Culture of the red alga Sarconema filiforme in open waters and hybrid carrageenan from the cultivated seaweeds

Abstract

This is a first time report on the successful cultivation of the red alga Sarconema filiforme, employing floating rafts along the south-east coast of India, with an associated study of carrageenan content. Experiments were carried out on seasonality of growth rate and biomass of S. filiforme for 30 months, from August 2010 to January 2013. Harvest was done at the end of 25-day growth. In addition, experiments were also carried out optimizing harvests at the end of different duration of culture period (i.e. 20-, 25- and 30-day culture), and measurements were made at different localities (e.g. Ervadi and Thonithurai). Maximum biomass density (2.28 ± 0.03 kg fresh wt. m−2) and daily growth rates (DGR; 11.63 ± 0.06 %) were found from August to September each year, during the study, and these values were significantly different. Harvesting at the end of 25-day duration of culture period resulted in a maximum biomass (i.e. 4.24 ± 0.95 kg fresh wt. m−2), while 20-day duration of culture period showed higher DGR i.e. 13.20 ± 0.20 % which were significantly different from those plants harvested after 30 days. The range of biomass (i.e. 2.22 to 6.46 kg fresh wt. m−2) and DGR (i.e. 5.0 to 10.91 %) was higher at Ervadi than at Thonithurai site and was significantly different (P < 0.001). Physico-chemical analyses, infra-red and 13C nuclear magnetic resonance (NMR) spectral analyses of extracted carrageenan revealed the presence of hybrid lambda and iota carrageenan. The carrageenan yield from the cultivated material was higher than that of the wild stock of S. filiforme of Indian waters. The results of the study revealed that the peak growth period of S. filiforme was between September and December. Harvesting at the end of the 25-day growth period was more ideal. This study further revealed that production of better strains having hybrid, sulphated galactan, with higher yield and rheological properties the same as the wild stocks, could be possible through cultivation.