Mechanism of the accumulation of free amino acids in seaweed with cell and tissue culture

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1. Effects of bacteria on the accumulation of free amino acids in seaweed were studied, using free living conchocellis phase of red alga Porphyra yezoensis as the experimental alga. Amino acid pattern was determined with amino acid analyzer. Almost the same amino acid pattern was obtained between axnic and bacteria-contaminated cultures. However, the amounts of free amino acid in bacteria-contaminated alga was 1.4-fold that of axnic one. The symbiotic bacteria, therefore, was responsible to the accumulation of free amino acids.2. Effects of the stage of life cycle, sex, fertility and maturation on the free amino acid pattern were examined. The algae used in this study were Laminaria japonica (female and male gametophytes, zoosporangial sori and sporophyte), Undaria pinnatifida (female and male gametophytes, sporophyte, and sporophyll), P.yezoensis (conchocelis phase and thalli), fertile and sterile Ulva pertusa. Free amino acid pattern differed very much in quantity and quality among the stage of life cycle, sex, fertility and maturation in each species of alga.3. Changes of free amino acid pattern during growth of algae were tested using L.japonica, U.pinnatifida, P.yezoensis as experimental algae. The growth of these algae did not affect to the free amino acid patters. However, the amino acid contents showed specific increasing or decreasing tendency with the growth of each seaweed.4. The mechanism of the accumulation of free amino acid was studied, using giant coenocytic green alga Valonia macrophysa which contains counsiderable amounts of free cystine in its ethanolic extracts. In the cell sap of the intact alga, free cysteine, not cystine, was detected using HPLC and fluorometric detection with thiol-specific reagent. When the cysteine synthase activity was measured, Valonia was found tohave very strong activity (about 5-fold) than the other algae. This enzyme localized in chloroplast obtained by cell fractionation.