Laboratory Studies (cont)

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National Renewable Energy Laboratory

Eustigmatophytes. This group represents an important component of the

"picoplankton," which are very small cells (2-4 µm in diameter). The genus

Nannochloropsis is one of the few marine species in this class, and is

common in the world's oceans. Chlorophyll a is the only chlorophyll

present in the cells, although several xanthophylls serve as accessory

photosynthetic pigments.

Cyanobacteria. This group is prokaryotic, and therefore very different from

all other groups of microalgae. They contain no nucleus, no chloroplasts,

and have a different gene structure. There are approximately 2,000 species

of cyanobacteria, which occur in many habitats. Although this group is

distinguished by having members that can assimilate atmospheric N (thus

eliminating the need to provide fixed N to the cells), no member of this class

produces significant quantities of storage lipid; therefore, this group was not

deemed useful to the ASP.

Collection and Screening of Microalgae: Programmatic Rationale

The in-house collection effort focused on collecting strains from inland saline habitats, particularly

in Colorado, New Mexico, and Utah. The reasoning behind collecting strains from these habitats

was that the strains would be adapted to at least some of the environmental conditions in mass

culture facilities in the southwestern United States (i.e., high light intensity and high

temperatures). They would also be well suited for growth in the saline waters available for use in

such facilities. In addition, many of the aquatic habitats in this region are shallow, and therefore

subject to large variations in temperature and salinity; thus, the strains collected in this region

might be expected to better withstand the fluctuations that would occur in a commercial

production pond. Cyanobacteria, chrysophytes and diatoms often dominate inland saline habitats.

The latter were of particular interest to the program because of their propensity to accumulate

lipids. There had never been a large-scale effort to collect strains with this combination of

characteristics; therefore, they were not available from culture collections.

The stated objectives2 of the SERI culture collection and screening effort were to:

Assemble and maintain a set of viable mono-specific algal cultures stored

under conditions best suited to the maintenance of their original

physiological and biochemical characteristics.

Develop storage techniques that will help maintain the genetic variability and

physiological adaptability of the species.

Taken from the Proceedings of the April 1984 Aquatic Species Program Principal Investigators= Meeting.

A Look Back at the Aquatic Species Program--Technical Review