Strain selection in Chondracanthus teedei (Gigartinaceae, Rhodophyta) using tetraspore and carpospore progeny: growth rates, tolerance to temperature and carrageenan yield

The feasibility of strain selection using tetraspore and carpospore progeny from wild fronds of Chondracanthus teedei to obtain strains with high growth rates, tolerance to temperature, and high yield of native carrageenan was investigated. A total of 34 strains were isolated, 14 from gametophytic progenitors and 20 from tetrasporophytic progenitors. The strains showed a heterogeneity of morphologies, colors, sizes, and growth. These differences were observed right from the early stages of development, resulting in individuals with more than one characteristic different from the others. Ninety days after selection, the strains differed in their growth rate, ranging from 0.57 to 5.13% day−1 in strains from gametophytic progenitors and 2.16 to 6.79% day−1 in strains from tetrasporophytic progenitors. When exposed to the temperature gradient, most strains (24 of 34) showed optimal growth rate values at the intermediate temperature used (25 °C) or without significant differences between 25 °C and one of the other temperatures used. However, four strains showed optimal growth rate values only at the extreme temperatures used and two gametophytic strains maintained their growth rate values without significant differences, irrespective of temperatures used, with a higher mean value for strain S27I (6.46 ± 0.07% day−1). The yields of carrageenan also varied among strains and temperatures with maximum value for strain S27I (74% DW for 15 °C and 25 °C; 73% DW for 30 °C). Thus, we believe that a combination of strains in different seasons could provide greater stability in biomass production and native carrageenan to, in turn, provide economically viable production.