Cellulase Production by <Emphasis Type="Italic">Streptomyces viridobrunneus</Emphasis> SCPE-09 Using Lignocellulosic Biomass as Inducer Substrate

An actinomycete strain, isolated from a soil sample under a sugar cane plantation in Brazil and identified as Streptomyces viridobrunneus SCPE-09, was selected as a promising cellulolytic strain, and tested for its ability to produce cellulases from agro-industrial residues. Sugar cane bagasse or wheat bran was tested as carbon source, and corn steep liquor tested as nitrogen source. Different concentrations of carbon and nitrogen were tested using factorial design to identify optimal cellulose production. The results showed that media containing wheat bran 2.0% (w/v) and corn steep liquid 0.19% (w/v) lead to the highest production, 2.0 U mL⁻¹ of CMCase, obtained on the fifth day of fermentation. The pH and temperature profile showed optimal activity at pH 4.9 and 50°C. As for thermostability, endoglucanases were most tolerant at 50°C, retaining more than 80% of maximal activity even after 2 h of incubation. Zymogram analyses using supernatant from growth under optimized conditions revealed the presence of two CMCase bands with apparent molecular masses of 37 and 119 kDa. The combination of pH tolerance and CMCase production from agro-industrial residues by S. viridobrunneus SCPE-09 offers promise for future bioethanol biotechnologies.     

Gelatinization properties of native starches and their Näegeli dextrins

Cassava, potato, sweet potato, and Peruvian carrot starches were hydrolyzed with 15% v/v sulfuric acid solution for up to 30 days. Näegeli dextrins obtained from 1, 3, 6, 12, and 30 days were evaluated using differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). Two phases of hydrolysis were found. The first phase was attributed to faster degradation of amorphous areas of granules, whereas the second phase corresponded to slower degradation of crystalline regions. Peruvian carrot starch was the most susceptible to acid, whereas potato and sweet potato starches were the most resistant. From DSC, it was observed a progressive reduction in peak height and a broadening of peaks with increasing hydrolysis time. The peaks shifted to higher temperatures. Onset temperature decreased on first day of hydrolysis for cassava and Peruvian carrot starches, and on third day for potato and sweet potato. Enthalpy decreased during first stage of hydrolysis in cassava and Peruvian carrot starches, and during second phase, it reduced in all starches. SEM showed that the granule surfaces were degraded by erosion on the first day of treatment, followed by degradation of amorphous areas. On third day, potato and sweet potato starches still displayed some granules almost intact, whereas cassava and Peruvian carrot starch granules were totally degraded, confirming their high susceptibility to acid attack. On sixth day of hydrolysis, starch granules had faceted structures, characteristic of crystalline material. The effect that acid hydrolysis had on thermal properties of starches depended on both hydrolysis stage and starch source.     

Electropolymerization of <Emphasis Type="Italic">trans</Emphasis>-[RuCl<Subscript>2</Subscript>(vpy)<Subscript>4</Subscript>] complex—EQCM and Raman studies

The electropolymerization of trans-[RuCl₂(vpy)₄] (vpy=4-vinylpyridine) on Au or Pt electrodes was studied by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) technique, and Raman spectroscopy. Cyclic voltammetry of the monomer at a microelectrode shows the typical Ru(III/II) and Ru(IV/III) waves, together with the vinyl reduction waves at −1.5 and −2.45 V and adsorption wave at −0.8 V. Electrodeposition on EQCM technique performed under potential cycling between −0.9 and −2.0 V revealed that the polymerization proceeded well in advance of the vinyl reduction waves. At potentials more positive than −0.9 V, soluble oligomers were deposited irreversibly on the electrode during the oxidative sweep. The film also showed reversible mass changes due to the oxidation and accompanying ingress of charge-balancing anions and solvent into the film. In contrast, potentiostatic growth of the polymer at −1.6 V was slower because the oligomeric material was lost completely from the electrode. Unreacted vinyl groups were detected by in situ Raman spectroscopy for films grown at −0.7, −0.9, and −1.6 V but were absent when the polymerization was carried out at −2.9 V vs Ag/Ag⁺.     

Analysis of organic components of smokeless gunpowders: high-performance liquid chromatogaphy vs. micellar electrokinetic capillary chromatography

The aim of the present study was to verify the analytical performances of high-performance liquid chromatography (HPLC) and micellar electrokinetic capillary chromatography (MEKC) for the separation and qualitative determination of a selected group of organic components of smokeless gunpowders. The HPLC method was based on a gradient reversed-phase elution with a mobile phase composed of 0.17 M H(3)PO(4)/methanol; detection was performed by UV absorption at the wavelengths of 220, 254, and 270 nm. The MEKC experiments were carried out by using uncoated fused-silica capillaries (50 microm inside diameter, 50 cm effective length) and a running buffer composed of 10 mM sodium tetraborate at pH 9.24 added with 25 mM sodium dodecyl sulfate (SDS); the applied voltage was 25 kV; detection was either at a fixed wavelength UV of 214 nm or with a diode-array detector operating in the wavelength range from 190 to 350 nm. Both reversed-phase HPLC and MEKC techniques succeeded in resolving the tested standard mixtures of organic components of smokeless powders. Although the sequence of elution of the different analytes was slightly different between HPLC and MEKC, a statistical analysis based on the Spearman's rank correlation test showed that the two separation patterns were highly correlated. HPLC and MEKC were comparable in terms of elution/migration time precision, whereas MEKC showed higher reproducibility of peak areas. The interfacing of capillary electrophoresis with diode array UV detection provided distinct UV spectra of the individual analytes, thus improving, on the detection side, the analytical selectivity and identification power of capillary electrophoresis.     

Rapid and direct analysis of gamma-hydroxybutyric acid in urine by capillary electrophoresis-electrospray ionization ion-trap mass spectrometry

The present work was aimed at the development of a capillary electrophoretic analysis of gamma-hydroxybutyric acid (GHB) using electrospray ion trap mass spectrometry to achieve the direct and unequivocal detection of this analyte in human urine. Optimized capillary electrophoretic conditions were: injection, 20 s at 0.5 psi (1 psi = 6894.76 Pa); buffer electrolyte, 12.5 mM ammonium formate adjusted to pH 8.35 with diethylamine; fused silicacapillary: 100 cm x 50 microm i.d.; separation voltage, 25 kV (forward polarity) + 0.5 psi; room temperature. Electrospray and mass spectrometric conditions were: drying gas and nebulizing gas (nitrogen) at flow rate 3 l/min, temperature 250 degrees C, nebulizer pressure: 10 psi; sheath liquid solution: methanol-water (90:10) containing 0.1% ammonia delivered at 3 microl/min; spray voltage 3.5 kV. Mass spetrometric detection was carried out in the selected ion monitoring mode of negative molecular ions at 103 m/z for GHB and 115 m/z for maleic acid (I.S.). Under these conditions the baseline separation of GHB and the I.S. was obtained. The selectivity of the analysis allowed for direct injection of unextracted urine, previously diluted 1:4 with water. Linearity was assessed in the GHB concentration range from 80 to 1280 microg/ml in urine. Analytical sensitivity (as limit of detection) resulted about 5 microg/ml in water and 20 microg/ml in original urine. Analytical precision was fairly acceptable with R.S.D. values lower than 5% for migration times and 18% for quantitation in real samples, in both intra day and day-to-day experiments. On these grounds, the developed method can be adopted for rapid identification of acute intoxications from GHB in humans.     

Neoclerodanes from Teucrium orientale

Two new neoclerodane diterpenoids, 6-deacetyl-teucrolivin A (5) and 8beta-hydroxy-teucrolivin B (6), were isolated from the aerial parts of Teucrium orientale, along with four already known neoclerodane diterpenoids, teucrolivin A (1), teucrolivin B (2), teucrolivin C (3) and teucrolivin H (4), previously isolated from Teucrium oliverianum. Their structures were elucidated on the basis of spectroscopic evidence and chemical transformations. Compounds 1-3 were assayed for antifeedant activity against Spodoptera littoralis, S. frugiperda and Heliocoverpa armigera. Teucrolivin A was the most potent of the three compounds tested.     

Spectroelectrochemistry of type II cytochrome c3 on a glycosylated self-assembled monolayer

A modified silver electrode was prepared by the self-assembly of a thiol-derivatized neoglycoconjugate, forming a 2D surface with maltose functionality. This self-assembled-monolayer-modified electrode was utilized for adsorption and spectroelectrochemical studies of tetraheme-containing type II cytochrome c3. The glycosylated surface allowed for the determination of the hemes' redox potentials and demonstrated enhanced spectroelectrochemical performance, in comparison to the widely used self-assembled monolayer of 11-mercapto-undecanoic acid.     

Mono-, di-, and oligonuclear complexes of Cu(II) ions and p-hydroquinone ligands: syntheses, electrochemical properties, and magnetic behavior

Four highly soluble square-planar Cu(II) and Ni(II) complexes of siloxy-salens (2SiCu, 2SiNi) and hydroxy-salens (2Cu, 2Ni) have been synthesized. An X-ray crystal structure analysis was performed on 2SiCu, 2SiNi, and 2Ni. The compounds have been investigated by cyclic voltammetry, UV-vis-NIR spectroelectrochemistry, and EPR spectroscopy. According to these results, the monooxidized species [2SiCu]+ and [2SiNi]+ are to be classified as Robin-Day class II and III systems, respectively. Magnetic measurements on the dinuclear (PMDTA)Cu(II) complex 1Cu2 x (PF6)2 with deprotonated 1,4-dihydroxy-2,5-bis(pyrazol-1-yl)-benzene (1) linker revealed antiferromagnetic coupling between the two Cu(II) ions thereby resulting in an isolated dimer compound. Coordination polymers [1Cu]n(H2O)(2n) of Cu(II) ions and bridging p-hydroquinone linkers were obtained from CuSO4 x 5 H2O and 1,4-dihydroxy-2,5-bis(pyrazol-1-yl)benzene. X-ray crystallography revealed linear chains running along the crystallographic a-direction and stacked along the b-axis. Within these chains, the Cu(II) ions are coordinated by two pyrazolyl nitrogen atoms and two p-hydroquinone oxygen atoms in a square-planar fashion.     

Different complexation properties of some hydroxy keto heterocycles toward beryllium(II) in aqueous solutions: experimental and theoretical studies

Four heterocycles containing hydroxy and keto functionalities have been tested as chelating agents of beryllium(II). These are in the order (i) 3-hydroxy-2-methyl-4H-pyran-4-one (maltol, Hma), (ii) 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one (kojic acid, Hka), (iii) 3-hydroxy-1,2-dimethyl-4-pyridinone (Hdpp), (iv) 1-(3-hydroxy-2-furanyl)ethanone (isomaltol, Hima). Although the skeletons of the first three species, with one nitrogen or oxygen heteroatom at the six-membered ring, are almost superimposable, straightforward synthesis and crystallization is achieved only for the 1:2 adduct Be(dpp)(2), 1. Also the complex Be(ima)(2), 2, precipitates in high yield but the ima(-) ligand has a different skeletal structure. X-ray determinations of 1 and 2 showed that the Be(2+) ion is pseudotetrahedrally coordinated by two chelating ligands with slightly asymmetric Be-O(alkoxo) and Be-O(keto) bonds. The complex Be(ma)(2) precipitates in low yields together with large amounts of unreacted Hma while, under the same conditions, no trace of the analogous species Be(ka)(2) has been observed. This paper presents the results of potentiometric and NMR studies in the aqueous solutions as well as of DFT structural optimizations for all of the free acids, their associated bases, and the adducts of the type [BeL(H(2)O)(2)](+) and BeL(2) in the gas phase. It is consistently found that the basicity of the ligands and the stability of their complexes decrease in the order dpp(-) > ma(-) > ka(-) > ima(-). In solution, all of the anionic ligands form adducts of the type [BeL(H(2)O)(2)](+) at low pH values, whereas higher concentrations of the free anion are required to form 1:2 adducts. The pH, the basicity, and the stability constants of the complexes as well as the formation of competing beryllium hydroxide species are strictly correlated factors for the obtainment of the latter type of adduct. The DFT calculations account nicely for the different donor powers of the various chelates in terms of electronic redistribution and associated energetics.