Insights into the Fe3+ Doping Effects on the Structure and Electron Distribution of Cr2O3 Nanoparticles.

Herein, we carefully investigated the Fe3+ doping effects on the structure and electron distribution of Cr2O3 nanoparticles using X-ray diffraction analysis (XRD), maximum entropy method (MEM), and density functional theory (DFT) calculations. We showed that increasing the Fe doping induces an enlargement in the axial ratio of c/a, which is associated with an anisotropic expansion of the unit cell. We found that as Fe3+ replaces Cr in the Cr2O3 lattice, it caused a higher interaction between the metal 3d states and the oxygen 2p states, which led to a slight increase in the Cr/Fe-O1 bond length followed by an opposite effect for the Cr/Fe-O2 bonds. Our results also suggest that the excitations characterize a well-localized bandgap region from occupied Cr d to unoccupied Fe d states. The Cr2O3 and Fe-doped Cr2O3 nanoparticles behave as Mott-Hubbard insulators due to their band gap being in the d-d gap, and Cr 3d orbitals dominate the conduction band. These findings suggest that the magnitude and the character of the electronic density near the O atom bonds in Cr2O3 nanoparticles are modulated by the Cr-Cr distances until its stabilization at the induced quasi-equilibrium of the Cr2O3 lattice when the Fe3+ doping values reaches the saturation level range.

Investigating the Correlation between the Microstructure and Electrical Properties of FeSbO4 Ceramics.

FeSbO4 powder was prepared using the solid-state reaction method in this work. Afterward, the dense and porous ceramics were obtained by sintering the pressed powder calcined at temperatures of 900 and 1000 °C for 4 h. Rietveld profile analysis of the X-ray powder diffraction data showed that FeSbO4 adopts the trirutile-type structure (space group P42/mnm, with a ≅ 4.63 Å and c ≅ 9.23 Å). SEM images showed that the powder calcined at 900 °C after being sintered at 1200 °C resulted in ceramics of higher crystallinity, larger grains, and consequently, low porosity. The dielectric properties were measured in the frequency range of 10−1 Hz−1 MHz as a function of temperature (25−250 °C). The real (σ') and imaginary (σ″) parts of the complex conductivity increase with rising annealing temperature for both samples. The real conductivity in the AC region for 𝑓 = 100 kHz was 1.59×10−6 S·cm−1 and 7.04×10−7 S·cm−1 for the ceramic samples obtained from the powder calcined at 900 (C-900) and 1000 °C (C-1000), respectively. Furthermore, the dielectric constants (k') measured at room temperature and f=100 kHz were 13.77 (C-900) and 6.27 (C-1000), while the activation energies of the grain region were Ea = 0.53 eV and Ea = 0.49 eV, respectively. Similar activation energy (Ea = 0.52 eV and 0.49 eV) was also obtained by the brick-layer model and confirmed by the adjustment of activation energy by DC measurements which indicated an absence of the porosity influence on the parameter. Additionally, loss factor values were obtained to be equal to 3.8 (C-900) and 5.99 (C-1000) for measurements performed at 100 Hz, suggesting a contribution of the conductivity originated from the combination or accommodation of the pores in the grain boundary region. Our results prove that the microstructural factors that play a critical role in the electrical and dielectric properties are the average grain size and the porosity interspersed with the grain boundary region.

Evaluation of the Photocatalytic Activity of Distinctive-Shaped ZnO Nanocrystals Synthesized Using Latex of Different Plants Native to the Amazon Rainforest.

ZnO nanocrystals with three different morphologies have been synthesized via a simple sol-gel-based method using Brosimum parinarioides (bitter Amapá) and Parahancornia amapa (sweet Amapá) latex as chelating agents. X-ray diffraction (XRD) and electron diffraction patterns (SAED) patterns showed the ZnO nanocrystals were a pure hexagonal wurtzite phase of ZnO. XRD-based spherical harmonics predictions and HRTEM images depicted that the nanocrystallites constitute pitanga-like (~15.8 nm), teetotum-like (~16.8 nm), and cambuci-like (~22.2 nm) shapes for the samples synthesized using bitter Amapá, sweet Amapá, and bitter/sweet Amapá chelating agent, respectively. The band gap luminescence was observed at ~2.67-2.79 eV along with several structural defect-related, blue emissions at 468-474 nm (VO, VZn, Zni), green emissions positioned at 513.89-515.89 (h-VO+), and orange emission at 600.78 nm (VO+-VO++). The best MB dye removal efficiency (85%) was mainly ascribed to the unique shape and oxygen vacancy defects found in the teetotum-like ZnO nanocrystals. Thus, the bitter Amapá and sweet Amapá latex are effective chelating agents for synthesizing distinctive-shaped ZnO nanocrystals with highly defective and remarkable photocatalytic activity.

Visible-Light-Responsive Photocatalytic Activity Significantly Enhanced by Active [VZn+VO+] Defects in Self-Assembled ZnO Nanoparticles.

Defect influences on the photoactivity of ZnO nanoparticles prepared by a powdered coconut water (ACP) assisted synthesis have been studied. The crystalline phase and morphology of ZnO nanoparticles were effectively controlled by adjusting the calcination temperature (400-700 °C). An induced transition of hybrid Zn5(CO3)2(OH)6/ZnO nanoparticles to single-phase ZnO nanoparticles was obtained at 480 °C. The morphological analysis revealed a formation of ZnO nanoparticles with semispherical (∼6.5 nm)- and rod-like (∼96 nm) shapes when the calcination temperatures were 400 and 700 °C, respectively. Photoluminescence characterizations revealed several defects types in the samples with VZn and VO+ being in the self-assembly of semispherical- and rod-like ZnO nanoparticles. The photocatalytic activity of the ZnO nanoparticles was examined by assessing the degradation of methylene blue in an aqueous solution under low-intensity visible-light irradiation (∼3 W m-2). The results point toward the self-assembly of semispherical- and rod-like ZnO nanoparticles that had significantly better photocatalytic activity (∼31%) in comparison to that of spherical-agglomerated- or near-spherical-like species within 120 min of irradiation. The possible photocatalytic mechanism is discussed in detail, and the morphology-driven intrinsic [VZn+VO+] defects are proposed to be among the active sites of the ZnO nanoparticles enhancing the photocatalytic activity.

Feeding differing direct-fed microbials and its influence on growth and haematological parameters of growing lambs.

A 4 mo feeding trial was conducted to ascertain the effect of direct-fed microbial (DFM) and their products, namely rumen enhancer three (RE3), Paenibacillus polymyxa (P3), and a fermentation product of RE3-RE3 Plus on the growth and haematological profile of lambs at different stages of growth (suckling, weaner, and grower phases). The lambs weighing 2.5 ± 2 kg were blocked by their weights and allotted to four dietary treatments, namely Control, RE3, RE3 Plus, and P3 in a randomized complete block design. Blood sampling of lambs to investigate the effect of the treatments on the haematological and blood biochemistry variables was done on monthly basis and analysis of variance in a repeated measures design was done using the Statistical Analysis System. Feed intake (FI) by lambs was not significantly (P > 0.05) influenced by DFM supplementation for all the phases of growth. However, feed conversion ratio (FCR) for the grower phase of the lamb was higher for T2. Similar (P > 0.05) hemoglobin (Hb), red blood cell (RBC), pack cell volume (PCV), mean corpuscular volume, mean corpuscular hemoglobin concentration (MCHC), eosinophil, lymphocyte, and basophil composition were recorded for lambs on the different experimental diets. Neutrophil and monocytes levels were, however, different (P < 0.05) for lambs fed the varying dietary treatments with lambs on RE3 Plus diets recording the lowest (P < 0.05) neutrophil levels. Monocytes levels were highest (P < 0.05) in lambs fed diets fortified with RE3. Sampling period influenced (P < 0.05) the Hb, RBC, PCV, MCHC, eosinophil, monocyte, and lymphocyte levels. The trial revealed a significant treatment × sampling period interaction (P < 0.0001) for the blood parameters examined. The inclusion of the different DFM products had no influence on the growth characteristics and blood profile of growing lambs.

In Silico and Experimental Data Claiming Safety Aspects and Beneficial Attributes of the Bacteriocinogenic Strain Enterococcus faecalis B3A-B3B.

This study aimed at comparing the genome of Enterococcus faecalis B3A-B3B, a bacteriocinogenic strain recently isolated from a healthy Iraqi infant to those of Enterococci of clinical and beneficial grades. The putative genes gelE, cpd, efaAfm, ccf, agg, and cob coding for virulence factors were detected in B3A-B3B strain, which meanwhile resulted to be non-cytotoxic, non-hemolytic, devoid of inflammatory effects, and sensitive to most of the antibiotics tested except for clindamycin and trimethoprim, which resistance is usually ascribed to intrinsic nature. B3A-B3B strain was remarkable for its hydrophobicity, auto-aggregation, adhesion to human Caco-2 cells, and survival in simulated gastrointestinal conditions, and cholesterol assimilation fulfilling therefore key beneficial attributes.

Enterocin B3A-B3B produced by LAB collected from infant faeces: potential utilization in the food industry for Listeria monocytogenes biofilm management.

Enterococcus faecalis B3A-B3B produces the bacteriocin B3A-B3B with activity against Listeria monocytogenes, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium perfringens, but apparently not against fungi or Gram-negative bacteria, except for Salmonella Newport. B3A-B3B enterocin has two different nucleotides but similar amino acid composition to the class IIb MR10A-MR10B enterocin. B3A-B3B consists of two peptides of predicted molecular mass of 5176.31 Da (B3A) and 5182.21 Da (B3B). Importantly, B3A-B3B impeded biofilm formation of the foodborne pathogen L. monocytogenes 162 grown on stainless steel. The antimicrobial treatment of stainless steel with nisin (1 or 16 mg ml-1) decreased the cell numbers by about 2 log CFU ml-1, thereby impeding the biofilm formation by L. monocytogenes 162 or its nisin-resistant derivative strain L. monocytogenes 162R. Furthermore, the combination of nisin and B3A-B3B enterocin reduced the MIC required to inhibit this pathogen grown in planktonic or biofilm cultures.

Incorportation of Ethyl Esters of EPA and DHA in Soybean Lecithin Using Rhizomucor miehei Lipase: Effect of Additives and Solvent-Free Conditions.

The transesterification of soybean lecithin with ethyl esters of polyunsaturated fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) using immobilized lipase from Rhizomucor miehei was tested in the presence or absence of organic solvent (hexane) and additives (urea with Ca(2+) or Mg(2+)). The reaction was carried out at a water concentration of 4 % and ethyl ester to phospholipid mass ratio of 3:1. After 24 h of reaction without solvent or additive, fatty acid incorporation reached 29.1 % and thereafter increased only slightly. After 48 h, incorporation was highest in the presence of Mg(2+), urea, and solvent. After 72 h, it was highest with Mg(2+) and urea in the presence or absence of solvent (56.8 and 45.7 %, respectively). Incorporation of EPA and DHA was thus initially fast without solvent and additive, but was increased after prolonged reaction in the presence of Mg(2+) and urea with or without solvent. These results are innovative and promising since they show that immobilized Rhizomucor miehei lipase has potential as a biocatalyst for interesterification reactions without solvent.

A mixture of Lactobacillus casei, Lactobacillus lactis, and Paenibacillus polymyxa reduces Escherichia coli O157:H7 in finishing feedlot cattle.

A direct-fed microbial (DFM) containing Paenibacillus polymyxa, Lactobacillus casei, and Lactobacillus lactis was fed to cattle (n = 120) to determine impacts on shedding and survival of Escherichia coli O157:H7 in feces. Cattle were individually penned and fed diets containing 0 (control), 4 × 10(7) CFU (DFM-4), 8 × 10(7) CFU (DFM-8), or 1.2 × 10(8) CFU (DFM-12) lactobacilli per kg of dietary dry matter over 84-day fall-winter growing and 140-day spring-summer finishing periods. Fecal grab samples were collected from cattle at 28-day intervals, E. coli O157:H7 was detected by immunomagnetic separation, and isolates were compared by pulsed-field gel electrophoresis. During the growing period, feces negative for E. coli O157 from each dietary treatment were inoculated with 10(5) CFU/g nalidixic acid-resistant E. coli O157:H7 and were incubated at 4 and 22(u) C for 11 weeks. Fecal pH and fecal dry matter were measured on days 0, 1, 3, and 7 and weekly thereafter, with E. coli O157:H7 enumerated through dilution plating. Treatment with DFMs did not affect survival of E. coli O157:H7 in feces or fecal pH (P > 0.05). Only one steer was positive for E. coli O157:H7 during the growing period, but during the finishing period, DFM-8 and DFM-12 reduced the prevalence of E. coli O157:H7 in feces (P < 0.05). Feeding DFMs also reduced the frequency of individual steers shedding E. coli O157:H7 during finishing (P < 0.05), with control steers shedding E. coli O157:H7 up to four times, whereas DFM-12 steers shed E. coli O157:H7 a maximum of twice. Treatment with DFMs influenced pulsed-field gel electrophoresis profiles; steers that were fed DFM-8 and DFM-12 shed more diverse subtypes of E. coli O157:H7 than did control or DFM-4 steers. Because a companion study found linear improvement in performance with increasing dosage of DFMs in the first 28 days of the growing period, targeted use of DFM-12 during this time and for the final 1 or 2 weeks prior to slaughter may optimize performance and reduce E. coli O157:H7 while minimizing feed costs.

Required characteristics of Paenibacillus polymyxa JB-0501 as potential probiotic.

The ability of Paenibacillus polymyxa to inhibit the growth of Escherichia coli generic ATCC 25922 (Escherichia coli ATCC 25922) and to adhere to monolayers of the enterocyte-like human cell line Caco-2 was evaluated. P. polymyxa JB-0501 (P. polymyxa JB-0501), found in a livestock feed probiotic supplement, was compared to P. polymyxa reference strain ATCC 43685 and ATCC 7070 (P. polymyxa ATCC) in terms of carbohydrate utilization and resistance to lysozyme, acid, bile salts, and hydrogen peroxide. JB-0501 grew at pH 4.5 and at H2O2 concentrations less than 7.3 µg/ml and presented a higher affinity to hexadecane and decane. Bile salts at 0.2 % inhibited the growth of all three strains. P. polymyxa JB-0501 and P. polymyxa ATCC 43865 adhered to Caco-2 cell monolayers. The percentage of cells that adhered ranged from about 0.35 to 6.5 % and was partially proportional to the number applied. Contact time (from 15 min to 1 h) had little impact on adhesion. P. polymyxa JB-0501 inhibited the growth of E. coli ATCC 25922, as proven by the diffusion tests in agar. Taken together, these results suggested that P. polymyxa JB-0501 has the potential probiotic properties to justify its consideration as a livestock feed supplement.

Synergistic effect between colistin and bacteriocins in controlling Gram-negative pathogens and their potential to reduce antibiotic toxicity in mammalian epithelial cells.

Pathogens resistant to most conventional antibiotics are a harbinger of the need to discover novel antimicrobials and anti-infective agents and develop innovative strategies to combat them. The aim of this study was to assess the in vitro activity of colistin alone or in combination with two bacteriocins, nisin A and pediocin PA-1/AcH, against Salmonella choleraesuis ATCC 14028, Pseudomonas aeruginosa ATCC 27853, Yersinia enterocolitica ATCC 9610, and Escherichia coli ATCC 35150 (O157:H7). The strain most sensitive to colistin was enterohemorrhagic E. coli O157:H7, which was inhibited at a concentration of about 0.12 µg/ml. When nisin A (1.70 µg/ml) or pediocin PA-1/AcH (1.56 µg/ml) was combined with colistin, the concentrations required to inhibit E. coli O157:H7 were 0.01 and 0.03 µg/ml, respectively. The in vitro antigenotoxic effect of colistin was determined by using the comet assay method to measure the level of DNA damage in freshly isolated human peripheral blood leukocytes (PBLs) incubated with colistin for 1 h at 37°C. Changes in the tail extents of PBLs of about 69.29 ± 0.08 µm were observed at a final colistin concentration of about 550 ng/ml. Besides the synergistic effect, the combination of colistin (1 mg/ml) and nisin (2 mg/ml) permitted us to re-evaluate the toxic effect of colistin on Vero (monkey kidney epithelial) cells.

Effects of cinnamon leaf, oregano and sweet orange essential oils on fermentation and aerobic stability of barley silage.

BACKGROUND: Silage additives are marketed with the primary aim of improving the fermentation and/or aerobic stability of silage. The objective of this study was to evaluate the impact of three different essential oils (EOs; cinnamon leaf (CIN), oregano (ORE) and sweet orange (SO)) on the fermentation characteristics and stability of barley silage. Chopped whole-plant barley (Hordem vulgare L.) forage was ensiled either untreated (0 mg kg⁻¹ dry matter (DM)) or treated with CIN, ORE or SO (37.5, 75 and 120 mg kg⁻¹ DM). RESULTS: Moulds were not detected in any treatments, including the control, after 7 days of air exposure. All EOs at a concentration of 120 mg kg⁻¹ silage DM decreased (P = 0.001) yeast populations in comparison with the control during air exposure. Net gas, methane and ammonia concentrations in vitro did not differ among treatments. Changes in volatile fatty acid concentrations were small, and in situ data showed no changes in DM and neutral detergent fibre digestion rates for CIN, ORE or SO at concentrations up to 120 mg kg⁻¹ DM. CONCLUSION: The findings from this study show that a concentration of 120 mg EO kg⁻¹ DM decreased yeast counts during aerobic stability tests. However, all EO treatments had minimal effects on data from in vitro and in situ incubations.

Antibiotic and antimicrobial peptide combinations: synergistic inhibition of Pseudomonas fluorescens and antibiotic-resistant variants.

Variants resistant to penicillin G (RvP), streptomycin (RvS), lincomycin (RvL) and rifampicin (RvR) were developed from a colistin-sensitive isolate of Pseudomonas fluorescens LRC-R73 (P. fluorescens). Cell fatty acid composition, K(+) efflux and sensitivity to antimicrobial peptides (nisin Z, pediocin PA-1/AcH and colistin) alone or combined with antibiotics were determined. P. fluorescens was highly sensitive to kanamycin, tetracycline and chloramphenicol at minimal inhibitory concentrations of 0.366, 0.305 and 0.732 µg/ml respectively. P. fluorescens, RvP, RvS, RvL and RvR were resistant to nisin Z and pediocin PA-1/AcH at concentrations ≥100 µg/ml but sensitive to colistin at 0.076, 0.043, 0.344, 0.344 and 0.258 µg/ml respectively. A synergistic inhibitory effect (FICI ≤0.5) was observed when resistant variants were treated with peptide/antibiotic combinations. No significant effect on K(+) efflux from the resistant variants in the presence of antibiotics or peptides alone or combined was observed. The proportion of C16:0 was significantly higher in antibiotic-resistant variants than in the parent strain, accounting for 32.3%, 46.49%, 43.3%, 40.1% and 44.1% of the total fatty acids in P. fluorescens, RvP, RvS, RvL and RvR respectively. Combination of antibiotics with antimicrobial peptides could allow reduced use of antibiotics in medical applications and could help slow the emergence of bacteria resistant to antibiotics.

Colistin A and colistin B among inhibitory substances of Paenibacillus polymyxa JB05-01-1.

Recently, we isolated and reported the antagonism of Paenibacillus polymyxa JB05-01-1 (P. polymyxa JB05-01-1) against Gram-negative bacteria. Here, we provide more insights and attribute the abovementioned antagonism to the production of colistins A and B, which were purified by Amberlite column exchange, C18 column hydrophobicity, superdex 75 16/60 gel filtration chromatography connected to fast protein liquid chromatography and identified by MALDI TOF/TOF, and manual nanospray analysis. The amount of colistin A and colistin B recovered from 500 ml of culture supernatant was about 0.05 mg. The specific activity and the average recovery of the eluted substances were 5,120 AU/mg and 1.1%, respectively. The minimal inhibitory concentrations of the purified colistins against Escherichia coli O157:H7 and Pseudomonas fluorescens LRC R73 were 0.13 and 0.62 µg/ml, respectively.

Antibacterial activity of class I and IIa bacteriocins combined with polymyxin E against resistant variants of Listeria monocytogenes and Escherichia coli.

Development of resistance could render antimicrobial peptides ineffective as bio-preservatives in food. Variants resistant to nisin A or pediocin PA-1 were developed from Listeria monocytogenes and a variant resistant to polymyxin E was developed from Escherichia coli RR1. Inhibition of these organisms by these agents alone or in combination was assessed using critical dilution microassay and optical density measurement. The combination of pediocin or nisin with polymyxin E was synergistic against all five strains. The polymyxin/nisin combination at 9.3/32, 4.7/62.5 and 0.6/15.6 µg/ml inhibited growth of nisin-resistant L. monocytogenes, pediocin-resistant L. monocytogenes and polymyxin-resistant E. coli, respectively, by factors of 94%, 97% and 74% compared to controls. The pediocin/nisin combination was effective against L. monocytogenes and its variants, but not E. coli or its variant. Polymyxin (0.21 µg/ml) and polymyxin/nisin (0.3/7.8 µg/ml) reduced E. coli growth measured in the log phase by, respectively, 31.25% and 93.54%. L. monocytogenes growth in the logarithmic and stationary phases was reduced, respectively, by 90.46% and 77.52% by polymyxin/pediocin at 4.7/25 µg/ml. Our results suggest that the effective concentration of bacteriocin for control of resistant L. monocytogenes and E. coli variants could be lowered considerably by combination with polymyxin E. This suggests searching for polymyxin-like compounds to increase the efficiency of bacteriocins and slow the emergence of resistant mutants. This could be an important step towards the expanded use of bacteriocins in the medical arena.

Paenibacillus polymyxa JB05-01-1 and its perspectives for food conservation and medical applications.

The aim of this study was to isolate a novel bacterial strain with strong and broad spectrum antibacterial activity from a livestock feed prebiotic supplement. A novel strain, termed Paenibacillus polymyxa JB05-01-1, was isolated using traditional microbiological methods and identified on the basis of its phenotypic and biochemical properties as well as its 16S rRNA gene sequence. This strain was able to inhibit growth of gram-negative bacteria including Escherichia coli RR1, Pseudomonas fluorescens R73, Pantoea agglomerans BC1, Butyrivibrio fibrisolvens OR85, and Fibrobacter succinogenes. The above antagonism against the aforementioned bacteria was attributed to production of an antimicrobial substance(s) termed "JB05-01-1." Its production was optimal during the stationary phase. JB05-01-1 has a molecular weight of 2.5 KDa, its mode of action is bactericidal, and the divalent cations, Ca(2+) and Mn(2+), reduced its lethality. The antibacterial activity was heat-stable and was effective at a pH range of 2-9. Enzymes like trypsin, α-chymotrypsin, and proteinase K have abolished the antibacterial activity of JB05-01-1 indicating a proteinaceous motif. This type of naturally occurring bacteria and inhibitory substance(s) could represent an additional value in livestock feed supplements. The natural presence of antibacterial activity indicates an opportunity to decrease the addition of antibiotics.

Nisin A and Polymyxin B as Synergistic Inhibitors of Gram-positive and Gram-negative Bacteria.

Nisin A and polymyxin B were tested alone and in combination in order to test their antagonism against Listeria innocua HPB13 and Escherichia coli RR1, respectively. While the combination of both antibacterial substances was synergistically active against both target bacteria, nisin A alone did not show any inhibition of E. coli RR1. The nisin A/polymyxin B combination at 1.56/2.5 µg ml(-1) caused lysis of about 35.86 ± 0.35 and 73.36 ± 0.14% of L. innocua HPB13 cells after 3 and 18 h, respectively. Polymyxin B at 0.12 µg ml(-1) and nisin A/polymyxin B at 4.64/0.12 µg ml(-1) decreased the numbers of viable E. coli RR1 cells by about 0.23 and 0.65 log10 CFU ml(-1), respectively, compared to the control. Our data suggest that the concentration of nisin A required for the effective control of pathogenic strains Listeria spp. could be lowered considerably by combination with polymyxin B. The use of lower concentrations of nisin A or polymyxin B should slow the emergence of bacterial populations resistant to these agents.