Showing papers in "Journal of Applied Phycology in 2014"

Plant biostimulants: a review on the processing of macroalgae and use of extracts for crop management to reduce abiotic and biotic stresses

Abstract: A biostimulant is an organic material that, when applied in small quantities, enhances plant growth and development such that the response cannot be attributed to the application of traditional plant nutrients. This review is aimed at highlighting developments in the processing of macroalgae for agricultural biostimulants (AB), summarising the biologically active components of brown macroalgae and examining the factors supporting the use of macroalgal AB for managing abiotic and biotic stresses in crop plants. The policy drivers supporting the use of macroalgal-derived ABs in agriculture are also emphasised. We examine the use of macroalgal ABs in crop production and evaluated the benefits of seed priming, foliar application, soil drenches and hydroponic treatments. The use of macroalgal ABs on crop plants can generate multiple benefits with reported effects including enhanced rooting, higher crop and fruit yields, freezing, drought and salt tolerance, enhanced photosynthetic activity and resistance to fungi, bacteria and virus. ABs can be applied as an alternative, or used in conjunction with synthetic crop protection products and plant growth regulators, and may have a role in maintaining crop production levels, health and quality in the future when many active ingredients will be lost to the industry due to changes in European Union regulations. Worldwide, macroalgae remain largely unexploited, we highlight some of the future research and development priorities.

Effect of liquid seaweed extracts on growth of tomato seedlings (Solanum lycopersicum L.)

Abstract: Seaweed extracts are used as nutrient supplements, biostimulants, or biofertilizers in agriculture and horticulture to increase plant growth and yield. In this study, we examined the effect of liquid seaweed extracts (LSEs) made from Ulva lactuca, Caulerpa sertularioides, Padina gymnospora, and Sargassum liebmannii as biostimulants on the germination and growth of tomato (Solanum lycopersicum) under laboratory and greenhouse conditions using foliar and soil drench applications of LSEs. We assessed LSEs at different concentrations (0.2, 0.4, and 1.0 %) on germination parameters (percentage, index, mean time, energy, and seedling vigor index) and growth parameters (plumule length, radical length, shoot length, root length, fresh weight, and dry weight) of tomato seedlings. Our results indicate that seeds treated with LSEs of U. lactuca and P. gymnospora at lower concentrations (0.2 %) showed enhanced germination (better response in germination rate associated with lower mean germination time, high germination index and germination energy, and consequently greater seedling vigor and greater plumule and radicle length). Application as a soil drench was found to be more effective in influencing the height of the plant (up to 79 cm) than the foliar spray application (75 cm). Plants receiving LSEs of U. lactuca and P. gymnospora showed increased shoot length, root length, and weight. Furthermore, U. lactuca and P. gymnospora were found to be more successful and better candidates for developing effective biostimulants to improve the growth of tomato plants. This study provides important information on the identification and utilization of Mexican seaweed resources for agriculture and is the first study to report on the uses of these seaweeds as a source of liquid extracts as biostimulants in agriculture.

Seaweeds: an opportunity for wealth and sustainable livelihood for coastal communities

Abstract: The European, Canadian, and Latin American seaweed industries rely on the sustainable harvesting of natural resources. As several countries wish to increase their activity, the harvest should be managed according to integrated and participatory governance regimes to ensure production within a long-term perspective. Development of regulations and directives enabling the sustainable exploitation of natural resources must therefore be brought to the national and international political agenda in order to ensure environmental, social, and economic values in the coastal areas around the world. In Europe, Portugal requires an appraisal of seaweed management plans while Norway and Canada have developed and implemented coastal management plans including well-established and sustainable exploitation of their natural seaweed resources. Whereas, in Latin America, different scenarios of seaweed exploitation can be observed; each country is however in need of long-term and ecosystem-based management plans to ensure that exploitation is sustainable. These plans are required particularly in Peru and Brazil, while Chile has succeeded in establishing a sustainable seaweed-harvesting plan for most of the economically important seaweeds. Furthermore, in both Europe and Latin America, seaweed aquaculture is at its infancy and development will have to overcome numerous challenges at different levels (i.e., technology, biology, policy). Thus, there is a need for regulations and establishment of “best practices” for seaweed harvesting, management, and cultivation. Trained human resources will also be required to provide information and education to the communities involved, to enable seaweed utilization to become a profitable business and provide better income opportunities to coastal communities.

Effect of nutrient supply status on biomass composition of eukaryotic green microalgae

Abstract: In eukaryotic green microalgae, manipulation of metabolic pathways by altering the culture medium and/or culture conditions represents a powerful tool for physiological control and is usually more practicable than metabolic or genetic engineering. Strategies for nutrient-induced shifts in biomass composition are generally cost-efficient, environmentally friendly, applicable on a large scale and flexible for various industrially attractive microalgae species. In addition, processes, such as nutrient limitation/deprivation, can be readily scheduled and optimised to achieve high levels of productivity for the desired target compound(s). These strategies are currently used in microalgae to achieve overproduction of metabolites such as lipids, polysaccharides and pigments. This paper presents an overview of the species and strain-specific responses of eukaryotic, green microalgal cells that are triggered by variations in selected macronutrient and micronutrient availability. Individual and mutually associated physiological responses to nutrient supply status are described at the molecular level as well as discussed from the perspective of potential biotechnological applications.

pH effects on growth and lipid accumulation of the biofuel microalgae Nannochloropsis salina and invading organisms

Abstract: Biofuels derived from non-crop sources, such as microalgae, offer their own advantages and limitations. Despite high growth rates and lipid accumulation, microalgae cultivation still requires more energy than it produces. Furthermore, invading organisms can lower efficiency of algae production. Simple environmental changes might be able to increase algae productivity while minimizing undesired organisms like competitive algae or predatory algae grazers. Microalgae are susceptible to pH changes. In many production systems, pH is kept below 8 by CO2 addition. Here, we uncouple the effects of pH and CO2 input, by using chemical pH buffers and investigate how pH influences Nannochloropsis salina growth and lipid accumulation as well as invading organisms. We used a wide range of pH levels (5, 6, 7, 8, 9, and 10). N. salina showed highest growth rates at pH 8 and 9 (0.19 ± 0.008 and 0.19 ± 0.011, respectively; mean ± SD). Maximum cell densities in these treatments were reached around 21 days into the experiment (95.6 × 106 ± 9 × 106 cells mL−1 for pH 8 and 92.8 × 106 ± 24 × 106 cells mL−1 for pH 9). Lipid accumulation of unbuffered controls were 21.8 ± 5.8 % fatty acid methyl esters content by mass, and we were unable to trigger additional significant lipid accumulation by manipulating pH levels at the beginning of stationary phase. Ciliates (grazing predators) occurred in significant higher densities at pH 6 (56.9 ± 39.6 × 104 organisms mL−1) than higher pH treatments (0.1–6.8 × 104 organisms mL−1). Furthermore, the addition of buffers themselves seemed to negatively impact diatoms (algal competitors). They were more abundant in an unbuffered control (12.7 ± 5.1 × 104 organisms mL−1) than any of the pH treatments (3.6–4.7 × 104 organisms mL−1). In general, pH values of 8 to 9 might be most conducive to increasing algae production and minimizing invading organisms. CO2 addition seems more valuable to algae as an inorganic carbon source and not as an essential mechanism to reduce pH.

Abscisic acid, gibberellins and brassinosteroids in Kelpak®, a commercial seaweed extract made from Ecklonia maxima

Abstract: The seaweed extract Kelpak® made from the kelp Ecklonia maxima is registered as a biostimulant for use in agriculture. It elicits many beneficial responses including improved root and shoot growth, higher yields and greater resistance to abiotic and biotic stresses. Previously, cytokinins, auxins and polyamines were identified in Kelpak®. The aim of the present study was to quantify other groups of plant growth regulators (PGRs)—abscisic acid (ABA), gibberellins (GAs) and brassinosteroids—that may be present in E. maxima and Kelpak®. Kelpak® samples harvested between 2008 and 2010 and stored for up to 26 months were analysed using ultra performance liquid chromatography tandem mass spectrometry. ABA levels were below the limits of detection in E. maxima but were detected in low concentrations in Kelpak®, ranging from 0.31 to 20.70 pg mL−1 Kelpak®. Eighteen GAs were found in E. maxima and Kelpak® with concentrations from 187.54 to 565.96 pg mL−1 Kelpak®. The biologically active GAs (GA1, GA3, GA4, GA5, GA6 and GA7) comprised less than 3 % in Kelpak®. Although GA13 (a final product in the metabolic pathway) was present in low concentrations in E. maxima, very high concentrations were present in Kelpak®. The brassinosteroids brassinolide (BL) and castasterone (CS) were identified in E. maxima and Kelpak®. Concentrations varied with harvest and storage time, ranging from 384.72 to 793.23 pg BL mL−1 Kelpak® and 62.84 to 567.51 pg CS mL−1 Kelpak®. It is likely that this cocktail of natural PGRs present in Kelpak® may act individually or in concert and thus contribute to the numerous favourable physiological responses elicited by Kelpak® application to plants.

Seaweeds for animal production use

Abstract: Early scientific studies conducted at the turn of the twentieth century failed to support the inclusion of seaweeds into animal rations at high inclusion rates. At that time, based on proximate analysis and energy availability studies, dried seaweeds or kelp meal largely fell out of favor as a recommended animal feed source. Nevertheless, kelp meal was still regarded by some as having properties which improved animal health and productivity which were not conveniently explained by conventional feed analysis. In the 1970s, research leads to the discovery that chelated micromineral sources were more efficient for the delivery of microelements than conventional inorganic sources. This prompted renewed interest in seaweeds as rich sources of over 60+ microelements. However, it was only in the early 2000s, when detailed analysis of the complex structure of the polysaccharides associated with seaweeds was tied to their prebiotic actions, that a clear explanation for the basis of productivity and health enhancement was attained. Further analysis indicated that other constituents in various brown seaweeds such as phlorotannins and antioxidants also contributed to the observed bioactivities. Of all of the brown seaweeds cited in studies, the one most scientifically documented is Ascophyllum nodosum, and of all of these sources, Tasco®, a sundried, high-quality macroalgal product, produced by Acadian Seaplants has been the most studied. The latest studies of Tasco® suggest prebiotic potencies at least five times that of the reference prebiotic inulin with additional performance-enhancing benefits in animal rations that rival antibiotic inclusions.

Fatty acid contents and profiles of 16 macroalgae collected from the Irish Coast at two seasons

Abstract: Due to the established health benefits of omega-3 long-chain polyunsaturated fatty acids (LC-PUFA), there is a globally increasing demand for alternative natural resources with appropriate fatty acid profiles. To assess the suitability of macroalgae as a source, 16 species (nine Phaeophyceae, five Rhodophyta and two Chlorophyta) were collected at two seasons (June and November) from the Irish west Coast, and total fatty acid contents and specific profiles were determined. Total fatty acid contents, expressed per percentage of dry weight, ranged from 6.4 % ± 0.3 (Pelvetia canaliculata, Phaeophyceae) to 0.8 % ± 0.2 (Porphyra dioica, Rhodophyta). Most common fatty acids were palmitic (16:0), oleic (OLE, 18:1 n-9), α-linolenic (ALA, 18:3 n-3), arachidonic (ARA, 20:4 n-6) and eicosapentaenoic (EPA, 20:5 n-3) acids. Fatty acid profiles were highly variable between and within algal groups; red and brown seaweeds were generally richer in LC-PUFA (e.g. 20:4 n-6 and 20:5 n-3), while high levels of saturated fatty acids such as palmitic acid (16:0) were observed in green species. Most omega-3 PUFA-rich species investigated had a omega-6/omega-3 fatty acid ratio close to 1, which is favourable for human health. The two seasonal sampling times revealed significant differences in total fatty acid and 20:5 n-3 (EPA) contents, with changes depending on species, thus implying varying suitability as potential target species for EPA production. At both times of the year, Palmaria palmata was identified as most promising species as a source of 20:5 n-3 (EPA) amongst all species investigated, with levels ranging from 0.44 to 0.58 % of dry weight in June and November, respectively.

Economic valuation of kelp forests in northern Chile: values of goods and services of the ecosystem

Abstract: Kelp beds, besides being one of the most important benthic resources in northern Chile, provide a variety of environmental goods and services. In order to evaluate economically the wild kelp populations in northern Chile (26° to 32° S) more than simply their commercial value as a source of raw materials for alginate extraction, we used several economic indicators to holistically assess the value of a group of brown seaweeds of economic importance, Lessonia spp. and Macrocystis pyrifera: (1) market value of biomass as a source of raw material for extraction of alginic acid, (2) market value of associated species of economic importance, (3) value as a source of scientific information, (4) value as a climate buffer (CO2 capture and release of O2), (5) value of associated biodiversity (non-commercial species), (6) value as cultural heritage and (7) value as a reservoir of biodiversity. Existence values of kelp beds which estimate the willingness of citizens to pay and work without payment to preserve the ecosystem were calculated using the contingent valuation technique. The results indicate that kelp beds in northern Chile have a total value of US $540 million. Of this total, kelp fishery accounts for 75 % and associated-species fisheries account for 15 %. In this context, the economic value of Chilean kelp beds is mainly associated with the industry of alginate extraction. By contrast, existence value as a source of scientific information or environmental buffer for CO2 capture or O2 production represents only 9 % of the total value, representing a very low relative importance to society. The economic valuation of coastal resources and marine ecosystems is a complementary tool for decision making and implementation of public policies related to the conservation and sustainable exploitation of renewable resources and their ecosystems.

Microalgae-based agro-industrial wastewater treatment: a preliminary screening of biodegradability

Abstract: The potential of algal–bacterial symbiosis for the removal of carbon, nitrogen and phosphorus from five agro-industrial wastewaters was investigated in enclosed batch biodegradation tests using a mixed microalgae consortium and activated sludge as model microorganisms. The target wastewaters were obtained from potato processing (PW), fish processing (FW), animal feed production (MW), coffee manufacturing (CW) and yeast production (YW). The initial C/N/P ratio of the agro-industrial wastewater was correlated with its biodegradability. Thus, the highest removals of total organic carbon (TOC) and nitrogen were recorded in two fold diluted FW (64 ± 2 % and 85 ± 1 %, respectively), while the maximum P-PO4 3− removal achieved was 89 ± 1 % in undiluted PW. The biodegradable TOC was in most cases the limiting component in the treatment of the wastewaters evaluated. This study confirmed the potential of coupling carbon and nutrient recovery from agro-industrial effluents with the production of a valuable algal–bacterial biomass, despite their poor biodegradability.

Proteomics to reveal metabolic network shifts towards lipid accumulation following nitrogen deprivation in the diatom Phaeodactylum tricornutum

Abstract: The marine diatom Phaeodactylum tricornutum is attracting considerable interest as a candidate for biofuel production due to its fast growth and high lipid content. Nitrogen deficiency can increase the lipid content in certain microalgae species, including P. tricornutum. However, the molecular basis of such changes remains unclear without analyzing metabolism at the proteomic level. We attempted to systematically analyze protein expression level changes of P. tricornutum upon N deprivation. We observed translational level changes that could overall redirect the metabolic network from carbon flux towards lipid accumulation. N deprivation led to an increase in the expression of genes involved in nitrogen assimilation and fatty acid biosynthesis and a concomitant decrease in photosynthesis and lipid catabolism enzymes. These molecular level changes are consistent with the observed physiological changes, e.g., in photosynthesis rate and saturated lipid content. Our results provide information at the proteomic level of the key enzymes involved in carbon flux towards lipid accumulation in P. tricornutum and suggest candidates for genetic manipulation in microalgae breeding for biodiesel production.

Seasonal variation in light utilisation, biomass production and nutrient removal by wastewater microalgae in a full-scale high-rate algal pond

Abstract: There has been renewed interest in the combined use of high-rate algal ponds (HRAP) for wastewater treatment and biofuel production. Successful wastewater treatment requires year-round efficient nutrient removal while high microalgal biomass yields are required to make biofuel production cost-effective. This paper investigates the year-round performance of microalgae in a 5-ha demonstration HRAP system treating primary settled wastewater in Christchurch, New Zealand. Microalgal performance was measured in terms of biomass production, nutrient removal efficiency, light absorption and photosynthetic potential on seasonal timescales. Retention time-corrected microalgal biomass (chlorophyll a) varied seasonally, being lowest in autumn and winter (287 and 364 mg m−3day−1, respectively) and highest in summer (703 mg m−3day−1), while the conversion efficiency of light to biomass was greatest in winter (0.39 mg Chl-a per μmol) and lowest in early summer (0.08 mg Chl-a per μmol). The percentage of ammonium (NH4–N) removed was highest in spring (79 %) and summer (77 %) and lowest in autumn (47 %) and winter (53 %), while the efficiency of NH4–N removal per unit biomass was highest in autumn and summer and lowest in winter and spring. Chlorophyll-specific light absorption per unit biomass decreased as total chlorophyll increased, partially due to the package effect, particularly in summer. The proportional increase in the maximum electron transport rate from winter to summer was significantly lower than the proportional increase in the mean light intensity of the water column. We concluded that microalgal growth and nutrient assimilation was constrained in spring and summer and carbon limitation may be the likely cause.

Organic and inorganic nitrogen utilization by nitrogen-stressed cyanobacteria during bloom conditions

Abstract: Cyanobacterial blooms often occur in lakes that have high phosphorus (P) and low nitrogen (N) concentrations, and the growth rate of the blooms is often constrained by N. For these reasons, many researchers have suggested that regulation of both P and N is required to control eutrophication. However, because N occurs in many bioavailable forms, regulation of a particular form may be beneficial rather than regulation of all N forms. To address how N-stressed cyanobacteria respond to various N inputs, N enrichment experiments (nitrate, ammonium, urea, and alanine) were performed during N-limited cyanobacterial blooms in Maumee and Sandusky Bays of Lake Erie and in Grand Lake St. Marys (GLSM). Bioavailable N (nitrate, urea, and ammonium) concentrations were also determined. Microcystis aeruginosa dominated the Maumee Bay bloom, where the highest growth rates were in response to ammonium additions, and lowest growth rates were in response to nitrate. Urea and the amino acid alanine resulted in intermediate growth rates. Planktothrix agardhii dominated the Sandusky Bay and GLSM blooms, where nitrate, ammonium, and urea addition resulted in similar growth rates. Additions of alanine did not stimulate growth of the Planktothrix blooms. Incubations using stable isotope 15N showed the cyanobacteria had a preference for ammonium, but the other forms were also assimilated in the presence of ammonium. These results show that cyanobacterial blooms will assimilate multiple forms of N to support growth. Thus, if lake managers do decide that N abatement is necessary, then all forms of bioavailable N need to be constrained.

Cultivation of tropical red seaweeds in the BIMP-EAGA region

Abstract: The Brunei–Indonesia–Malaysia–Philippines East Asia Growth Area (BIMP-EAGA) is located within the Coral Triangle, known to have the world’s richest biodiversity in marine flora and fauna. This region lies within the 10° N and 10° S of the Equator where natural populations of both Kappaphycus and Eucheuma grow luxuriantly and abundantly. It is in this same region where commercial cultivation of Kappaphycus and Eucheuma began in the Philippines around the mid-1960s. Commercial farming of Kappaphycus (which was originally called Eucheuma) was successful in the Philippines from the early 1970s, after which the technology was transferred to Indonesia and Malaysia in the late 1970s. No seaweed cultivation has been reported in Brunei. At present, carrageenophytes are cultivated in sub-tropical to tropical countries circumferentially around the globe within the 10° N and S of the Equator. However, their combined production is still low as compared to Indonesia, the Philippines, and Malaysia. Notably, few improvements in farming techniques have been made since its first introduction. Some of the major improvements were the introduction of deep-water farming using hanging long lines, multiple rafts, and spider webs in the Philippines; the use of short and long ‘loops’, instead of plastic ‘tie-tie’ in Indonesia; and mechanization in harvesting and use of solar “greenhouse” drying in Malaysia. Commercial cultivation of tropical red seaweeds in the BIMP-EAGA region is dominated by Kappaphycus and Eucheuma (carrageenophytes) and Gracilaria (agarophytes) and the area became the major region for the production of carageenophytes and agarophytes globally. In particular, Indonesia is a major center for the production of Gracilaria. There is an increasing demand for other agarophytes/carrageenophytes in the international market such as Gelidium spp., Pterocladia spp., Porphyroglossum sp., and Ptilophora sp. for paper and ethanol production in Indonesia and Malaysia, and Halymenia for phycoerythrin pigments in the Philippines currently pursued in an experimental stage. A summary of the present status, problems, sustainability, and challenges for the cultivation of tropical red seaweeds in the BIMP-EAGA region are discussed in this paper.

Biomass and oil content of Chlorella sp., Haematococcus sp., Nannochloris sp. and Scenedesmus sp. under mixotrophic growth conditions in the presence of technical glycerol

Abstract: The growth of algae strains Chlorella sp., Haematococcus sp., Nannochloris sp. and Scenedesmus sp. under mixotrophic conditions in the presence of different concentrations of technical glycerol was investigated with the aim of increasing biomass growth and algae oil content. The highest concentration of lipid obtained in media with 5 g L−1 glycerol for Chlorella sp., Scenedesmus sp., Nannochloris sp. and Haematococcus sp. was 17.77, 22.34, 27.55 and 34.22 % larger than during the autotrophic growth of these species. Increases in triacylglycerols of up to ten times was observed for Scenedesmus sp. under mixotrophic conditions (using 10 g L−1 glycerol), whereas an increase of 2.28 times was found for Haematococcus sp. The content of saturated fatty acids of Scenedesmus, Chlorella, Haematococcus and Nannochloris was 67.11, 34.63, 23.39 and 24.23 %, and the amount of unsaturated fatty acids was 32.9, 65.06, 79.61 and 75.78 % of total fatty acids, respectively. Growth on technical glycerol of these strains with light produced higher biomass concentrations and lipid content compared with autotrophic growth. The fatty acid content of oils from these species suggests their potential use as biodiesel feedstock.

Nutritional and bioactive properties of three edible species of green algae, genus Caulerpa (Caulerpaceae)

Abstract: The green algae genus Caulerpa is coenocytic, and the thallus consists of only one cell with many nuclei. It is widely distributed in the tropical seas. In the Southeast Asian waters, there are at least ten known species. Three species, particularly Caulerpa racemosa var. clavifera f. macrophysa (Kutzing) Weber-van Bosse, C. racemosa var. laetevirens (Montagne) Weber-van Bosse, and Caulerpa lentillifera J. Agardh are widely consumed. The proximate analysis and secondary metabolite composition of these three species were determined to describe their lipid and nutritional values. Glycolipids and phospholipids were the major lipid classes, with significant levels of triacylglycerol. Polyunsaturated fatty acids (PUFA) were the major fatty acids of all the three species. Typical n-3 and n-6 PUFA such as 18:3n-3, 18:4n-3, 20:5n-3, 18;2n-6, and 20:4n-6 were found in significant amount in all these three species. All three species contained a red-pigmented secondary metabolite determined as caulerpin. All three extracts exhibited potent antimicrobial activity against human food pathogenic bacteria and anti-inflammatory activity against the murine macrophage cell line, RAW 264.7.

The interactions between Chlorella vulgaris and algal symbiotic bacteria under photoautotrophic and photoheterotrophic conditions

Abstract: A Chlorella vulgaris ATCC 13482 culture was semi-continuously cultivated for 18 months in a 4-L photobioreactor and formed associated consortia with other symbionts. Three symbiotic bacterial strains were isolated on heterotrophic medium agar plates. Based on 16S rDNA analysis, they were found to show closest similarity to Pseudomonas alcaligenes, Elizabethkingia miricola and Methylobacterium radiotolerans. C. vulgaris was co-cultured with each bacterial strain, and it was found that the symbiotic bacterium Pseudomonas sp. had a growth-promoting effect on C. vulgaris while the other two inhibited algal growth. The interactions between C. vulgaris and Pseudomonas sp. were further investigated under different cultivation conditions. The co-culture resulted in 1.4 times greater algal cell concentration than that of C. vulgaris alone under photoautotrophic condition. In contrast, the algal cell concentration was lower in the co-culture compared with single algal culture when glucose was supplied in the medium (photoheterotrophic). Under both cultivation conditions, the number of Pseudomonas sp. increased at the beginning of experiment, and then decreased. However, the bacterial number decreased to almost zero under photoheterotrophic conditions, while the growth of bacteria went into a stationary phase under photoautotrophic conditions. The chlorophyll content in C. vulgaris cell was higher in co-culture than in single algal culture. Algal cells in photoautotrophic condition showed higher photosynthetic efficiency compared to those in photoheterotrophic condition. Extracellular organic carbon dissolved in the medium continuously increased under photoautotrophic condition. The mutualistic and competing relationships between C. vulgaris and symbiotic bacteria observed in this study could aid our understanding of algae–bacteria interactions in nature as well as broadening its practical applications.

The effect of nutrient concentrations, nutrient ratios and temperature on photosynthesis and nutrient uptake by Ulva prolifera: implications for the explosion in green tides

Abstract: The green-tide macroalga, Ulva prolifera, was tested in the laboratory to determine its nutrient uptake and photosynthesis under different conditions. In the nutrient concentration experiments U. prolifera showed a saturated uptake for nitrate but an escalating uptake in the tested range for phosphorus. Both N/P and NO3 −/NH4 + ratios influenced nutrient uptake significantly (p 0.05) remained unaffected. The maximum N uptake rate (33.9 ± 0.8 μmol g−1 DW h−1) and P uptake rate (11.1 ± 4.7) was detected at N/P ratios of 7.5 and 2.2, respectively. U. prolifera preferred NH4 +-N to NO3 −-N when the NO3 −-N/NH4 +-N ratio was less than 2.2 (p < 0.05). But between ratios of 2.2 and 12.9, the uptake of NO3 −-N surpassed that of NH4 +-N. In the temperature experiments, the highest N uptake rate and [Y(II)] were observed at 20 °C, while the lowest rates were detected at 5 °C. P uptake rates were correlated with increasing temperature.

Biochemical and antiviral activities of enzymatic hydrolysates from different invasive French seaweeds.

Abstract: Proliferations of green, brown and red algae appear in shallow sandy bays in North Brittany (France), and they represent a real economic constraint for the affected communities. In addition to the nuisance for residents and tourist activity, the communities must carry out systematic collection. The collected algae are spread on agricultural land spreading or composted, but these solutions reach their limits rapidly, bringing little added value to the collected algae. Seaweeds are potentially excellent sources of bioactive metabolites that could represent useful leads in the development of new functional ingredients in pharmaceutical and cosmetic industries. The aim of this study was to propose the use of an enzyme-assisted extraction as a tool to improve the extraction efficiency of antiviral compounds from three invasive French seaweeds. We selected the red Solieria chordalis, the green Ulva sp. and the brown Sargassum muticum as models for these experiments. In comparison with water extraction at 50 °C for the same time of treatment, enzymatic hydrolysis increased the yields. The data suggest the potential of enzymatic hydrolysis for producing active fractions in the function of the algal biomass, the behaviour of the cell wall, the selectivity and the action of the enzyme. Enzymatic hydrolysis appeared less effective for polyphenol recovery, but was a promising softer technique for recovering proteins, neutral sugars, uronic acids and sulphate groups. The solvent-free process, higher extraction rate and higher yields, coupled to time-saving and lower cost, make this method economical and sustainable. By using a cell viability assay, all hydrolysate fractions tested were shown to be non-toxic to Vero cells. After 3 days of treatment, no microscopically visible alteration of normal cell morphology was observed even at 500 μg mL−1. S. chordalis extracts have an effective antiviral activity with EC50 between 23.0 and 101.1 μg mL−1 at a multiplicity of infection of 0.001 ID50/cells; 100 % and 98 % cellular protection were obtained for 500 μg mL−1 of hydrolysate extracts carbohydrase C3 and blank, respectively. Other extracts from S. chordalis inhibited viral production less effectively.

The effect of seaweed composite flour on the textural properties of dough and bread

Abstract: Seaweeds as food and seaweed-derived food flavors, colors, and nutrients are attracting considerable commercial attention. In the baking industries, hydrocolloids are of increasing importance as bread making improvers, where their use aims to improve dough handling properties, increase the quality of fresh bread, and extend the shelf life of stored bread. Seaweeds contain a significant amount of soluble polysaccharides and have the potential function as a source of dietary fiber. In this study, red seaweed (Kappaphycus alvarezii) powder was incorporated (2–8 %) with wheat flour and used to produce bread. The effect of seaweed composite flour on dough rheological properties and the quality of bread was investigated using various techniques. Farinograph tests were applied to determine the effect of seaweed powder on the rheological properties of wheat flour dough, while texture profile analysis (TPA) was used to measure the textural properties of dough as well as the final product. The results showed that the additions of seaweed powder (2–8 %) increased the water absorption of the dough. TPA results showed that the addition of seaweed powder decreased stickiness properties. Bread produced with seaweed composite flour showed higher values of firmness.

The potential of seaweed as a source of drugs for use in cancer chemotherapy

Abstract: This review discusses studies on marine macroalgae that have been investigated for their potential as sources of novel anti-cancer drugs The review highlights the very large number of studies of crude, partially purified and purified seaweed extracts, collected from many locations, which have shown potential as sources of potent anti-cancer drugs when tested in vitro and/or in vivo The activity of polysaccharides, polyphenols, proteinaceous molecules, carotenoids, alkaloids, terpenes and others is described here In some reports, mechanistic studies have identified specific inhibitory activity on a number of key cellular processes including apoptosis pathways, telomerase and tumour angiogenesis However, despite the potential shown by these studies, translation to clinically useful preparations is almost non-existent It is hoped this review will serve as a source document and guide for those carrying out research into the potential use of macroalgae as a source of novel anti-cancer agents

Influence of extraction solvent system on the extractability of lipid components from the biomass of Nannochloropsis gaditana

Abstract: Microalgae oils are considered to be promising alternative sources of omega-3 LC-PUFA. The aim of this work was therefore to evaluate different solvent (mixtures), currently accepted for use in the food industry, for the extraction of lipids from Nannochloropsis gaditana, an omega-3 LC-PUFA-rich microalga. Importantly, not only the total lipid yield but also the lipid class, eicosapentaenoic acid, carotenoid, and sterol yield were investigated. It was shown that the highest yield for each of the components was obtained with dichloromethane/ethanol (1:1). All extracts except the one obtained with dichloromethane/ethanol (1:1) were enriched in neutral lipids and depleted in polar lipids, when compared to the total lipid extract (chloroform/methanol 1:1). Hexane/isopropanol (3:2) seems to be the second best option: it has the advantage of performing better at criteria such as toxicity, but has the disadvantage that almost half of the interesting oil cannot be recovered.

Microwave-assisted extraction of the Carrageenan from Hypnea musciformis (Cystocloniaceae, Rhodophyta)

Abstract: Hypnea musciformis (Wulfen in Jacqu.) J. V. Lamour. (Rhodophyta) was investigated for its carrageenan production. Traditionally, the desulfation process for carrageenans has been promoted by an alkaline treatment of up to 3 h by conventional heating during carrageenan extraction. New extraction techniques based on microwave irradiation may accelerate this reaction with the advantages of reduced consumption of solvents, energy, and extraction time, suggesting the feasibility of this method as a “Green” technology. In this study, aqueous- and alkali-treated carrageenans from H. musciformis collected along Quintana Roo coast of Yucatan Peninsula (Mexico) were extracted by conventional method and by microwave-assisted extraction (MAE). Microwave irradiation in closed vessels was used to carry out the alkaline modification. The influence of temperature (85, 95, and 105 °C) and extraction time (10 and 20 min) in MAE was investigated in terms of yield, sulfate, and 3,6-anhydrogalactose contents, and Fourier transformed infrared spectra. Although lower carrageenan yields were obtained during MAE extraction, the κappa/iota hybrid carrageenan obtained by this novel method is comparable to that extracted by conventional technique. At the maximum temperature used for MAE (105 °C), an increase of 3,6-anhydrogalactose as well as an increase of the κappa-proportion was observed indicating that MAE could be an adequate procedure for carrageenan extraction of H. musciformis; however, further extraction parameters should be tested to optimize extraction.

Fatty acid composition and biological activities of Isochrysis galbana T-ISO, Tetraselmis sp. and Scenedesmus sp.: possible application in the pharmaceutical and functional food industries

Abstract: Organic and water extracts of Isochrysis galbana T-ISO (=Tisochrysis lutea), Tetraselmis sp. and Scenedesmus sp. were evaluated for their antioxidant activity, acetylcholinesterase (AChE) inhibition, cytotoxicity against tumour cell lines, and fatty acids and total phenolic content (TPC). I. galbana T-ISO had the highest TPC (3.18 mg GAE g−1) and radical scavenging activity, with an IC50 value of 1.9 mg mL−1 on the acetone extract. The extracts exhibited a higher ability to chelate Fe2+ than Cu2+, and the maximum Fe2+ chelating capacity was observed in the hexane extract of Scenedesmus sp. (IC50=0.73 mg mL−1) and Scenedesmus sp. (IC50 = 0.73 mg mL−1). The highest ability to inhibit AChE was observed in the water and ether extracts of Scenedesmus sp., with IC50 values of 0.11 and 0.15 mg mL−1, respectively, and in the water extract of I. galbana (IC50 = 0.16 mg mL−1). The acetone extract of I. galbana T-ISO significantly reduced the viability of human hepatic carcinoma HepG2 cells (IC50 = 81.3 μg mL−1) as compared to the non-tumour murine stromal S17 cell line, and displayed a selectivity index of 3.1 at the highest concentration tested (125 μg mL−1). All species presented a highly unsaturated fatty acids profile. Results suggest that these microalgae, particularly I. galbana T-ISO, could be a source of biomolecules for the pharmaceutical industry and the production of functional food ingredients and can be considered as an advantageous alternative to several currently produced microalgae.

TLC screening of thraustochytrid strains for squalene production

Abstract: Screenings of thraustochytrids (Labyrinthulomycetes) have been conducted for 176 strains isolated from various sites in the Asian region to investigate what type of species and strains accumulate high levels of squalene. Thin layer chromatography (TLC) screening for squalene production revealed that 38 strains were rated as “+” (high), 29 as “±” (medium), and 109 as “−” (low). Further, high performance liquid chromatography analysis strongly supported the TLC screening results. Besides the 18W-13a strain of Aurantiochytrium sp., which was previously recognized as a squalene-rich strain, several strains produced squalene at approximately 1 g L−1 of culture volume. Squalene production was strongly related to locality, colony color, and phylogenetic clade. Most strains with “+” squalene spots were isolated from Okinawa, a subtropical region of Japan, while the strains with “±” and “−” squalene spots were isolated from wide geographical regions from tropical to subarctic. Approximately half the strains with orange colonies on GTY medium plates produced a high amount of squalene, whereas the other strains with different colors showed less or no squalene spots on TLC. All the squalene-rich strains were assigned to the Aurantiochytrium clade. Overall, our results suggest that (1) the thraustochytrids show tendentious locality in terms of squalene production, (2) a relationship exists between the metabolic synthesis of carotenoid pigments and squalene production, and (3) the Aurantiochytrium clade may have evolved to accumulate squalene.

Cultivation and utilisation of red seaweeds in the Western Indian Ocean (WIO) Region

Abstract: Seaweed farming in the Western Indian Ocean (WIO) Region is carried out in a number of countries, most of them farming Eucheuma denticulatum, Kappaphycus alvarezii and Kappaphycus striatum. These species are farmed mostly in Tanzania with limited production in Madagascar, Mozambique and Kenya; current production (2012) stands at 15,966 t (dry weight) year−1 of Eucheuma and Kappaphycus, valued at US$ 4.2 million with 95 % of this tonnage coming from Tanzania. Other countries in the region have limited or no seaweed production owing to problems of epiphytes, ice ice and markets. The problem of epiphytes coupled with ice ice that WIO countries are facing causes die-off of Kappaphycus which is the preferred species in foreign markets for its thicker gel, kappa carrageenan (vs. the weaker iota carrageenan from Eucheuma). New efforts are put to curb these problems including moving seaweed farms to deeper waters and cultivation trials of other carrageenophytes as well as agar-producing species, agarophytes. Research work has been initiated to evaluate Gracilaria and Hypnea farming and processing in Tanzania, the Republic of Mauritius and Mayotte. Gracilaria farming is at experimental stages as a biofilter of fishpond effluents and as potential species for the production of agar with growth rates of 1.5–1.9 % day−1. Hypnea farming is only being initiated in Mauritius and Mayotte at present. Other innovations including value addition by making various seaweed products and encouraging the consumption of seaweed as food at least in Tanzania and Mauritius are increasing further the importance of the seaweed farming and processing industry in the WIO Region.

Comparison of growth of Tetraselmis in a tubular photobioreactor (Biocoil) and a raceway pond

Abstract: Microalgae cultivation systems can be divided broadly into open ponds and closed photobioreactors. This study investigated the growth and biomass productivity of the halophilic green alga Tetraselmis sp. MUR-233, grown outdoors in paddle wheel-driven open raceway ponds and in a tubular closed photobioreactor (Biocoil) at a salinity of 7 % NaCl (w/v) between mid-March and June 2010 (austral autumn/winter). Volumetric productivity in the Biocoil averaged 67 mg ash-free dry weight (AFDW) L−1 day−1 when the culture was grown without CO2 addition. This productivity was 86 % greater, although less stable, than that achieved in the open raceway pond (36 mg L−1 day−1) grown at the same time in the autumn period. The Tetraselmis culture in the open raceway pond could be maintained in semi-continuous culture for the whole experimental period of 3 months without an additional CO2 supply, whereas in the Biocoil, under the same conditions, reliable semi-continuous culture was only achievable for a period of 38 days. However, stable semi-continuous culture was achieved in the Biocoil by the addition of CO2 at a controlled pH of ~7.5. With CO2 addition, the volumetric biomass productivity in the Biocoil was 85 mg AFDW L−1 day−1 which was 5.5 times higher than the productivity achieved in the open raceway pond (15 mg AFDW L−1 day−1) with CO2 addition and 8 times higher compared to the productivity in the open raceway pond without CO2 addition (11 mg AFDW L−1 day−1), when cultures were grown in winter. The illuminated area productivities highlight an alternative story and showed that the open raceway pond had a three times higher productivity (3,000 mg AFDW m−2 day−1) compared to the Biocoil (850 mg AFDW m−2 day−1). Although significant differences were found between treatments and cultivation systems, the overall average lipid content for Tetraselmis sp. MUR-233 was 50 % in exponential phase during semi-continuous cultivation.

Non-destructive hydrocarbon extraction from Botryococcus braunii BOT-22 (race B)

Abstract: There is worldwide interest in developing algal biofuel. One main reason for the lack of success so far in producing a sustainable transport fuel from microalgae is the high cost of biomass processing, especially dewatering and oil extraction. There is also a significant cost involved in the energy content of the nutrient fertilisers required for biomass production. Non-destructive oil extraction or “milking” from algae biomass has the potential to bypass all of these hurdles. Using a “milking” strategy means that there would be no need for (a) biomass dewatering, (b) breaking cells for oil extraction and (c) addition of nutrients to the culture, resulting in a significant reduction in energy and fertiliser cost involved in production of biofuel from algae. We make use of the natural tendency of Botryococcus to produce external hydrocarbon in the extracellular matrix. In current study, we showed that external hydrocarbon from Botryococcus braunii BOT-22 can be non-destructively extracted using n-heptane (optimum contact time with n-heptane = 20 min). We were able to recover almost the entire de novo-produced external hydrocarbons at 5- and 11-day intervals when the culture was maintained with or without 1 % CO2 addition, respectively. This repeated non-destructive extraction of external hydrocarbon of B. braunii was possible for up to 70 days when 1 % CO2 was supplied to the culture. When CO2 was limited, a 70 % lower external hydrocarbon productivity was achieved using the same process. Although the productivity of external hydrocarbon of 9.33 mg L−1 day−1 of the “milked” culture is low in these un-optimised cultures, it was 1.3 ± 0.2-fold higher compared with that of a conventional semicontinuous culture, showing the potential of this method.

Cultivation of red seaweeds: a Latin American perspective

Abstract: The Latin American seaweed industry plays an important role at a global scale as 17 % of all seaweeds and 37 % of red seaweeds for the phycocolloid industry comes from this region. Increased market demand for algal raw materials has stimulated research and development into new cultivation technologies, particularly in those countries with economically important seaweed industries such as Argentina, Brazil, Chile, Mexico, and Peru. The marine area of Latin America includes almost 59,591 km2 of coastline ranging in latitude from 30oN to 55oS and encompasses four different oceanic domains: Temperate Northern Pacific, Tropical Eastern Pacific, Temperate South America, and Tropical Atlantic. Commercial cultivation of red seaweed in Latin America has been basically centered in the production of Gracilaria chilensis in Chile. Attempts have been made to establish seaweed commercial cultivation in other countries, going from experimental research-oriented studies to pilot community/enterprise based cultivation trials. Some genera such as Kappaphycus and Eucheuma have been studied in Brazil and Mexico, Gracilaria species in Argentina and Brazil, Gracilariopsis in Peru and Venezuela, and Chondracanthus chamissoi in Peru and Chile. In this short review, we address the Latin America perspective on the status and future progress for the cultivation of red seaweeds and their sustainable commercial development, and discuss on the main common problems. Particular emphasis is given to the needs for comprehensive knowledge necessary for the management and cultivation of some of the most valuable red seaweed resources in Latin America.

Quantitative analysis of extracted phycobilin pigments in cyanobacteria-an assessment of spectrophotometric and spectrofluorometric methods.

Abstract: Phycobilins are an important group of pigments that through complementary chromatic adaptation optimize the light-harvesting process in phytoplankton cells, exhibiting great potential as cyanobacteria species biomarkers. In their extracted form, concentrations of these water-soluble molecules are not easily determined using the chromatographic methods well suited to solvent-soluble pigments. Insights regarding the quantitative spectroscopic analysis of extracted phycobilins also remain limited. Here, we present an in-depth study of two methods that utilize the spectral properties of phycobilins in aqueous extracts. The technical work was carried out using high-purity standards of phycocyanin, phycoerythrin, and allophycocyanin. Calibration parameters for the spectrofluorometer and spectrophotometer were established. This analysis indicated the possibility of detecting pigments in concentrations ranging from 0.001 to 10 μg cm−3. Fluorescence data revealed a reproducibility of 95 %. The differences in detection limits between the two methods enable the presence of phycobilins to be investigated and their amounts to be monitored from oligotrophic to eutrophic aquatic environments.