Macrocystis pyrifera (Giant Kelp), a dominant macroalgal species in southern California, produced I71 ng per g fresh wt (gfwt) per day of CHBr, and 48 ng gfwt-' d-' of CH,Br, during laboratory incubations of whole blades. Comparable rates were measured during in situ incubations 01 intact fronds. Release of CHBr, and CH,Br, by M. pyr$eru was affected by light and algal photosynthetic activity, suggesting that environmental factors influencing kelp physiology can affect halomethane release to the atmosphere. Data from H,O, additions suggest that brominated methane production during darkness is limited by bromide oxidant supply. A bromine budget constructed for a region of southern California indicated that bromine emitted from the use of CH,Br as a fumigant (1 X 1 Ox g BI yr -I) dominates macroalgal sources (3 X 10" g Br yr-I). Global projections, however, suggest that combined emissions of marine algae (including microalgac) contribute substantial amounts of bromine to the global cycle, perhaps on the same order of magnitude as anthropogenic sources.
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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.
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With the world’s rapidly expanding population, it is necessary to provide sustainable and nutritious food. Aquaculture is the world’s fastest growing food production sector and carries with it some major tradeoffs and constraints. It is facing a major sustainability challenge as it is heavily dependent upon marine-derived feedstocks such as fishmeal. With the inevitable increase in the price of fishmeal, declining supply and rising demand, more emphasis has been given to alternative feed sources. The partial replacement of fishmeal with plant based protein sources in the aquaculture has been steadily increasing, however, many of these ingredients can be used as human food directly. Furthermore, the anti-nutritional factors in many plant ingredients can have negative effects in carnivorous fish such as salmonids. Large efforts have been made to develop the technology to produce alternative protein sources by using unicellular microorganisms such as microalgae, yeasts, fungi or bacteria. In this thesis, we have produced microbial protein from Norwegian bioresources such as brown seaweed and Norway spruce that could partially replace fishmeal in the Atlantic salmon diets. The work included characterization of the feedstocks, enzymatic saccharification of seaweed, fermentation for microbial protein production and fish feed trials. This study is based on five research papers: A detailed characterization of Saccharina latissima biomass is presented in the Paper I. The paper describes the biomass production and chemical composition of S. latissima cultivated at different depths and harvested at different time points. The enzymatic saccharification process of S. latissima by using a blend of cellulases and an alginate lyase are described in Paper II. It was shown that the inclusion of alginate lyases improved the saccharification yield of the seaweed, particularly at high solid loading. The carbohydrate content and the enzymatic saccharification of the brown seaweeds Macrocystis pyrifera from Chile and Saccharina latissima from Norway was compared in Paper III. For both seaweeds, recombinant alginate lyases and oligoalginate lyases in combination with cellulases gave higher sugar release than using cellulases only. However, for saccharification of pretreated seaweed only cellulases were needed to achieve high sugar release, indicating that the pretreatment partially hydrolysed the alginate. Moreover, it was shown that seaweed hydrolysate could be used as a growth medium for the yeast Candida utilis.
The cultivation of microbial yeast (C. utilis) from enzymatic hydrolysates of brown seaweed and spruce at different fermentation scales was studied in Paper IV. The yeast product quality in terms of amino acids composition, and mineral content were also studied. A feeding experiment with Atlantic salmon showed that the yeast biomass could partly replace a fishmeal diet, without affecting the growth, but with sub-optimal nutrient digestibility. The nutrient digestibility of C. utilis cultivated from three different carbon and nutrient sources: 1) a blend of woody hydrolysate and molasses, 2) spend sulphite liquor, and 3) a blend of brown seaweed and woody hydrolysate, and the impact of the different yeast biomasses on faecal mineral excretion was evaluated in Paper V. Inclusion of 30 % yeast cultivated on seaweed and spruce hydrolysates resulted in reduced digestibility of protein compared to both the fishmeal-diet and the two other yeast-based diets. In conclusion, this study demonstrated a proof-of-concept for utilization of brown seaweed and wood biomass for the production of microbial protein ingredients for the aquaculture sector.
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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.
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The facultative methylotroph Bacillus methanolicus MGA3 has previously been genetically engineered to overproduce the amino acids L-lysine and L-glutamate and their derivatives cadaverine and γ-aminobutyric acid (GABA) from methanol at 50°C. We here explored the potential of utilizing the sugar alcohol mannitol and seaweed extract (SWE) containing mannitol, as alternative feedstocks for production of chemicals by fermentation using B. methanolicus. Extracts of the brown algae Saccharina latissima harvested in the Trondheim Fjord in Norway were prepared and found to contain 12–13 g/l of mannitol, with conductivities corresponding to a salt content of ∼2% NaCl. Initially, 12 B. methanolicus wild type strains were tested for tolerance to various SWE concentrations, and some strains including MGA3 could grow on 50% SWE medium. Non-methylotrophic and methylotrophic growth of B. methanolicus rely on differences in regulation of metabolic pathways, and we compared production titers of GABA and cadaverine under such growth conditions. Shake flask experiments showed that recombinant MGA3 strains could produce similar and higher titers of cadaverine during growth on 50% SWE and mannitol, compared to on methanol. GABA production levels under these conditions were however low compared to growth on methanol. We present the first fed-batch mannitol fermentation of B. methanolicus and production of 6.3 g/l cadaverine. Finally, we constructed a recombinant MGA3 strain synthesizing the C30 terpenoids 4,4′-diaponeurosporene and 4,4′-diapolycopene, experimentally confirming that B. methanolicus has a functional methylerythritol phosphate (MEP) pathway. Together, our results contribute to extending the range of both the feedstocks for growth and products that can be synthesized by B. methanolicus.
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The seasonal population dynamics of Laminaria longicruris de la Pyl. were studied in Long Island Sound (Connecticut, USA). Llnear growth rates were minimal during August and September, subsequently increased through the remainder of the year and reached a maximum (2.5 cm d-') in May. Productivity per plant (fresh weight) was maximal January to May (11.4 to 15.7 mg g-' d-'); productivity m-2 was maximum in May (110.53 g m-2 d-' in 1986 and 413.32 g m-2 d-' in 1987).Production was 10.6 kg m-2 m 1986 and was estimated to have been 46 to 50 kg m-2 in 1987. Maximum standing crop was observed In May (1986: 24 kg m-2; 1987: 47 kg m2)M. aximum densities of new recruits were 1000 ind m-'.
Densities of plants with blades > 50 g were 92 and 167 plants m-2 in January and May, respectively. Carbon and nitrogen contents were minimal and maximal, respectively, in winter; the reverse was true for summer measurements. Highest percentages of fertile plants were observed during October to December. Succession in generations of plants behaving as either annuals or biennials is also noted and Iscussed.
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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.
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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.
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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).
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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
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