I.A.1.d. Collection and Screening Activities-1985

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National Renewable Energy Laboratory

I.A.1.d. Collection and Screening Activities-1985

In 1985, the strain enrichment procedure that used the rotary screening apparatus described

previously was modified to include incubation of samples in SERI Type I and Type II media (25

and 55 mmho@cm-1 conductivity) and in artificial seawater, in addition to the original site water.

The cultures that exhibit substantial algal growth were further treated to isolate the predominant

strains as unialgal (clonal) isolates. These strains were then tested for growth using the

temperature-salinity matrix described earlier.

Collection activities.

Collection efforts by SERI researchers in 1985 again focused on shallow inland saline habitats.

This time collecting trips were also made to New Mexico and Nebraska, in addition to Colorado

and Utah. Eighty-six sites were sampled during the year, 53 of which were sampled in the spring.

From these 53 sites, 17 promising strains were isolated. An analysis was conducted comparing

the results of the new protocol with those that would have resulted from the protocol used in prior

years. This analysis indicated that the revised protocol was in fact superior to the older protocol.

For example, only six of the 17 strains selected via the new protocol would also have been

selected using the old protocol. Only three of the 17 strains grew best in the artificial medium

type that most closely resembled the collection site water; in fact, only six were even considered

to grow well in the collection site water relative to growth in at least one of the artificial medium.

This analysis clearly indicated the value of performing the initial screening and enrichment in a

variety of relevant media. The results suggest that the shallow saline environments sampled

probably contain a large number of species whose metabolism is arrested at any given time. In

other words, the water quality of such sites varies greatly, depending on precipitation and

evaporation, so probably only a few of the many species present are actively growing at any given

time. This also may explain the wide range of salinities and temperatures tolerated by many of

these strains.

Growth rates.

Six promising strains were analyzed in SERI Type I, Type II, and ASW (Rila) using the

temperature-salinity gradient described previously. These included the diatoms Chaetoceros

muelleri (CHAET14), Navicula (NAVIC1), Cyclotella (CYCLO2), Amphora (AMPHO1 and

AMPHO2), and the chlorophyte Monoraphidium minutum (MONOR2). (NAVIC1 and CYCLO2

were actually collected from the Florida Keys; the remaining strains were collected in Colorado

and Utah.) All strains exhibited rapid growth over a wide range of conductivities in at least two

media types. Furthermore, all strains exhibited temperature optima of 301C or higher. Maximal

growth rates of these strains, along with the optimal temperature, conductivity, and media type

determined in these experiments are shown in Table II.A.1. (Higher growth rates were determined

for some of these strains in subsequent experiments; see results presented in Barclay et al. [1987].)

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