EFFECTS OF GROWTH-RATE AND OTHER FACTORS ON PROTOPLAST YIELD FROM 4 SPECIES OF GRACILARIA (RHODOPHYTA)

High yields of protoplasts (105-107 g-1 fresh weight) from four species of Gracilaria were released by enzymatic degradation of the cell wall. The effects of different enzymes at different concentrations, varying pre-cultivation conditions, and the osmolality of the enzyme solution on algal protoplast yields were tested. Large numbers of protoplasts from G. lemanaeformis were released in 10 of 13 tested enzyme mixtures and at all tested growth rates. Virtually no protoplasts were released from G. sordida and G. tenuistipitata unless the plants were cultivated at a permissive growth rate. The yield of protoplasts was also influenced by the osmolality of the enzyme solution. Addition of mannitol to a final concentration of 0.2 —0.4 M in the enzyme solution, in combination with a growth rate of 15 — 25% biomass increase day-1, was found to give an optimal protoplast yield from G. sordida. The yield of protoplasts was also studied in relation to the agar composition of the cell wall. Cultivation conditions which enhanced algal growth rate resulted in a higher yield of agar soluble in water at room temperature. This increased agar solubility was correlated with a raised protoplast yield from G. sordida and G. tenuistipitata in the present study. © 1990, Walter de Gruyter. All rights reserved.