Abstract: Biosecure algae and methods for preparing biosecure algae that have a substantially decreased capability to survive in a natural environment are described. The methods include transforming a genetically modified alga to include an essential gene that is operably linked to a promoter system that is active only in the presence of an inducer compound, transforming the genetically modified alga to include a lethal gene that is operably linked with a promoter system that is inactive only in the presence of a repressor compound. The biosecure algae are only able to survive in an artificial algae culture that includes factors or conditions not found in a natural environment.

Abstract: Recombinant oleaginous alga that include one or more heterologous genes that increase the ability of the alga to use one or more natural saccharides such as cellulosic or hemicellulosic sugars for algal growth are described. The recombinant oleaginous algae are transformed to include one or more genes expressing sugar metabolizing enzymes or sugar transporting proteins, along with suitable control elements. Use of natural saccharides as a carbon source can allow the algae to produce biofuel precursors in a relatively efficient manner. Processes for preparing the alga, growing the alga, and extracting the biofuel precursors from the alga are also described.

Abstract: The use of acoustic focusing together with a non-destructive extraction process for obtaining lipids from oleaginous algae is described. Acoustic focusing can be used to concentrate oleaginous algae before they are subjected to non-destructive extraction, or acoustic focusing can be used as part of the non-destructive extraction process itself by moving the algae from the algae culture to the extracting solvent. The use of acoustic focusing for removing extraneous particulate matter from algae cultures is also described, as well as the use of non-destructive extraction for controlling levels of algae predators.

Abstract: Methods for increasing the levels of lipids in oleaginous algae are described. Lipid levels in algae can be increased by stress, such as nutrient stress, after which the lipid can be harvested from the algae using a non-destructive extraction process. The stress may be provided in a periodic or “pulsed” fashion. Lipid levels in oleaginous algae can also be increased using simulated stress by treating the algae with a chemical inhibitor or by using recombinant technology to insert a sequence expressing a protein such as a nitrate reductase inhibitor that is expressed when a stressed state is desired. A method for maintaining the temperature and water levels of algae ponds using buoyant spheres is also described.