Potential of water surface-floating microalgae for biodiesel production: Floating-biomass and lipid productivities
Section snippets
Strain and growth conditions
A green microalga species (termed strain AVFF007) found floating naturally on a water surface, was isolated from a freshwater pond in Kyoto, Japan. Strain AVFF007 was maintained in CSi medium (17) under continuous illumination using cool white fluorescent lights. To obtain the floating biomass, the strain AVFF007 was statically inoculated into 40 mL volume plastic cases (size: W50 × D63 × H25 mm, AS ONE, Osaka, Japan) in a desiccator (AS ONE), at an initial cell density of 1 × 105 cells/mL.
Characterization of strain AVFF007
Fig. 1 shows a typical static culture of strain AVFF007 in a glass flask. Most of the cells floated naturally upon the surface of the medium during static cultivation, while a portion of cells settled to the bottom of the medium. The floating cells formed biofilm, the surface of which was completely dry. Static cultivation was essential for the flotation ability of the cells to result in biofilm formation, since biofilms were not observed under well-mixed culture conditions with continuous
Discussion
This study evaluated the feasibility of biodiesel production by a water surface-floating microalga, strain AVFF007, which was tentatively identified as B. sudetica. B. sudetica (UTEX2629) has recently been proposed to be a potentially useful strain for microalgal biomass production (26). However, its ability to float at the surface of water and its possible use for biodiesel production have not been reported. Comparisons between the biomass yields and lipid productivities of strain AVFF007 and
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