Showing papers in "Journal of Applied Phycology in 2011"

Bioactive compounds in seaweed: functional food applications and legislation

Abstract: Seaweed is more than the wrap that keeps rice together in sushi. Seaweed biomass is already used for a wide range of other products in food, including stabilising agents. Biorefineries with seaweed as feedstock are attracting worldwide interest and include low-volume, high value-added products and vice versa. Scientific research on bioactive compounds in seaweed usually takes place on just a few species and compounds. This paper reviews worldwide research on bioactive compounds, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp., Fucus sp., Ascophyllum nodosum, Chondrus crispus, Porphyra sp., Ulva sp., Sargassum sp., Gracilaria sp. and Palmaria palmata. In addition, Undaria pinnatifida is included in this review as this is globally one of the most commonly produced, investigated and available species. Fewer examples of other species abundant worldwide have also been included. This review will supply fundamental information for biorefineries in Atlantic Europe using seaweed as feedstock. Preliminary selection of one or several candidate seaweed species will be possible based on the summary tables and previous research described in this review. This applies either to the choice of high value-added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired. Data are presented in tables with species, effect and test organism (if present) with examples of uses to enhance comparisons. In addition, scientific experiments performed on seaweed used as animal feed are presented, and EU, US and Japanese legislation on functional foods is reviewed.

Seaweed extract stimuli in plant science and agriculture

Abstract: Both micro- and macroalgae have long been used to augment plant productivity and food production in various regions of the world through their beneficial effects when applied to soils. Interactions of algae with the soil community undoubtedly are complex and benefits are dependent on the crop and the local environmental conditions. This has resulted in much speculation as to mechanisms involved as well as the validity of the results reported. It is now 60 years since the first commercial seaweed extract was manufactured for agricultural use. These aqueous extracts allowed for the first time the direct application of soluble seaweed constituents to specific plant organs such as leaves and roots. The earlier concept that benefits of seaweeds and their extracts were due mainly to their manurial value or to their micronutrient suites is no longer tenable. Seaweeds likewise have been used for millennia as fodder supplements to improve animal nutrition and productivity. Recent research is focusing on their mode of action, specific health benefits, and the mechanisms of action in animals. Improved analytical techniques and instrumentation coupled with the use of molecular genetic tools are establishing that seaweed extracts can modify plant and animal responses at a fundamental level. It therefore seems appropriate to review key developments over the years and to remark on novel findings. A new and exciting vista has opened for seaweed extracts in both plant and animal applications.

A decade of change in the seaweed hydrocolloids industry

Abstract: Seaweed hydrocolloid markets continue to grow, but instead of the 3–5% achieved in the 1980s and 1990s, the growth rate has fallen to 1–3% per year. This growth has been largely driven by emerging markets in China, Eastern Europe, Brazil, etc. Sales of agar, alginates and carrageenans in the US and Europe are holding up reasonably well in spite of the recession. However, price increases to offset costs in 2008 and 2009 have begun to have a dampening effect on sales, especially in markets where substitution or extension with less expensive ingredients is possible. These higher prices have been driven by higher energy, chemicals and seaweed costs. The higher seaweed costs reflect seaweed shortages, particularly for carrageenan-bearing seaweeds. The Philippines and Indonesia are the dominant producers of the farmed Kappaphycus and Eucheuma species upon which the carrageenan industry depends and both countries are experiencing factors limiting seaweed production. Similar tightening of seaweed supplies are beginning to show up in brown seaweeds used for extracting alginates, and in the red seaweeds for extracting agar. The structure of the industry is also undergoing change. Producers in China are getting stronger, and while they have not yet developed the marketing skills to compete effectively in the developed world markets, they have captured much of their home market. China does not produce the red and brown seaweeds needed for higher end food hydrocolloid production. Stocking their factories with raw material has led to the supply problems. Sales growth continues to suffer from few new product development successes in recent years; although some health care applications are showing some promise, i.e., carrageenan gel capsules and alginate micro-beads.

Harvesting of microalgae by bio-flocculation

Abstract: The high-energy input for harvesting biomass makes current commercial microalgal biodiesel production economically unfeasible. A novel harvesting method is presented as a cost and energy efficient alternative: the bio-flocculation by using one flocculating microalga to concentrate the non-flocculating microalga of interest. Three flocculating microalgae, tested for harvesting of microalgae from different habitats, improved the sedimentation rate of the accompanying microalga and increased the recovery of biomass. The advantages of this method are that no addition of chemical flocculants is required and that similar cultivation conditions can be used for the flocculating microalgae as for the microalgae of interest that accumulate lipids. This method is as easy and effective as chemical flocculation which is applied at industrial scale, however in contrast it is sustainable and cost-effective as no costs are involved for pre-treatment of the biomass for oil extraction and for pre-treatment of the medium before it can be re-used.

Using marine macroalgae for carbon sequestration: a critical appraisal

Abstract: There has been a good deal of interest in the potential of marine vegetation as a sink for anthropogenic C emissions (“Blue Carbon”). Marine primary producers contribute at least 50% of the world’s carbon fixation and may account for as much as 71% of all carbon storage. In this paper, we analyse the current rate of harvesting of both commercially grown and wild-grown macroalgae, as well as their capacity for photosynthetically driven CO2 assimilation and growth. We suggest that CO2 acquisition by marine macroalgae can represent a considerable sink for anthropogenic CO2 emissions and that harvesting and appropriate use of macroalgal primary production could play a significant role in C sequestration and amelioration of greenhouse gas emissions.

Factors affecting lipid accumulation by Nannochloropsis oculata in a two-stage cultivation process

Abstract: Reserve lipids of microalgae are promising for biodiesel production. However, optimization of cultivation conditions for both biomass yield and lipid production of microalgae is a contradictory problem because required conditions for both targets are different. In this study, a two-stage cultivation strategy is proposed to enhance lipid production of the microalga Nannochloropsis oculata. Biomass growth and lipid production were carried out in two separate and non-interacting stages. In first-stage cultivation, microalgae were cultivated in optimal conditions for cell growth. Then, microalgae were harvested and transferred into a growth-limited environment, thus enhancing lipid production of microalgae. Here, optimization of the lipid production stage (second stage) with respect to different levels of inoculum concentration, salinity of culture broth, and intensity of irradiance was performed. The results show that irradiance exhibits a significant influence on lipid production. The highest lipid productivity of 0.324 g L−1 day−1 was obtained with an inoculum concentration of 2.3 g L−1, a salinity of 35 g L−1, and an irradiance of 500 μmol photons m−2 s−1. The final yield of lipid obtained from the two-stage process was 2.82-times higher than that from traditional single-stage batch cultivation systems.

Protein, fatty acid, and pigment content of Chlorella vulgaris under different light regimes

Abstract: The effects of irradiance and photoperiod on growth rates, chlorophyll a, β-carotene, total protein, and fatty acid content of Chlorella vulgaris were determined. The maximum growth rate (1.13 day−1) was at 100 μmol photons m−2 s−1 and 16:8-h light/dark photoperiod. Chlorophyll a and β-carotene contents significantly differed under different light regimes with chlorophyll a content lower at high irradiance and longer light duration, while β-carotene showed the inverse trend. The total protein and fatty acid content also significantly differed in different light regimes; the maximum percentage of protein (46%) was at 100 μmol photons m−2 s−1 and 16:8 h photoperiod, and minimum (33%) was at 37.5 μmol photons m−2 s−1 and 8:16 h photoperiod; the total saturated fatty acids increased, while monounsaturated and polyunsaturated fatty acids decreased with increasing irradiance and light duration.

Minerals, PUFAs and antioxidant properties of some tropical seaweeds from Saurashtra coast of India

Abstract: Twenty-two tropical seaweeds from the Rhodophyta, Phaeophyta and Chlorophyta were examined for their possible use as nutritional supplements. All seaweeds contained balanced Na/K and C/N ratio and high amounts of macroelements (Na, K, Ca, and Mg) as compared to the terrestrial vegetables. Among the microelements, Fe was the highest followed by Zn, Mn, Cu and other trace elements. Fatty acid distribution showed high level of n-6 and n-3 polyunsaturated fatty acids (PUFAs), and their ratios were within the WHO prescribed limits. The higher ratios of PUFA/SFA (>0.4) are in agreement with the recommendations of nutritional guidelines. Most of the species, especially the Chlorophyta and Phaeophyta, had permissible intake values of unsaturation, atherogenic and thrombogenic indexes comparable to milk-based products. Principal component analysis demonstrated a correlation between total phenolic content, total antioxidant activity, DPPH, and O2•− radical scavenging activity, suggesting polyphenols as the chief contributor to the antioxidant activity in seaweeds. These results indicate that these seaweeds could be a potential source of natural antioxidants, minerals and high-quality PUFAs and may be efficiently used as ingredients in functional foods.

Effect of seaweed liquid extract on growth and yield of Triticum aestivum var. Pusa Gold

Abstract: The effect of seaweed liquid extract (SLE) of Sargassum wightii on germination, growth and yield of Triticum aestivum var. Pusa Gold was studied. Application of a lower concentration (20%) of SLE enhanced the percentage of seed germination, growth and yield, as measured by kernel number and seed dry weight. All growth and yield parameters were found to be highest at the 20% concentration SLE treatment. Total (100%) seed germination was observed for the 20% concentration SLE treatment, an 11% increase over the control. The present study demonstrated that seaweed liquid extract could serve as an alternative biofertilizer as is eco-friendly, cheaper, deliver substantial economic and environmental benefits to farmers.

Effect of aqueous extract of Sargassum johnstonii Setchell & Gardner on growth, yield and quality of Lycopersicon esculentum Mill.

Abstract: Experiments were conducted on tomato to study the potential of brown alga Sargassum johnstonii as a biofertilizer. Seaweed extract was applied as a foliar spray, soil drench, and soil drench + foliar spray to assess its effect on plant growth, yield, and concentration of lycopene and vitamin C. The main objective of the study was to enhance the biochemical constituents with neutraceutical and antioxidant values in tomato fruit. Different concentrations (0.1%, 0.4%, 0.8%, 2%, 6%, 8%, and 10%; v/v) of seaweed extract were used and growth was observed over a period of 7 months. A total of 14 sprays/drenches were applied at 15-day intervals during the entire vegetative and reproductive phase. A statistically significant increase in vegetative growth (plant height, shoot length, root length, and number of branches), reproductive parameters (flower number, fruit number, and fresh weight), and biochemical constituents (photosynthetic pigments, proteins, total soluble sugars, reducing sugars, starch, phenols, lycopene, and vitamin C) was recorded following all three methods of treatment at higher concentrations of seaweed extract. The study also reports auxin- and cytokinin-like activity, and the presence of macro- (Ca, Mg, Na, and K) and micronutrients (Fe, Cu, Zn, and Mn), in seaweed extract of S. johnstonii, which makes it a potential biofertilizer.

Commercial extract from the brown seaweed Ascophyllum nodosum reduces fungal diseases in greenhouse cucumber

Abstract: This study examined the effects of Stimplex™, a marine plant extract formulation from Ascophyllum nodosum, on some common cucumber fungal pathogens. Greenhouse cucumber plants were sprayed and/or root drenched using Stimplex™ at 0.5% or 1% concentration twice at 10-day intervals. Treatments also included application of fungicide (chlorothalonil, 2 g L−1) alternating with Stimplex™ application. Treated plants were inoculated with four cucumber fungal pathogens including Alternaria cucumerinum, Didymella applanata, Fusarium oxysporum, and Botrytis cinerea. Stimplex™ application resulted in a significant reduction in disease incidence of all the pathogens tested. The disease control effect was greater for Alternaria and Fusarium infection, followed by Didymella and Botrytis. Combined spray and root drenching with Stimplex™ was more effective than either spray or root drenching alone. The alternation of one fungicide application, alternated with Stimplex™ application, was highly effective and found to be the best treatment in reducing the disease ratings. Plants treated with Stimplex™ showed enhanced activities of various defense-related enzymes including chitinase, β-1,3-glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, and lipoxygenase. Altered transcript levels of various defense genes, including chitinase, lipoxygenase, glucanase, peroxidase, and phenylalanine ammonia lyase were observed in treated plants. Cucumber plants treated with Stimplex™ also accumulated higher level of phenolics compared to water controls. These results suggest that seaweed extracts enhance disease resistance in cucumber probably through induction of defense genes or enzymes.

Medium pH and nitrate concentration effects on accumulation of triacylglycerol in two members of the chlorophyta

Abstract: Algal-derived biodiesel is of particular interest because of several factors including: the potential for a near-carbon-neutral life cycle, the prospective ability for algae to capture carbon dioxide generated from coal, and algae’s high per acre yield potential. Our group and others have shown that in nitrogen limitation, and for a single species of Chlorella, a rise in culture medium pH yields triacylglycerol (TAG) accumulation. To solidify and expand on these triggers, the influence and interaction of pH and nitrogen concentration on lipid production was further investigated on Chlorophyceae Scenedesmus sp. and Coelastrella sp. Growth was monitored optically and TAG accumulation was monitored by Nile red fluorescence and confirmed by gas chromatography. Both organisms grew in all treatments and TAG accumulation was observed by two distinct conditions: high pH and nitrogen limitation. The Scenedesmus sp. was shown to grow and produce lipids to a larger degree in alkaliphilic conditions (pH >9) and was used to further investigate the interplay between TAG accumulation from high pH and/or nitrate depletion. Results given here indicate that TAG accumulation per cell, monitored by Nile red fluorescence, correlates with pH at the time of nitrate depletion.

Sustainability and cyanobacteria (blue-green algae): facts and challenges

Abstract: Cyanobacteria (blue-green algae) are widely distributed Gram-negative oxygenic photosynthetic prokaryotes with a long evolutionary history. They have potential applications such as nutrition (food supplements and fine chemicals), in agriculture (as biofertilizer and in reclamation of saline USAR soils) and in wastewater treatment (production of exopolysaccharides and flocculants). In addition, they also produce wide variety of chemicals not needed for their normal growth (secondary metabolites) which show powerful biological activities such as strong antiviral, antibacterial, antifungal, antimalarial, antitumoral and anti-inflammatory activities useful for therapeutic purposes. In recent years, cyanobacteria have gained interest for producing biofuels (both biomass and H2 production). Because of their simple growth needs, it is potentially cost-effective to exploit cyanobacteria for the production of recombinant compounds of medicinal and commercial value. Recent advances in culture, screening and genetic engineering techniques have opened new ways to exploit the potential of cyanobacteria. This review analyses the sustainability of cyanobacteria to solve global problems such as food, energy and environmental degradation. It emphasizes the need to adopt multidisciplinary approaches and a multi-product production (biorefinery) strategy to harness the maximum benefit of cyanobacteria.

Isolation of high-lipid content strains of the marine microalga Tetraselmis suecica for biodiesel production by flow cytometry and single-cell sorting

Abstract: Biodiesel from algae is considered an alternative for a third generation of biofuels. However, most microalgae are not lipogenic during fast growth periods, but high-lipid content occurs at resting stages. Microalgae biomass production for biodiesel needs continuous high volumetric and aerial yields and large amount of neutral lipid in the biomass. These requirements are similar to demanding a marathon runner to be obese. We show that by using cell sorting capabilities of flow cytometers, in combination with the lipid-soluble fluorescent dye Nile Red, we can isolate and select cells with a high and stable lipid content. In our study, we were able to select the equivalent of a stable “fat marathon runner” through three sorting events obtained from wild populations of Tetraselmis suecica.

Effect of salinity on the biochemical composition of the alga Botryococcus braunii Kütz IPPAS H-252

Abstract: The effect of 0.3 and 0.7 M NaCl on biomass yield, total nitrogen content, intracellular lipid content, and fatty acid profile of the lipids of the alga Botryococcus braunii IPPAS H-252 in different phases of the culture cycle was studied. The presence of sodium chloride in the medium inhibited the growth of algal cells for the first 3 days of the experiment, causing a decrease in total nitrogen, enhanced synthesis of triacylglycerols, and considerable changes in the lipid fatty acid profile: decreases in polyenoic acid contents (from 68.34% to 29.38% and 12.8%) and proportions of long-chain saturated acids (from 0.53% to 5.3% and 14.13% of the total fatty acids) at 0.3 M NaCl and 0.7 M NaCl, respectively. In later phases of the culture, at 0.3 M NaCl, the content of polyenoic acids rose to the values characteristic of the active growth phase of this alga. At 0.7 M NaCl, the proportion of polyenoic acids grew less significantly, but biomass concentration and total nitrogen increased, similarly to the experiment with 0.3 M NaCl.

Effects of carbon source on growth and morphology of Botryococcus braunii

Abstract: The green colonial alga Botryococcus braunii is characterized by the ability to produce and accumulate large amounts of hydrocarbons. We isolated and established an axenic clonal strain of B. braunii B70 and investigated the effects of organic carbon sources, including glucose, mannose, fructose, galactose, or acetate, on growth under light and dark conditions. This algal strain had the capacity to grow photo-, mixo-, or heterotrophically. Growth was promoted substantially following exposure of the algae to glucose or mannose under light exposure. Cells could grow under continuous darkness with glucose or mannose. In the presence of glucose under light or dark conditions, cell and colony size, and the intracellular granules containing oil, were markedly larger than those cultured without glucose.

Inducing autoflocculation in the diatom Phaeodactylum tricornutum through CO2 regulation

Abstract: The effect of pH on flocculation was studied using the diatom Phaeodactylum tricornutum and the green algae Scenedesmus cf. obliquus as surrogate species. There was a distinct, species-specific threshold of pH where flocculation started. P. tricornutum started to flocculate at pH 10.5 and S. cf. obliquus at pH 11.3. Above this threshold, settling rates up to 360 cm h−1 were observed for P. tricornutum and the concentrating factor was up to 60-fold. The combined effect of pH, turbulence, and cell density on flocculation of P. tricornutum was additionally studied in a factorial 53-design experiment. pH was the most important factor affecting flocculation, but at the pH threshold (pH 10.5), the concentrating factor was increased by increasing cell density and turbulence. Algae increases the pH during photosynthesis, and the P. tricornutum and S. cf. obliquus cultures increased the pH to a maximum of 10.8 and 9.5, respectively, after discontinuing the CO2 supply. For P. tricornutum, this was above the flocculation threshold, and rapid settling of this species due to increased pH was observed in a matter of hours after the CO2 supply was turned off. This could be used as a simple, low-cost, initial dewatering step for this species.

The commercial red seaweed Kappaphycus alvarezii—an overview on farming and environment

Abstract: Commercial cultivation of the red alga Kappaphycus alvarezii (Doty) Doty has been satisfying the demand of the carrageenan industry for more than 40 years. For the past four decades, this species has been globally introduced to many maritime countries for experimental and commercial cultivation as a sustainable alternate livelihood for coastal villagers. Accompanying the introduction is an increasing concern over the species effects on the biodiversity of endemic ecosystems. The introductions of non-endemic cultivars have resulted in the adaptation of quarantine procedures to minimize bioinvasions of additional invasive species. The present review focuses on Kappaphycus farming techniques through the application of biotechnological tools, ecological interactions with endemic ecosystems, future K. alvarezii farming potentials in Asia, Africa, and the Pacific, and the challenges for prospective farmers, i.e., low raw material market value, diseases, grazing, etc. The introduction of Kappaphycus cultivation to tropical countries will continue due to the high production values realized, coastal villages searching for alternative livelihoods, and the increased global industrial demand for carrageenan.

Extraction protocols for the quantification of phycobilins in aqueous phytoplankton extracts

Abstract: Phycobiliproteins are light harvesting pigments in cryptophytes, cyanobacteria, and rhodophytes that allow these organisms to absorb light in the green and orange regions of the electromagnetic spectrum. Unlike chlorophylls and carotenoids, however, phycobilins are rarely quantified as part of routine photobiological studies because they require different extraction protocols. The objectives of this study were (1) to compare 10 existing methods to determine that with the highest extraction efficiency and (2) to determine the maximum time limit for the storage of phycobilins before degradation. Cells of the cryptophyte Rhodomonas salina and the cyanobacterium Synechococcus bacillaris were harvested either by centrifugation or filtration and then subjected to lyophilization, mechanical disruption, or freeze–thaw techniques. The extraction efficiency for pigments in cells collected on glass fiber filters was always <32 ± 5% and thus always significantly lower than in samples harvested by centrifugation, which had extraction efficiencies of 53 ± 6–98 ± 11%. Disruption of cells by freezing–thawing and sonication both resulted in significantly higher (ANOVA, p < 0.01) extraction efficiencies than disruption with a tissue grinder. Storage of samples at −80°C showed no significant pigment degradation over the course of 24 weeks.

Nutritional value of selected macroalgae

Abstract: Macroalgae are traditionally used in human and animal nutrition. Their protein and fiber content have been widely studied and differ according to the species, their geographic origin and their seasonal conditions. In addition to their value for human nutrition, seaweeds have multiple therapeutically applications (e.g., weight control, hypocholesterolemic, antioxidant and antitumor activities, others) and, in general, contribute and promote human health. In the archipelago of the Azores, the consumption of seaweeds is widespread and accepted as a common practice in some islands. This work is aimed at providing information on the protein and fiber content of the locally consumed species, to promote this regional food product that can be potentially profitable from the biotechnology and commercial perspective, and also benefit public health, particularly, taking into account the low level of marine pollution in the Azores archipelago. Protein and fiber content of eight seaweeds (Porphyra sp., Osmundea pinnatifida, Pterocladiella capillacea, Sphaerococcus coronopifolius, and Gelidium microdon, Rhodophyta; Cystoseira abies-marina and Fucus spiralis, Phaeophyta; Ulva compressa, Chlorophyta) were determined using the Kjeldahl method and the Weende method, respectively. The protein content ranged from 6.81 to 26.62 of dry weight for C. abies-marina and U. compressa, respectively. Fiber content was generally higher as compared with that in seaweeds from other origins and ranged from 33.82 to 63.88 for O. pinnatifida and F. spiralis, respectively.

Extraction and characterisation of alginate from brown seaweeds (Fucales, Phaeophyceae) collected from Port Dickson, Peninsular Malaysia

Abstract: Four species of brown seaweeds, namely Sargassum baccularia, Sargassum binderi, Sargassum siliquosum and Turbinaria conoides, harvested from Port Dickson, Negeri Sembilan, Malaysia were analysed for ash content, alginate yield and alginate properties. Seaweeds calcined at 450°C were found to have low amount of non-combustible residue as these were not contaminated by calcareous animals. Alginate was extracted from these seaweeds by two methods: hot and cold. In the hot method, the storing time was 3 h and the processing temperature was 50°C, whilst in the cold method, the sample was stored overnight at room temperature. Higher yield of alginate was obtained by the hot method compared to the cold method, but alginate extracted by the cold method gave higher molecular weight. In the hot method, 49.9% of alginate was extracted from S. siliquosum, followed by T. conoides (41.4%), S. binderi (38.9%) and S. baccularia (26.7%). Alginate extracted from T. conoides has an average molecular weight, M w, of 8.06 × 105 g mol−1, whereas alginate from S. siliquosum was the lowest in M w (4.81 × 105 g mol−1) when the extraction was done at room temperature. Alginate extracted from S. baccularia was found to be very heat-sensitive. Its M w has dropped more than 83%, from 7.52 × 105 to 1.23 × 105 g mol−1, when the extraction temperature was raised. The effect of heat on the extent of depolymerisation of the alginate molecule of the other three brown seaweed species was less significant, with decrease in molecular weight ranging between 13% and 16%.

Improved Nile Red staining of Nannochloropsis sp.

Abstract: High-throughput screening of microalgae for use as a potential feedstock for biodiesel requires a reliable method for the rapid detection of intracellular neutral lipid content. In this study, we report a modified and improved Nile Red (NR) fluorescence staining procedure for use as a rapid and sensitive screening tool to estimate levels of intracellular neutral lipid in the picopleustonic microalgae, Nannochloropsis sp. Addition of either glycerol or dimethyl sulfoxide (DMSO) into microalgae cultures greatly enhances lipid staining efficiency and increases the fluorescence intensity of stained cells. The optimized procedure requires glycerol and DMSO at the concentration of 0.1 and 0.165 g mL−1, respectively, for peak fluorescence in a live culture of Nannochloropsis sp. Incubation for 5 min for glycerol-NR staining and 10 min for DMSO-NR staining at room temperature, in darkness, is used for the NR concentration of 0.3 and 0.7 μg mL−1 for glycerol and DMSO, respectively. For the selection of lipid-rich cells of Nannochloropsis sp. using flow cytometric cell sorting, the glycerol-NR procedure is recommended as glycerol, unlike DMSO, does not inhibit subsequent growth of sorted cells.

Single-step chromatography for simultaneous purification of C-phycocyanin and allophycocyanin with high purity and recovery from Spirulina (Arthrospira) platensis

Abstract: The cyanobacterium Spirulina (Arthrospira) platensis is a good source of phycobiliprotein purification. C-phycocyanin (C-PC) is the major phycobiliprotein, while allophycocyanin (APC) is less abundant in S. platensis. Previously reported methods for C-PC purification are only able to offer either high purity or high efficiency. This paper describes one-step anion exchange chromatography method with continuous pH gradient elution for simultaneous purification of C-PC and APC with high purity and high recovery. Crude C-PC and APC were extracted and concentrated by ammonium sulfate fractionation at saturation of 25% and 60%, then purified on a DEAE-Sepharose Fast Flow chromatography column with continuous pH gradient elution from pH 5.0 to 3.6. After this single-step chromatography, C-PC and APC with high purity and recovery were simultaneously obtained. The purity ratios of C-PC and APC reached 5.59 (A620/A280) and 5.19 (A650/A280), respectively. Their purity was further demonstrated by electrophoresis and fluorescence emission spectroscopy. Moreover, the total recovery yield of pure C-PC and APC were 67.04% and 80.0%, representing 111.83 and 29.28 mg·g−1 lyophilized weight, respectively. The obtained C-PC and APC remained stable over a pH range of 4–9. This purification method for high purity and recovery of C-PC and APC proved to be fairly efficient compared with previously reported methods.

Toxicity of cadmium and zinc on two microalgae, Scenedesmus obliquus and Desmodesmus pleiomorphus, from Northern Portugal

Abstract: Aquatic environments often contain toxic heavy metals that may enter the food web via uptake by microalgae and eventually cause severe poisoning problems at higher trophic levels. The effects of Cd and Zn cations upon growth of two native green microalgal species, Scenedesmus obliquus and Desmodesmus pleiomorphus (previously isolated from a polluted site in Northern Portugal), were accordingly evaluated. Growth inhibition of the microalgal cells was determined following exposure for 96 h to several initial concentrations of aqueous solutions of either of those two metals. At the higher end of Cd and Zn experimental concentration ranges, a significant reduction in cell density was observed in the cultures; EC50 values, calculated after fitting a Weibull model to the experimental data, were 0.058 and 1.92 mg L−1 for Cd and 16.99 and 4.87 mg L−1 for Zn in the case of S. obliquus and D. pleiomorphus, respectively. One observed that S. obliquus can tolerate higher Zn concentrations than D. pleiomorphus, but the reverse holds regarding exposure to Cd.

Cultivation of Chlorella emersonii with flue gas derived from a cement plant

Abstract: The present study reviews the options of cultivating the green alga, Chlorella emersonii, under photoautotrophic conditions with flue gas derived from a cement plant. It was conducted in the Lafarge Perlmooser plant in Retznei, Austria, where stone coal and various surrogate fuels such as used tyres, plastics and meat-and-bone meal are incinerated for heating limestone. During 30 days of cultivation, flue gas had no visible adverse effects compared to the controls grown with pure CO2. The semi-continuous cultivation with media recycling was performed in 5.5-L pH-stat photobioreactors. The essay using CO2 from flue gas yielded a total of 2.00 g L−1 microalgal dry mass and a CO2 fixation of 3.25 g L−1. In the control, a total of 2.06 g L−1 dry mass was produced and 3.38 g L−1 CO2 was fixed. Mean growth rates were between 0.10 day−1 (control) and 0.13 day−1 (flue gas). No accumulation of flue gas residues was detected in the culture medium. At the end of the experiment, however, the concentration of lead was three times higher in algal biomass compared to the control, indicating that cultures aerated with this type of flue gas should not be used as food supplements or animal feed.

Differential growth response of Ulva lactuca to ammonium and nitrate assimilation

Abstract: Controlled cultivation of marine macroalgal biomass such as Ulva species, notably Ulva lactuca, is currently studied for production of biofuels or functional food ingredients. In a eutrophic environment, this macrophyte is exposed to varying types of nutrient supply, including different and fluctuating levels of nitrogen sources. Our understanding of the influences of this varying condition on the uptake and growth responses of U. lactuca is limited. In this present work, we examined the growth response of U. lactuca exposed to different sources of nitrogen (NH 4 + ; NO 3 − ; and the combination NH4NO3) by using photo-scanning technology for monitoring the growth kinetics of U. lactuca. The images revealed differential increases of the surface area of U. lactuca disks with time in response to different N-nutrient enrichments. The results showed a favorable growth response to ammonium as the nitrogen source. The NH4Cl and NaNO3 rich media (50 μM of N) accelerated U. lactuca growth to a maximum specific growth rate of 16.4 ± 0.18% day−1 and 9.4 ± 0.72% day−1, respectively. The highest biomass production rate obtained was 22.5 ± 0.24 mg DW m−2·day−1. The presence of ammonium apparently discriminated the nitrate uptake by U. lactuca when exposed to NH4NO3. Apart from showing the significant differential growth response of U. lactuca to different nitrogen sources, the work exhibits the applicability of a photo-scanning approach for acquiring precise quantitative growth data for U. lactuca as exemplified by assessment of the growth response to two different N-sources.

Hydrocarbon productivities in different Botryococcus strains: comparative methods in product quantification.

Abstract: Six different strains of the green microalgae Botryococcus belonging to the A-race or B-race, accumulating alkadiene or botryococcene hydrocarbons, respectively, were compared for biomass and hydrocarbon productivities. Biomass productivity was assessed gravimetrically upon strain growth in the laboratory under defined conditions. Hydrocarbon productivities were measured by three different and independent experimental approaches, including density equilibrium of the intact cells and micro-colonies, spectrophotometric analysis of hydrocarbon extracts, and gravimetric quantitation of eluted hydrocarbons. All three hydrocarbon-quantitation methods yielded similar results for each of the strains examined. The B-race microalgae Botryococcus braunii var. Showa and Kawaguchi-1 constitutively accumulated botryococcene hydrocarbons equivalent to 30% and 20%, respectively, of their overall biomass. The A-race microalgae Botryococcus braunii, varieties Yamanaka, UTEX 2441 and UTEX LB572 constitutively accumulated alkadiene hydrocarbons ranging from 14% to 13% and 10% of their overall biomass, respectively. Botryococcus sudeticus (UTEX 2629), a morphologically different green microalga, had the lowest hydrocarbon accumulation, equal to about 3% of its overall biomass. Results validate the density equilibrium and spectrophotometric analysis methods in the quantitation of botryococcene-type hydrocarbons. These analytical advances will serve in the screening and selection of B. braunii and of other microalgae in efforts to identify those having a high hydrocarbon content for use in commercial applications.

Enhanced immunostimulatory and antitumor activity of different derivatives of κ-carrageenan oligosaccharides from Kappaphycus striatum

Abstract: Chemical modification of carbohydrates can lead to differences in their biological activities. We previously showed that kappa-carrageenan oligosaccharides from Kappaphycus striatum have antitumor and immunomodulation effects on S180-bearing mice. In this study, we tested the hypothesis that different chemical modifications of carrageenan oligosaccharides enhance their activities. The mice inoculated with S180 cell suspension were treated p.o. with carrageenan oligosaccharides and their sulfated, acetylated, and phosphorylated derivatives (50, 100, and 200 mu g g(-1)) for 14 days. Transplantable tumor inhibition rate and macrophage phagocytosis, quantitative hemolysis of sheep red blood cells, lymphocyte proliferation, the activity of natural killer cells, production of interleukin-2, and tumor necrosis factor-alpha were also analyzed. As expected, treatment with different kappa-carrageenan oligosaccharides derivatives resulted in an increase in tumor inhibition rate and macrophage phagocytosis and cellular immunity, especially on spleen lymphocyte proliferation. The sulfated derivative at the dose 200 mu g g(-1) per day showed the highest antitumor activity with the 54.12% tumor weight inhibition and elicited an increase in nature killer cells activity up to 76.1% on S180-bearing mice, which were both significantly higher than the unmodified oligosaccharides. It suggested that chemical modification (especially sulfation) of carrageenan oligosaccharides can enhance their antitumor effect and boost their antitumor immunity.

Effects of temperature and irradiance on photosynthesis and growth of a green-tide-forming species (Ulva linza) in the Yellow Sea

Abstract: Samples of the massive drifting green alga, Ulva linza, were collected from the coastal waters of the Yellow Sea, southwest of Korea, in early July 2009, and cultured under laboratory conditions. The effects of various temperature (10–30°C) and irradiance levels (0–1,000 μmol photons m−2 s−1) on photosynthesis, growth, and tissue nutrient content of U. linza were investigated in laboratory for both individuals of the late-stage vegetation (LSV) and the early-stage vegetation (ESV). After 1 h acclimation to various irradiance and temperature conditions, maximum gross photosynthetic rate of ESV was significantly higher than those of LSV. In the long-term (7-d) acclimation experiments to various irradiance and temperature levels, gross photosynthetic rates of ESV individuals were also significantly higher than those of LSV individuals. High photosynthetic rate of ESV individuals induced increase in mass of about 60% over the growth saturation irradiance (136 μmol photons m−2 s−1) and about 20% under low temperature conditions (10–15°C) during 7-d. The gross photosynthesis of LSV individuals was low when examined under temperature and irradiance conditions that were optimum for ESV growth. Consequently, free-floating U. linza exhibits cellular senescence beginning in early July in the Yellow Sea, and green tides formed by this species cannot be maintained beyond this time in the open sea. However, we expect that U. linza can proliferate quickly after settlement on new coastal habitats of the Yellow Sea because of the high tissue nitrogen utilization for photosynthesis in ESV, which is formed by germination of reproductive cells.

Isolation and chemical characterization of algal polysaccharides from the green seaweed Ulva clathrata (Roth) C. Agardh

Abstract: In order to obtain information on the content and composition of the water-soluble polysaccharides from Ulva clathrata, an extraction at 60°C, in different media, was performed: water, EDTA and HCl (F-I), each followed by a sequential extraction in NaOH 0.1 M (F-II). The extracts were recovered and analyzed for total carbohydrates, proteins, rhamnose, uronic acids and sulfate content. Differences were obtained in the yield and composition in both fractions of the different media (F-I and F-II). Higher yields resulted in the first fraction on all media. HCl extraction was the best in both fractions (14.83 ± 1.5% and 5.96 ± 1.1%, F-I and F-II, respectively). In all cases, F-I was more sulfated ranging from 27.87% to 35.8% and higher in rhamnose content, whereas F-II had higher protein and slightly higher uronic acid content. FTIR spectra showed that soluble polysaccharides from the green seaweed U. clathrata are sulfated polysaccharides, similar to ulvan obtained from other Ulva species and confirmed by the 1 H-NMR spectrum, where the characteristic signal for the deoxy sugar (rhamnose) is present.