The common sea hare Aplysia kurodai is known to be a good source for the enzymes degrading seaweed polysaccharides. Recently four cellulases, i.e., 95, 66, 45, and 21 kDa enzymes, were isolated from A. kurodai (Tsuji et al., 2013). The former three cellulases were regarded as glycosyl-hydrolase-family 9 (GHF9) enzymes, while the 21 kDa cellulase was suggested to be a GHF45 enzyme. The 21 kDa cellulase was significantly heat stable, and appeared to be advantageous in performing heterogeneous expression and protein-engineering study. In the present study, we determined some enzymatic properties of the 21 kDa cellulase and cloned its cDNA to provide the basis for the protein engineering study of this cellulase. The purified 21 kDa enzyme, termed AkEG21 in the present study, hydrolyzed carboxymethyl cellulose with an optimal pH and temperature at 4.5 and 40°C, respectively. AkEG21 was considerably heat-stable, i.e., it was not inactivated by the incubation at 55°C for 30 min. AkEG21 degraded phosphoric-acid-swollen cellulose producing cellotriose and cellobiose as major end products but hardly degraded oligosaccharides smaller than tetrasaccharide. This indicated that AkEG21 is an endolytic β-1,4-glucanase (EC 3.2.1.4). A cDNA of 1013 bp encoding AkEG21 was amplified by PCR and the amino-acid sequence of 197 residues was deduced. The sequence comprised the initiation Met, the putative signal peptide of 16 residues for secretion and the catalytic domain of 180 residues, which lined from the N-terminus in this order. The sequence of the catalytic domain showed 47–62% amino-acid identities to those of GHF45 cellulases reported in other mollusks. Both the catalytic residues and the N-glycosylation residues known in other GHF45 cellulases were conserved in AkEG21. Phylogenetic analysis for the amino-acid sequences suggested the close relation between AkEG21 and fungal GHF45 cellulases.
Digital library
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Petroleum-based plastics are mass produced to meet customers’ demand due to their low cost and versatility. However, plastic waste has become a serious environmental problem. Hence, degradable plastics from renewable sources (e.g. biomass) are now trending for their “green” properties. In this paper, properties of biofilms made from whole seaweed (WS), Kappaphycus sp. and pure kappa-carrageenan powder (PC) were compared. Glycerol, as plasticizer, was added at differing amounts (1%, 2%, 3%, 4% and 5%, v/v) and their appearance, physical and mechanical properties, solubility, and biodegradability were studied. As results, for colour difference and transparency, WS- 1% showed higher ΔE at 17.09 ± 0.85 with highest opacity at 13.73 mm-1 and least ΔE was at 2.73 ± 0.13 for PC-5% with opacity at 0.49 mm-1. For mechanical properties, PC- 1% has the highest tensile strength and elastic modulus at 26.63 ± 2.18 MPa and 253.53 ± 19.43 MPa, respectively, whereas WS-5% has the lowest at 0.71 ± 0.15 MPa and 2.47 ± 0.44 MPa, respectively. As for biodegradability, by the first week, WS-5% lost 80% of its weight and PC-1% only lost 3%. Overall, PC biofilms showed better quality in terms of mechanical and physical properties but WS biofilms were faster to degrade and dissolve in water. Glycerol concentration affects most of the properties except for mechanical properties for WS and solubility of both. This study suggests that PC may be a better base material for stronger biofilms but WS are a better choice from environmental and cost aspects.
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New in vitro anti-diabetes makgeolli was produced from rice by adding various quantities of Laminaria japonica, and the fermentation characteristics of the L. japonica makgeolli during the fermentation process were investigated. The contents of alcohol and reducing sugar, and viable count of yeast, of L. japonica makgeolli were not significantly changed when the proportion of L. japonica was increased. The total acid content decreased with an increase in L. japonica concentration; the pH and total bacterial cell count increased in proportion with the increase in L. japonica concentration. The L. japonica makgeolli contents of free sugars, such as fructose, glucose, and sucrose, and of organic acids, such as acetic acid, citric acid, succinic acid, and lactic acid, were altered during fermentation and showed various patterns. The effects of the quantity of L. japonica added on the acceptability and anti-diabetes activities of L. japonica makgeolli were also investigated. In a sensory evaluation, L. japonica makgeolli brewed by adding 2.5 or 5% L. japonica to the mash showed the best overall acceptability; the 12.5% L. japonica sample was least favored due to its seaweed flavor. L. japonica addition did not increase the peroxynitrite-scavenging activity of makgeolli. L. japonica makgeolli showed potent anti-diabetes activity, particularly that containing >7.5% L. japonica. Therefore, L. japonica makgeolli may represent a new functional makgeolli with anti-diabetes properties.
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Seaweed farming at sea is proving an increasingly competitive biomass production alternative for food and related uses. Farmed seaweed output has been growing exponentially, reaching 24 million tons by 2012. Remarkably, 99 % of this production occurred in merely eight Asian nations. Most of the remaining 150 countries and territories with coasts are yet to begin seaweed farming. With current technology and extensive available sea areas, requiring no land, freshwater or fertilizers, seaweed production can expand sustainably to the scale of agriculture, while providing a variety of valuable ecosystem services. Following a deductive or principle-based approach, that establishes seaweed primary productivity as a basis for food production, this chapter describes the fundamentals of seaweed farming, harvest and post-harvest techniques, ecological and economic considerations and a perspective on opportunities and challenges. The objective is to provide both an overall account of the state-of-the-art on seaweed farming as well as a contribution to the industry's sustainable development.
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Ocean acidification and warming may threaten future seafood production, safety and quality by negatively impacting the fitness of marine species. Identifying changes in nutritional quality, as well as species most at risk, is crucial if societies are to secure food production. Here, changes in the biochemical composition and nutritional properties of the commercially valuable oysters, Magallana gigas and Ostrea edulis, were evaluated following a 12-week exposure to six ocean acidification and warming scenarios that were designed to reflect the temperature (+3 °C above ambient) and atmospheric pCO2 conditions (increase of 350–600 ppm) predicted for the mid-to end-of-century. Results suggest that O. edulis, and especially M. gigas, are likely to become less nutritious (i.e. containing lower levels of protein, lipid, and carbohydrate), and have reduced caloric content under ocean acidification and warming. Important changes to essential mineral composition under ocean acidification and warming were evident in both species; enhanced accumulation of copper in M. gigas may be of concern regarding consumption safety. In light of these findings, the aquaculture industry may wish to consider a shift in focus toward species that are most robust to climate change and less prone to deterioration in quality, in order to secure future food provision and socio-economic benefits of aquaculture.
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Results obtained on the changes in growth, reproduction, alginic acid and mannitol contents of Turbinoria decurrens carried out for one year from March, 1973 to February, 1974 are presented. Young plants of T. decurrens appear in May and grow to a minimum size between December and February. Branching starts from August and maximum number of branched plants occur in November. Reproductive plants were observed throughout the year. The yield of alginic acid varies from 16.3 to 26.3 % and the estimated mannitol content from 1.5 to 8.7 %. T. decurrens may be harvested in the months between December and February for extraction of alginic acid.
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Results obtained on seasonal growth, yield and physical properties of agar in Gelidiella acerosa and Gracilaria edulis for a period of one year are presented. Vegetation of these two species occurred throughout the year with two peak growth periods.
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A detailed understanding of physiological and reproductive processes in seaweeds has repeatedly proven to be an essential pre-requisite in the successful development of a sustainable industry. The prime example of this was the classical discovery of the “conchocelis”- phase of Pyropia (Porphyra) by Kathleen Mary Drew-Baker in 1949. Such elegant research proved to be pivotal to the development of a globally important “nori” industry which transitioned from the simple provision of the enhanced surface area of the substrata for spore settlement to the sophisticated, mechanized and computerized operations in modern hatcheries supplied by seedling banks of selected species and their cultivars. All of the pre-requisite knowledge was acquired through intensive applied research. However, not all solutions need to be high-tech; problems caused by epiphytes and contaminants have been achieved by exposing Pyropia nets periodically and was found to be effective. This protocol was achieved based on fundamental observations by farmers which were then complemented and refined by laboratory trials. Techniques must be adapted for site-specific differences, as abiotic factors such as water current and movement, surface seawater temperature, light regime and photoperiod, nutrients dispersion and water quality are interrelated, either positively or negatively, influencing seaweed productivity and the end-use of the biomass. Unfortunately, positive techniques that have been shown in vitro/silica can prove to be impractical once attempted at large-scale cultivation and/or the return on investment is not justified by the commercial value of the resultant seaweed biomass. This chapter presents a summary of how the judicious application of knowledge based on the ecophysiological processes of common seaweed species from tropical and cold-waters can assist the future development and scale-up of the global seaweed industry
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Objective of Talk
Discuss the challenges with the selection of materials of construction, design of equipment, and assessment of equipment/material reliability for a continuous and commercially operating HTL (Hydrothermal Liquefaction) process in Saltwater environments
Agenda
1. Brief review of process operating conditions in HTL of Algal Biomass
2. Factors Affecting Materials Selection and Equipment Design
3. Considerations in Selection of Materials of Construction
4. Corrosion Mechanisms of Candidate Alloys
5. Factors Affecting Equipment Design
6. Conclusion and Recommendations
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Marine botanical research activities in the Western Indian Ocean region have increased significantly over the past two decades, contributing to a growing awareness and enhanced understanding of the important values and functions of the main primary producers in the coastal ecosystems of this region (UNEP 1982). Whereas a major proportion of the research has been descriptive, focusing on the distribution and general biology of mangrove, seaweed and seagrass plants and microalgae, more recent research has diversified its attention to include various other more quantitative and applied research topics (Björk et al. 1996). Throughout the region, increasing efforts are underway for coastal zone management, mangrove rehabilitation and marine conservation (e.g. Tanzania Coastal Management Partnership 1999), which call for a solid scientific knowledge base. Yet, new research initiated without a thorough review of past and recent research outputs may lead to a deficiency in the relevance of the knowledge being produced (Hatcher et al. 1989). The present review of the current status of marine botanical research (1950–2000) in the Eastern African region was made to provide a diagnosis of its strengths and weaknesses, with the aim of identifying the main research challenges to be faced to assist in the development of a solid basis for the management, conservation and wise use of the marine botanical resources in this region.
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