The biological CO2 fixation and utilization project by rite (2) — Screening and breeding of microalgae with high capability in fixing CO2 —

Abstract

In order to mitigate the potential problems associated with increasing atmospheric CO2 levels, RITE has started the biological CO2 fixation and utilization project in 1990 using photosynthetic microorganisms, such as microalgae and photosynthetic bacteria. Photosynthetic microorganisms utilize flue gas CO2 as a carbon source and solar energy as the energy source to produce biomass which can be used for useful materials. Extensive screening has been conducted to obtain photosynthetic microorganisms from nature with high capability in fixing CO2 and/or with the ability to produce useful materials. More than ten strains of microalgae with high capability in fixing CO2 and/or with the ability to produce useful materials have been obtained. Two green algal strains obtained by the screening, Chlorella sp. UK001 and Chlorococcum littorale, showed the high CO2 fixation rates exceeding the initial target value of 1gCO2/1/day at 24h illumination. Botryococcus braunii SI-30 was obtained as the alga producing hydrocarbons which can be used as recyclable fuel resource. This alga contains more than 15% of its dry weight as hydrocarbons and shows relatively high growth rate than other Botryococcus braunii strains. Efforts are now under way to increase their CO2 fixation rates by optimizing the culture conditions and to develop applications for the products.