Ethanol Production Using Immobilized <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> in Lyophilized Cellulose Gel

A new lyophilization technique was used for immobilization of Saccharomyces cerevisiae cells in hydroxyethylcellulose (HEC) gels. The suitability of the lyophilized HEC gels to serve as immobilization matrices for the yeast cells was assessed by calculating the immobilization efficiency and the cell retention in three consecutive batches, each in duration of 72 h. Throughout the repeated batch fermentation, the immobilization efficiency was almost constant with an average value of 0.92 (12–216 h). The maximum value of cell retention was 0.24 g immobilized cells/g gel. Both parameters indicated that lyophilized gels are stable and capable of retaining the immobilized yeast cells. Showing the yeast cells propagation within the polymeric matrix, the scanning electron microscope images also confirmed that the lyophilization technique for immobilization of S. cerevisiae cells in the HEC gels was successful. The activity of the immobilized yeast cells was demonstrated by their capacity to convert glucose to ethanol. Ethanol yield of 0.40, 0.43 and 0.30 g ethanol/g glucose corresponding to 79%, 84% and 60% of the theoretical yield was attained in the first, second and third batches, respectively. The cell leakage was less than 10% of the average concentration of the immobilized cells.     

Enhanced Production of Spinosad in <Emphasis Type="Italic">Saccharopolyspora spinosa</Emphasis> by Genome Shuffling

Spinosad (spinosyns A and D) is a mixture of secondary metabolites produced by Saccharopolyspora spinosa. It is used in agriculture as a potent insect control agent with exceptional safety to non-target organisms. In this study, we applied genome shuffling of S. spinosa to achieve a rapid improvement of spinosad production. Ten strains with subtle improvements in spinosad production were obtained from the populations generated by the mutation with nitrosoguanidine and ultraviolet irradiation, and then they were subjected for recursive protoplast fusion. After four rounds of genome shuffling, a high yielding strain, designated as S. spinosa 4-7, was successfully isolated. Its production reached 547 mg/L, which was increased by 200.55% and 436.27% in comparison with that of the highest parent strain and the original strain, respectively. The subculture experiments indicated that the high producer of S. spinosa 4-7 was stable. Spinosad fermentation experiments by S. spinosa 4-7 were carried out in a 5-L fermentor, and its production of spinosad reached 428 mg/L after 168 h of fermentation.     

Uranium adsorption by dry and wet immobilized <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Immobilized Saccharomyces cerevisiae (ISC) was prepared by the sodium alginate–gelatin embedding method after dry cells had been cross-linked by formaldehyde. Adsorption of uranium(VI) by incompletely and completely dry ISC was studied. The results indicated that incompletely dry ISC had greater adsorption capacity for U(VI), with physical adsorption being the primary mechanism, whereas completely dry ISC exhibited much greater rigidity and much smaller volume. Therefore, initial absorption of U(VI) by incompletely dry ISC followed by heating could be compared with glass solidification for disposal of radioactive waste. The influence of solution pH, temperature, and contact time on U(VI) absorption was also studied, with pH being found to be the main influencing factor. The adsorption mechanism of completely dry ISC was explored by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, indicating that the main adsorption mechanism is chemical adsorption.     

Structural analysis of <Emphasis Type="Italic">w</Emphasis>/<Emphasis Type="Italic">o</Emphasis>/<Emphasis Type="Italic">w</Emphasis> multiple emulsions by means of DSC

Summary The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems. Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are beneficial during manufacturing as in process controls, or to ensure product quality.     

Synthesis of new <Emphasis Type="Italic">N</Emphasis>-aminoglycosides based on halo-substituted <Emphasis Type="Italic">p</Emphasis>-phenylenediamines and <Emphasis Type="Italic">p</Emphasis>-aminophenols

Condensation of the monosaccharides D-glucose and D-galactose with synthesized halo-substituted p-phenylenediamines and 4-amino-2,6-dibromophenol was studied. It was found that glycosylation occurred only at the 4-amino group that was sterically unhindered by the halogen atom. The position of the aglycon in the glycoside was established by PMR spectroscopy.     

Unsteady mass transfer into a sphere under equilibrium condition <Emphasis Type="Italic">y</Emphasis> = <Emphasis Type="Italic">Ax</Emphasis> + <Emphasis Type="Italic">B</Emphasis>

We obtained an analytical solution of a problem of unsteady mass transfer under the equilibrium condition y = Ax + B to compare results with a problem solution in the case of equilibrium condition looking as y = Ax.     

Biological Synthesis of Gold Nanoparticles by Fungus <Emphasis Type="Italic">Epicoccum</Emphasis><Emphasis Type="Italic">nigrum</Emphasis>

Gold nanoparticles exhibit unique optical, thermal, chemical and physical properties. The microorganisms have high potential for production of nanoparticles with wide applications. Application of fungi to produce nanoparticles is potentially exciting because of their ability to secrete large amounts of enzymes. In this study, we investigated biosynthesis of gold nanoparticles by the fungus Epicoccum nigrum isolated from Andalian gold mine in north-west of Iran. The gold nanoparticles were produced intra and extracellular by reaction of an aqueous solution of chloroauric acid with the biomass of fungus E. nigrum. The produced gold nanoparticles were in the size range of 5–50 nm in spherical and rod shapes. This is the first report on the biosynthesis of gold nanoparticles by the fungus E. nigrum.     

Synthesis from geraniol of (2<Emphasis Type="Italic">E</Emphasis>,6<Emphasis Type="Italic">E</Emphasis>,10<Emphasis Type="Italic">E</Emphasis>,14<Emphasis Type="Italic">E</Emphasis>)-16-hydroxygeranylgeraniol and some of its derivatives

Several α,ω-bifunctional derivatives of E,E,E-geranylgeraniol were prepared via convergent synthesis starting with geraniol (8), which was converted in three steps into the tetrahydropyranyl ether of 8-chlorogeraniol (9) and 8-hydroxygeranylphenylsulfone (10). Combination of synthons 9 and 10 with subsequent reductive removal of the phenylsulfonyl group produced the tetrahydropyranyl ether of ω-hydroxygeranylgeraniol (5), hydrolysis of which gave exclusively trans-ω-hydroxygeranylgeraniol (1). Derivatives 5–7 of geranylgeraniol were synthesized using standard methods. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 231–234, May–June, 2007.