Identifying other suitable and potential indigenous carrageenophytes for commercial cultivation in India.

In India, Kappaphycus alvarezii is the only alga being cultivated commercially for kappa carrageenan production and also being utilized for the socioeconomic upliftment of coastal rural population in India in the form of their cultivation and marketing. The production has been substantially increased from 21 dry tonnes to 1490 dry tonnes with increasing market purchase value from US$ 0.061 to 0.469 kg dry wt−1 during 2001–2013. In India, annual import for carrageenan is 1800–2000 M tons year−1 and its demand is reported to be increased by 5–6% every year (Mantri et al. 2017). To date, Aquagri Pvt Ltd is the only company in India producing kappa carrageenan from cultivated Kappaphycus alvarezii (Mantri et al. 2017). However, few other marine phycocolloid processing factories are producing kappa carrageenan from Hypnea musciformis and Hypnea valentiae at cottage level. The total annual production of carrageenan in India ranges between 100 and 132 tons. There is tremendous demand for other carrageenan such as iota and lambda carrageenan in food, beverage, and consumer product manufacturing industries. In order to ascertain suitability of unexplored other indigenous carrageenophytes for commercial cultivation in India, several red algal species such as Agardhiella subulata, Ahnfeltiopsis pygmaea, Laurencia caraibica, and Solieria robusta were collected from wild habitats in Kanyakumari (N 08°08′10.36″; E 077°34′28.06″) Tamil Nadu, India, and were evaluated for their mariculture potential and the presence of carrageenan. Preliminary cultivation experiments were carried out by raft culture method (1 × 1 m) for 45 days at two harvest cycles at Thonithurai (N 09°16′53.45″; E 079°11′19.22″), Tamil Nadu, South eastern coast of India. Except Ahnfeltiopsis pygmaea, all other seaweeds investigated showed daily growth rate (DGR) in the range of 1.59 to 3.822% and confirmed its mariculture potential. Phycocolloid was extracted with yield 4.5 to 29.37% from dry seaweed residues obtained after extraction of lipids using both water and aqueous alkali [5% Ca (OH)2 solution]. Water was found the better solvent in terms of higher yield of the Phycocolloid (29.37%) from Solieria robusta. FT-IR of the extracted phycocolloid indicated presence of characteristic bands for carrageenan in all the samples. However, from the band positions, the presence of iota carrageenan was ascertained in the Agardhiella subulata and Solieria robusta and hybrid iota/kappa carrageenan is expected to be present in Laurencia caraibica and Ahnfeltiopsis pygmaea. [ABSTRACT FROM AUTHOR]