Bioactivity and Applications of Sulphated Polysaccharides from Marine Microalgae

Marine microalgae have been used for a long time as food for humans, such as Arthrospira (formerly, Spirulina), and for animals in aquaculture. The biomass of these microalgae and the compounds they produce have been shown to possess several biological applications with numerous health benefits. The present review puts up-to-date the research on the biological activities and applications of polysaccharides, active biocompounds synthesized by marine unicellular algae, which are, most of the times, released into the surrounding medium (exo- or extracellular polysaccharides, EPS). It goes through the most studied activities of sulphated polysaccharides (sPS) or their derivatives, but also highlights lesser known applications as hypolipidaemic or hypoglycaemic, or as biolubricant agents and drag-reducers. Therefore, the great potentials of sPS from marine microalgae to be used as nutraceuticals, therapeutic agents, cosmetics, or in other areas, such as engineering, are approached in this review.     

Plastids of Marine Phytoplankton Produce Bioactive Pigments and Lipids

Phytoplankton is acknowledged to be a very diverse source of bioactive molecules. These compounds play physiological roles that allow cells to deal with changes of the environmental constrains. For example, the diversity of light harvesting pigments allows efficient photosynthesis at different depths in the seawater column. Identically, lipid composition of cell membranes can vary according to environmental factors. This, together with the heterogenous evolutionary origin of taxa, makes the chemical diversity of phytoplankton compounds much larger than in terrestrial plants. This contribution is dedicated to pigments and lipids synthesized within or from plastids/photosynthetic membranes. It starts with a short review of cyanobacteria and microalgae phylogeny. Then the bioactivity of pigments and lipids (anti-oxidant, anti-inflammatory, anti-mutagenic, anti-cancer, anti-obesity, anti-allergic activities, and cardio- neuro-, hepato- and photoprotective effects), alone or in combination, is detailed. To increase the cellular production of bioactive compounds, specific culture conditions may be applied (e.g., high light intensity, nitrogen starvation). Regardless of the progress made in blue biotechnologies, the production of bioactive compounds is still limited. However, some examples of large scale production are given, and perspectives are suggested in the final section.     

Microalgae n-3 PUFAs Production and Use in Food and Feed Industries

N-3 polyunsaturated fatty acids (n-3 PUFAs), and especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential compounds for human health. They have been proven to act positively on a panel of diseases and have interesting anti-oxidative, anti-inflammatory or anti-cancer properties. For these reasons, they are receiving more and more attention in recent years, especially future food or feed development. EPA and DHA come mainly from marine sources like fish or seaweed. Unfortunately, due to global warming, these compounds are becoming scarce for humans because of overfishing and stock reduction. Although increasing in recent years, aquaculture appears insufficient to meet the increasing requirements of these healthy molecules for humans. One alternative resides in the cultivation of microalgae, the initial producers of EPA and DHA. They are also rich in biochemicals with interesting properties. After defining macro and microalgae, this review synthesizes the current knowledge on n-3 PUFAs regarding health benefits and the challenges surrounding their supply within the environmental context. Microalgae n-3 PUFA production is examined and its synthesis pathways are discussed. Finally, the use of EPA and DHA in food and feed is investigated. This work aims to define better the issues surrounding n-3 PUFA production and supply and the potential of microalgae as a sustainable source of compounds to enhance the food and feed of the future.     

不同微藻处理猪场废水的净化效果研究

旨在研究普通小球藻(Chlorella vulgaris)、雨生红球藻(Haematococcus pluvislis)、斜生栅藻(Scenedesmus obliquus)、莱茵衣藻(Chlamydo-monas reinhardti)4种单一微藻以及不同比例混合微藻对猪场废水的化学需氧量(COD)、总氮(TN)、氨...     

投喂螺旋藻、雨生红球藻对螺蛳体内类胡萝卜素积累效果的研究

在6个62 cm×78 cm×50 cm的水箱中每箱投放5 kg规格为(2.69±0.21)g的螺蛳。选取螺旋藻(Spiruli-na)、雨生红球藻(Haematococcus pluvialis)两种富含类胡萝卜素的微藻,分别以每箱每天12 g、10 g的量投喂,并采用水循环和充气的方式维持藻粉在水中均匀分布。于投喂前及投喂后4、8、12天取螺蛳200 g左右,采用分光光度法测定类胡萝卜素含量。结果显示:投喂螺旋藻的螺蛳经过8 d喂养体内类胡萝卜素含量从42.5μg/g提高到69.1μg/g,并不再显著提高。投喂雨生红球藻的螺蛳在4 d后类胡萝卜素含量已达213.3μg/g,并进一步缓慢提高。该结果表明螺蛳适宜作为向中华绒螯蟹传递类胡萝卜素的中间载体。     

Dietary supplementation with the microalgae Parietochloris incisa increases survival and stress resistance in guppy (Poecilia reticulata) fry

Dietary enrichments with the arachidonic acid (ARA)‐rich microalga, Parietochloris incisa, on the survival of guppy (Poecilia reticulata) fry were examined. Diets were applied via Artemia enrichment to fish from two commercial farms for 34 and 36 days of experimental period (trials 1 and 2, respectively). In trial 1, Artemia nauplii were enriched with dry biomass of whole algal cells at 0 (control), 0.1, 0.2 and 0.4 mg mL^?1. Fry fed with Artemia enriched with 0.4 mg mL^?1 demonstrated the lowest mortality rates (24% and 1% in farms 1 and 2, respectively) compared with controls (36% and 13% in farms 1 and 2, respectively). In trial 2, fry were fed with Artemia, enriched with whole algal cells (0.4 mg ml^?1), algal hexane extract (HE; containing primarily ARA‐rich triacylglycerols and β‐carotene; 0.19 mg ml^?1) or the extraction residue (0.28 mg ml^?1). Acute stress (5 min air exposure) was applied after 18 days. The lowest mortality was recorded in the whole alga‐fed group (av. 26% and 2.6% in farms 1 and 2, respectively), with a slightly, but not significantly higher mortality in the HE‐fed group (av. 29% and 6.2% in farms 1 and 2, respectively). Elevated lysozyme was associated with the reduced mortality. Overall, the use of P. incisa as a dietary supplement for guppy fry during their first month of life enhanced their survival and stress resistance.     

The effect of seaweed extracts,as a supplement or alternative culture medium,on the growth rate and biochemical composition of the microalga,Isochrysis galbana (Park 1949)

Aqueous extracts of green [Ulva lactuca Linnaeus and Enteromorpha intestinalis (Linnaeus) Nees] and red [Gracilaria corticata (J. Agardh) J. Agardh] seaweeds from the Persian Gulf of Iran were examined for their potential usefulness as components of microalga Isochrysis galbana culture medium against conventional f/2 medium. Isochrysis galbana was successfully cultured using the tested seaweed extracts (SWE) and exhibited higher or similar cell density and biomass when SWE were used as a supplement or an alternative medium respectively. When the SWE were used as an alternative medium, microalgal protein, lipid and ash content were similar but carbohydrate increased compared with control. Total saturated fatty acids decreased with a corresponding increase in total mono‐ and polyunsaturated fatty acids following supplementation of f/2 medium with SWE. Eicosapentaenoic acid (EPA) was not affected by SWE treatments but docosahexaenoic acid (DHA) tended to decrease, except for I. galbana cultured with U. lactuca extract. With the exception of potassium, SWE did not significantly impact the mineral content of cultured I. galbana. The study points to the potential usefulness of specific SWE in the production of microalgae as a food source in aquaculture.     

小球藻鉴定基因的筛选及高产油微藻的分子鉴定

[目的]选择合适的小球藻种属鉴定基因,对高产油微藻进行分子鉴定。[方法]从分子鉴定常用的4条基因[核基因组rDNA的18S rRNA gene、内转录间隔区（ITS）、内转录间隔区2（ITS-2）和叶绿体rbcL基因]中筛选出最为适用的小球藻鉴定基因,并对从自然水体中分离筛选出的5株油脂含量在30%以上的小球藻（Chlorellasp.）进行了分类鉴定。[结果]ITS序列变异程度高,片段长度短,序列长度在种间变异较大,而在小球藻种内高度保守,且种间距离（0.439 6±0.135 9）远大于种内距离（0.045 7±0.084 3）,适用于小球藻属内种的鉴定。应用ITS序列分别将5株高产油藻鉴定为1株C.vulgaris、2株C.sorokiniana藻和2株Chlorella sp.。[结论]为建立藻类的鉴定基因库提供了参考。     

Growth and fatty acid composition of juvenile Cerastoderma edule (L.) fed live microalgae diets with different fatty acid profiles

The importance of dietary 20:5n‐3 (EPA), 22:6n‐3 (DHA) and 20:4n‐6 (ARA) for growth, survival and fatty acid composition of juvenile cockles (Cerastoderma edule) was investigated. Cockles of 6.24 ± 0.04 mm and 66.14 ± 0.34 mg (live weight) were distributed into three treatments where live microalgae diets were fed constantly below the pseudofaeces production threshold, for three weeks. Diets had distinct fatty acid profiles: high EPA (53% Chaetoceros muelleri + 47% Pyramimonas parkeae), no DHA (47% Brachiomonas submarina + 53% Tetraselmis suecica) and low ARA concentrations (73% P. parkeae + 27% Phaeodactylum tricornutum). Growth was positively affected by high EPA and low ARA diets, whereas no significant growth was observed for the no DHA diet. High mortality of cockles fed no DHA diet raises questions about its suitability for cockles. In balanced diets with EPA and DHA, lower concentrations of ARA do not limit growth. The impact of dietary fatty acids was evident in the fatty acids of neutral and polar lipids of cockles. In polar lipids of all cockles, there was a decrease in EPA, in contrast to an increase in DHA. The combination of EPA and DHA in a live microalgae diet was beneficial for the growth and survival of juvenile cockles.     

能源微藻——葡萄藻生物学特性的研究进展

简要概述了葡萄藻的生物学特性、下游回收处理技术、基因工程等方面的研究进展。