13种饵料微藻的脂肪酸组成特点及在河蟹育苗中的应用

1996～1999年间对我国13种习见海、淡水微藻及部分单克隆藻株的高度不饱和脂肪酸(PUFA)组成进行分析.结果表明,在各自适宜培养条件下获得的13种藻类细胞中,硅藻门的三角褐指藻(Phaeodactylum tricornutum)、中肋骨条藻(Skeletonema costatum)、新月菱形藻(Nitzschia closterium)、牟氏角毛藻(Chaetoceros muelleri)和金藻门的绿色巴夫藻(Pavlova viridis)具有较高的EPA含量,占脂肪酸总量的比例分别为19.13%～28.00%、24.62%、27.80%、21.45%和26.65%;而13种藻类细胞中DHA的含量普遍较低,只有绿色巴夫藻、球等鞭金藻(Isochrysis galbana)和等鞭金藻(Isochrysis sp.)存在有意义的DHA含量.蓝藻门的钝顿螺旋藻(Spirulina platensis)、绿藻门的亚心形扁藻(Platymonas subcordiformis)、盐藻(Dunaliella salina)、海水小球藻(Chlorella sp)、淡水蛋白核小球藻(Chlorella pyrenoidosa)和淡水斜生栅藻(Scenedesmus obliquus)没有或仅有很小比例的EPA和DHA.利用高EPA藻种三角褐指藻和DHA含量较高的球等鞭金藻饲育河蟹第一期(ZI)和第二期蚤状幼体(Z2),Z1至Z2的变态率及大眼幼体(M)育成率均明显高于海水小球藻、螺旋藻和鸡蛋黄饲育的对照组.     

海洋微藻富集微量元素研究进展

论述了微量元素对人体的重要作用,以及目前海洋微藻生物富集硒、铬、锌等的研究现状,同时探讨了微藻富集微量元素的前景。     

Information fusion via constrained principal component regression for robust quantification with incomplete calibrations

Incomplete calibrations are encountered in many applications and hamper chemometric data analyses. Such situations arise when target analytes are embedded in a chemically complex matrix from which calibration concentrations cannot be determined with reasonable efforts. In other cases, the samples’ chemical composition may fluctuate in an unpredictable way and thus cannot be comprehensively covered by calibration samples. The reason for calibration model to fail is the regression principle itself which seeks to explain measured data optimally in terms of the (potentially incomplete) calibration model but does not consider chemical meaningfulness.     

Identification of microalgae by hyperspectral microscopic imaging system

Harmful algal blooms can lead to serious environment problems, and thus monitoring and classifying microalgae have received increasing attention. Microcystis aeruginosa, Chlorella pyrenoidosa, and Nannochloris oculata all are small in size and have a similar morphology, which lead to discriminant difficulties using a traditional optical microscope. In this experiment, an independently developed hyperspectral microscopic imaging system was used to obtain the hyperspectral images of microalgae samples, and a hyperspectral dataset was developed through pretreated steps. Then the Fisher algorithm was employed to identify the species of the microalgae, and its sensitivity and specificity were found to be high. The result demonstrated that this method can classify the microalgae in a quick and convenient manner; in addition, the quantity and spatial information of the samples can be acquired.     

鱼毒性藻类及其溶血活性的三维荧光光谱识别研究

利用小波分析和Fisher判别等方法,研究了典型鱼毒性藻类米氏凯伦藻(karenia mikimotoi)、海洋卡盾藻(chattonella marina)及卵圆卡盾藻(chattonella ovata)在不同铁浓度培养条件下各生长期的溶血毒素与三维荧光特征光谱的关系。通过Coif2小波分析发现,鱼毒性藻类与非鱼毒性藻类的荧光特征谱差异主要集中在第1～10个数据点(波长λ_em=650～680 nm)和35～47个数据点(波长λ_em=725～750 nm;λ_ex=400～425 nm)的荧光强度变化。利用该波段的藻类荧光强度及其对应的溶血活性值进行Fisher判别函数分析,对鱼毒性藻类的正确判别率为91.7%,非鱼毒性藻类的正确判别率高达100%,对具中等溶血活性(≥10 HU, <20 HU)藻类的正确判别率为70%,而对低活性(<10 HU)和高活性(≥20 HU)藻类的正确判别率均达80%以上。     

Effects of various elements on arsenic accumulation of the alga Dunaliella salina

The effect of 23 various elements (nitrogen, manganese, magnesium, molybdenum, zinc, selenium, gallium, nickel, cobalt, lithium, strontium, vanadium, tin, antimony, bismuth, cadmium, chromium, lead, iron, silver, copper, potassium and calcium) in water on growth and arsenic accumulation in Dunaliella saline was investigated. The order of growth inhibition of D. salina by these elements was Ag>Cd>Co>Ni>Cu>Zn>Fe>Sb>Ga>Cr>Bi>Sr>Mn>Sn>Se>Pb>V>Ca, Mg, Mo, K, Li. Arsenic accumulation in D. salina was unaffected by an increase in calcium and chromium. Also, the arsenic content in D. salina decreased at a potassium concentration of 100 mg dm^?3, and was also reduced by the addition of cadmium and nitrogen; however, it was increased by the addition of lithium at 100 mg dm^?3, tin, gallium, bismuth, strontium, vanadium, iron and manganese at 10 mg md^?3, lead, antimony, zinc, copper cobalt and nickel at 1 mg dm^?3, selenium at 0.1 mg dm^?3, and silver at 0.005 mg dm^?3, respectively. These results imply that arsenic accumulation by D. salina depends upon biological activity and physical adsorption.     

Biosorption of Co(II), Cr(III), Cd(II), and Pb(II) Ions from Aqueous Solution Using Nonliving Neochloris Pseudoalveolaris Deason & Bold: Equilibrium,Thermodynamic, and Kinetic Study

In this study, biosorption of cobalt(II), chromium(III), cadmium(II), and lead(II) ions from aqueous solution was studied using the algae nonliving biomass (Neochloris pseudoalveolaris, Np) as natural and biological sorbents. The effect of pH, contact time, temperature, and metal concentration on the adsorption capacity of metal ions was investigated. The maximum adsorption capacities for Co(II), Cr(II), Cd(II), and Pb(II) were found to be 20.1, 9.73, 51.4 and 96.2 mg/g at the optimum conditions, respectively. The experiments showed that when pH increased, an increase in the adsorption capacity of the biomass was observed too. The kinetic results of adsorption obeyed a pseudo second-order model. Freundlich and Langmuir isotherm models were applied to experimental equilibrium data of metal ions adsorption and the value of R _L for Pb(II), Cb,(II), Co(II), and Cr(III) was found to be 0.376, 0271, 0872, and 096, respectively. The thermodynamic parameters related to the adsorption process such as E _a , ΔG ⁰, ΔH ⁰, and ΔS ⁰ were calculated. ΔH ⁰ values (positive) showed that the adsorption mechanism was endothermic. Weber-Morris and Urano-Tachikawa diffusion models were also applied to experimental equilibrium data. The algae biomass was effectively used as a sorbent for the removal of metal ions from aqueous solutions.     

Recovering Microalgal Bioresources: A Review of Cell Disruption Methods and Extraction Technologies

Microalgae have evolved into a promising sustainable source of a wide range of compounds, including protein, carbohydrates, biomass, vitamins, animal feed, and cosmetic products. The process of extraction of intracellular composites in the microalgae industry is largely determined by the microalgal species, cultivation methods, cell wall disruption techniques, and extraction strategies. Various techniques have been applied to disrupt the cell wall and recover the intracellular molecules from microalgae, including non-mechanical, mechanical, and combined methods. A comprehensive understanding of the cell disruption processes in each method is essential to improve the efficiency of current technologies and further development of new methods in this field. In this review, an overview of microalgal cell disruption techniques and an analysis of their performance and challenges are provided. A number of studies on cell disruption and microalgae extraction are examined in order to highlight the key challenges facing the field of microalgae and their future prospects. In addition, the amount of product recovery for each species of microalgae and the important parameters for each technique are discussed. Finally, pulsed electric field (PEF)-assisted treatments, which are becoming an attractive option due to their simplicity and effectiveness in extracting microalgae compounds, are discussed in detail.     

Fatty Acid Composition and Cytotoxic Activity of Lipid Extracts from Nannochloropsis gaditana Produced by Green Technologies

Microalgae are alternatives and sustainable sources of omega-3 long chain-polyunsaturated fatty acids (LC-PUFA). However, the eco-friendly extraction of these bioactives remains unexplored. In this work, the use of enzyme-based methods in combination with ultrasounds was evaluated as green approaches to extract the omega-3 lipids from Nannochloropsis gaditana. Three commercial enzymatic solutions (Viscozyme^® L, Celluclast^® 1.5 L, and Saczyme^®) were investigated, and results were compared with the traditional Folch method. A promising extraction approach was developed by using Saczyme^®, achieving a lipid yield of 25.7% ± 0.5, comparable to the traditional method (27.3% ± 0.7) (p > 0.05). Similar omega-3 content was found by GC–MS analysis for both lipid extracts (30.2% ± 2.4 and 29.3% ± 0.8 for the green and the traditional method, respectively), showing that the green approaches did not affect the fatty acid profile. Moreover, the cytotoxic activity of produced lipids was assessed by comparing human colon cancer cells (HCT-116) and epithelial nontumorigenic immortalized cells (HCEC-1CT). Results suggest that the lipid extracts have a selective effect, reducing the viability of the colon carcinoma cells but not the nontumorigenic cells. Thus, this study provides new eco-innovative approaches for extracting the omega-3 LC-PUFA from microalgae with promising biological properties.     

Catalytic Deoxygenation of Hydrolyzed Oil of Chlorella Vulgaris Microalgae over Lanthanum-Embedded HZSM-5 Zeolite Catalyst to Produce Bio-Fuels

Microalgae is one of the most important sources of green hydrocarbons because it contains a high percentage of lipids and is likely to reduce reliance on fossil fuels. Several zeolite-based catalysts have a short lifetime due to coke-formation deactivation. In this study, a lanthanum-modified HZSM-5 zeolite catalyst for the conversion of crude oil into non-oxygenated compounds (hydrocarbons) and oxygenated compounds has been investigated. The crude oil of Chlorella Vulgaris microalgae was extracted using Soxhlet and converted into hydrolyzed oil (HO) through a transesterification reaction. The experiments were conducted in a batch reactor (300 °C, 1000 rpm, 7 bar of N₂, the catalyst to the algal HO ratio of 15% (wt.%) and 6 h). The results were organized into three groups: product yield, chemical composition, and carbon number distribution. The liquid products were investigated, including their elemental composition, higher heating value (HHV), atomic ratios of O/C and H/C, and degree of deoxygenation (DOD%). The loading of lanthanum into HZSM-5 zeolite with different loading percentages enhanced the acid sites needed for the algal HO conversion. Among all the synthesized catalysts, 10%La/HZSM-5 produced the highest conversion of the algal HO, the highest yield of hydrocarbons, the highest HHV, and the highest DOD%; those were 100%, 36.88%, 34.16 MJ/kg, and 56.11%, respectively. The enhanced catalytic conversion was due to the presence of lanthanum, which alters the active sites for the desired reactions of catalytic deoxygenation. The main effect of the modification of the parent HZSM-5 zeolite with lanthanum led to adjusting the acidic sites needed to increase the conversion (%) of the algal HO in the catalytic deoxygenation process and thus increase the hydrocarbon yield (%), which in turn led to an increase in the HHV and DOD%. The proposed La-based zeolite composite is promising for different energy applications due to its unique benefits compared to other expensive and less-stable catalysts.