K. Eswaran

Kappaphycus alvarezii as a source of bioethanol.

The present study describes production of bio-ethanol from fresh red alga, Kappaphycus alvarezii. It was crushed to expel sap--a biofertilizer--while residual biomass was saccharified at 100 °C in 0.9 N H2SO4. The hydrolysate was repeatedly treated with additional granules to achieve desired reducing sugar concentration. The best yields for saccharification, inclusive of sugar loss in residue, were 26.2% and 30.6% (w/w) at laboratory (250 g) and bench (16 kg) scales, respectively. The hydrolysate was neutralized with lime and the filtrate was desalted by electrodialysis. Saccharomyces cerevisiae (NCIM 3523) was used for ethanol production from this non-traditional bio-resource. Fermentation at laboratory and bench scales converted ca. 80% of reducing sugar into ethanol in near quantitative selectivity. A petrol vehicle was successfully run with E10 gasoline made from the seaweed-based ethanol. Co-production of ethanol and bio-fertilizer from this seaweed may emerge as a promising alternative to land-based bio-ethanol.

Detection and quantification of some plant growth regulators in a seaweed-based foliar spray employing a mass spectrometric technique sans chromatographic separation.

The sap expelled from the fresh harvest of Kappaphycus alvarezii , a red seaweed growing in tropical waters, has been reported to be a potent foliar spray. Tandem mass spectrometry of various organic extracts of the sap confirmed the presence of the plant growth regulators (PGRs) indole 3-acetic acid, gibberellin GA(3), kinetin, and zeatin. These PGRs were quantified in fresh state and after 1 year of storage by ESI-MS without recourse to chromatographic separation. Quantification was validated against HPLC data. The results may be useful in correlating with the efficacy of the sap. The methodology was extended to two other seaweeds. The method developed is convenient and precise and may find application in other agricultural formulations containing these growth hormones.

Tissue culture and regeneration of thallus from callus of Gelidiella acerosa (Gelidiaies, Rhodophyta)

Abstract The tissue culture of an economically important red alga Gelidiella acerosa (Gelidiales, Rhodophyta) included preparation of axenic material, culture of explants, subculture of excised callus and regeneration of de novo plants from callus in the laboratory. Sequential treatment of explants with sterile seawater consisting of 0.1% liquid detergent for 10 min, 2% betadine (with 0.5% w/v available iodine) for 5 min and 3.5% broad-spectrum antibiotic mixture with nystatin for 2 days enabled yields as high as 90% of viable and axenic explants. A prolific and rapid growth of filamentous callus on explants was observed on cut surfaces during the first month of culture. The highest level of callus induction occurred in Provasoli enriched seawater (PES) medium solidified with 1.5% agar incubated at 20–22°C and a photon flux density of 5 μmol photons m−2 s−1 with a 12: 12 light-dark photoperiod. Up to 90% of the explants cultured at 5 μmol photons m−2 s−1 produced callus, whereas at 30 and 70 μmol photons m−2 s−1, 70% and 9% produced callus, respectively. The explant culture medium with 0.5% agar content stimulated bud development in all explants, whereas higher agar concentrations (0.8%, 1.0%, 1.5%, 2.0% and 3.0%) resulted in a filamentous type of callus growth. Addition of the plant growth regulators naphthalene acetic acid and indole 3-acetic acid (auxins), and benzyl amino purine and kinetin (cytokinins) and different organic carbon supplements (glycerol, sucrose, sorbitol and mannitol) to the culture medium had no effect on callus growth or induction rate. All carbon supplies at 0.5 and 1.0 M concentration showed an inhibitory effect and most of the explants perished gradually after 2 weeks in culture. The callus mass with bud or shoot developments continued to grow when transferred to semisolid PES medium (0.2% agar w/v) on a rotary shaker. In 4 months, these shoots gave rise to 2–3 cm long plantlets of G. acerosa. The tissue-cultured Gelidiella germlings were successfully grown into full plants in the field on coral stones in 6 months.

Farming of agarophytes in India—a long-time sustainability for the industry and preserving wild stocks

In India, food-grade agar is produced from Gracilaria edulis while bacteriological-grade agar is extracted from Gelidiella acerosa. Agarose is directly obtained from Gracilaria dura. Seaweeds for agar production mainly come from wild stocks located in reefs of the Gulf of Mannar, southeast coast. Landings of Gr. edulis were peak (982 dry t) during 1990 while landings of Ge. acerosa reached maximum (665 dry t) during 2002–2003. Overexploitation is leading to a decrease in biomass of these two algae at an alarming rate for the last decade. Commercial cultivation of agarophytes is yet to increase in India in spite of growing pressure on wild stocks triggered by increase in demand of raw material by the industry. Taking this into consideration, a number of efforts have been initiated to develop feasible cultivation methods for agarophytes. The present paper summarizes various methods developed for commercial cultivation of Gr. edulis, Gr. dura, Gracilaria verrucosa and Ge. acerosa in the open sea. We also discuss the challenges in the development of commercial farming of agarophytes in India.