Separation and purification of two minor typical diarrhetic shellfish poisoning toxins from harmful marine microalgae via combined liquid chromatography with mass spectrometric detection

A novel method was developed for the purification of two typical diarrhetic shellfish poisoning toxins from toxin‐producing marine microalgae using macroporous resin, high‐speed countercurrent chromatography–mass spectrometry, and semipreparative high‐performance liquid chromatography–mass spectrometry. Analytical high‐performance liquid chromatography–mass spectrometry was used for identification and purity analysis of okadaic acid and dinophysistoxin‐1 because they exhibit no visible or ultraviolet absorption. First, four kinds of macroporous resins were investigated, and HP‐20 macroporous resin was selected for the preenrichment and cleanup of the two target toxins. Second, the resin‐purified sample was further purified using high‐speed countercurrent chromatography coupled with a mass spectrometer. The purities of the obtained okadaic acid and dinophysistoxin‐1 were 89.0 and 83.0%, respectively, as determined through analytical high‐performance liquid chromatography–mass spectrometry. Finally, further purification was carried out using semipreparative high‐performance liquid chromatography with mass spectrometry, and the purities of the final okadaic acid and dinophysistoxin‐1 products were both over 98.0% based on the analytical high‐performance liquid chromatography–mass spectrometry chromatograms and fraction spectra. This work demonstrates that the proposed purification process is a powerful method for the preparation of high‐purity okadaic acid and dinophysistoxin‐1 from toxin‐producing marine microalgae. Moreover, it is particularly important for the purification and preparation of minor toxins that exhibit no visible or ultraviolet absorption from harmful marine algae.     

Mass cultivation of various algal species and their evaluation as a potential candidate for lipid production

Microalgae have been proposed as a promising source for biodiesel production. Focusing on algal strains for biodiesel production, efforts should be made to search new strains. Experiments were carried out to investigate the effects of growth parameters (nutrients, pH, light, aeration and temperature) and the oil percentage of eight algal strains (Chlorella sp., Cladophora sp., Hydrodictylium sp., Oedogonium sp., Oscillatoria sp., Spirogyra sp., Stigeocolonium sp., Ulothrix sp.). Results show that 6.5–7.5 is the optimum pH for the growth of all algal species. Temperature showed a greater variation (25°40°C). Ulothrix sp. gave more biomass productivity and is the most suitable strain for biodiesel production due to higher oil percentage (62%). Least biomass production was observed for Stigeocolonium sp. and least oil content was obtained from Hydrodictylium sp. It was observed that among these eight algal strains for biodiesel production, Ulothrix and Chlorella are the most promising algae species.     

微藻脂肪合成与代谢调控

随着能源与环境问题的日益严峻,利用微藻生产生物柴油已经成为研究者们关注的焦点。与传统油料作物相比,微藻具有生长速度快、含油量高、不占用耕地等优势,是极具潜力的生物燃料生产原料。虽然许多微藻在压力条件下会在细胞内积累脂肪,特别是中性脂肪三酰甘油(TAG),它是生产生物柴油的主要原料,但目前对于微藻脂肪的合成和代谢调控还了解的很少。为了更好地理解和操纵微藻脂肪代谢以增强脂肪积累,本文综述了微藻脂肪合成与代谢调控的研究进展,包括TAG生物合成途径,提高脂肪积累的生化调控和基因工程策略,阐述了营养控制对脂肪积累的影响,总结了增强脂肪酸合成途径、增强Kennedy途径、调控TAG旁路途经、抑制脂肪合成的竞争途径、抑制脂肪的分解代谢等5种基因工程策略,同时也对微藻脂肪代谢研究的发展进行了展望。     

缢蛏稚贝优质微藻饵料的筛选

为了筛选缢蛏稚贝的合适饵料及其最优组合投饵方式,比较了8种常见饵料微藻单种投喂和混合投喂对缢蛏稚贝生长的影响．结果显示：单种投喂时,角毛藻和金藻饵料效果最佳,云微藻和XSWG仅次于角毛藻和金藻,对于规格较大的缢蛏稚贝扁藻饵料效果较佳,而对于规格较小的缢蛏稚贝其饵料效果并不太好,这5种微藻都可以作为缢蛏稚贝培育过程中的优良饵料选择：微绿球藻、巴夫藻饵料效果较差,不是缢蛏的良好饵料;而A5不仅对缢蛏稚贝没有饵料效果还具有一定的毒害作用．选择优良饵料微藻进行混合投喂,其效果要优于单种投喂;混合投喂时,一些单种投喂饵料效果不佳的微藻品种可以作为优质饵料不足时的补充;对缢蛏稚贝有毒害作用的微藻品种绝对不能作为混合投喂时的饵料选择．     

微藻高油脂化基因工程研究策略

石化能源危机与全球气候变化已成为人类的两大重要难题。生物柴油作为可替代普通柴油的环境友好且可再生的能源受到普遍关注。相比植物油和动物脂肪生产,藻类油脂产率高且容易培养,被认为是未来生物柴油发展的重要原料之一。通过转基因技术强化油脂代谢途径,提高富油微藻含油量,已经成为新的研究热点。已有植物研究表明,增强甘油酯酰基转移酶表达,可以提高Kennedy途径代谢中间体通量,从而增加甘油三酯(TAG)的积累。本文综述了微藻油脂代谢途径的国内外研究现状和提高油脂积累的代谢调控策略;详细阐述了基于植物油脂合成强化的成功经验,通过增强微藻Kennedy途径对提高TAG生物合成的重要作用;讨论了当前转基因微藻的遗传转化方法及其需要解决的关键性科学技术问题;分析了基因工程技术调控微藻脂类代谢途径生产高油脂的可能性,并对该研究的发展进行了展望。     

凝胶改性基底微藻细胞黏附特性及热力学分析

为强化微藻生物膜成膜过程中藻细胞与基底黏附,同时解决藻细胞残留造成的基底重复利用性差的问题,用聚N-异丙基丙烯酰胺(PNIPAAm)温缩型凝胶修饰基底.傅里叶红外光谱分析改性表面化学特性;结合微藻培养温度给出适宜藻细胞黏附的基底浸润特性;通过构建热力学模型,明晰温度对藻细胞与温缩型凝胶改性基底界面作用自由能的影响规律,...     

Monitoring of Spirulina Flakes and Powders from Italian Companies

Microalgae and microalgae-derived compounds have great potential as supplements in the human diet and as a source of bioactive products with health benefits. Spirulina (Arthrospira platensis (Nordstedt) Gomont, or Spirulina platensis) belongs to the class of cyanobacteria and has been studied for its numerous health benefits, which include anti-inflammatory properties, among others. This work was aimed at comparing some spirulina products available on the Italian market. The commercial products here analyzed consisted of spirulina cultivated and processed with different approaches. Single-component spirulina products in powder and flake form, free of any type of excipient produced from four different companies operating in the sector, have been analyzed. The macro- and micromorphological examination, and the content of pigments, phycobiliproteins, phenols, and proteins have shown differences regarding the morphology and chemical composition, especially for those classes of particularly unstable compounds such as chlorophylls and carotenoids, suggesting a great influence of both culture conditions and processing methods.     

Soluble Extracellular Polymeric Substances Produced by Parachlorella kessleri and Chlorella vulgaris: Biochemical Characterization and Assessment of Their Cadmium and Lead Sorption Abilities

In the present study, the potential of lead and cadmium removal by the extracellular polymeric substances (EPS) produced from Parachlorella kessleri and Chlorella vulgaris were investigated. Carbohydrates were the dominant components of EPS from both analyzed species. The contents of reducing sugars, uronic acids, and amino acids were higher in EPS synthesized by C. vulgaris than in EPS from P. kessleri. The analysis of the monosaccharide composition showed the presence of rhamnose, mannose and galactose in the EPS obtained from both species. The ICP-OES (inductively coupled plasma optical emission spectrometry) analyses demonstrated that C. vulgaris EPS showed higher sorption capacity in comparison to P. kessleri EPS. The sorption capacity of C. vulgaris EPS increased with the increase in the amount of metal ions. P. kessleri EPS had a maximum sorption capacity in the presence of 100 mg/L of metal ions. The FTIR analysis demonstrated that the carboxyl, hydroxyl, and carbonyl groups of EPS play a key role in the interactions with metal ions. The present study showed C. vulgaris EPS can be used as a biosorbent in bioremediation processes due to its biochemical composition, the presence of significant amounts of negatively charged uronic acids, and higher sorption capacity.     

Metabolic and Proteomic Analysis of Chlorella sorokiniana,Chloroidium saccharofilum,and Chlorella vulgaris Cells Cultured in Autotrophic,Photoheterotrophic, and Mixotrophic Cultivation Modes

Chlorella is one of the most well-known microalgal genera, currently comprising approximately a hundred species of single-celled green algae according to the AlgaeBase. Strains of the genus Chlorella have the ability to metabolize both inorganic and organic carbon sources in various trophic modes and synthesize valuable metabolites that are widely used in many industries. The aim of this work was to investigate the impact of three trophic modes on the growth parameters, productivities of individual cell components, and biochemical composition of Chlorella sorokiniana, Chloroidium saccharofilum, and Chlorella vulgaris cells with special consideration of protein profiles detected by SDS-PAGE gel electrophoresis and two-dimensional gel electrophoresis with MALDI-TOF/TOF MS. Mixotrophic conditions with the use of an agro-industrial by-product stimulated the growth of all Chlorella species, which was confirmed by the highest specific growth rates and the shortest biomass doubling times. The mixotrophic cultivation of all Chlorella species yielded a high amount of protein-rich biomass with reduced contents of chlorophyll a, chlorophyll b, carotenoids, and carbohydrates. Additionally, this work provides the first information about the proteome of Chloroidium saccharofilum, Chlorella sorokiniana, and Chlorella vulgaris cells cultured in molasses supplementation conditions. The proteomic analysis of the three Chlorella species growing photoheterotrophically and mixotrophically showed increased accumulation of proteins involved in the cell energy metabolism and carbon uptake, photosynthesis process, and protein synthesis, as well as proteins involved in intracellular movements and chaperone proteins.     

Accumulation of Arsenic by Rhaphydophyceae Chattonella antiqua (Hada) Ono

Rhaphydophyceae Chattonella antiqua (Hada) Ono was grown in seawater containing an arsenic concentration up to 50 mg dm⁻³, and survived even at 200 mg dm⁻³. The arsenic content increased with an increase of the surrounding arsenic, iron and manganese concentrations. However, arsenic accumulation was unaffected by phosphorus concentration. Also, arsenic content in C. antiqua decreased at a selenium concentration of up 20 mg dm⁻³, and was reduced by the addition of antimony. In the living cells, about 52% of the arsenic which accumulated in each cell was found in the intracellular fraction, 27% in the lipid fraction, and 21% in the cell wall fraction.