Continuous production of green cells of Haematococcus pluvialis: Modeling of the irradiance effect

This paper presents a model for the continuous production of green cells of the microalga Haematococcus pluvialis, in both indoor and outdoor conditions. To develop this model, the influence of irradiance and dilution rate on the performance of continuous cultures of H. pluvialis was studied in the laboratory but simulating outdoor conditions. Characterization of the cultures included biomass productivity, fluorescence of chlorophylls, pigment content, elemental composition of the biomass, cell density, cell size, homogeneity and nitrate consumption rate. Results showed that the optimal dilution rate was 0.04 h⁻¹, and that higher external irradiance resulted in higher biomass productivity in all cases, with a maximum value of 0.58 g L⁻¹day⁻¹. Continuous cultures were stable for more than 3 months, in spite of photoinhibition at noon, producing homogeneous biomass with a stable biochemical composition and cell morphology at each steady state. Astaxanthin accumulation was not observed in spite of the high levels of irradiance essayed, and cells remained in the flagellated-palmeloids green form whatever the culture conditions. High dilution rates produced small cells of 22 μm diameter, with a high nitrogen content of up to 10.0% d.wt. The average irradiance within the reactor was the main factor determining the behaviour of the cultures, although the external irradiance impinging on the reactor surface also influenced the results, indicating the existence of photoinhibition. The influence of both external and average irradiance on the growth of H. pluvialis was modelized. The accuracy of the model obtained was verified on a 0.22 m³ outdoor tubular photobioreactor operated in both discontinuous and continuous mode, obtaining a maximum biomass productivity of 0.68 g L⁻¹day⁻¹. The model reproduced the experimental data of biomass concentration and productivity, cell size and nitrate consumption, providing to be a powerful tool for optimizing the design and operation of outdoor photobioreactors for the production of green cells of H. pluvialis.     

Commercial production of microalgae: ponds, tanks, tubes and fermenters

The commercial culture of microalgae is now over 30 years old with the main microalgal species grown being Chlorella and Spirulina for health food, Dunaliella salina for β-carotene, Haematococcus pluvialis for astaxanthin and several species for aquaculture. The culture systems currently used to grow these algae are generally fairly unsophisticated. For example, Dunaliella salina is cultured in large (up to approx. 250 ha) shallow open-air ponds with no artificial mixing. Similarly, Chlorella and Spirulina also are grown outdoors in either paddle-wheel mixed ponds or circular ponds with a rotating mixing arm of up to about 1 ha in area per pond. The production of microalgae for aquaculture is generally on a much smaller scale, and in many cases is carried out indoors in 20–40 l carboys or in large plastic bags of up to approximately 1000 l in volume. More recently, a helical tubular photobioreactor system, the BIOCOIL™, has been developed which allows these algae to be grown reliably outdoors at high cell densities in semi-continuous culture. Other closed photobioreactors such as flat panels are also being developed. The main problem facing the commercialisation of new microalgae and microalgal products is the need for closed culture systems and the fact that these are very capital intensive. The high cost of microalgal culture systems relates to the need for light and the relatively slow growth rate of the algae. Although this problem has been avoided in some instances by growing the algae heterotrophically, not all algae or algal products can be produced this way.     

温度光照pH对雨生血球藻CG-11绿色营养细胞生长的影响

采用BBM培养基,以雨生血球藻Haematococcus pluvialis CG-11为研究材料,进行环境因子对雨生血球藻绿色营养细胞生长影响的实验。温度梯度为16℃、20℃、24℃、28℃;光照梯度为30μmoL photons m^-2·s^-1、60μmoL photons m^-2·s^-1、90μmoL photons m^-2·s^-1、120μmoL photons m^-2·s^-1。初始pH值为6.0、7.0、8.0、9.0,进行单因子试验,测定各组的藻密度及色素含量。结果显示,雨生血球藻H.pluvialis CG-11生长的最适温度范围20～24℃,光照90μmol photons m^-2·s^-1,初始pH8.0。     

Preparation and performance evaluation of glucomannan–chitosan–nisin ternary antimicrobial blend film

The material behaviour and antimicrobial effect of konjac glucomannan edible film incorporating chitosan and nisin at various ratio or concentrations is discussed. This activity was tested against food pathogenic bacteria namely Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. Mechanical and physical properties were determined and the results indicated that the blend film KC2 (mixing ratio konjac glucomannan 80/chitosan 20) showed the maximum tensile strength (102.8 ± 3.8 MPa) and a good transparency, water solubility, water vapor transmission ratio. The differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), etc. were used to characterize the structural change of the blend films. The results showed that the strong intermolecular hydrogen bonds took place between chitosan and konjac glucomannan. Incorporation of nisin at 42,000 IU/g of film for the selected blend film KC2 was found to have antimicrobial activity against S. aureus, L. monocytogenes, and B. cereus. The antimicrobial effect of chitosan or KC2 incorporating nisin was much better than that of konjac glucomannan incorporating nisin at each corresponding concentration and existed significant difference (p < 0.05), however, there was no significant difference on the antimicrobial effect between chitosan and KC2 both incorporating nisin. At all these levels, the ternary blend film KC2-nisin had a satisfactory mechanical, physical properties and antimicrobial activity, and could be applied as a potential ‘active’ packaging material.     

氮、磷营养对雨生血球藻绿色细胞生长的影响

采用BBM培养基,以雨生血球藻(Haematococcus pluvialis CG-11)为研究材料,通过测定细胞生长速率、叶绿素和类胡萝卜素含量、生物量和虾青素含量,探讨氮、磷营养对雨生血球藻营养细胞生长的影响.结果显示:H.pluvialis CG-11生长的适宜氮源形式是NaNO₃和NH₄NO₃;适宜H.pluvialis CG-11生长的氮浓度为41.2mg·L^-1,磷浓度为5.3～53.3mg·L^-1.     

Astaxanthin accumulation in Haematococcus requires a cytochrome P450 hydroxylase and an active synthesis of fatty acids.

Astaxanthin accumulation by green microalgae is a natural phenomenon known as red snows and blood rains. The fact that astaxanthin synthesis requires oxygen, NADPH and Fe²⁺ led Cunningham and Gantt [Annu. Rev. Plant Physiol. Plant Mol. Biol. 49 (1998) 557–583] to propose that a cytochrome P450-dependent enzyme might be involved in the transformation of β-carotene to astaxanthin. In Haematococcus only esterified astaxanthin molecules accumulate, but it is not determined whether a fatty acid synthesis should occur simultaneously to allow pigment accumulation. The aim of this contribution was to answer these two questions using specific inhibitors of β-carotene (norflurazon) and fatty acid (cerulenin) synthesis, and of cytochrome P450 enzyme activity (ellipticine).     

Properties and microstructure of protein-based film from round scad (Decapterus maruadsi) muscle as affected by palm oil and chitosan incorporation

The properties of protein-based film prepared from round scad (Decapterus maruadsi) muscle in the absence and the presence of palm oil and/or chitosan were investigated. Films added with 25% palm oil (as glycerol substitiution) had the slight decrease in water vapor permeability (WVP) and elongation at break (EAB) (p < 0.05). WVP and tensile strength (TS) of films increased but EAB decreased when 10–40% chitosan (as protein substitution) was incorporated (p < 0.05). Hydrophobic interactions and hydrogen bonds, together with disulfide and non-disulfide covalent bonds, played an important role in stabilizing the film matrix. The a* and b*-values increased with increasing chitosan levels (p < 0.05). Films added with chitosan were less transparent and had the lowered transmission in the visible range. The incorporation of 25% palm oil and 40% chitosan yielded the films with the improved TS but decreased water vapor barrier property. Apart from film strengthening effect, chitosan inconjunction with Tween-20 most likely functioned as the emulsifier/stabilizer in film forming solution containing palm oil.     

Haematococcus astaxanthin: applications for human health and nutrition

The carotenoid pigment astaxanthin has important applications in the nutraceutical, cosmetics, food and feed industries. Haematococcus pluvialis is the richest source of natural astaxanthin and is now cultivated at industrial scale. Astaxanthin is a strong coloring agent and a potent antioxidant - its strong antioxidant activity points to its potential to target several health conditions. This article covers the antioxidant, UV-light protection, anti-inflammatory and other properties of astaxanthin and its possible role in many human health problems. The research reviewed supports the assumption that protecting body tissues from oxidative damage with daily ingestion of natural astaxanthin might be a practical and beneficial strategy in health management.     

壳聚糖和ε-聚赖氨酸处理对双孢蘑菇贮藏过程中品质的影响

以延长双孢蘑菇货架期为目标,探讨壳聚糖和ε-聚赖氨酸处理对采后双孢蘑菇在4 ℃贮藏过程中生理特性、营养品质和贮藏特性的影响。结果表明：与对照组双孢蘑菇相比,壳聚糖与ε-聚赖氨酸6:4复配溶液处理能够有效抑制双孢蘑菇表面微生物的生长和多酚氧化酶活性的增加,保持双孢蘑菇子实体较高的L*值和硬度,延缓双孢蘑菇的质量损失和细胞膜透性的升高,减少双孢蘑菇子实体的腐烂,保持较高商品率。在4 ℃条件下,壳聚糖与ε-聚赖氨酸6:4复配溶液对双孢蘑菇的保鲜性能最优,能够有效保持双孢蘑菇的商品品质和延长其贮藏时间。     

Embryonic inheritance of the chromatin organisation of the imprinted H19 domain in mouse spermatozoa

Insulin-like growth factor 2 (Igf 2) and H19 genes are oppositely imprinted and as such have been most extensively studied imprinted genes both genetically and at the molecular level. Imprints of the H19 gene, being established during spermatogenesis, are epigenetically transmitted to the somatic cells of the embryo. Current hypotheses attempting to explain the allele-specific silence of the H19 gene include DNA methylation and chromatin condensation. In order to understand the molecular basis of H19 epigenesis, it is crucial to identify the markings in the chromatin organising the imprinted domain in spermatozoa. Using Micrococcal nuclease (MNase), DNase I and Methidiumpropyl-EDTA. iron II (MPE·Fe(II)) as chromatin probes, we demonstrate that in mouse epididymal spermatozoa, at least 4 kb DNA upstream of the H19 ‘cap’ site, containing the imprinted and differentially methylated domain (DMD), is heterochromatic. The cleavage sites in this domain (−2 to −4 kb) exhibit ~425 bp periodicity. This structure is maintained in the paternal allele of normal embryos and is disrupted at −2.2, −2.65 and at −3.5 kb in embryos maternally disomic for the distal end of chromosome 7 (MatDp 7). The hypersensitive sites in chromatin precisely register the MPE·Fe(II) cleavage sites in chromosomal DNA. Therefore, the DNA sequences in the imprinted domain constrain the chromatin structure in a way similar to that of 1.688 g/cm³ Drosophila satellite chromatin. In addition, we find that condensation of the paternal allele correlates with methylation-dependent alteration in the structure of DNA sequences in DMD. These results suggest that CpG-methylation induces localised changes in DNA conformation and these facilitate consequent remodelling of chromatin thereby allowing the paternal and maternal H19 alleles to be distinguished.     

Inhibition of oxidative injury of biological membranes by astaxanthin

The value of astaxanthin, a carotenoid pigment, in the treatment of oxidative injury is assessed. Astaxanthin protects the mitochondria of vitamin E-deficient rats from damage by Fe2(+)-catalyzed lipid peroxidation both in vivo and in vitro. The inhibitory effect of astaxanthin on mitochondrial lipid peroxidation is stronger than that of alpha-tocopherol. Thin layer chromatographic analysis shows that the change in phospholipid components of erythrocytes from vitamin E-deficient rats induced by Fe2+ and Fe3(+)-xanthine/xanthine oxidase system was significantly suppressed by astaxanthin. Carrageenan-induced inflammation of the paw is also significantly inhibited by administration of astaxanthin. These data indicate that astaxanthin functions as a potent antioxidant both in vivo and in vitro.     

Malolactic fermentation in chardonnay wine by immobilised Lactobacillus casei cells

The kinetics of malolactic fermentation in Chardonnay wine by immobilised Lactobacillus casei cells has been studied. Calcium pectate gel and chemically modified chitosan beads were used as supports for immobilisation. Repeated batch fermentations were carried out with different wine samples, some of which were treated with sulfur dioxide (free 19–25 mg/litre and total 80–88 mg/litre), in shake flask at 36, 25 and 20°C without any loss of activity. The degradation of malic acid obtained using immobilised cells was twice as high as that obtained with free cells. At an initial pH 3·2, decrease of malic acid of about 30% was observed at 25°C in one hour using L. casei cells immobilised either in pectate gel or on chitosan. Among the physico-chemical parameters studied, temperature was the main factor affecting metabolism of the organic acids as well as the rate of the malolactic fermentation. Operational stability of calcium pectate gel beads and chemically modified chitosan beads was 6 months after eight fermentations and 2 months after five fermentations, respectively, which proved the possibility of industrial application of the chosen supports in wine making.     

Antimicrobial activity of aqueous extracts of Larrea divaricata Cav (jarilla) against Helicobacter pylori

We studied here the effect of aqueous extracts of Larrea divaricata Cav on the growth of Helicobacter pylori. Results show that cold extract, infusion, decoction and simulated digestion had inhibitory activity at 0.04–0.1 mg/l against clarithromycin and metronidazole susceptible and resistant H. pylori strains. These results support the popular use of L. divaricata Cav in gastric disturbances and prompt further research to characterize these compounds with a therapeutic potential against gastric ulcers and gastric cancer associated with H. pylori.     

Halothiobacillus neapolitanus strain OSWA isolated from "The Old Sulphur Well" at Harrogate (Yorkshire, England)

The “Old Sulphur Well” has a subterranean input of water containing 5.5 mM total sulfide, which would be inhibitory to the growth of most bacteria. The obligately chemolithoautotrophic Halothiobacillus neapolitanus is a sulfur bacterium known to tolerate and metabolize high sulfide concentrations, and we report the isolation of H. neapolitanus strain OSWA from this source. Strain OSWA grows well on thiosulfate and tetrathionate as energy sources, and tolerates at least 5 mM sulfide. Its specific growth rates and yields in batch culture were 0.22 h⁻¹ and 5.3 g mol⁻¹ (thiosulfate), and 0.23 h⁻¹ and 9.5 g mol⁻¹ (tetrathionate). Its 16S rRNA gene sequence shows >99% identity to reference sequences of H. neapolitanus, and it shares morphological and physiological characteristics typical of the species. It is one of a very small number of strains of H. neapolitanus described to date, and the first to be isolated from an ancient sulfide-rich natural spa.     

Protective effect of Ecklonia cava enzymatic extracts on hydrogen peroxide-induced cell damage

In this study, Ecklonia cava was enzymatically hydrolyzed to prepare water-soluble extracts, using five carbohydrases (Viscozyme, Celluclast, AMG, Termamyl, and Ultaraflo) and five proteases (Protamex, Kojizyme, Neutase, Flavourzyme, and Alcalase), and the potential antioxidant activity of each was assessed. The Celluclast and Viscozyme extracts of E. cava evidenced good hydrogen peroxide (H₂O₂) scavenging activities (73.25% and 72.92%, respectively) as compared to those of other enzymatic extracts. Therefore, the Celluclast enzymatic extract was selected for use in further experiments, and separated into four different molecular weight fractions (<1, 1–10, 10–30 and >30 kDa). Among these fractions, the >30 kDa fraction manifested the most profound H₂O₂ scavenging activity, with a measured IC₅₀ of 13 μg/ml. The >30 kDa fraction also strongly enhanced cell viability against H₂O₂-induced oxidative damage, and evidenced relatively good lipid peroxidation inhibitory activity in a Chinese hamster lung fibroblast (V79-4) cell line. This fraction also effected a reduction in the proportion of cells undergoing H₂O₂-induced apoptosis, as was demonstrated by a decreased quantity of sub-G₁ hypodiploid cells and decreased apoptotic body formation on the flow cytometry assay. These results clearly indicate that the >30 kDa fraction of E. cava possesses good antioxidant activity against H₂O₂ mediated cell damage in vitro.     

Allelopathic effects of Ulva lactuca on selected species of harmful bloom-forming microalgae in laboratory cultures

Allelopathic effects of the green macroalgae Ulva lactuca on the growth of three species of red tide microalgae, Heterosigma akashiwo, Alexandrium tamarense, and Skeletonema costatum were tested in laboratory co-cultures precluding the nutrient and light limitation and the effect of high pH. The growth of all three species of microalgae was significantly (p < 0.01) inhibited by fresh U. lactuca. In nutrient replete semicontinuous co-cultures with U. lactuca, H. akashiwo was completely dead in 12 days, and the growth of A. tamarense and S. costatum was reduced by 48 and 46%, respectively by U. lactuca within 12 days. The U. lactuca culture filtrate exhibited a significant (p < 0.05) inhibitory effect on the microalgae in the first 1 or 2 days, but growth resumed in the following days, and S. costatum growth was slightly (p > 0.05) promoted from day 3. The results suggested that the allelopathic compounds are quickly degradable and a long-term inhibition might need the continuous addition of compounds originated from macroalgae. Dried U. lactuca also exhibited inhibitory effects on the microalgae, and the normalized mean growth rates of microalgae decreased with the biomass of dried U. lactuca. The dependent relationships were y = −2.1208x² + 1.0159x + 0.9752 for H. akashiwo, y = 0.7133x² − 3.5813x + 1.1665 for A. tamarense, and y = −0.2114x² − 1.063x + 1.0873 for S. costatum, respectively. The potential feasibility of utilization of dried U. lactuca against red tide microalgae was 2.0 g dry wt L⁻¹. The present study shows that U. lactuca exhibits negative allelopathic effects on harmful bloom-forming microalgae.     

虾青素复合有氧运动对D-半乳糖诱导大鼠肾脏衰老的干预作用及其机制

目的:研究虾青素复合有氧运动对D-半乳糖诱导大鼠肾脏衰老的干预作用及其机制.方法:60只3月龄SPF级SD大鼠采用两因素两水平2×2析因设计随机分为空白对照组(C组)、急性衰老组(S组)、虾青素+急性衰老组(AS组)、有氧运动+急性衰老组(ES组)、虾青素+有氧运动+急性衰老组(AES组),每组12只.大鼠腹腔注射10...     

Metal accumulation by Halodule wrightii populations

Metal concentrations and population parameters of the seagrass Halodule wrightii were determined at three locations at Rio de Janeiro State, Brazil. The possible increase of metal availability in one of these areas, Sepetiba Bay, as a result of dredging of contaminated bottom sediments which ocurred, was evaluated by analyses of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn in root, rhizome and shoots. In addition, analyses were carried out in H. wrightii populations from non-contaminated areas located at northwestern (Cabo Frio) and southeastern (Angra do Reis) regions of Rio de Janeiro State. Concurrently, abundance and density data of the seagrass populations were obtained. It was found that concentration from Sepetiba Bay samples up to 1.6 ± 0.4 μg g⁻¹ of Cd, 12 ± 1.0 μg g⁻¹ of Cr, 27 ± 2.4 μg g⁻¹ of Pb, 291 ± 47 μg g⁻¹ of Mn, 128 ± 23 μg g⁻¹ of Zn were significantly higher than that from two other collection sites. An increase in Cd and Zn concentration was observed in H. wrightii from Sepetiba Bay indicating that metal mobilization from contaminated sediments through dredging activities were, at least in part, transferred to the biotic compartment via accumulation by the seagrass. The populations of seagrass within the region demonstrated quite substantial changes in biomass data but not in shoot or rhizome density during the study. Such changes in biomass are to be expected, as these dynamics are typical of the small, isolated monospecific populations of H. wrightii along the Rio de Janeiro coast.     

Immobilization of catalase into chemically crosslinked chitosan beads

Bovine liver catalase was immobilized into chitosan beads prepared in crosslinking solution. Various characteristics of immobilized catalase such as the pH–activity curve, the temperature–activity curve, thermal stability, operational stability, and storage stability were evaluated. Among them the pH optimum and temperature optimum of free and immobilized catalase were found to be pH 7.0 and 35 °C. The K_m value of immobilized catalase (77.5 mM) was higher than that of free enzyme (35 mM). Immobilization decreased in V_max value from 32,000 to 122 μmol (min mg protein)⁻¹. It was observed that operational, thermal and storage stabilities of the enzyme were increased with immobilization.     

Antinociceptive activity of the volatile oils of Hyptis pectinata L. Poit. (Lamiaceae) genotypes

Hyptis pectinata L. Poit (Lamiaceae) is known popularly in Brazil as “sambacaita” or “canudinho” and is used in the treatment of inflammations, bacterial infections and ache. The antinociceptive activity of the volatile oils of six genotypes, at doses of 100, 200 and 400 mg/kg body wt., were investigated using abdominal writhe models induced by acetic acid and hot plate tests. The volatile oils of all the genotypes are composed mainly of sesquiterpenoids. All the genotypes showed antinociceptive effects in both models used; the SAM002 genotype showed the major inhibitory effect at dose of 100 mg/kg body wt. These results suggest that the volatile oil of H. pectinata has peripheral (writhe reduction) and central (time delay of thermal reaction) effects. These observations indicate that H. pectinata may be useful as an analgesic drug.