Subcontractor: Principal Investigator: Period of Performance: Subcontract Number:

Montana State University Keith E. Cooksey 3/86 — 4/87 XK-4-04136-04

The goal of this research was to develop a technique for rapidly screening microalgae for high lipid content, and to use this method to select microalgae with potential for liquid fuel production. Dr. Cooksey’s laboratory initiated the development of the Nile Red lipid staining procedure, which is fully described in Section II. A.l. f. The Nile Red staining procedure was used to screen for high lipid strains of microalgae, first using cultures collected mainly from Florida and maintained at Montana State University, and in cultures containing diatoms freshly isolated from hot springs in Yellowstone National Park. Because algae to be used in outdoor mass culture in the desert southwest would be subject to high temperatures, the Florida strains, isolated at 28°C, were first tested for growth and lipid production at 35°C. Although some strains produced fairly high levels of lipid, most grew poorly. Some diatom strains were then isolated from the hot springs, based on the premise that they would be more likely to tolerate extremes of temperature and pH variation. In these cultures, Nile Red was used to screen the initial sample for lipid-producing strains. These cells were then cultured, made unialgal and axenic, and tested for growth rate and lipid production. The strains tested showed growth rates of 0.5 to 2 doublings/d and lipid contents of 9%-54%, similar to the properties of oil-producing algae isolated by other methods.