Organic onion growth, yield and storage improved by foliar sprays of microalgae and fulvic acid as a natural biofertilizer

The use of microalgae as natural biofertilizer in horticulture has recently been reported, while the use of humic substances is widespread. However, the combined use of microalgae with humic substances applied to plant leaves is still unexploited. Thus, the objective of this work was to combine fulvic acid (FA) with the Scenedesmus subspicatus microalga biomass (SC) as a natural biofertilizer applied via leaf in two onion cultivars in organic system. Four experiments were conducted: i) bioassays to verify the bioactive effect of FA, SC and combinations using the Vigna radiata model plant; ii) greenhouse pot experiment with foliar applications of FA, SC and combination in two onion cultivars; iii) field experiment in organic system with foliar applications of FA, SC and combination in two onion cultivars; and iv) onion bulb storage experiment. The bioactive effect of SC, FA and their combinations was identified by promoting changes in root growth of V. radiata. In pots, treatments containing FA, SC and combination promoted increase in fresh and dry leaf mass. The foliar application of FA, SC and combination promoted an increase in field bulb productivity, reduced mass loss in stored bulbs and increased carbohydrate, amino acid and protein contents in onion bulbs.

Cultivation of Scenedesmus dimorphus for C/N/P removal and lipid production

Background CO2 emission, water pollution and petroleum shortage are the issues coming with the development of industry. A cost effective system was constructed to fix the CO2 in flue gas (15% CO2), remove nitrogen and phosphorus from manure wastewater and produce biofuels at the same time. The significant cultivation conditions were selected by Plackett-Burman design, and then optimized with central composite design. Results Optimum culture condition was predicted at light intensity of 238 µmol·m- 2·s- 1, TN of 152 mg·L- 1, inoculum density of 0.3 g·L- 1, under which the measured CO2 fixation rate, total nitrogen and phosphorus removing rate, and lipid content were 638.13 mg·L- 1·d- 1, 88.16%, 73.98% and 11.9%, respectively. The lipid content was then enhanced to 24.2% by a nitrogen starvation strategy. Conclusion A cultivation strategy was suggested to achieve effective C/N/P removal from flue gas and manure wastewater, and meanwhile obtained high lipid content from microalgal biomass.

Demography of zooplankton (Anuraeopsis fissa, Brachionus rubens and Moina macrocopa) fed Chlorella vulgaris and Scenedesmus acutus cultured on different media

Generally zooplankton growth is often limited by the quality of their algal diet. A cheaper common practice in aquaculture, is to culture algae with fertilizers; however, the demography of zooplankton when fed these algae has not yet been evaluated. We studied the population growth and life table demography of the rotifers Anuraeopsis fissa and Brachionus rubens, and the cladoceran Moina macrocopa. For this, the algae Scenedesmus acutus or Chlorella vulgaris were cultured on defined (Bold’s basal) medium or the commercial liquid fertilizer (Bayfolan). Experiments were conducted at one algal concentration 1.0x10(6)cells/mL of C. vulgaris or its equivalent dry weight of 0.5x10(6)cells/mL of S. acutus. The population dynamics were tested at 23±1ºC in 100mL transparent jars, each with 50mL of the test medium, with an initial density of 0.5indiv/mL, for a total of 48 test jars (3 zooplankton 2 algal species x 2 culture media x 4 replicates). For the life table experiments with M. macrocopa, we introduced 10 neonates (<24h old) into each test jar containing the specific algal type and concentration. For the rotifer experiments, we set 5mL tubes with one neonate each and 10 replicates for each algal species and culture medium. We found that the average rotifer life span was not influenced by the diet, but for M. macrocopa fed S. acutus cultured in Bold’s medium, the average lifespan was significantly lower than with the other diets. The gross and net reproductive rates of A. fissa (ranging from 18-36 offspring per female) were significantly higher for C. vulgaris cultured in Bold medium. Regardless of the culture medium, Chlorella resulted in significantly higher gross and net reproductive rates for B. rubens than S. acutus diets. The reproductive rates of M. macrocopa were significantly higher in all the tested diets except when fed with S. acutus in Bold medium. The population increase rate, derived from growth experiments of A. fissa and B. rubens, ranged from 0.1-0.25/d and were significantly higher on C. vulgaris cultured in liquid fertilizer as compared to the other diets. The growth rates of M. macrocopa ranged from 0.1 to 0.38/d, and were highest with diets of C. vulgaris cultured in Bold medium and S. acutus cultured in fertilizer. Thus, regardless of the culture medium used, the growth rates of the evaluated zooplankton species were higher with Chlorella than with Scenedesmus. The peak population density was highest (2 800ind/mL) for A. fissa fed Chlorella that was cultured on liquid fertilizers, while B. rubens and M. macrocopa had peak abundances of 480 and 12ind/mL, respectively under similar conditions.

Generalmente el crecimiento del zooplancton está a menudo limitado por la calidad de su dieta de algas. La demografía del zooplancton durante la alimentación con algas no ha sido estudiada, a pesar de que el cultivo de algas con fertilizantes es una práctica económica común en acuacultura. Se analizó la demografía de Anuraeopsis fissa y Brachionus rubens (rotíferos) y Moina macrocopa (cladóceros), alimentados con las algas verdes Scenedesmus acutus o Chlorella vulgaris cultivadas en medio Bold o fertilizante líquido comercial (Bayfolan, de Bayer). En los rotíferos no se observaron diferencias significativas en el promedio de vida, sin embargo, este parámetro en M. macrocopa con S. acutus cultivada en Medio Bold, fue significativamente menor que en otras dietas. Las tasas de reproducción bruta y neta de A. fissa fueron significativamente mayores con C. vulgaris cultivada en medio Bold, que con el fertilizante; estas tasas en B. rubens, independientemente del medio de cultivo, resultaron significativamente mayores con Chlorella que S. acutus. La tasa de reproducción de M. macrocopa fue significativamente mayor en todas, a excepción de S. acutus en Bold. En el crecimiento poblacional con A. fissa y B. rubens la tasa de crecimiento poblacional varió de 0.1 hasta 0.25/d, significativamente mayores en C. vulgaris cultivadas con fertilizante, en comparación con las otras dietas; en M. macrocopa la tasa de crecimiento varió desde 0.1 hasta 0.38/d, las más altas fueron: con C. vulgaris cultivadas en medio Bold y S. acutus cultivadas con fertilizante. Así, en todas las especies, la tasa de crecimiento fue más alta con Chlorella que con Scenedesmus.

Análisis del efecto de las interacciones de tres variables de proceso para la producción de exopolisacáridos en la microalga Scenedesmus obliquus (UTEX 393) / Analysis of the effect of the interactions among three processing variables for the production of exopolysaccharides in the microalgae Scenedesmus obliquus (UTEX 393)

Microalgae are capable of producing biomolecules that have a wide variety of applications in agriculture, food industry, and medicine. In this study, three process variables are evaluated in order to determine its incidence on biomass and exopolysaccharides production. The effect of light intensity, agitation and carbon concentration on Scenedesmus obliquus (UTEX 393) growth and expolysaccaharides production is evaluated using 23 factorial design through the screening methodology. The simultaneous effect of level variation for three different experimental variables is examined in the present study in three levels for each parameter (Light intensity: 80, 130, 180 µE m-2 s-1, Agitation: 0, 600, 1200 rpm, carbon concentration 0, 2, 4% v/v Air-CO2). Specific growth rate and the exopolysaccharides concentration are the selected response variables. Results show that the optimal conditions for the two response variables correspond to the maximum levels of the three experimental variables (180 µE m-2 s-1, 4% air-CO2, and 1200 rpm), obtaining a specific growth rate of 0.64 d-1 and a exopolysaccharides concentration of 24.7 mg L-1. A significant interaction between the variables is observed, which has direct effects on cellular growth and exopolysaccharides production. The EPS production is facilitated by the turbulent flow (agitation maximum level), which is associated with a higher availability and better distribution of energy sources (light) and carbon dioxide. The validation of polynomials models verifies the relevance of the analysis performed.

Effect of molybdenum,vitamin [C] and vitamin [B[1]] on the growth criteria, photosynthetic pigments and metabolic activities of stressed-scenedesmus obliquus cultures

The growth criteria [cell count and dry weight] and total photosynthetic pigments, total carbohydrates, total proteins, free amino acids and praline of stressed- Scenedesmus obliquus cultures were significantly increased up to the level 3 ppm of MoCl[2] of that the control cultures, there above the values all these parameters were significantly decreased. When treated stressed-Scenedesmus obliquus cultures with 200 ppm of either ascorbic acid or thlamine were both supplemented of them separately, the growth criteria, total photosynthetic pigments, total proteins, free amino acids and praline of stressed-Scenedesmus obliquus cultures were significantly increased, as comparison with that the control cultures. Conversely, the total carbohydrate contents significantly decreased, when the algal cultures subjected to various levels [1.5, 3 and 4.5 ppm] of MoCl[2] and treated with 200 of either ascorbic acid or thiamine

Cultivating an oleaginous microalgae with municipal wastewater / 生物工程学报

Municipal wastewater is usually problematic for the environment. The process of oleaginous microalgal culture requires large amounts of nutrients and water. Therefore, we studied the feasibility of oleaginous microalgal culture of Scenedesmus dimorphus in bubbled column photobioreactor with municipal wastewater added with different nutrients. S. dimorphus could adapt municipal nutrient-rich wastewater by adding some nutrients as nitrogen, phosphorus, ferric ammonium citrate and trace elements, and the amounts of such nutrients have significant effects on cell growth, biomass yield and lipid accumulation. At optimum compositions of wastewater medium, the algal cell concentration could reach 8.0 g/L, higher than that of 5.0 g/L in standard BG11. Furthermore, S. dimorphus had strong capacity to absorb inorganic nitrogen and phosphorus from its culture water. There was almost no total nitrogen and phosphorus residues in culture medium after three or four days culturing when the adding mounts of nitrate and phosphate in wastewater medium were no more than 185.2 mg/L and 16.1 mg/L respectively under the experimental conditions. As a conclusion, it was feasible to cultivate oleaginous microalgae with municipal nutrient-rich wastewater, not only producing feedstock for algal biodiesel, but also removing inorganic nitrogen and phosphorus from wastewater.

Plastocyanin microheterogeneity in Scenedesmus acutus MT8.

Two total plastocyanin (PC) fractions - loosely bound (lPC) and strongly bound (sPC) were extracted (84% and 16%, respectively) from the homogenate of Scenedesmus acutus MT8. Two-fold isolation-purification procedure including DE-52 chromatography separated IPC into a smaller oxidized [IPC (II)] and a larger reduced [IPC(I)] fractions, in contrast to sPC, where sPC(ll) greatly dominated over sPC(I). Analytical isoelectric focusing (IEF) separated IPC(II) into two main fractions only in the presence of 8 M urea, implying microheterogeneity. Preparative IEF in immobiline pH-gradient of 3.2-4.1 separated IPC(II) into two blue fractions - a more alkaline IPC(II) and a more acidic IPC"(II), which were probably stereoisomers. Their UV-Vis spectra exhibited rarely observed tryptophane (291.5 nm) and some differences at 270 and 287 nm. The exact molecular masses of apo-/holo-lPC (10131 Da/10194 Da) were determined by mass spectrometry. The number of -SH groups was determined from the mass difference between alkylated with 4-vinylpyridine (4-VP) and non-alkylated protein. Additionally, a simple procedure for simultaneous separation of both primary structure and stereoisomers of PC was developed.

Prediction of toxicity of phenols and anilines to algae by quantitative structure-activity relationship / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To measure the toxicity of phenol, aniline, and their derivatives to algae and to assess, model, and predict the toxicity using quantitative structure-activity relationship (QSAR) method.</p><p><b>METHODS</b>Oxygen production was used as the response endpoint for assessing the toxic effects of chemicals on algal photosynthesis. The energy of the lowest unoccupied molecular orbital (E(LUMO)) and the energy of the highest occupied molecular orbital (E(HOMO)) were obtained from the ChemOffice 2004 program using the quantum chemical method MOPAC, and the frontier orbital energy gap (deltaE) was obtained.</p><p><b>RESULTS</b>The compounds exhibited a reasonably wide range of algal toxicity. The most toxic compound was alpha-naphthol, whereas the least toxic one was aniline. A two-descriptor model was derived from the algal toxicity and structural parameters: log1/EC50 = 0.268,logKow - 1.006deltaE + 11.769 (n = 20, r2 = 0.946). This model was stable and satisfactory for predicting toxicity. CONCLUSION Phenol, aniline, and their derivatives are polar narcotics. Their toxicity is greater than estimated by hydrophobicity only, and addition of the frontier orbital energy gap deltaE can significantly improve the prediction of logKow-dependent models.</p>

Karyotypic differences and evolutionary tendencies of some species from the subgenus Obliquodesmus Mlad. of genus Scenedesmus Meyen (Chlorophyta, Chlorococcales).

Karyotype structures of Scenedesmus acuminatus (Lagerch.) Chod. and Scenedesmus pectinatus Meyen are compared. The karyotype of S. acuminatus (n = 5) is described for the first time. It reveals four large metacentric and one large submetacentric chromosomes (4M + 1SM). The established karyotype differences have been helpful in clarifying the taxonomic position of these two species. The cytological analyses of other related clonal cultures suggest an evolutionary transition from S. pectinatus towards S. regularis through S. pectinatus f. regularis, which correlates with the morphological data about their variability. These results are discussed from the cytogenetic, morphological and evolutionary point of view. On the basis of the karyotypic analysis, it was confirmed that from a taxonomic point of view S. pectinatus, S. acuminatus and S. regularis are separate biological species.