Water shortage is one of the leading global problems along with the depletion of energy resources and environmental deterioration. Recent industrialization, global mobility, and increasing population have adversely affected the freshwater resources. The wastewater sources are categorized as domestic, agricul- tural and industrial effluents and their disposal into water bodies poses a harmful impact on human and animal health due to the presence of higher amounts of nitrogen, phosphorus, sulfur, heavy metals and other organic/inorganic pollutants. Several conventional treatment methods have been employed, but none of those can be termed as a universal method due to their high cost, less efficiency, and non- environment friendly nature. Alternatively, wastewater treatment using microalgae (phycoremediation) offers several advantages over chemical-based treatment methods. Microalgae cultivation using wastew- ater offers the highest atmospheric carbon fixation rate (1.83 kg CO2/kg of biomass) and fastest biomass productivity (40–50% higher than terrestrial crops) among all terrestrial bio-remediators with concomi- tant pollutant removal (80–100%). Moreover, the algal biomass may contain high-value metabolites including omega-3-fatty acids, pigments, amino acids, and high sugar content. Hence, after extraction of high-value compounds, residual biomass can be either directly converted to energy through thermo- chemical transformation or can be used to produce biofuels through biological fermentation or transes- terification. This review highlights the recent advances in microalgal biotechnology to establish a biorefinery approach to treat wastewater. The articulation of wastewater treatment facilities with microalgal biorefinery, the use of microalgal consortia, the possible merits, and demerits of phycoreme- diation are also discussed. The impact of wastewater-derived nutrient stress and its exploitation to mod- ify the algal metabolite content in view of future concerns of cost-benefit ratios of algal biorefineries is also highlighted.
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A culture system for the commercial production of the seaweed Gracilaria parvispora using shrimp-farm effluents for fertilization and floating cage-culture for grow-out has been developed on Molokai, HI. This two-phase system produces high-quality products for direct human consumption. The mean relative growth rates (RGRs) of effluent-enriched thalli in the cage system ranged from 8.8% to 10.4% day−1, a significant increase over the growth (4.6% day−1) of thalli fertilized with inorganic fertilizer. Thalli were also grown directly in the effluent ditch, where mean growth rates of 4.7% day−1 were obtained, less than in cage-culture. In the cage-culture system, thallus nitrogen content declined without fertilization. Effluent-enriched thalli grown in the cages steadily declined in nitrogen content, to about 1%, and their C:N ratios increased to between 20 and 30. However, when nitrogen-depleted thalli were transferred to the effluent ditch for enrichment, N content rapidly increased over 5 days to approximately 3%, with a C:N ratio near 10. Benefits of this two-phase polyculture system include enhanced growth of G. parvispora and the use of effluent from commercial shrimp farms as a resource.
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Over the past decade, the large-scale cultivation of seaweed Gracilaria has expanded rapidly in the Chinese coastal waters. The production of Gracilaria increased from 50,536 tons (t, dry weight) in 2003 to 114,722 t in 2010. The production of the seaweed ranks third only to kelps Saccharina (formerly referred to as Laminaria) and Undaria in China. Nan'ao located in Shantou City, Guangdong Province has been successfully developed as one of the major cultivation bases of Gracilaria lemaneiformis at an industrial scale in South China since 2000, and the farmed area increased by 11,538-fold from 0.13 ha in 2000 to 1500 ha in 2011. From lab-scale study to field industrial practice, it has been documented that Gracilaria cultivation is beneficial in environmental improvements such as mitigating eutrophication, controlling harmful algal blooms, maintaining healthy mariculture systems, and sequestrating CO2. Gracilaria may significantly remediate contaminants in mariculture ecosystems and improve the water environment, and its cultivation provides a new approach to coastal environmental improvement in China and the world.
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Work on the culture of commercially important agarophyte Gracilaria edulis has already been carried out by Raju and Thomas (1971) and Umamaheswara Rao (1974) in a sandy lagoon on the eastern side of Krusadai Island and near-shore areas around Mandapam, respectively. The present account deals with the possibilities and advantages of culture of Gracilaria edulis in the submerged floating condition in the inshore water of Gulf of Mannar (Mandapam).
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Thallus erect or prostrate (decumbent), branched subdichotomously, laterally, secondly, radially or irregularly; axes and branches terete to flattened. Attached to solid substratum by a small discoid holdfast or living on sandy bottoms with part of the thallus immersed in the sand. Sometimes loose lying or floating in calm waters. Uniaxial construction but appearing multiaxial, pseudoparenchymatous with a small celled medulla.
Life history triphasic with isomorphic gametophytes and tetrasporapytes. In the genus Gracilaria, cystocarps exhibit traversing nutritive cells between the carposporophyte and the pericarp and spermataagia are in pits or conceptacles. In the genus Gracilariopsis, cystocarps lack the traversing nutritive cells and spermatangia are superficial. -
There are many rural communities along the nation's 95,000 miles of coastline which would be ideal candidtaes for NCRI investment, but there are few regions which are in greater need of the Institute's assistance than the island of Molokai in the Hawaiian chain. Molokai has the highest proportion of native Hawaiians for all the islands except Niihau. Most of these natice Hawaiians are rural coastal residents who face an erosion of their traditional lifestlyle and economic base. Unemployment is high, job skills are relatively low, and marin/coastal-based employment opportunities are severly limited.
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Even with seaweed aquaculture growing rapidly over the last decade, global demand for seaweed-based products has surpassed supply. There is a large and diverse array of applications and uses of macroalgal products. The seaweed industry is estimated to have an annual value of some US$6 billion, the largest share of which (US$5 billion) is human food products. The remaining US$1 billion is largely based on seaweed extracts, such as hydrocolloids for use in animal feeds, fertilizers and bioactives.
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Seaweeds have received huge interest in recent years given their promising potentialities. Their antioxidant, anti-inflammatory, antitumor, hypolipemic, and anticoagulant effects are among the most renowned and studied bioactivities so far, and these effects have been increasingly associated with their content and richness in both primary and secondary metabolites. Although primary metabolites have a pivotal importance such as their content in polysaccharides (fucoidans, agars, carragenans, ulvans, alginates, and laminarin), recent data have shown that the content in some secondary metabolites largely determines the effective bioactive potential of seaweeds. Among these secondary metabolites, phenolic compounds feature prominently. The present review provides the most remarkable insights into seaweed research, specifically addressing its chemical composition, phytopharmacology, and cosmetic applications.
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A variety of lung diseases such as emphysema, infections, and lung cancers as well as lung injury from trauma, including battlefield trauma, and complications of respirator life support of critically ill patients in intensive care units can result in lung collapse that can be immediately life-threatening or result in chronic leaking of air or fluid out of the lung. These remain challenging medical problems for which few good options are currently available and result in significant morbidity, mortality, hospital stays, health care costs, and other complications. New options are thus desperately needed. We are developing a novel approach to provide an easy-to-apply lung sealant which can repair lung leaks. This initially involved use of a chemically modified form of alginate, a naturally occurring seaweed derivative, increasingly being explored for a variety of biomedical applications. Particular attributes include easy availability, low cost, easy use, biodegradability, and lack of significant toxicity. In the studies to date, we have done extensive materials characterization not just of modified alginates but now a number of other biologic compounds that also have potential as pleural sealants. We have further extensively evaluated promising compounds using small rodent and large pig ex vivo lung models and have performed initial in vivo evaluations of several compounds in a non-survival surgery rat lung injury model. The studies to date have thus identified several promising compounds that will be further evaluated in the non-survival surgery and also a survival surgery rat lung injury model during the 6 month extension period of the grant. These will lead to a firm platform for further investigations in large animal survival surgery models and subsequent discussions with the FDA about new IND for a clinical investigation.
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Land-based seaweed (Gracilaria) cultivation systems may provide products with high quality and biosafety for human consumption, as well as for other high value applications. However, a limitation for this land based system is high management costs. The objective of this study was to determine if the management costs for Gracilaria cultivation can be reduced without a decrease in productivity by using CO2 injection along with a high stocking density and high photosynthetically active radiation (PAR), and commercially available fertilizers. When Gracilaria tikvahiae was cultivated at a high stocking density and high PAR, coupled with CO2 enhancement, the productivity was significantly higher than that at a lower stocking density, low light without CO2 injection. We also found that G. tikvahiae grown in a medium of commercially available fertilizer (Jack's Special, JS) showed a similar growth rate and productivity to that grown in von Stosch's enriched (VSE) seawater, while the cost for JS media is only 2% of the cost for VSE. These results suggest that CO2 injection and commercial fertilizer may be a potential way to provide sustainability in land-based Gracilaria cultivation systems.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
Funding for this web portal is provided by the World Wildlife Fund and the University of Hawaii-Hilo.