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Co-cultivation of Two Freshwater Microalgae Species to Improve Biomass Productivity and Biodiesel Production
- Rashid, Naim, Ryu, Ae Jin, Lee, Bongsoo, Chang, Yong-Keun
- Energy conversion and management 2019
- Chlorella, Ettlia, biodiesel, biomass production, carbohydrates, chemical composition, coculture, fatty acids, freshwater, fuel production, microalgae, pigments, symbiosis
- This study aimed to investigate the symbiotic relationship of two freshwater microalgae species, Ettlia sp. and Chlorella sp. HS-2 to improve biomass productivity. The species were co-cultivated autotrophically under the inoculation ratios (Chlorella/Ettlia) of 1:01, 1:04, 1:08, and 1:16. The performance of co-cultivation was compared with monoculture. It found that the co-cultivation returned higher biomass productivity (P<0.05) than the monoculture under all inoculation ratios. The highest biomass productivity of 0.70±0.02 g L-1 day-1 was achieved with an inoculation ratio of 1:08. The biomass productivity further increased to 0.74± 0.06 g L-1 day-1 by switching the cultivation mode to the mixotrophic condition. The biomass productivity of mixotrophic co-cultivation was higher P<0.05 (0.74± 0.06 g L-1 day-1) than the mixotrophic mono-culture of Ettlia (0.41±0.06 g L-1 day-1) but equal to mixotrophic mono-culture of Chlorella. FACS analysis revealed that the biomass obtained after co-cultivation contained 81% of Chlorella cells. In biochemical composition, co-cultivation (autotrophic) biomass contained protein 41%, carbohydrates 33%, lipids 11%, and pigments 2% of dry cell weight. The major fatty acids produced in the co-cultivation were C16-C18, which are favorable for biodiesel production. It is concluded that the co-cultivation is more favorable than the monoculture to obtain high biomass productivity and stable biomass composition.