共查询到20条相似文献，搜索用时 46 毫秒
1.
Marine organisms constitute unlimited resource of bioactive substances due to their high biodiversity and represent a valuable source of new compounds. This study optimized the alkali-extraction conditions and antioxidant activities of soluble polysaccharides from the body wall of Sipunculus nudus. The effects of solid-liquid ratio, extraction duration, extraction temperature, and alkali concentration on the yield of S. nudus polysaccharides (SNP) were examined, according to which the optimal combination of extraction parameters was obtained by an orthogonal test. The relative influencing importance of different extraction parameters on the yield of SNP followed the order as solid-liquid ratio > extraction temperature > alkali concentration > extraction duration. The highest extraction yield, 1.98%, was achieved under an optimal extraction condition: temperature 60°C, solid-liquid ratio 1:6 g mL?1, duration 5 h, and alkali (NaOH) mass fraction 6%. The in vitro antioxidant activities examination showed that extracted SNP under this optimized condition had strong power in reducing certain hydroxyl and superoxide radical scavenging abilities. The promising results showed that extracted SNP could be a potent natural antioxidant. 相似文献
2.
The procedures of ultrasonic extraction and clean-up were optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. Samples were ultrasonically extracted, and the extracts were purified with a miniaturized silica gel chromatographic column and analyzed with high performance liquid chromatography (HPLC) with a fluorescence detector. Ultrasonication with methanol-dichloromethane (2:1, v/v) mixture gave higher extraction efficiency than that with dichloromethane. Among the three elution solvents used in clean-up step, dichloromethane-hexane (2:3, v/v) mixture was the most satisfactory. Under the optimized conditions, the recoveries in the range of 54.82% to 94.70% with RSDs of 3.02% to 23.22% for a spiked blank, and in the range of 61.20% to 127.08% with RSDs of 7.61% to 26.93% for a spiked matrix, were obtained for the 15 PAHs studied, while the recoveries for a NIST standard reference SRM 1941b were in the range of 50.79% to 83.78% with RSDs of 5.24% to 21.38%. The detection limits were between 0.75 ng L-1 and 10.99 ng L-1for different PAHs. A sample from the Jiaozhou Bay area was examined to test the established methods. 相似文献
3.
Phaeodactylum tricornutum is a potential livestock for the combined production of eicosapentaenoic acid (EPA) and fucoxanthin. In this study, six marine diatom strains identified as P. tricornutum were cultured and their total lipid, fatty acid composition and major photosynthetic pigments determined. It was found that the cell dry weight concentration and mean growth rate ranged between 0.24–0.36 g/L and 0.31–0.33/d, respectively. Among the strains, SCSIO771 presented the highest total lipid content, followed by SCSIO828, and the prominent fatty acids in all strains were C16:0, C16:1, C18:1, and C20:5 (EPA). Polyunsaturated fatty acids, including C16:2, C18:2, and EPA, comprised a significant proportion of the total fatty acids. EPA was markedly high in all strains, with the highest in SCSIO828 at 25.65% of total fatty acids. Fucoxanthin was the most abundant pigment in all strains, with the highest in SCSIO828 as well, at 5.50 mg/g. The collective results suggested that strain SCSIO828 could be considered a good candidate for the concurrent production of EPA and fucoxanthin. 相似文献
4.
The ciliate Tetrahymena is a valuable model organism in the studies of ecotoxicology. Changes in intracellular metabolism are caused by exogenous chemicals in the environment. Intracellular metabolite changes signify toxic effects and can be monitored by metabolomics analysis. In this work, a protocol for the GC-MS-based metabolomic analysis of Tetrahymena was established. Different extraction solvents showed divergent effects on the metabolomic analysis of Tetrahymena thermophila. The peak intensity of metabolites detected in the samples of extraction solvent Formula 1(F1) was the strongest and stable, while 61 metabolites were identified. Formula 1 showed an excellent extraction performance for carbohydrates. In the samples of extraction solvent Formula 2(F2), 66 metabolites were characterized, and fatty acid metabolites were extracted. Meanwhile, 57 and 58 metabolites were characterized in the extraction with Formula 3(F3) and Formula 4(F4), respectively. However, the peak intensity of the metabolites was low, and the metabolites were unstable. These results indicated that different extraction solvents substantially affected the detected coverage and peak intensity of intracellular metabolites. A total of 74 metabolites(19 amino acids, 11 organic acids, 2 inorganic acids, 11 fatty acids, 11 carbohydrates, 3 glycosides, 4 alcohols, 6 amines, and 7 other compounds) were identified in all experimental groups. Among these metabolites, amino acids, glycerol, myoinositol, and unsaturated fatty acids may become potential biomarkers of metabolite set enrichment analysis for detecting the ability of T. thermophila against environmental stresses. 相似文献
5.
张朝辉 高昕Department of Food Engineering Ocean University of China Qingdao China Yuri Tashiro Shingo Matsukawa Hiroo Ogawa 《中国海洋湖沼学报》2005,23(4):400-405
1 INTRODUCTIONSolar ultraviolet radiation on the earth's surfaceincreases with the depletion of stratospheric ozone(Crutzen, 1992; Kerr and McElroy, 1993; Mad-ronich et al., 1998). Ultraviolet radiation is a highlyactive component of solar spectrum. The excessiveUV radiation has deleterious effects on all plant,animal and microbial groups exposed to solar radia-tion, including the destruction of DNA, proteins andother molecules (Harm, 1980), inhibition of photo-synthesis and growth (W… 相似文献
6.
Healthy sporophytes of two gametophyte mutants of Laminaria japonica with different heat resistances: kelp 901 (901, with comparatively stronger heat-resistance) and Rongcheng No.1 (RC, sensi- tive to heat stress), were respectively collected during October to December 2002 from Yantai and Rong- cheng Sea Farm in the Shandong Peninsula of China. The contents of some biochemical materials and antioxidant capacity were analyzed under controlled laboratory conditions to identify if there is any rela- tion between the overall antioxidant capacity and the heat-resistance in L. japonica and to understand possible mechanism of heat-resistance. Results show that: (1) the overall antioxidant capacity in healthy sporophyte of 901, such as vitamin E, polyphenol, and ascorbic acid contents and the enzymatic activity of SOD, POD, CAT, Gpx, PPO, and PAL, were not always higher than that of RC under controlled labo- ratory conditions, and no significance (P>0.05) was shown in total antioxidant capacity (T-AOC) in 901 and RC. Result suggested that the difference in antioxidant capacity was not a decisive factor for different heat-resistances in L. japonica; (2) the simultaneous assay on isozymes was carried out using vertical polyacrylamide gel electrophoresis (PAGE). Considerable differences in peroxide (PRX), malate dehy- drogenase (MDH), malic enzyme (ME), polyphenol oxidase (PPO) and glutamate dehydrogenase (GDH) were obtained in 901 and RC from either the band number, relative mobility (Rf), or staining intensity, and ME could be used as an indicator to distinguish healthy sporophyte of 901 and RC under controlled labo- ratory conditions. 相似文献
7.
The response surface methodology (RSM) combined with bioassays was employed to optimize the extraction process of crude fucose-containing sulphated polysaccharides (cFCSP) from Sargassum fusiforme. The central composite design (CCD) was used with four variables, five levels, and four responses. The four variables were pH value of hydrochloric acid solution, extraction temperature (°C), ratio of liquid to raw material (mL g?1), and extraction time (h), respectively. Chemical and bioassay indices were used in combination as the response parameters, which included the yield of cFCSP, fucose content, proliferation rate of spleen cells, and lipopolysaccharide-induced proliferation of splenocytes. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis, and examined using the appropriate statistical methods. The best extraction conditions were as follows: the pH value of hydrochloric acid solution was 3.50; the extraction temperature was 100°C; the ratio of liquid to raw material was 15.00 mL g?1 and the extraction time was 2.50 h. The experimental yield was close to the predicted from the model. The extract could promote spleen lymphocyte proliferation, especially the lipopolysaccharide-induced lymphocyte proliferation in vitro, which suggested that its immunomodulatory effect on B lymphocytes. Therefore, cFCSP extracted from S. fusiforme could be utilized as an immunostimulant in functional foods and pharmaceutical industry in future. 相似文献
8.
Gracilaria tenuistipitata var Liui were mono-cultivated and co-cultivated with Pinctada martensii under high(33) and low(21) salinity conditions in laboratory.The daily growth rate of the alga was determined.Tissue carbon and nitrogen contents,the yield and fractional composition of agar were analyzed.Results showed that:1.Gracilaria grew better under low salinity conditions,the daily growth rate was twice that under high salinity conditions.Co-cultivated algae grew faster than mono-culti-vated algae under low salinity conditions,the daily growth rate was about 37.6?higher.2.Compared with mono-cultivated algae,tissue nitrogen contents of co-cultivated algae were higher,while the C:N ratios were much lower.3.The agar yields of co-cultivated algae were much lower than those of mono-culti-vated algae.Agar yield was found to be negatively correlated to the tissue nitrogen contents,and positively correlated to the C:N ratios.4.The highest fractional yields obtained from co-cultivated algae were extracted with 40?ethanol,while from mono-cultivated algae,the highest fractional yields obtained were extracted with distilled water at room temperature. 相似文献
9.
The industrially important organic compound 1,3-propanediol(1,3-PDO) is mainly used as a building block for the production of various polymers. In the present study, response surface methodology protocol was followed to determine and optimize fermentation conditions for the maximum production of 1,3-PDO using marine-derived Klebsiella pneumoniae HSL4. Four nutritional supplements together with three independent culture conditions were optimized as follows: 29.3 g/L glycerol, 8.0 g/L K 2 HPO 4, 7.6 g/L(NH 4) 2 SO 4, 3.0 g/L KH 2 PO 4, pH 7.1, cultivation at 35°C for 12 h. Under the optimal conditions, a maximum 1,3-PDO concentration of 14.5 g/L, a productivity of 1.21 g/(L·h) and a conversion of glycerol of 0.49 g/g were obtained. In comparison with the control conditions, fermentation under the optimized conditions achieved an increase of 38.8% in 1,3-PDO concentration, 39.0% in productivity and 25.7% in glycerol conversion in flask. This enhancement trend was further confirmed when the fermentation was conducted in a 5-L fermentor. The optimized fermentation conditions could be an important basis for developing lowcost, large-scale methods for industrial production of 1,3-PDO in the future. 相似文献
10.
Euphausia pacific is an important source of natural astaxanthin.Studies were carried out to assess the extractability of astaxanthin from E.pacific using subcritical 1,1,1,2-tetrafluoroethane(R134a).To examine the effects of multiple process variables on the extraction yield,astaxanthin was extracted under various conditions of pressure(30-150 bar),temperature(303-343 K),time(10-50 min),flow rate(2-10 g min-1),moisture content(5.5%-63.61%),and particle size(0.25-0.109 mm).The results showed that the extraction yield increased with temperature,pressure,time and flow rate,but decreased with moisture content and particle size.A maximum yield of 87.74% was obtained under conditions of 100 bar,333 K,and 30 min with a flow rate of 6 g min-1 and a moisture content of 5.5%.The substantial astaxanthin yield obtained under low-pressure conditions demonstrates that subcritical R134a is a good alternative to CO 2 for extraction of astaxanthin from E.pacific. 相似文献
11.
During late February to mid-March, 1991, when mature N. japonica swarmed in the sea surface off Jimo County, Qingdao, seawater containing numerous early embryos was pumped into a nearby 2.7 ha. muddy-sand shrimp pond, where the embryos continued to develop. 800000 Penaeus chinensis seedlings were introduced into the pond on May 30, 1991. Monthly benthic samplings were carried out to determine the population dynamics and production of N. japonica in this atypical environ -ment.The density of N. japonica varied from 0 to 20400 ind./m2. The predation of P. chinensis was considered to be responsible for the mass mortality of N. japonica in June through July, when the worms were 2.2-3.3cm in length and lived in the top 2-4cm sediment. From August to September of 1991, the hottest period in the site, there was no substantial mortality of N. japonica as reported in earlier literature. This was explained by the deeper burrowing of the' worms that protected them from predation by shrimps.Monthly biomass ranged f 相似文献
12.
The use of a microwave-assisted extraction(MAE) method for the extraction of phlorotannins from Saccharina japonica Aresch(S.japonica) has been evaluated with particular emphasis on the influential parameters,including the ethanol concentration,solid/liquid ratio,extraction time,extraction temperature,and microwave power.The MAE procedure was optimized using single-factor design and orthogonal array design(OAD).The content of total phlorotannins in S.japonica was determined using a Folin-Ciocalteu(FC) assay.A maximum total phlorotannin content of 0.644 mg of phloroglucinol equivalent per gram of dry weight plant(mg PGE/g DW) was obtained using the optimized model,which included an ethanol concentration of 55%,solid/liquid ratio of 1:8,extraction time of 25 min,irradiation power of 400 W,and temperature of 60°C.Under similar conditions,the application of a conventional extraction method led to a lower phlorotannin yield of 0.585 mg PGE/g WD.These results demonstrated that the MAE approach provided better results for the extraction of phlorotannins from S.japonica and was a promising technique for the extraction of phenolic compounds from S.japonica and other materials.In addition,screening tests for the inhibitory activity showed that the phlorotannin-containing extracts significantly inhibited the growth of human hepatocellular carcinoma cells(HepG2) by inducing their apoptosis.The morphological changes that occurred during cell apoptosis were characterized using Hoechst33258 staining. 相似文献
13.
14.
Genomic mining has identified a novel microbial alkaline esterase from the Indian Ocean. This esterase was overexpressed in E. coli BL21 (DE3) and further functionally characterized. Under optimal conditions (10 mmol/L substrate, pH 6.0, 2 h at 40 °C), this esterase can hydrolyze racemic methyl mandelate to (R)-methyl mandelate with very high optical purity (e.e. >99%) and yield (nearly 90%). Interestingly, the stereoselectivity of this esterase is opposite to that of two previously reported lipases that can generate (S)-methyl mandelate through the hydrolysis of racemic methyl mandelate. No organic solvents or other additives were required to optimize the optical purity and production of the final chiral product (R)-methyl mandelate, which can potentially simplify the production procedure of (R)-methyl mandelate catalyzed by esterase. 相似文献
15.
16.
以小杂鱼、低值鱼为原料，采用溶剂萃取法研究了溶剂种类、温度、时间和溶剂量对鱼蛋白提取过程中脱水、脱脂、脱色和脱腥的影响，筛选出提取浓缩鱼蛋白的最佳工艺条件。结果表明，在该工艺条件下制得的浓缩鱼蛋白，其蛋白质含量高达９２．２８％，脂肪含量仅为０．０９２％。 相似文献
17.
Calculation and comparative study of the chlorophyll fluorescence ratio F685/F735 in brown algae (Laminaria japonica, Underia pinnatifida and Padina crassa) excited by blue and green light showed that the fluorescence ratios were higher when the algae were excited by blue light (440 nm), but reduced obviously under green light (540 nm) excitation. The values also reduced under dehydration but could recover during rehydration if the stress was not serious. The variation of the fluorescence ratio under dehydration was mainly because changes in fluorescence emission at 735 nm were always sharper than those at 685 nm. The ratio was sensitive to stress and has potential as a stress indicator in phycological research. Measurement of the fluorescence excitation spectra showed that the only peak at 540 hm changed apparently during dehydration. It meant that the function of the Chl a /Fucoxanthin protein complex for energy transfer was easily inhibited by water stress. However, no variation of the ratio was foun 相似文献
18.
A lipase gene, lip1233, isolated from Pseudoalteromonas lipolytica SCSIO 04301, was cloned and expressed in E. coli. The enzyme comprised 810 amino acid residues with a deduced molecular weight of 80 kDa. Lip1233 was grouped into the lipase family X because it contained a highly conserved motif GHSLG. The recombinant enzyme was purified with Ni-NTA affinity chromatography. The optimal temperature and pH value of Lip1233 were 45°C and 8.0, respectively. It retained more than 70% of original activity after being incubated in pH ranging from 6.0 to 9.5 for 30 min. It was stable when the temperature was below 45°C, but was unstable when the temperature was above 55°C. Most metal ions tested had no significant effect on the activity of Lip1233. Lip1233 remained more than original activity in some organic solvents at the concentration of 30% (v/v). It retained more than 30% activity after incubated in pure organic solvents for 12 h, while in hexane the activity was nearly 100%. Additionally, Lip1233 exhibited typical halotolerant characteristic as it was active under 4M NaCl. Lip1233 powder could catalyze efficiently the synthesis of fructose esters in hexane at 40°C. These characteristics demonstrated that Lip1233 is applicable to elaborate food processing and organic synthesis. 相似文献
19.
以月腹刺鲀(Gastrophysus lunaris)卵巢为原料,利用超声波辅助提取河豚毒素(Tetrodotoxin,TTX)。通过单因素实验及二次回归旋转组合设计实验研究液料比、超声温度、超声时间等因素对提取率的影响,确定超声波辅助提取河豚毒素的最佳工艺条件。结果表明:在实验范围内影响河豚毒素得率的各因素大小依次为液料体积质量比、超声温度、超声时间;超声波辅助提取河豚毒素的最佳工艺条件为液料体积(mL)质量(g)比3.03∶1,超声温度39℃,超声时间22 min,该工艺条件下提取河豚毒素得率为63.57μg/g。 相似文献
20.
A method for determining calcium(Ca),potassium(K),magnesium(Mg) and iron(Fe) in four fish species was optimized and validated.It included microwave mineralization of the samples and subsequent quantification by flame atomic absorption spectroscopy(FAAS) with Zeeman-effect background correction.Using HNO3(65%) and H2O2(33%) as extraction solutions,the optimal conditions of extraction were established as follows:0.5 g of sample mass;microwave time program of 300 W/5 min and 600 W/5 min.The method was free of matrix interferences.The linear correlation coefficients were ≥0.9991,the recovery percentage of analytes was from 99.31% to 103.70% and the RSD(relative standard deviation) was lower than 2.06%.The detection limits obtained were 32.3,43.2,14.0 and 68.6 ng mL-1 for Ca,K,Mg and Fe in FAAS respectively.It is shown that the method is rapid,simple,sensitive and accurate.The method was applied to the studies of digestibility and measurement of these nutrients in samples of fish collected from Norway,Japan and China. 相似文献