SELECTIVE CONDITIONS AND ISOLATION OF MUTANTS IN SALT-TOLERANT, LIPID-PRODUCING MICROALGAE

Suitable conditions for the isolation and selection of generic markers were determined by testing the growth of nine axenic strains of lipid-producing algae (Bacillariophyceae, Eustigmatophyceae, and Chlorophyceae) under a variety of conditions. Mixotrophic, heterotrophic, or anaerobic growth on twenty different carbon compounds was determined. Ten different nitrogen-containing compounds were supplied as the sole nitrogen source to ascertain which of these could be utilized. Resistances to antibiotics and herbicides were assessed. The algae utilized a variety of compounds as their sole nitrogen source, and some species also grew heterotrophically or mixotrophically on a variety of carbon compounds. This suggests that the algae are not only able to transport these compounds into the cell but that the biochemical pathways necessary for their utilization are present and could be targeted for mutagenesis. Anaerobic growth was not possible on any of the fermentable sugars. All the microalgae were sensitive to the photosystem II inhibitors diuron and atrazine and the 70S ribosome inhibitors erythromycin and streptomycin.