Selection of native freshwater microalgae and cyanobacteria for CO2 biofixation

One of the technologies available for coping with problems related to the rise in atmospheric concentrations of carbon dioxide is CO2 biofixation with microalgae or cyanobacteria. The selection of native strains that grow well at the specific site where the technology is to be used will increase the success possibilities of such a technology. Thus, with the aim of finding a suitable local variety for use in a CO2 biofixation system, three recently isolated freshwater strains, Scenedesmus sp., Chlorogonium sp. and Synechocystis sp. were studied. Chlorella sorokiniana was used as a control strain. All the strains were grown under the same culture conditions for seven days of batch culture, and various growth and CO2 biofixation parameters were determined. Synechocystis sp. showed the highest specific growth rate at 1.75 per day (l/d). Results for CO2 biofixation ranged between 0.650 and 0.953 g of carbon dioxide per litre per day (g CO2/l/d), but differences among native strains were noted, although they were not statistically significant. However, Synechocystis sp. was selected as the most suitable strain for CO2 biofixation, owing to its good capacity to use light in dense cultures, an essential requirement for sustainable commercial systems.