CHARACTERIZATION OF RUTIN-CYCLODEXTRIN INCLUSION COMPOUNDS

The objectives of this study were to examine the potential of beta-cyclodextrin to improve the solubility of rutin and obtain inclusion compounds that were analyzed by different techniques: UV-Vis, IR spectroscopy, thermal analysis. The presence of β-cyclodextrin raises the content of rutin in water. The inclusion compounds were prepared by dry mixing, complexation in semisolid and liquid medium in 1:2 molar ratio rutin - β-cyclodextrin. The UV-Vis and IR analysis demonstrated the obtaining of inclusion compounds and the thermal analysis show that these compounds are more stable than the parent substance

STUDY ON ALCOHOLIC FERMENTATION IN A STATIONARY BASKET BIOREACTOR WITH IMMOBILIZED YEAST CELLS

The use of a stationary basket bioreactor with immobilized S. cerevisiae cells indicated the possibility to extend the number of alcoholic fermentation cycles that can be carried out with the same biocatalysts to over nine. Although the rates of glucose consumption and ethanol production were lower than those recorded for the mobile beds of immobilized yeast cells, the mechanical lysis of the biocatalysts is avoided in the case of basket bed. Due to the substrate and product accumulation inside the basket bed, the fermentation process can be improved by washing out the biocatalysts bed over two or four cycles

KINETIC STUDIES ON BIODEGRADATION OF LIPIDS FROM OLIVE OIL MILL WASTEWATERS WITH FREE AND IMMOBILIZED Bacillus sp. CELLS

The studies on the biodegradation of lipids from olive oil mill wastewater with free and immobilized Bacillus sp. cells indicated that the maximum specific rate of the process is reached at pH = 8. The use of immobilized cells allows to increasing the number of biodegradation process cycles, but reduces the rate of the process. In this case, the process rate depends on the biocatalysts size and cells concentration inside them. Thus, at bacterial cells concentration of 9 g d.w./100 mL biocatalyst, the apparent specific rate varied from 4.65 to 1.46×10-2 h-1 by increasing the biocatalyst particles diameter from 3 to 4.2 mm.The cumulated influences of the particles size and cells concentration have been included in a mathematical model for the apparent specific rate of lipids biodegradation. The model offers a good concordance with the experimental data, the average deviation being of +/- 7.38%

Improved Production of α-Amylase by <i>Aspergillus terreus</i> in Presence of Oxygen-Vector

n-Dodecane has been investigated as an oxygen-vector for improving α-amylase biosynthesis using the strain Aspergillus terreus. In aerobic microbial cultivation, continuous supply of oxygen is required especially due to its low solubility in the growth medium, in particular at high viscosity, but the limitations of oxygen mass transfer in these systems can be overcome by the addition of water-insoluble compounds which possess a strong affinity for oxygen, namely oxygen-vectors. The use of n-dodecane (as an oxygen-vector) in the fermentation medium of A. terreus can significantly improve the bioprocess performance and enhance α-amylase production. Using 5% n-dodecane at 35 °C, an increase of 1.8–2 times in the enzymatic activity was recorded. In the oxygen-vector’s absence, the highest amount of biomass was obtained at 35 °C, while in the presence of 5% vol. n-dodecane, the amount of fungal biomass increased by approximately 70%, with a shift in optimum temperature to 40 °C, generating also an enzymatic activity increase of 2.30 times. Moreover, the oxygen-vector’s addition in the fermentation broth influenced the fungal morphological development in the form of larger pellets with a more compact structure compared to the system without n-dodecane, with a positive effect on the fermentation performance (higher α-amylase activity production)

Comparative analysis of mixing efficiency and distribution induced by radial impellers in bioreactors with stirred bed of immobilized cells

The influences of the main factors on the mixing efficiency and distribution for a bioreactor with stirred/mobile bed of immobilized S. cerevisiae cells in alginate (biocatalyst particles with 4, 4.6 and 5.2 mm diameters) have been comparatively analyzed for six radial impellers: a disperser sawtooth, Smith turbine, a pumper mixer, a curved bladed turbine, a paddle with six blades, a pitched bladed turbine vs. Rushton turbine. The most efficient impellers, from the viewpoint of intensity and uniformity of the suspension circulation were found to be the Smith turbine, the paddle with six blades and the pitched bladed turbine. The mathematical correlations describing the influence of the main factors on mixing time were established for each studied impeller offering a good concordance with the experimental data (the average deviations vary from ±7.9% for pitched bladed turbine to ±12.1% for disperser sawtooth)

RADIAL IMPELLERS IN BIOREACTORS WITH

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