Electrophoretic, antioxidant, and FTIR profiles of some varieties of amaranth, quinoa, and buckwheat seeds and their by products were compared. Water extracts of these products were evaluated by the Folin–Ciocalteau method in order to determine total phenolic content. The antioxidant activities were determined by 2,2′-azobis-2-methyl-propanimidamide, ferric-reducing/antioxidant power, and cupric reducing antioxidant capacity radical scavenging assays. FTIR spectra showed the secondary structure of pseudocereals in the ranges of amides I, II, and III shifts. Results of evaluated methods could be used to control several products (seeds, flours, extracts, flakes, roasting) with high phenolic content and antioxidant activity suitable for supplementation in food applications.
The aim of this paper was to evaluate different strategies of chitosan activation using cross-linking reagent like glycidol, epichlorohydrin, and glutaraldehyde for Thermomyces lanuginosus lipase (TLL) immobilization. Operational activity and stability by esterification of oleic acid with ethanol and thermal inactivation using these derivatives were investigated. Derivative obtained by sequentially activation with glycidol, ethylenediamine, and glutaraldehyde and subsequent TLL immobilization showed the best performance, with high hydrolytic activity value. Its stability was 15-fold higher than solubilized TLL in the evaluated inactivation conditions (60 °C, 25 mM sodium phosphate buffer pH 7). After 5 cycles of oleic acid esterification, only a few percentage of its conversion has reduced. On the other hand, glycidol-activated chitosan derivative showed very low hydrolytic activity value. Epichlorohydrin-activated chitosan derivative showed regular hydrolytic activity value. Both derivatives showed low immobilization yields. Operational stability of this last derivative was very low, where after the first cycle of oleic acid esterification, only 56% of its initial conversion was obtained.
Multiwalled carbon nanotubes (MWNTs) were modified by imidazole-based ionic liquids with different alkyl groups. The modified support samples were characterized by scanning transmission electron microscopy, Raman spectra, thermogravimetric analyses, and X-ray photoelectron spectroscopy. The samples were used to immobilize Candida antarctic lipase (CALB) and the influence of alkyl chain length of ionic liquids on enzymatic properties was investigated by the hydrolysis reaction of triacetin. The results revealed that functionalized ionic liquids modification did not destroy the structure of MWNTs. Compared with the immobilized CALB on MWNTs, the immobilized CALB on novel carriers all exhibited higher activity, thermal stability, and reusability. Especially, the activity of MWNTs-IL (8C)-CALB improved 15.23-folds than MWNTs-CALB, meanwhile, after incubation at 70 °C for 20 min, residual enzyme activity of MWNTs-IL (8C)-CALB was 46% of the initial activity, while MWNTs-CALB already lost all activity. Besides, MWNTs-IL (8C)-CALB retained 64.5% of its initial activity after 4 cycles, while MWNTs-CALB retained only 2.12%.
Integration of wheat straw for a biorefinery-based energy generation process by producing ethanol and biogas together with the production of high-protein fungal biomass (suitable for feed application) was the main focus of the present study. An edible ascomycete fungal strain Neurospora intermedia was used for the ethanol fermentation and subsequent biomass production from dilute phosphoric acid (0.7 to 1.2% w/v) pretreated wheat straw. At optimum pretreatment conditions, an ethanol yield of 84 to 90% of the theoretical maximum, based on glucan content of substrate straw, was observed from fungal fermentation post the enzymatic hydrolysis process. The biogas production from the pretreated straw slurry showed an improved methane yield potential up to 162% increase, as compared to that of the untreated straw. Additional biogas production, using the syrup, a waste stream obtained post the ethanol fermentation, resulted in a combined total energy output of 15.8 MJ/kg wheat straw. Moreover, using thin stillage (a waste stream from the first-generation wheat-based ethanol process) as a co-substrate to the biogas process resulted in an additional increase by about 14 to 27% in the total energy output as compared to using only wheat straw-based substrates.
Currently, the heavy metal pollution is of grave concern, and the part of microorganism for metal bioremediation should take into account as an efficient and economic strategy. On this framework, the heavy metal stress consequences on exopolysaccharide (EPS)-producing agricultural isolate, Pantoea agglomerans, were studied. The EPS production is a protective response to stress to survive and grow in the metal-contaminated environment. P. agglomerans show tolerance and mucoid growth in the presence of heavy metals, i.e., mercury, copper, silver, arsenic, lead, chromium, and cadmium. EDX first confirmed the metal accumulation and further, FTIR determined the functional groups involved in metal binding. The ICP-AES identified the location of cell-bound and intracellular metal accumulation. Metal deposition on cell surface has released more Ca2+. The effect on bacterial morphology investigated with SEM and TEM revealed the sites of metal accumulation, as well as possible structural changes. Each heavy metal caused distinct change and accumulated on cell-bound EPS with some intracellular deposits. The metal stress caused a decrease in total protein content and increased in total carbohydrate with a boost in EPS. Thus, the performance of P. agglomerans under metal stress indicated a potential candidate for metal bioremediation.
The authors describe a method for the detection of DNA by using immobilized molecular beacons (MBs) on the surface of silicon, with a view on possible application in biosensing. MB hybridization and protein recognition were interrogated on silicon-on-insulator (SOI) surfaces by using fluorescently tagged probes. In order to better understand the conformational changes that occur to MBs upon hybridization, the process was studied by using dual polarization interferometry (DPI). A model system was developed that matches thickness, mass, and density parameters. The results experimentally demonstrate that hybridization promotes the displacement of a protein away from the surface. This finding may be further exploited in techniques such as photonic sensors, thereby paving the way to the design of more sensitive biosensors based on the use of MBs.
Graphical abstract Schematic of a new DNA/RNA detection scheme by using immobilized molecular beacons (MBs) on silicon, with a view on possible application in biosensing. A study was performed on the conformational changes that occur to MBs upon hybridization by Dual Polarization Interferometry (DPI).
ε-Poly-l-lysine (ε-PL) is a natural preservative for food processing industry. A thermo-responsive polymer, attached with Cu2+ or Ni2+, was prepared for metal-chelate affinity precipitation for purification of ε-PL. The low critical solution temperatures (LCSTs) of these polymers were close to the room temperature (31.0–35.0 °C). The optimal adsorption conditions were as follows: pH 4.0, 0 mol/L NaCl, ligand density 75.00 μmol/g, and 120 min. The ligand Cu2+ showed a stronger affinity interaction with ε-PL and the highest adsorption amount reached 251.93 mg/g polymer. The elution recovery of ε-PL could be 98.42% with 0.50 mol/L imidazole (pH = 8.0) as the eluent. The method could purify ε-PL from fermentation broth and the final product was proved as electrophoretic pure by SDS-PAGE. Moreover, these affinity polymers could be recycled after the purification of ε-PL and the recoveries were above 95.00%.
Rhodococcus sp. has a broad catabolic diversity and unique enzymatic capabilities, and it is able to adapt under extreme conditions. Thereby, the production of this remarkable bacterium has a great biotechnological and industrial importance. In this sense, we sought to improve the R. erythropolis ATCC 4277 growth through a central composite design, by varying the components of nutrient medium (glucose, malt extract, yeast extract, CaCO3), temperature, and agitation. It was found that the concentrations of glucose and malt extract are not statistically significant, being reduced of 4.0 and 10.0 g L-1 to 2.0 and 5.0 g L?1, respectively. The CaCO3 concentration and temperature were also diminished of 2.0 to 1.16 g L?1and 28 to 23.7 °C, respectively. Optimal growth conditions provided a 240% increase in final biomass concentration, an increment in specific growth rate, and a growth yield coefficient about five times greater. Application of the optimal conditions in biodesulfurization and biodenitrogenation processes showed that desulfurization capability is not associated with optimal growth conditions; however, it was achieved a 47% of nitrogen removal in the assay containing 10% (w/w) of heavy gas oil.
Sugarcane bagasse (SCB) and molasses, known as carbohydrate-rich biomass derived from sugar production, can serve as feedstock for bio-ethanol production. To establish a simple process, the production of bio-ethanol through integration of whole pretreated slurry (WPS) of SCB with molasses was investigated. The results showed that microwave-assisted dilute sulfuric acid pretreatment reduced the formation of toxic compounds compared to a pretreatment process involving “conventional heating”. Pretreatment at 180 oC with 10% w v?1 solid loading and 0.5% w v?1 H2SO4 was sufficient to achieve efficient enzymatic saccharification of WPS. By conducting separate hydrolysis and fermentation (SHF), an ethanol yield of 90.12% was obtained from the mixture of WPS and molasses, but the ethanol concentration of 33.48 g L?1 was relatively low. By adopting fed-batch SHF, the ethanol concentration reached 41.49 g L?1. Assuming that the molasses were converted to ethanol at an efficiency of 87.21% (i.e., ethanol was obtained from fermentation of molasses alone), the ethanol yield from WPS when a mixture of WPS and molasses was fermented was 78.30%, which was higher than that of enzymatic saccharification of WPS (73.53%). These findings suggest that the production of bio-ethanol via integration of WPS with molasses is a superior method.
Porcine pancreatic lipase (PPL) was immobilized onto functionalized ionic liquid-modified silica carrier using gelatinization and physical adsorption. The immobilized lipase was characterized with N2 adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) before and after modification and immobilization. The results showed that the modification of the ionic liquid and the introduction of lipase had been successfully approved. The rate of enzymatic reaction and its influencing factors was primarily studied by enzymatic reaction kinetics. Km values of PPL-SiO2@CA and PPL-IM/BF4-SiO2@CA were 4.9 and 3.7 mg/ml, respectively. It indicated that the modification of the functionalized ionic liquid enhanced the affinity between the immobilized enzyme and the substrate. The immobilization efficiency, specific activity, optimum temperature, optimum pH, thermal stability, reusability, and storage stability of the immobilized enzyme were investigated. We found that the stability of the immobilized enzyme was significantly higher than that of the unmodified immobilized enzyme. Specially, PPL-IM/BF4-SiO2@CA maintained good thermal stability and retained more than 92% of its activity at 65 °C after preheating 3 h.
Structural isomers and enantiomers of hexachlorocyclohexane (HCH) were separated using a chiral column by gas chromatography and quantitatively determined by multiphoton ionization mass spectrometry using an ultraviolet femtosecond laser (200 and 267 nm) as the ionization source. The order of elution of the enantiomers (i.e., (+)-α-HCH and (-)-α-HCH) was predicted from stabilization energies calculated for the complexes using permethylated γ-cyclodextrin as the stationary phase of the column, and the results were compared with the experimental data. The molecular ions observed for HCH were weak, even though they can be ionized through a process of resonance enhanced two-photon ionization at 200 nm. This unfavorable result can be attributed to the dissociation of the molecular ion, as predicted from quantum chemical calculations.
An enzyme immobilized on a mesoporous silica nanoparticle can serve as a multiple catalyst for the synthesis of industrially useful chemicals. In this work, MCM-41 nanoparticles were coated with polyethylenimine (MCM-41@PEI) and further modified by chelation of divalent metal ions (M = Co2+, Cu2+, or Pd2+) to produce metal-chelated silica nanoparticles (MCM-41@PEI-M). Thermomyces lanuginosa lipase (TLL) was immobilized onto MCM-41, MCM-41@PEI, and MCM-41@PEI-M by physical adsorption. Maximum immobilization yield and efficiency of 75 ± 3.5 and 65 ± 2.7% were obtained for MCM@PEI-Co, respectively. The highest biocatalytic activity at extremely acidic and basic pH (pH = 3 and 10) values were achieved for MCM-PEI-Co and MCM-PEI-Cu, respectively. Optimum enzymatic activity was observed for MCM-41@PEI-Co at 75 °C, while immobilized lipase on the Co-chelated support retained 70% of its initial activity after 14 days of storage at room temperature. Due to its efficient catalytic performance, MCM-41@PEI-Co was selected for the synthesis of ethyl valerate in the presence of valeric acid and ethanol. The enzymatic esterification yield for immobilized lipase onto MCM-41@PEI-Co was 60 and 53%, respectively, after 24 h of incubation in n-hexane and dimethyl sulfoxide media.
Graphical Abstract Divalent metal chelated polyethylenimine coated MCM-41 (MCM-41@PEI-M) was used for immobilization of Thermomyces lanuginosa lipase catalyzing green apple flavor preparation
A modified Kendrick Mass Defect (KMD) analysis was applied to the analysis of polycyclic aromatic hydrocarbons (PAHs) and fullerenes in the diffusion flame from a handheld butane torch.
The analysis of many hydrogen exchange (HX) experiments depends on knowledge of exchange rates expected for the unstructured protein under the same conditions. We present here some minor adjustments to previously calibrated values and a stringent test of their accuracy.
The heat capacity and density of solutions of cadmium and mercury diiodides in methylpyrrolidone (MP) at 298.15 K were studied by calorimetry and densimetry. The data obtained are discussed in relation to the special features of solvation and complex formation in solutions of the salts. The standard partial molar heat capacities and volumes (
Differential or field asymmetric waveform ion mobility spectrometry (FAIMS) operating at high electric fields fully resolves isotopic isomers for a peptide with labeled residues. The naturally present isotopes, alone and together with targeted labels, also cause spectral shifts that approximately add for multiple heavy atoms. Separation qualitatively depends on the gas composition. These findings may enable novel strategies in proteomic and metabolomic analyses using stable isotope labeling.
The development of tandem ion mobility spectroscopy (IMS) known as IMS-IMS has led to extensive research into isomerizations of isolated molecules. Many recent works have focused on the retinal chromophore which is the optical switch used in animal vision. Here, we study a shortened derivative of the chromophore, which exhibits a rich IM spectrum allowing for a detailed analysis of its isomerization pathways, and show that the longer the chromophore is, the lower the barrier energies for isomerization are.
Quadrupole mass filters using non-sinusoidal driving potentials present exciting opportunities for new functionality. Predicting figures of merit like resolving power and transmission efficiency helps characterize these emerging devices. To this end, matrix methods of solving the Hill equation of ion motion are employed to calculate stability diagrams and pseudopotential well depth maps in the a,q plane for arbitrary waveforms. The theoretical resolving power and well depth of digital, trapezoidal and sinusoidal mass filters are compared. Simplified expressions for digital mass filter operation are presented.
Current literature shows a gap for methods which can identify yeast sub-species (strains or serovars) in samples where there are no viable cells remaining. Presented here is a technique for the analysis of yeast supernatant, including solid phase extraction, data-dependent acquisition liquid chromatography/mass spectrometry (LC-MS), and two chemometric methods to identify and classify yeast strains. Five strains of Saccharomyces cerevisiae were successfully identified in various stages of growth. In addition, peptide/protein identification was performed, without the need for additional data acquisition.
Proof of concept evidence is presented for a new method for the determination of isoaspartate, an important post-translational modification. Chemical derivatization is performed using common reagents for the modification of carboxylic acids and shown to yield suitable diagnostic information with regard to isomerization at the aspartate residue. The diagnostic gas phase chemistry is probed by collision-induced dissociation mass spectrometry, on the timescale of the MS experiment and semi-quantitative calibration of the percentage of isoaspartate in a peptide sample is demonstrated.
