Optimization of parameters for isolation of protoplasts from Gracilaria verrucosa (Rhodophyta).

A systematic method was designed for the isolation of a large number of protoplasts from an agarophyte alga Gracilaria verrucosa using agarase from a marine bacterium Vibrio sp. PO-303 and commercial enzymes (Cellulase Onozuka RS and Macerozyme R-10). Pretreatment of the tissue with 5% papain at 22 degreesC for 30 min before digestion with polysaccharide-degrading enzymes increased the protoplast yield. Suitable pH and temperature for the polysaccharide-degrading enzyme reaction were 6.5 and 22 degreesC, respectively. Mannitol (0.7 M) was found to be an excellent osmotic stabilizer. When the tissue (1 g, fresh wt.) of G. verrucosa pretreated with 5% papain solution (20 mM MES buffer, pH 7.5, containing 0.7 M mannitol) was digested with an enzyme mixture consisting of 4 units of agarase, 4% Cellulase Onozuka, 2% Macerozyme, and 0.7 M mannitol in 20 mM MES buffer (pH 6.5) with gentle agitation for 150 min at 22 degreesC, 1.03 x 10(8) protoplasts were obtained.