INFLUENCE OF CULTURE CONDITIONS ON GROWTH AND PHYSICOCHEMICAL PROPERTIES OF CARRAGEENANS IN GIGARTINA-TEEDII (RHODOPHYCEAE, GIGARTINALES)

Female gametophytes of Gigartina teedii collected on the coasts of Bri ttany (France) contain in equal proportion kappa- and iota-carrageenan s. In order to increase exploitable quantities of G. teedii, by keepin g high the yield of carrageenan, without modifying qualities of gelifi cation or viscosity, we have studied in controlled culture the action of some factors: light, temperature and nitrogen on the growth rate of G. teedii as well their effect on physicochemical caracteristics of t he polymer. Temperatures of 20 to 25-degrees-C and light intensities o f 500 muE m-2 s-1 give active growth. On the other hand, high light in tensities induce active synthesis of rhodamylon at the expense of the yield of colloid. A medium without nitrate decreases growth, but incre ases yields of carrageenans. We have established for each factor an op timal value for maximum growth, with the estimation of the quality and the quantity of phycocolloid produced in the following of this growth .