Antimicrobial Peptides from the Aurein Family Form Ion‐Selective Pores in Bacillus subtilis

The mechanism of action of aurein 2.2 and aurein 2.3, antimicrobial peptides from the frog Litoria aurea, was investigated. Proteomic profiling of the Bacillus subtilis stress response indicates that the cell envelope is the main target for both aureins. Upon treatment, the cytoplasmic membrane depolarizes and cellular ATP levels decrease. Global element analysis shows that intracellular concentrations of certain metal ions (potassium, magnesium, iron, and manganese) strongly decrease. Selective translocation of some ions over others was demonstrated in vitro. The same set of ions also leaks from B. subtilis cells treated with sublethal concentrations of gramicidin S, MP196, and nisin. Aureins do not permeabilize the cell membrane for propidium iodide thus excluding formation of large, unspecific pores. Our data suggest that the aureins acts by forming small pores thereby causing membrane depolarization, and by triggering the release of certain metal ions thus disturbing cellular ion homeostasis.     

Fecal shedding of enterohemorrhagic Escherichia coli in weaned calves following treatment with probiotic Escherichia coli

The fecal shedding and pathogenicity of enterohemorrhagic E. coli (EHEC) O26:H11, EHEC O111:NM, and EHEC O157:H7 in weaned calves (8 to 10 weeks of age) were compared with and without treatment with a three-strain mixture of probiotic bacteria (competitive-exclusion E. coli). Three groups of 12 calves were each perorally given a five-strain mixture of one of the EHEC serotypes (10(10) CFU of total bacteria per calf). Seventy-two hours later, six calves from each group were each administered 10(10) CFU of probiotic bacteria. None of the EHEC serotypes caused significant clinical disease, although a few calves developed mild transient diarrhea or pyrexia. Gross or microscopic lesions attributable to EHEC were not detected in control or probiotic-treated calves at necropsy. For probiotic-treated calves given E. coli O157:H7 and for probiotic-treated calves given E. coli O111:NM, fecal shedding was reduced compared with that for untreated calves. For the probiotic-treated calves given E. coli O157:H7, the reductions in fecal shedding on days 8, 12, 14, 16, 20, 22, 28, and 30 after peroral administration were statistically significant (P<0.05). For probiotic-treated calves given E. coli O111:NM, there were statistically significant reductions (P<0.05) in fecal shedding on days 6, 8, 10, and 12. In contrast, there was no reduction in fecal shedding for calves administered E. coli O26:H11 and treated with the probiotic bacteria. In fact, calves in both the treated and the nontreated groups continued to shed large populations of E. coli O26:H11 throughout the 32-day trial. At necropsy, E. coli O157:H7 was isolated from five of six untreated calves and from only two of six probiotic-treated calves. E. coli O111:NM was isolated from four of six untreated calves at necropsy and from two of six probiotic-treated calves. However, E. coli O26:H11 was isolated from five of six untreated calves and from all six probiotic-treated calves. The results obtained in this study indicate that probiotic E. coli substantially reduced or eliminated fecal shedding of E. coli O157:H7 and E. coli O111:NM 8 to 30 days and 6 to 12 days after the administration of the probiotic culture, respectively, and reduced the persistence of E. coli O157:H7 in the gastrointestinal tract at necropsy (31 to 33 days after the administration of the probiotic culture). The probiotic E. coli did not reduce fecal shedding or gastrointestinal persistence of E. coli O26:H11.     

Selective adsorption of limonin and naringin from orange juice to natural and synthetic adsorbents

In the majority of citrus juices, bitterness is mainly ascribed to the presence of limonoids (triterpenes) and flavanone glycosides (flavonoids), namely limonin and naringin. In this study, the selective removal of limonin and naringin from citrus juice by batch adsorption to different materials was investigated. Since the removal of reducing sugars, pigments and vitamin C may also occur, the eventual adsorption of these compounds was also investigated. The following adsorbents were tested: activated diatomaceous earths, granulated activated carbon and synthetic neutral resins (Amberlite XAD-4, XAD-7 and XAD-16). Both Freundlich and Langmuir isotherm models showed a good fit to the adsorption of limonin to the resins used. Concerning naringin adsorption, a good fit of these models was only observed when the XAD-7 resin was used. Sigmoidal profiles were obtained for the adsorption of limonin to granular activated carbon. Unfavourable isotherms were also observed for limonin and naringin adsorption to activated earths. These isotherm adsorption profiles can be explained by a multilayer adsorption phenomenon. The highest adsorption efficiency for the bitter compounds was observed when synthetic neutral resin, Amberlite XAD-7 was used. The separation factor limonin/naringin varied from 16 (with earths) to 57 (with XAD-7 resin). The adsorption of sugars and pigments to the resins was low. No adsorption of vitamin C was detected for any of the adsorbents tested. The estimated affinity and separation factors show that the neutral resins tested are adequate for the selective removal of limonin from orange juices. The estimated values of free energy of adsorption, lower than -13.3 kJ mol^-1 K^-1, indicate that a physiosorption process occurred.     

The effect of kefir addition on microstructure parameters and physical properties of porous white bread

The effect of kefir concentration on the quality of porous white bread has been investigated. Quality evaluation was done using flatbed scanning (FBS) for measuring crumb porosity, instrumental texture profile analysis (TPA), crust and crumb color (L ^* a ^* b ^*), moisture, specific volume, and density determination techniques. The correlations between porosity, brightness, and firmness were also investigated. Long fermentation time of the sourdough changed significantly (p<0.05) the cell mean area (mm²), cell mean perimeter (mm), firmness (N), chewiness (N), light reflectance, and specific volume (ml/g). A strong correlation was found between microstructure of porous white bread, brightness (L), and firmness from TPA test. Kefir prolonged the shelf life of bread.     

Antioxidant activity of commercial ready-to-drink orange juice and nectar

Total antioxidant activity (TAA), total phenolic compounds (TPC), and physicochemical characteristics of ready-to-drink orange juice and nectar from the most consumed brands available in Brazil were evaluated. TPC ranged from 18.7 to 54.2 mg of gallic acid/100 mL, and TAA varied from 57.88 to 349.32 μmol TEAC/100 mL ready-to-drink orange juice and nectar. The ascorbic acid content was the only physicochemical parameter that showed strong variation among packages and brands. Correlation of TPC with TAA showed that the higher the level of TPC the higher the TAA. Correlation of ascorbic acid content with TAA is higher for ready-to-drink orange juice than nectar. The same was found for the correlation of ascorbic acid content with TPC. The results confirm the contribution of the TPC to TAA.     

Effects of Combined Allogenic Adipose Stem Cells and Hyperbaric Oxygenation Treatment on Pathogenesis of Osteoarthritis in Knee Joint Induced by Monoiodoacetate

The beneficial effects of HBO in inflammatory processes make it an attractive type of treatment for chronic arthritis. In addition, the effects of combination therapy based on adipose stem cells and HBO on OA progression have not been fully investigated. The current study explored the efficacy of intra-articular injection of allogeneic adipose-derived mesenchymal stem cells (ADMSCs) combined with hyperbaric oxygenation treatment (HBO) in a rat osteoarthritis (OA) model. The rat OA model was induced by intra-articular injection of monoiodoacetate (MIA) and 7 days after application of MIA rats were divided into five groups: healthy control (CTRL), osteoarthritis (OA), ADMSCs (ADS), the HBO+ADS^21day and HBO+ADS^28day groups. A single dose of 1 × 10⁶ allogeneic ADMSCs suspended in sterile saline was injected into the knee joint alone or in combination with HBO treatment. Rats were sacrificed at 3 or 4 weeks after MIA injection. Treatment outcomes were evaluated by radiographic, morphological and histological analysis and by specific staining of articular cartilage. We also measured the level of inflammatory and pro/antioxidative markers. We confirmed that combined treatment of ADMSCs and HBO significantly improved the regeneration of cartilage in the knee joint. Rtg score of knee joint damage was significantly decreased in the HBO+ADS^21day and HBO+ADS^28day groups compared to the OA. However, the positive effect in the HBO+ADS^28day group was greater than the HBO+ADS^21day group. The articular cartilage was relatively normal in the HBO+ADS^28day group, but moderate degeneration was observed in the HBO+ADS^21day compared to the OA group. These findings are in line with the histopathological results. A significantly lower level of O₂⁻. was observed in the HBO+ADS^28day group but a higher NO level compared to the HBO+ADS^21day group. Moreover, in the HBO+ADS^28day group significantly higher concentrations of IL-10 were observed but there was no significant difference in proinflammatory cytokine in serum samples. These results indicate that a single intra-articular injection of allogeneic ADMSCs combined with HBO efficiently attenuated OA progression after 28 days with greater therapeutic effect compared to alone ADMSCs or after 3 weeks of combined treatment. Combined treatment might be an effective treatment for OA in humans.     

The comparative study of biocomposites based on hydrochar and chitosan-modified urea-formaldehyde resins

To provide new insight into the field of urea-formaldehyde (UF) adhesives science, in this work, for the first time, UF resin was modified with hydrochar of spent mushroom substrate (HCUF) and chitosan (CHUF) to investigate the effect of these bio-fillers on the hydrolytic and thermal stability of in situ prepared UF resins. The characterization of the modified UF biocomposites was performed using X-ray diffraction analysis (XRD), Fourier transforms infrared spectroscopy (FTIR), non-isothermal thermogravimetric analysis (TG), differential thermal gravimetry (DTG), and differential thermal analysis (DTA). Scanning electron micrographs (SEM) of the CHUF and HCUF biocomposites show a spherical structure that differs from each other because the surface of the CHUF biocomposite has pronounced pores that form a network structure. With its hydroxyl and amino groups, chitosan bonding to UF resin through hydrogen bonds, which is confirmed by FTIR analysis. The content of free FA in CHUF biocomposite is 0.06%, while that of HCUF is higher and amounts to 0.48%. The content of released FA in both modified UF biocomposites was similar (2.5% and 2.8% for CHUF and HCUF, respectively). The hydrolytic stability of CHUF is slightly higher compared to the HCUF biocomposite. Thermal analysis shows that the CHUF is thermally more stable because it starts to decompose at a slightly higher temperature than the HCUF biocomposite.     

Structural Explanation of the Dielectric Enhancement of Barium Titanate Nanoparticles Grown under Hydrothermal Conditions

When synthesized under certain conditions, barium titanate (BaTiO₃, BTO) nanoparticles are found to have the non-thermodynamic cubic structure at room temperature. These particles also have a several-fold enhanced dielectric constant, sometimes exceeding 6000, and are widely used in thin-layer capacitors. A hydrothermal approach is used to synthesize BTO nanocrystals, which are characterized by a range of methods, including X-ray Rietveld refinement and the Williamson–Hall approach, revealing the presence of significant inhomogeneous strain associated with the cubic phase. However, X-ray pair distribution function measurements clearly show the local structure is lower symmetry than cubic. This apparent inconsistency is resolved by examining 3D Bragg coherent diffraction images of selected nanocrystals, which show the existence of ≈50 nm-sized domains, which are interpreted as tetragonal twins, and yet cause the average crystalline structure to appear cubic. The ability of these twin boundaries to migrate under the influence of electric fields explains the dielectric anomaly for the nanocrystalline phase.     

Biopolymers as green-based food packaging materials: A focus on modified and unmodified starch-based films

The ideal food packaging materials are recyclable, biodegradable, and compostable. Starch from plant sources, such as tubers, legumes, cereals, and agro-industrial plant residues, is considered one of the most suitable biopolymers for producing biodegradable films due to its natural abundance and low cost. The chemical modification of starch makes it possible to produce films with better technological properties by changing the functional groups into starch. Using biopolymers extracted from agro-industrial waste can add value to a raw material that would otherwise be discarded. The recent COVID-19 pandemic has driven a rise in demand for single-use plastics, intensifying pressure on this already out-of-control issue. This review provides an overview of biopolymers, with a particular focus on starch, to develop sustainable materials for food packaging. This study summarizes the methods and provides a potential approach to starch modification for improving the mechanical and barrier properties of starch-based films. This review also updates some trends pointed out by the food packaging sector in the last years, considering the impacts of the COVID-19 pandemic. Perspectives to achieve more sustainable food packaging toward a more circular economy are drawn.