Vol. 3, Issue 6, Part K (2017)

Abstract
One of the most important factors in obtaining oil from microalgae is the choice of the right algal species to be used. To identify some desirable algal strains for future study and/or the production of algae-based biofuel, 05 algal strains were successfully isolated from freshwaters, and then incubated in the laboratory bioreactors for the growth and oil accumulation investigations. Five isolates (Chlorella sp, Ulothrix, Cosmarium nitudulum, Spirulina Sp, and Botryococcus braunii) of the microalgal cultures isolated were selected based on their purity and growth rates. During a 25 day incubation experiment, the accumulations of their biomass and total lipids, together with the lipid productivities for these algal strains were systematically investigated and compared. Results indicated that the accumulations of biomass for the 05 algal strains ranged from 0.3 g/L to 1.4 g/L during the experiments, with the highest biomass of 1.4 g/L for Botryococcus braunii. The lipid content for the tested algal strains varied from 8% to 40% of the dry biomass at the end of cultivation experiments. Algae Botryococcus braunii is one of the best oil producers based on this investigations, with the total lipid content of 40% of dry biomass. Taking the growth rates and the accumulations of intracellular lipids into the consideration, Botryococcus braunii was considered to have significant potential for biofuel applications. In addition, the lipid productivities of the selected strain were further investigated