A comparative analysis of agarans from commercial species of Gracilaria (Gracilariales, Rhodophyta) grown in vitro

The agaran yield, 3,6-anhydrogalactopyranose (3,6-AG) and sulphate content were compared in four commercial species of Gracilaria grown under parallel conditions in vitro. Gracilaria chilensis Bird, McLachlan et Oliveira from Chile provided the highest agaran yield (59%), followed by G. tenuistipita ta Zhang et Xia var. liui Zhang et Xia from China (53%), Gracilaria gracili s (Stackhouse) Steentoft, Irvine et Farnham from Namibia (34%) and from Arg entina (26%), and Gracilaria caudata J. Agardh from Brazil (32%). The algae from Chile, China and Namibia gave higher yields after alkali treatment wh ile those from Brazil and Argentina gave higher yields for the native agara ns. Lower percentages of 3, 6-AG and higher sulphate contents were found in the species from warmer waters (Brazil and China), indicating agarans of l ower commercial value. The results indicate that the Chilean Gracilaria had a superior yield of agaran, although G. gracilis from Argentina presented the highest 3,6-AG content after alkali treatment compared to other species considered for commercial cultivation in Brazil.