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Carbon Source Used (carbon + source_used)
Selected AbstractsOptimization of C:N ratio and minimal initial carbon source for poly(3-hydroxybutyrate) production by Bacillus megateriumJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2009Débora Jung Luvizetto Faccin Abstract BACKGROUND: The aim of this research was the optimization of poly(3-hydroxybutyrate),P(3HB),production in submerged cultures of Bacillus megaterium in a mineral medium using sucrose as carbon source and nitrogen as the limiting substrate. Small-scale experiments were carried out in shake flasks at 30 °C and 160 rpm in order to evaluate the best initial sucrose concentration and carbon:nitrogen ratio to maximize biomass accumulation and biopolymer production. An objective function in terms of residual sucrose and P(3HB) production was proposed in order to optimize the amount of carbon source used and the production of P(3HB). RESULTS: High production of P(3HB) was obtained, with approximately 70% (CDW) accumulation in cells without nitrogen limitation and strongly correlated with the pH of the culture. Scaling-up the system to cultures in a bioreactor, with or without pH control, a reduction of P(3HB) accumulation (around 30% CDW) was observed when compared with shaker cultures, suggesting a possible role of oxygen limitation as a stress signaling for P(3HB) synthesis. CONCLUSIONS: Results of our experiments showed that Bacillus megaterium was able to produce P(3HB) at one of the highest production rates so far reported for this bacterium, making this microorganism very interesting for industrial applications. Comparisons of shaker and bench-scale bioreactor experiments show both the importance of pH and aeration strategies. It is likely that complex aeration strategies linked to cell metabolism will be necessary for further developments using this bacterium. Copyright © 2009 Society of Chemical Industry [source] A new route for the direct synthesis of Al2O3/SiC nanopowder mixtures by the carbothermal reduction of parent oxidesAICHE JOURNAL, Issue 5 2010Cavus Falamaki Abstract The direct synthesis of Al2O3/SiC nanopowders from the parent oxides Al2O3 and SiO2 through mullite carbothermal reduction as intermediate phase has been investigated. The effect of the amount of excess stoichiometric carbon (active charcoal, AC) as sole carbon source on the microstructure evolution has been studied. The effect of type of carbon source (AC, graphite (G), 50 wt % AC 50 wt % G mixture, 57 wt % AC 43 wt % G mixture) on the microstructure evolution was investigated using 30 wt % excess stoichiometric carbon. The effect of reaction temperature, reaction duration, initial green compact thickness, and carbon source on the mullite conversion, morphology, and surface area of the final powders has been thoroughly investigated. The calculated activation energy is in the range of 203,230 kJ mol,1, depending on the carbon source used. The synergetic effect observed for the AC/G mixtures has been accordingly explained. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Changes in 13C/12C of oil palm leaves to understand carbon use during their passage from heterotrophy to autotrophy,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2009Emmanuelle Lamade The carbon isotope composition of leaf bulk organic matter was determined on the tropical tree Elaeis guineensis Jacq. (oil palm) in North Sumatra (Indonesia) to get a better understanding of the changes in carbon metabolism during the passage from heterotrophy to autotrophy of the leaves. Leaf soluble sugar (sucrose, glucose and fructose) contents, stomatal conductance and dark respiration, as well as leaf chlorophyll and nitrogen contents, were also investigated. Different growing stages were sampled from leaf rank ,6 to rank 57. The mean values for the ,13C of bulk organic matter were ,29.01,±,0.9, for the leaflets during the autotrophic stage, ,27.87,±,1.08, for the petioles and ,28.17,±,1.09, for the rachises, which are in the range of expected values for a C3 plant. The differences in ,13C among leaf ranks clearly revealed the changes in the origin of the carbon source used for leaf growth. Leaves were 13C-enriched at ranks below zero (around ,27,). During this period, the ,spear' leaves were completely heterotrophic and reserves from storage organs were mobilised for the growth of these young emerging leaves. 13C-depletion was then observed when the leaf was expanding at rank 1, and there was a continuous decrease during the progressive passage from heterotrophy until reaching full autotrophy. Thereafter, the ,13C remained more or less constant at around ,29.5,. Changes in sugar content and in ,13C related to leaf ranks showed an interesting similarity of the passage from heterotrophy to autotrophy of oil palm leaves to the budburst of some temperate trees or seed germination reported in the literature. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of different carbon sources on the nutritional value of bioflocs, a feed for Macrobrachium rosenbergii postlarvaeAQUACULTURE RESEARCH, Issue 4 2010Roselien Crab Abstract A 15-day lab-scale experiment was performed to determine the possible use of bioflocs as a feed for Macrobrachium rosenbergii postlarvae. The bioflocs were grown on acetate, glycerol and glucose. A glycerol-fed reactor was initially inoculated with a Bacillus spores mixture. The highest protein content was obtained in the (glycerol+Bacillus) bioflocs, i.e. 58±9% dry weight (DW). The glycerol and acetate bioflocs showed a lower, but similar content (42,43% DW) and glucose bioflocs contained 28±3% DW. Higher total n-6 fatty acid contents were observed in the glycerol and (glycerol+Bacillus) bioflocs. The vitamin C content was variable, up to 54 ,g ascorbic acid g,1 DW in the glycerol bioflocs. Bioflocs were fed to M. rosenbergii postlarvae as the sole feed. High survival levels were obtained in the (glycerol+Bacillus) and glucose groups, i.e. 75±7% and 70±0% respectively. This was significantly higher than the starvation control (0% survival after 15 days). This indicated that the prawns were able to feed on the bioflocs. These results are in accordance with the biofloc's nutritional parameters and suggest that the choice of the carbon source used for growing bioflocs is of prime importance. [source] Nitrogen-Doped Carbon Materials Prepared by Ammoxidation as Solid Base Catalysts for Knoevenagel Condensation and Transesterification ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Naokatsu Kan-nari Abstract Nitrogen-doped carbon materials were prepared by ammoxidation of commercial carbon sources (carbon black and activated carbon) and applied as base catalysts for Knoevenagel and transesterification reactions. It was shown that these carbon materials were active and the activities were different depending on the ammoxidation conditions (temperature and ammonia concentration in air) and carbon sources used. The bulk, textural, and surface properties of the nitrogen-doped carbon materials were examined by several methods to clarify possible factors determining their final catalytic activities. The activated carbon-derived catalysts were more active than the carbon black-derived ones. The surface area and porosity were not responsible for this difference between the two carbon sources but the difference in the reactivity with oxygen was important. The reactivity of carbon sources with oxygen should influence the doping of nitrogen onto their surfaces by ammoxidation with ammonia and air and the resulting activities as base catalysts. The catalytic activity increases with the amount of nitrogen doped and, therefore, the nitrogen doped should be responsible for the catalytic activities. In addition, the activities are maximal at a ratio of nitrogen to oxygen of around 1, suggesting the importance of cooperative functions of nitrogen and oxygen on the surface of carbons. [source] | ||||||||||