Macroalgae (mainly marine macroalgae, i.e. seaweeds) are considered as a very promising source for bioethanol production, because they have high carbohydrate contents, superior productivity, and wide adaptability. Macroalgae are generally grouped into three major categories: red, green, and brown algae. Each category has thousands of species, and each species possesses its unique cellular structure, biochemistry, and constitutes. Converting macroalgae to bioethanol involves pretreatment, saccharification, fermentation, and distillation; and the establishment of economic pretreatment methods is always the first key step for bioethanol production. In present, dilute-acid or alkali hydrolysis is typically used to treat macroalgal biomass. Macroalgae can be depolymerized under mild conditions as they have low lignin content. The resulting polysaccharides can be converted to ethanol through enzymatic hydrolysis, followed by adding bacteria, such as Saccharomyces cerevisiae and recombinant Escherichia coli KO11. Compared with the separate hydrolysis and fermentation process, the simultaneous saccharification and fermentation process often provided higher ethanol titer and conversion efficiency. However, the research on bioethanol production from macroalgae is still in its early stage due to both technical and economic barriers, significant amount of research and development work is needed prior to the commercialization of bioethanol manufacture from macroalgae.
Digital library
-
-
Gracilaria edulis was successfully cultured by the reproductive propagation method in the Gulf of Mannar, during November-March 1991-'92 and 1992-'93. Healthy young plants were harvested twice during 1993 within 135 days of culture period. Nursery rearing for a brief period was done for the carpospores to grow upto the germling stage in enriched seawater before transplanting to the sea. The plant attained maximum length of 34 cm (average length 21.55 ± 7.30 cm) and a fresh weight of 12.430 kg on harvest. The quantitative estimation of agar showed an average yield of 14.57 % with gelling temperature of 48.8°C, melting temperature of 85.0°C and gel strength of 98.6 g/cm^.
-
Aim: Climate change is predicted to alter the distribution and abundance of marine species, including canopy‐forming seaweeds which provide important ecosystem functions and services. We asked whether continued warming will affect the distribution of six common canopy‐forming species: mid‐intertidal fucoids (Ascophyllum nodosum, Fucus vesiculosus), low‐intertidal Irish moss (Chondrus crispus), subtidal laminarian kelps (Saccharina latissima, Laminaria digitata) and the invasive Codium fragile. Location: Northwest Atlantic. Methods: We used occurrence records and the correlative presence‐only species distribution model Maxent to determine present‐day distribution. This distribution was compared to each species’ warm‐water physiological thresholds indicating areas of stable or reduced growth and mortality. Present‐day models were then projected to mid‐century (2040–2050) and end‐century (2090–2100) using two contrasting carbon emission scenarios (RCP2.6 and 8.5) and two global climate models from CMIP5 based on changes in ocean temperatures. Results: Projected range shifts were minimal under low emissions (RCP2.6), but substantial species‐specific range shifts were projected under high emissions (RCP8.5), with all species except C. fragile predicted to experience a northward shift in their southern (warm) edge of ≤406 km by the year 2100. Northward expansions outweighed southern extirpations for fucoids and C. crispus leading to overall range expansions, while range contractions were projected for kelps and C. fragile. Model projections generally agreed with physiological thresholds but were more conservative suggesting that range shifts for kelps may be underpredicted. Main conclusions: Our results highlight the benefits to be gained from strong climate change mitigation (RCP2.6), which would limit changes in rocky shore community distribution and composition. The business‐as‐usual RCP8.5 scenario projected major range shifts, seaweed community reorganization and transitions in dominant species south of Newfoundland by 2100 (~47°N). As canopy‐forming seaweeds provide essential habitat, carbon storage, nutrient cycling and commercial value, understanding their response to continued climate warming is critical to inform coastal management and conservation planning
-
Nutritious noodles made from seaweed are bringing new hope to poor families in Bicol and raising the incomes of seaweed farmers there, according to the Bureau of Agricultural Research (BAR) of the Department of Agriculture (DA).
-
In the 1970s, only 3 million tonnes of aquatic animals and plants were grown in aquaculture; today, the total production exceeds 100 million tonnes and strong growth continues. Women work in all sections of the aquaculture value chain but their opportunities have not kept pace with its growth. Indeed, many opportunities have contracted under the prevalent growth strategies. Women are more common in small-scale production, post-harvest industrial and artisanal processing, value addition, marketing and sales. When aquaculture intensifies and scales up, women tend to be displaced or relegated to the lowest paid, low grade work. Few women are senior staff, owners, managers and executives in the larger enterprises.
-
Seaweeds constitute one of the commercially important marine living renewable resources. They are the only source for the production of phytochemicals such as agar, agarose, carrageenan and algin which are widely used in various industries as gelling, stabilising and thickening agents. Seaweeds are good sources of food and medicine. Food products like jelly, jam, pickle etc. can be prepared from seaweeds. Many bioactive compounds can be extracted from seaweeds. Seaweed meal and seaweed liquid fertilizer are also' manufacture.d from marine algae. The methods for manufacturing different phyto-chemicals and products from seaweeds are given in this paper.
-
The demand for vegetable proteins increases globally and seaweeds are considered novel and promising protein sources. However, the tough polysaccharide-rich cell walls and the abundance of polyphenols reduce the extractability and digestibility of seaweed proteins. Therefore, food grade, scalable, and environmentally friendly protein extraction techniques are required. To date, little work has been carried out on developing such methods taking into consideration the structural differences between seaweed species. In this work, three different protein extraction methods were applied to three Swedish seaweeds (Porphyra umbilicalis, Ulva lactuca, and Saccharina latissima). These methods included (I) a traditional method using sonication in water and subsequent ammonium sulfate-induced protein precipitation, (II) the pH-shift protein extraction method using alkaline protein solubilization followed by isoelectric precipitation, and (III) the accelerated solvent extraction (ASE®) method where proteins are extracted after pre-removal of lipids and phlorotannins. The highest protein yields were achieved using the pH-shift method applied to P. umbilicalis (22.6 ± 7.3%) and S. latissima (25.1 ± 0.9%). The traditional method resulted in the greatest protein yield when applied to U. lactuca (19.6 ± 0.8%). However, the protein concentration in the produced extracts was highest for all three species using the pH-shift method (71.0 ± 3.7%, 51.2 ± 2.1%, and 40.7 ± 0.5% for P. umbilicalis, U. lactuca, and S. latissima, respectively). In addition, the pH-shift method was found to concentrate the fatty acids in U. lactuca and S. latissima by 2.2 and 1.6 times, respectively. The pH-shift method can therefore be considered a promising strategy for producing seaweed protein ingredients for use in food and feed.
-
Since the establishment of abalone farming, there has been an increase in the demand for Macrocystis as a food source. Therefore, the pressure on natural stock has also augmented and the sustainability of the actual harvesting practices has been questioned. In this article, an attempt to farm Macrocystis pyrifera by zoospores in northern Chile is described; initially under laboratory conditions and subsequently by cultivation in the sea. The experiments were executed during 1 year and two different cultivation methodologies were used: a direct and an indirect method. A maximum frond length of 175 cm was reached and 22 kg m−1 of rope was produced after 120 to 150 days of cultivation in the sea. The algae grew under both methodologies, and no differences in algal length and biomass were detected between the two cultivation systems. However, the direct culture method can be recommended for productive and practical reasons.
-
Green seaweed Ulva lactuca harvested from the North Sea near Zeeland (The Netherlands) was characterized as feedstock for acetone, ethanol and ethanol fermentation. Solubilization of over 90% of sugars was achieved by hot-water treatment followed by hydrolysis using commercial cellulases. A hydrolysate was used for the production of acetone, butanol and ethanol (ABE) by Clostridium acetobutylicum and Clostridium beijerinckii. Hydrolysate-based media were fermentable without nutrient supplementation. C. beijerinckii utilized all sugars in the hydrolysate and produced ABE at high yields (0.35 g ABE/g sugar consumed), while C. acetobutylicum produced mostly organic acids (acetic and butyric acids). These results demonstrate the great potential of U. lactuca as feedstock for fermentation. Interestingly, in control cultures of C. beijerinckii on rhamnose and glucose, 1,2 propanediol was the main fermentation product (9.7 g/L).
-
The publication describes the production, properties and main applications of the three major phyco-colloids extracted from seaweed: agar, alginate and carrageenan. There is also a supplementary chapter on the preparation and marketing of seaweeds as food. Although this is based mainly as Japanese experience it is included in order to encourage increased consumption of seaweeds as human food.
Pages
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.