I.A.1.e. Collection and Screening Activities-1986 and 1987

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National Renewable Energy Laboratory

occurred for nutrient-deficient AMPHO1 cells, whereas the lipid content of CYCLO2 was similar

in exponential phase and nutrient-deficient cells, and actually decreased in AMPHO2 as a result

of nutrient deficiency.

These results suggested that high lipid content was indeed achievable in many strains by

manipulating the nutrient levels in the growth media. However, these experiments did not provide

information on actual lipid productivity in the cultures, which is the more important factor for

developing a commercially viable biodiesel production process. This lack of lipid productivity

data also occurred with most of the ASP subcontractors involved in strain screening and

characterization, but was understandable because the process for maximizing lipid yields from

microalgae grown in mass culture never was optimized. Therefore, there was no basis for

designing experiments to estimate lipid productivity potential.

Publications:

Barclay, B.; Nagle, N.; Terry, K. (1986) AScreening microalgae for biomass production potential:

protocol modification and evaluation.@ FY 1986 Aquatic Species Program Annual Report, Solar

Energy Research Institute, Golden, Colorado, SERI/SP-231-3071, pp. 22-40.

Barclay, W.R.; Terry, K.L.; Nagle, N.J.; Weissman, J.C.; Goebel, R.P. (1987) APotential of new

strains of marine and inland saline-adapted microalgae for aquaculture.@ J. World. Aquaculture

Soc. 18:218-228.

II.A.1.e. Collection and Screening Activities-1986 and 1987

SERI in-house algal strain collection and screening efforts during 1986-1987 focused in three

separate areas. First, detailed characterization of previously collected strains continued. Second,

because the desert southwest sites targeted for biodiesel production facilities can be quite cool

during the winter, a new effort to collect strains from cold-water sites was initiated. Finally, a

strategy was developed and implemented to reduce the number of strains that had accumulated

as a result of in-house and subcontracted research efforts, which allowed researchers to focus on

the most promising strains.

Strain characterization.

Eight additional strains collected previously from warm-water sites that grew well during the

initial screening procedures were characterized with respect to temperature and salinity tolerances,

growth rates, and lipid content under various conditions. These strains were Chaetoceros

muelleri (strains CHAET6, CHAET9, CHAET10, CHAET15, and CHAET39), Cyclotella

cryptica (CYCLO4), Pleurochrysis carterae (PLEUR1), and Thalassiosira weissflogii

(THALA2). Each strain was grown in a variety of temperature-salinity combinations by the use

of a temperature-salinity gradient table. The maximal growth rate achieved under these conditions

occurred with CHAET9, which exhibited a growth rate of 4.0 doublings$day-1. The remaining

strains all had maximum growth rates that exceeded 1.4 doublings$day-1, and several grew at rates

exceeding 2.5 doublings$day-1 (i.e., CHAET6, CHAET10, and CHAET39). All had an optimal

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