Production and characterization of poly-(3-hydroxybutyrate) from recombinant Escherichia coli grown on cheap renewable carbon substrates

Although the biopolymer poly-(3-hydroxybutyrate), P[3HB], presents physicochemical properties that make it an alternative material to conventional plastics, its biotechnological production is quite expensive. As carbon substrates contribute greatly to P[3HB] production cost, the utilization of a cheaper carbon substrate and less demanding micro-organisms should decrease its cost. In the present study a 23 factorial experimental design was applied, aiming to evaluate the effects of using hydrolysed corn starch (HCS) and soybean oil (SBO) as carbon substrates, and cheese whey (CW) supplementation in the mineral medium (MM) on the responses, cell dried weigh (DCW), percentage P[3HB] and mass P[3HB] by recombinant Escherichia coli strains JM101 and DH10B, containing the P[3HB] synthase genes from Cupriavidus necator (ex-Ralstonia eutropha). The analysis of effects indicated that the substrates and the supplement and their interactions had positive effect on CDW. Statistically generated equations showed that, at the highest concentrations of HCS, SO and CW, theoretically it should be possible to produce about 2 g L(1) DCW, accumulating 50% P[3HB], in both strains. To complement this study, the strain that presented the best results was cultivated in MM added to HCS, SBO and CW ( in best composition observed) and complex medium (CM) to compare the obtained P[3HB] in terms of physicochemical parameters. The obtained results showed that the P[3HB] production in MM (1.29 g L(-1)) was approximately 20% lower than in CM (1.63 g L(-1)); however, this difference can be compensated by the lower cost of the MM achieved by the use of cheap renewable carbon sources. Moreover, using differential scanning calorimetry and thermogravimetry analyses, it was observed that the polymer produced in MM was the one which presented physicochemical properties (Tg and Tf) that were more similar to those found in the literature for P[3HB].

Microcystis aeruginosa lipids as feedstock for biodiesel synthesis by enzymatic route

The cyanobacterium Microcystis aeruginosa strain NPCD-1, isolated from sewage treatment plant and characterized as a non-microcystin producer by mass spectrometry and molecular analysis, was found to be a source of lipid when cultivated in ASM-1 medium at 25 degrees C under constant white fluorescent illumination (109 mu mol photon m(-2) s(-1)). In these conditions, biomass productivity of 46.92 +/- 3.84 mg L-1 day(-1) and lipid content of 28.10 +/- 1.47% were obtained. Quantitative analysis of fatty acid methyl esters demonstrated high concentration of saturated fatty acids (50%), palmitic (24.34%) and lauric (13.21%) acids being the major components. The remaining 50% constituting unsaturated fatty acids showed higher concentrations of oleic (26.88%) and linoleic (12.53%) acids. The feasibility to produce biodiesel from this cyanobacterial lipid was demonstrated by running enzymatic transesterification reactions catalyzed by Novozym (R) 435 and using palm oil as feedstock control. Batch experiments were carried out using tert-butanol and iso-octane as solvent. Results showed similarity on the main ethyl esters formed for both feedstocks. The highest ethyl ester concentration was related to palmitate and oleate esters followed by laurate and linoleate esters. However, both reaction rates and ester yields were dependent on the solvent tested. Total ethyl ester concentrations varied in the range of 44.24-67.84 wt%, corresponding to ester yields from 80 to 100%. Iso-octane provided better solubility and miscibility, with ester yield of 98.10% obtained at 48 h for reaction using the cyanobacterium lipid, while full conversion was achieved in 12 h for reaction carried out with palm oil. These results demonstrated that cyanobacterial lipids from M. aeruginosa NPCD-1 have interesting properties for biofuel production. (c) 2012 Elsevier B.V. All rights reserved.

Additional scaled solutions to Richards' equation for infiltration and drainage

Warrick and Hussen developed in the nineties of the last century a method to scale Richards' equation (RE) for similar soils. In this paper, new scaled solutions are added to the method of Warrick and Hussen considering a wider range of soils regardless of their dissimilarity. Gardner-Kozeny hydraulic functions are adopted instead of Brooks-Corey functions used originally by Warrick and Hussen. These functions allow to reduce the dependence of the scaled RE on the soil properties. To evaluate the proposed method (PM), the scaled RE was solved numerically using a finite difference method with a fully implicit scheme. Three cases were considered: constant-head infiltration, constant-flux infiltration, and drainage of an initially uniform wet soil. The results for five texturally different soils ranging from sand to clay (adopted from the literature) showed that the scaled solutions were invariant to a satisfactory degree. However, slight deviations were observed mainly for the sandy soil. Moreover, the scaled solutions deviated when the soil profile was initially wet in the infiltration case or when deeply wet in the drainage condition. Based on the PM, a Philip-type model was also developed to approximate RE solutions for the constant-head infiltration. The model showed a good agreement with the scaled RE for the same range of soils and conditions, however only for Gardner-Kozeny soils. Such a procedure reduces numerical calculations and provides additional opportunities for solving the highly nonlinear RE for unsaturated water flow in soils. (C) 2011 Elsevier B.V. All rights reserved.

The Effect of Contact on the Filter Paper Method for Measuring Soil Suction

The filter paper method is one of the most commonly used and critiqued techniques for measuring soil suction. However, many aspects related to its use still require some clarification. The results of a comprehensive study on the effect of the contact between the soil grains and soil water and the filter paper are presented herein. We investigated the influence of the equilibration time, the texture of the porous material and the degree of contact, or lack thereof, between the soil grains and the filter paper using Miamian #42 and three different types of porous material. To enhance the difference between the total suction and the matrix suction, osmotic suction was induced by saturating the specimens with a sodium chloride solution.

Mixed colonies of two species of congeneric stingless bees (Hymenoptera: Apinae, Meliponini) display environmentally-acquired and endogenously-produced recognition signals

Nestmate recognition is fundamental for the maintenance of social organization in insect nests. It is becoming well recognized that cuticle hydrocarbons mediate the recognition process, although the origin of recognition cues in stingless bees remains poorly explored. The present study investigates the effects of endogenously-produced and environmentally-acquired components in cuticular hydrocarbons in stingless bees. The tests are conducted using colonies of Plebeia droryana Friese and Plebeia remota Holmberg. Recognition tests are performed with four different groups: conspecific nestmates, conspecific non-nestmates, heterospecifics and conspecific, genetically-related individuals that emerge in a heterospecific nest. This last group is produced by introducing brood cells of P. droryana into a P. remota colony, and the resulting adult bees are tested for acceptance 10 days after emergence. For all groups, 15 individuals are sampled for chemical analysis. The results show the acceptance of all conspecific nestmates, and the rejection of almost every conspecific non-nestmate and every heterospecific bee. Genetically-related individuals emerging from heterospecific nests present intermediate rejection (66.7% rejection). Chemical analysis shows that P. droryana individuals emerging in a P. remota nest have small amounts of alkene and diene isomers found in P. remota cuticle that are not found in workers from the natal nest. The data clearly show that the majority of the compounds present in P. droryana cuticle are endogenously produced, although a few unsaturated compounds are acquired from the environment, increasing the chemical differences and, consequently, the rejection percentages.

Flow-injection spectrophotometric determination of captopril in pharmaceutical formulations using a new solid-phase reactor containing AgSCN immobilized in a polyurethane resin

A simple flow-injection analysis procedure was developed for determining captopril in pharmaceutical formulations employing a novel solid-phase reactor containing silver thiocyanate immobilized in a castor oil derivative polyurethane resin. The method was based on silver mercaptide formation between the captopril and Ag(I) in the solid-phase reactor. During such a reaction, the SCN- anion was released and reacted with Fe3+, which generated the FeSCN2+ complex that was continuously monitored at 480 nm. The analytical curve was linear in the captopril concentration range from 3.0 x 10(-4) mol L-1 to 1.1 x 10(-3) mol L-1 with a detection limit of 8.0 x 10(-5) mol L-1. Recoveries between 97.5% and 103% and a relative standard deviation of 2% for a solution containing 6.0 x 10(-4) mol L-1 captopril (n = 12) were obtained. The sample throughput was 40 h(-1) and the results obtained for captopril in pharmaceutical formulations using this procedure and those obtained using a pharmacopoeia procedure were in agreement at a 95% confidence level.

Chemical Modifications in Styrene-Butadiene Rubber after Microwave Devulcanization

Microwave devulcanization has been studied as a method for elastomer recycling, which is based on the conversion of the reticulated and infusible structure of thermosetting rubbers in free polymeric chains able to be remolded by thermomechanical processing in recycling operations for the manufacture of other products. Elastomeric wastes are often irregularly discarded in nature, producing serious environmental damage, and their mechanical recycling is still considered a challenge. Thus, the development of alternatives for elastomer recycling is directly related to the actions of sustainable development and economic benefits to companies that pay to discard their wastes. The aim of this work is to evaluate the chemical modifications occurring in styrene butadiene rubber (SBR) after microwave devulcanization. Compounds of SBR were vulcanized in the presence of vulcanization agents and variable amounts of carbon black, and then the rubbers were milled and submitted to microwave treatment. Only the SBR with high carbon black content shows some portion of devulcanized material. However, the rubber with lower content of carbon black which was devulcanized by microwave radiation shows an increase in cross-link density. The microwave treatment also causes cross-link breaks mainly in polysulfidic bonds as well as decomposition of chemical groups containing sulfur attached to the chemical structure of SBR, while. the chemical bonds of higher energy such as monosulfidic bonds remain preserved. The improvement of the microwave method for rubber devulcanization represents a way for viable recycling of thermosetting rubbers.

Invariant Solutions of Richards' Equation for Water Movement in Dissimilar Soils

Scaling methods allow a single solution to Richards' equation (RE) to suffice for numerous specific cases of water flow in unsaturated soils. During the past half-century, many such methods were developed for similar soils. In this paper, a new method is proposed for scaling RE for a wide range of dissimilar soils. Exponential-power (EP) functions are used to reduce the dependence of the scaled RE on the soil hydraulic properties. To evaluate the proposed method, the scaled RE was solved numerically considering two test cases: infiltration into relatively dry soils having initially uniform water content distributions, and gravity-dominant drainage occurring from initially wet soil profiles. Although the results for four texturally different soils ranging from sand to heavy clay (adopted from the UNSODA database) showed that the scaled solution were invariant for a wide range of flow conditions, slight deviations were observed when the soil profile was initially wet in the infiltration case or deeply wet in the drainage case. The invariance of the scaled RE makes it possible to generalize a single solution of RE to many dissimilar soils and conditions. Such a procedure reduces the numerical calculations and provides additional opportunities for solving the highly nonlinear RE for unsaturated water flow in soils.

Effect of supplementation of two sources and two levels of copper on lipid metabolism in Nellore beef cattle

This study was conducted with 35 Nellore beef cattle to determine the effect of supplementation of two levels and two copper sources (organic and inorganic) on metabolism of lipids and cholesterol of meat. The five treatments used were: Control: without copper supplementation, 110 or 140: 10 or 40 mg/kg DM (as Cu sulfate), O10 or O40: 10 or 40 mg/kg DM (as Cu proteinate). In general, the copper supplementation changed the fatty acid profile of meat (p < 0.05), with a higher proportion of unsaturated fatty acids and reduction of saturated fatty acids. There was no effect of supplementation on blood cholesterol and triglycerides, however; in general, there was a reduction in cholesterol concentration in the L dorsi (p < 0.05) compared to the control treatment through the reduction (p < 0.05) in the concentrations of GSH and GSH/GSSG ratio. The Cu supplementation did have an influence on metabolism of lipids. The production of healthier meat is beneficial to public health by reducing the risk of cardiovascular disease. (C) 2012 Elsevier Ltd. All rights reserved.

Tannin-phenolic resins: Synthesis, characterization, and application as matrix in biobased composites reinforced with sisal fibers

A tannin-phenolic resin (40 wt% of tannin, characterized by H-1 nuclear magnetic resonance (NMR) and C-13 NMR, Fourier transform infrared, thermogravimetry, differential scanning calorimetry) was used to prepare composites reinforced with sisal fibers (30-70 wt%). Inverse gas chromatography results showed that the sisal fibers and the tannin-phenolic thermoset have close values of the dispersive component and also have predominance of acid sites (acid character) at the surface, confirming the favoring of interaction between the sisal fibers and the tannin-phenolic matrix at the interface. The Izod impact strength increased up to 50 wt% of sisal fibers. This composite also showed high storage modulus, and the lower loss modulus, confirming its good fiber/matrix interface, also observed by SEM images. A composite with good properties was prepared from high content of raw material obtained from renewable sources (40 wt% of tannin substituted the phenol in the preparation of the matrix and 50 wt% of matrix was replaced by sisal fibers). (C) 2012 Elsevier Ltd. All rights reserved.

Lipase-catalyzed kinetic resolution of beta-borylated carboxylic esters

The kinetic resolution of chiral beta-borylated carboxylic esters via lipase-catalyzed hydrolysis and transesterification reactions was studied. The enantioselective hydrolysis catalyzed by CAL-B furnished the beta-borylated carboxylic acid with reasonable enantiomeric excess (62% ee), while both methyl and ethyl beta-borylated carboxylic esters were recovered with excellent ee (>99%). Meanwhile, the transesterification reaction of beta-borylated carboxylic esters and several alcohols, catalyzed by CAL-B, only indicated a high selectivity when ethanol and methyl-(beta-pinacolylboronate)-butanoate were used as substrates, which gave ethyl-(beta-pinacolylboronate)-butanoate with >99% ee. (C) 2012 Elsevier Ltd. All rights reserved.

Omega-6 polyunsaturated fatty acids prevent atherosclerosis development in LDLr-KO mice, in spite of displaying a pro-inflammatory profile similar to trans fatty acids

The development of atherosclerosis and the inflammatory response were investigated in LDLr-KO mice on three high-fat diets (40% energy as fat) for 16 weeks: trans (TRANS), saturated (SAFA) or omega-6 polyunsaturated (PUFA) fats. The following parameters were measured: plasma lipids, aortic root total cholesterol (TC), lesion area (Oil Red-O), ABCA1 content and macrophage infiltration (immunohistochemistry), collagen content (Picrosirius-red) and co-localization of ABCA1 and macrophage (confocal microscopy) besides the plasma inflammatory markers (IL-6, TNF-alpha) and the macrophage inflammatory response to lipopolysaccharide from Escherichia coli (LPS). As expected, plasma TC and TG concentrations were lower on the PUFA diet than on TRANS or SAFA diets. Aortic intima macrophage infiltration, ABCA1 content, and lesion area on PUFA group were lower compared to TRANS and SAFA groups. Macrophages and ABCA1 markers did not co-localize in the atherosclerotic plaque, suggesting that different cell types were responsible for the ABCA1 expression in plaques. Compared to PUFA, TRANS and SAFA presented higher collagen content and necrotic cores in atherosclerotic plaques. In the artery wall, TC was lower on PUFA compared to TRANS group; free cholesterol was lower on PUFA compared to TRANS and SAFA; cholesteryl ester concentration did not vary amongst the groups. Plasma TNF-alpha concentration on PUFA and TRANS-fed mice was higher compared to SAFA. No difference was observed in IL-6 concentration amongst groups. Regarding the macrophage inflammatory response to LPS, TRANS and PUFA presented higher culture medium concentrations of IL-6 and TNF-alpha as compared to SAFA. The PUFA group showed the lowest amount of the anti-inflammatory marker IL-10 compared to TRANS and SAFA groups. In conclusion, PUFA intake prevented atherogenesis, even in a pro-inflammatory condition. (c) 2012 Elsevier Ireland Ltd. All rights reserved.

Photo-activated phase separation in giant vesicles made from different lipid mixtures

Using giant unilamellar vesicles (GUVs) made from POPC. DPPC, cholesterol and a small amount of a porphyrin-based photosensitizer that we name PE-porph, we investigated the response of the lipid bilayer under visible light, focusing in the formation of domains during the lipid oxidation induced by singlet oxygen. This reactive species is generated by light excitation of PE-porf in the vicinity of the membrane, and thus promotes formation of hydroperoxides when unsaturated lipids and cholesterol are present. Using optical microscopy we determined the lipid compositions under which GUVs initially in the homogeneous phase displayed Lo-Ld phase separation following irradiation. Such an effect is attributed to the in situ formation of both hydroperoxized POPC and cholesterol. The boundary line separating homogeneous Lo phase and phase coexistence regions in the phase diagram is displaced vertically towards the higher cholesterol content in respect to ternary diagram of POPC:DPPC:cholesterol mixtures in the absence of oxidized species. Phase separated domains emerge from sub-micrometer initial sizes to evolve over hours into large Lo-Ld domains completely separated in the lipid membrane. This study provides not only a new tool to explore the kinetics of domain formation in mixtures of lipid membranes, but may also have implications in biological signaling of redox misbalance. (C) 2011 Elsevier B.V. All rights reserved.

Exploring the intrinsic polar [4?+?2+] cycloaddition reactivity of gaseous carbosulfonium and carboxonium ions

Gas-phase reactions of model carbosulfonium ions (CH3-S+?=?CH2; CH3CH2-S+?=?CH2 and Ph-S+?=?CH2) and an O-analogue carboxonium ion (CH3-O+?=?CH2) with acyclic (isoprene, 1,3-butadiene, methyl vinyl ketone) and cyclic (1,3-cyclohexadiene, thiophene, furan) conjugated dienes were systematically investigated by pentaquadrupole mass spectrometry. As corroborated by B3LYP/6-311?G(d,p) calculations, the carbosulfonium ions first react at large extents with the dienes forming adducts via simple addition. The nascent adducts, depending on their stability and internal energy, react further via two competitive channels: (1) in reactions with acyclic dienes via cyclization that yields formally [4?+?2+] cycloadducts, or (2) in reactions with the cyclic dienes via dissociation by HSR loss that yields methylenation (net CH+ transfer) products. In great contrast to its S-analogues, CH3-O+?=?CH2 (as well as C2H5-O+?=?CH2 and Ph-O+?=?CH2 in reactions with isoprene) forms little or no adduct and proton transfer is the dominant reaction channel. Isomerization to more acidic protonated aldehydes in the course of reaction seems to be the most plausible cause of the contrasting reactivity of carboxonium ions. The CH2?=?CH-O+?=?CH2 ion forms an abundant [4?+?2+] cycloadduct with isoprene, but similar to the behavior of such alpha,beta-unsaturated carboxonium ions in solution, seems to occur across the C?=?C bond. Copyright (c) 2012 John Wiley & Sons, Ltd.

Chemical Bonding of Hydrocarbons to Metal Surfaces

Using x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) in combination with density functional theory (DFT) the changes in electronic and geometric structure of hydrocarbons upon adsorption are determined. The chemical bonding is analyzed and the results provide new insights in the mechanisms responsible for dehydrogenation in heterogeneous catalysis. In the case of alkanes, n-octane and methane are studied. XAS and XES show significant changes in the electronic structure upon adsorption. XES shows new adsorption induced occupied states and XAS shows quenching of CH*/Rydberg states in n-octane. In methane the symmetry forbidden gas phase lowest unoccupied molecular orbital becomes allowed due to broken symmetry. New adsorption induced unoccupied features with mainly metal character appear just above the Fermi level in XA spectra of both adsorbed methane and n-octane. These changes are not observed in DFT total energy geometry optimizations. Comparison between experimental and computed spectra for different adsorbate geometries reveals that the molecular structures are significantly changed in both molecules. The C-C bonds in n-octane are shortened upon adsorption and the C-H bonds are elongated in both n-octane and methane. In addition ethylene and acetylene are studied as model systems for unsaturated hydrocarbons. The validity of both the Dewar-Chatt-Duncanson chemisorption model and the alternative spin-uncoupling picture is confirmed, as well as C-C bond elongation and upward bending of the C-H bonds. The bonding of ethylene to Cu(110) and Ni(110) are compared and the results show that the main difference is the amount of back-donation into the molecular π* orbital, which allows the molecule to desorb molecularly from the Cu(110) surface, whereas it is dehydrogenated upon heating on the Ni(110) surface. Acetylene is found to adsorb in two different adsorption sites on the Cu(110) surface at liquid nitrogen temperature. Upon heating the molecules move into one of these sites due to attractive adsorbate-adsorbate interaction and only one adsorbed species is present at room temperature, at which point the molecules start reacting to form benzene. The bonding of the two species is very similar in both sites and the carbon atoms are rehybridized essentially to sp2.