Sunlight is the ultimate source of all fossil fuels and biomass. In light of dwindling supplies of fossil fuels, biomass will be accorded a greater role in supplying future energy needs. To meet anticipated energy needs, the most productive phototrophic systems must be utilized. Microalgae are the most productive photosynthetic organisms on earth, often producing 5 to 10 times the dry matter per area per unit of time as the most efficient vascular plant communities and farmlands. Without expending anabolic energy for construction and maintenance of supportive tissues, microalgae often store as much as 85% of their total biomass as excess photosynthate. In some cases oily lipids are stored. An opportunity exists to utilize lipid-accumulating, oleaceous microalgae as alternative sources of liquid fuels. To date, very few species have been investigated for potential utility in this regard. This proposal would help to fill this gap in applied microalgal research by isolating from soil novel strains of microalgae able to accumulate significant amounts of hydrophobic materials. Screening and selection procedures will include assessment of microalgal characteristics that influence the commercial feasibility of their mass culture. Laboratory growth experiments will be conducted to determine maximum specific growth rates and total lipid yields of microalgae that accumulate greater than 25cVo of their biomass as lipids in response to nitrogen depletion. Other aspects of mass culture critical to eventual commercialization include ability of selected strains to compete effectively with microalgal weed species and harvestability. Laboratory experiments will address the first problem by means of one-on-one competitive growth trials with a common mass culture contaminant. The latter problem will be assessed by estimating removal efficiency from water and concentration factors for sedimentation, chemical flocculation, and microstraining. Finally, isolates demonstrating commercial potential will be identified.AnticipatedResults Potential Commercial Applications as described by the awardee:Solar energy will make a significant contribution to Anierica's energy needs if lipid-accumulating microalgae can be encouraged to achieve high oil-production rate per unit land area. This research will identify novel strains of microalgae able to realize this contribution. Strains will be selected on the basis of experiments designed to estimate productivity, lipid yield, competitive ability, and harvestability.
