International Journal of Coal Science & Technology - A mutualistic relationship between grasses, coal-degrading fungi, and arbuscular mycorrhizal fungi was proposed to account for the... 相似文献
This work reports the application of banana peel as a novel bioadsorbent for in vitro removal of five mycotoxins (aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A). The effect of operational parameters including initial pH, adsorbent dose, contact time and temperature were studied in batch adsorption experiments. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pHpzc) analysis were used to characterise the adsorbent material. Aflatoxins’ adsorption equilibrium was achieved in 15 min, with highest adsorption at alkaline pH (6–8), while ochratoxin has not shown any significant adsorption due to surface charge repulsion. The experimental equilibrium data were tested by Langmuir, Freundlich and Hill isotherms. The Langmuir isotherm was found to be the best fitted model for aflatoxins, and the maximum monolayer coverage (Q0) was determined to be 8.4, 9.5, 0.4 and 1.1 ng mg?1 for AFB1, AFB2, AFG1 and AFG2 respectively. Thermodynamic parameters including changes in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined for the four aflatoxins. Free energy change and enthalpy change demonstrated that the adsorption process was exothermic and spontaneous. Adsorption and desorption study at different pH further demonstrated that the sorption of toxins was strong enough to sustain pH changes that would be experienced in the gastrointestinal tract. This study suggests that biosorption of aflatoxins by dried banana peel may be an effective low-cost decontamination method for incorporation in animal feed diets. 相似文献
There is growing demand for functional food products enriched with long chain omega-3 polyunsaturated fatty acids (LCω3PUFA). Nanoemulsions, systems with extremely small droplet sizes have been shown to increase LCω3PUFA bioavailability. However, nanoemulsion creation and processing methods may impact on the oxidative stability of these systems. The present systematic review collates information from studies that evaluated the oxidative stability of LCω3PUFA nanoemulsions suitable for use in functional foods. The systematic search identified seventeen articles published during the last 10 years. Researchers used a range of surfactants and antioxidants to create systems which were evaluated from 7 to 100 days of storage.
Nanoemulsions were created using synthetic and natural emulsifiers, with natural sources offering equivalent or increased oxidative stability compared to synthetic sources, which is useful as consumers are demanding natural, cleaner label food products. Equivalent vegetarian sources of LCω3PUFA found in fish oils such as algal oils are promising as they provide direct sources without the need for conversion in the human metabolic pathway. Quillaja saponin is a promising natural emulsifier that can produce nanoemulsion systems with equivalent/increased oxidative stability in comparison to other emulsifiers. Further studies to evaluate the oxidative stability of quillaja saponin nanoemulsions combined with algal sources of LCω3PUFA are warranted. 相似文献
Recurrent protein folding motifs include various types of helical bundles formed by α-helices that supercoil around each other. While specific patterns of amino acid residues (heptad repeats) characterize the highly versatile folding motif of four-α-helical bundles, the significance of the polypeptide chain directionality is not sufficiently understood, although it determines sequence patterns, helical dipoles, and other parameters for the folding and oligomerization processes of bundles. To investigate directionality aspects in sequence-structure relationships, we reversed the amino acid sequences of two well-characterized, highly regular four-α-helical bundle proteins and studied the folding, oligomerization, and structural properties of the retro-proteins, using Circular Dichroism Spectroscopy (CD), Size Exclusion Chromatography combined with Multi-Angle Laser Light Scattering (SEC-MALS), and Small Angle X-ray Scattering (SAXS). The comparison of the parent proteins with their retro-counterparts reveals that while the α-helical character of the parents is affected to varying degrees by sequence reversal, the folding states, oligomerization propensities, structural stabilities, and shapes of the new molecules strongly depend on the characteristics of the heptad repeat patterns. The highest similarities between parent and retro-proteins are associated with the presence of uninterrupted heptad patterns in helical bundles sequences. 相似文献
Sulfhydryl groups and disulfide bond were introduced in mungbean's major storage protein, 8Sα globulin, by protein engineering to improve structural stability and functional properties. Five modified proteins or mutants (F59C, I99C, A213C, one free sulfhydryl group; I99C/A213, one disulfide bridge; F59C/I99C/A213C, one free sulfhydryl group and one disulfide linkage) were expressed in Escherichia coli at a yield similar to that of the unmodified protein or wild type (WT) in soluble form (38%). The number of introduced groups in the mutants was confirmed by Ellman analysis. Mutant and WT proteins exhibited similar elution patterns on gel filtration indicating their trimeric native conformation. Mutants had 2 to 3.8 °C higher Tm values than WT and were digested by chymotrypsin at 52–58% in 60 min but exhibited different digestion patterns. All mutants showed greater hardness of heat-induced gels than WT, especially I99C/A213C and F59C/I99C/A213C. Results indicate the improved structural stability of the modified 8Sα globulin. 相似文献
One of the advances in biotechnology has been the development of the capability to produce large quantities of highly purified polypeptides and proteins. Unfortunately, the circulatory half-lives of many of these agents are short, usually of the order of minutes and the time required for a response in tissues is usually long compared to the half-life. Hence, there is always demand for polymeric systems which can deliver the proteins for prolonged period and also to protect the molecules from degradation. The present work was attempted to develop heparin-functionalized gelatin microspheres (HMS) to deliver heparin-binding growth factors particularly for wound-healing applications. The heparin conjugation was carried out using EDC/NHS coupling protocol. Heparin-binding EGF-like growth factor (HB-EGF) was loaded in HMS and its in vitro release behaviour in an environment with or without proteases was studied. The bioactivity of the HB-EGF released from the microspheres was assessed using NIH 3T3 mouse embryonic fibroblast culture. The extent of heparin modification was found to be 1.97 μmol/g of HMS and demonstrated significant protection against enzymatic degradation and sustained release of HB-EGF for more than 10 days. The bioactivity of HB-EGF released from the HMS was retained during the observed release period. The HMS was also found to be non-toxic as determined by calcein AM fluorescent staining. The overall study suggests that the HMS could be used as a growth factor’s delivery component in tissue engineering scaffolds particularly for wound-healing applications. 相似文献