichment, green algae Scenedesmus species dominated the algal community. Isolated Scenedesmus strains are able to grow rapidly with high CO2, wastewater, chicken manure nutrient, etc. The growth of algae also increased alkalinity and pH in the culture which can lead to additional carbon sequestration via the formation of CaCO3 precipitate. To understand how Scenedesmus obliquus responds to 10% CO2 exposure at the molecular level, we applied time-resolved transcriptomics (2, 12, 24 and 72 hrs) to investigate differential gene expression of the alga. Certain genes responsible for light-harvesting, chlorophyll synthesis, and carbon fixation (i.e. rbcS) were up-regulated at 10% CO2, and these functional responses are consistent with the increased photosynthesis efficiency and algal biomass under 10% CO2. Key genes like RuBisCO (rbcL) and carbonic anhydrase in carboxysomes did not respond actively to 10% CO2. S. obliquus responded quickly (2 hr) and became adaptive within 12 h when exposed to 10% CO2.  

Primary Presenter: Feng Chen, University of Maryland Center for Environmental Science (chenf@umces.edu)

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