Development of marine multi-algae cultures for biodiesel production

The concept of community ecology has become a central issue for sustainable biofuel production. However the development of appropriate multi-algae cultures for the industry remains challenging. Natural marine algae blooms collected from coastal areas of Cyprus were induced to form multi-algae cultures, and five (5) of those were developed and tested. Algae growth characteristics, biomass, and lipid productivity were assessed, and the dominant microalga was isolated in all cultures. Growth characteristics, lipid productivity, and FAME composition varied considerably among the different multi-algae cultures as well as their corresponding dominant species. Our results suggest that competitiveness and species complementarity could be crucial factors for biomass and lipid productivity. In material collected from the marina in Larnaca of Cyprus, the induced BL1_LCA bloom was the most promising culture, dominated by Nannochloropsis sp. and accompanied by cyanobacteria assemblages, exhibiting the highest biomass and lipid productivity compared to the other developed blooms. Biomass and lipid productivity of an axenic monoculture of Nannochloropsis sp. were 2.1 and 2.2 times lower compared to those measured in BL1_LCA. The growth parameters of BL1_LCA and its corresponding dominant species were further tested under culture media of different seawater and wastewater ratios. An increase of wastewater ratio in the culture media resulted in a significant reduction of lipid, FAME concentration as well as biomass productivity both in BL1_LCA and its dominant isolate. Overall, our findings suggest that the complex interactions within microalgae community might be crucial for biodiesel production; moreover, the general assumption that wastewater can be applied as an alternative nutrient source should be used cautiously since species-specific responses seem to take place.