Efficient malachite green biodegradation by Pseudomonas plecoglossicide MG2: process optimization, application in bioreactors, and degradation pathway.

Microbial degradation of synthetic dyes is considered a promising green dye detoxification, cost-effective and eco-friendly approach. A detailed study on the decolorization and degradation of malachite green dye (MG) using a newly isolated Pseudomonas plecoglossicide MG2 was carried out. Optimization of MG biodegradation by the tested organism was investigated by using a UV-Vis spectrophotometer and the resultant degraded products were analyzed by liquid chromatography-mass spectrometry and FTIR. Also, the cytotoxicity of MG degraded products was studied on a human normal retina cell line. The optimum conditions for the significant maximum decolorization of MG dye (90-93%) by the tested organism were pH 6-7, inoculum size 4-6%, and incubation temperature 30-35 °C, under static and aerobic conditions. The performance of Pseudomonas plecoglossicide MG2 grown culture in the bioreactors using simulated wastewater was assessed. MG degradation (99% at 100 and 150 mg MG/l at an optimal pH) and COD removal (95.95%) by using Pseudomonas plecoglossicide MG2 culture were the best in the tested culture bioreactor in comparison with that in activated sludge or tested culture-activated sludge bioreactors.The FTIR spectrum of the biodegraded MG displayed significant spectral changes, especially in the fingerprint region 1500-500 as well as disappearance of some peaks and appearance of new peaks. Twelve degradation intermediates were identified by LC-MS. They were desmalachite green, didesmalachite green, tetradesmalachite green, 4-(diphenylmethyl)aniline, malachite green carbinol, bis[4-(dimethylamino)phenyl]methanone, [4-(dimethylamino)phenyl][4-(methyl-amino)phenyl]methanone, bis[4-(methylamino)phenyl]methanone, (4-amino- phenyl)[4-(methylamino)phenyl]methanone, bis(4-amino phenyl)methanone, (4-amino phenyl)methanone, and 4-(dimathylamino)benzaldehyde. According to LC-MS and FTIR data, two pathways for MG degradation by using Pseudomonas plecoglossicide MG2 were proposed. MG showed cytotoxicity to human normal retina cell line with LC50 of 28.9 µg/ml and LC90 at 79.7 µg/ml. On the other hand, MG bio-degraded products showed no toxicity to the tested cell line. Finally, this study proved that Pseudomonas plecoglossicide MG2 could be used as an efficient, renewable, eco-friendly, sustainable and cost-effective biotechnology tool for the treatment of dye wastewater effluent.

Potential of silver nanoparticles synthesized using low active mosquitocidal Lysinibacillus sphaericus as novel antimicrobial agents.

Silver nanoparticles (AgNPs) were synthesized using extracellular filtrates of some Lysinibacillus sphaericus (Ls) strains under simple conditions. Ls synthesized AgNPs showed the optical absorption peaks at 388-412 nm as detected by UV-visible spectrophotometer. Transmission electron micrographs of bacterial synthesized AgNPs revealed that they were polycrystalline with spherical, hexagonal, cuboidal, rod and irregular shapes. The average diameter of the tested AgNPs were ranged from 14-21 nm and they were negatively charged as detected by DLS (-18.2 to -28.9). FTIR spectra showed the presence of nitrogenous biomolecules capping the synthesized AgNPs. The filtrates of tested Ls strains showed nitrate reductase activity (1.45-2.56 µmol/ml/min). Tested AgNPs showed bactericidal activity against Gram positive and Gram negative bacteria, fungicidal activity against yeast and filamentous fungi, and virucidal activity against rotavirus. In addition, it showed synergistic antimicrobial effect to cephradine and nizoarm against all tested microorganisms. Cytotoxicity test revealed the safety of the tested nanoparticles at tested concentrations.Finally, Ls strains represent microbial sources for ecofriendly, simple and economic biosynthesis of antimicrobial AgNPs. Also, this research may contribute to the medicinal chemistry and pharmaceutical industry for the development of new products used for the public health.

Multi-bioactive silver nanoparticles synthesized using mosquitocidal Bacilli and their characterization.

Silver nanoparticles (AgNPs) were synthesized using cell-free filtrates of some mosquitocidal Bacilli. They showed the optical absorption peaks at 386-412 nm. They were polycrystalline spherical, hexagonal, cuboidal, rod and anisotropic shapes as detected by TEM. These nanoparticles were negatively charged with sizes ranging from 15 to 21 nm average diameter as detected by DLS. FTIR spectra showed that the main absorption bands of biomolecules capping AgNPs appeared at average wave numbers of 3435 cm-1 [ν(N-H) of amide A overlapped by ν(O-H)], 1631 cm-1 [(ν(C=O) of amide I], 1396 cm-1 [ν(C-N) of amide I], 2929 cm-1 (aliphatic C-H) and 1040 cm-1 (C-C-O). FTIR spectra confirmed the presence of protein biomolecules in the bacterial filtrate-formed coat covering AgNPs through free amide groups resulting in their stabilization in the aqueous medium. Nitrate reductase activity was found in all tested bacterial filtrates and ranged from 1.66 to 2.51 µmol/ml/min. These findings point to the probable role of nitrate reductase in reducing silver ions to silver nanoparticles and their stabilization. Tested AgNPs were multi-bioactive nanometals and showed mosquitocidal, bactericidal, fungicidal and virucidal activities. In addition, they exhibited highly synergistic mosquitocidal effect to spore toxin complex of mosquitocidal Bacilli at a very low concentration. AgNPs exhibited activities that were not or slightly cytotoxic to MA 104 cell line at tested concentrations. Therefore, they can be applied in the medical field. Finally, this study offered a simple, highly efficient, eco-friendly, economic method for biosynthesis of multi-bioactive AgNPs by some mosquitocidal Bacilli.

Combination of Human Amniotic Fluid Derived-Mesenchymal Stem Cells and Nano-hydroxyapatite Scaffold Enhances Bone Regeneration.

BACKGROUND: Human amniotic fluid-derived stem cells (hAF-MSCs) have a high proliferative capacity and osteogenic differentiation potential in vitro. The combination of hAF-MSCs with three-dimensional (3D) scaffold has a promising therapeutic potential in bone tissue engineering and regenerative medicine. Selection of an appropriate scaffold material has a crucial role in a cell supporting and osteoinductivity to induce new bone formation in vivo. AIM: This study aimed to investigate and evaluate the osteogenic potential of the 2nd-trimester hAF-MSCs in combination with the 3D scaffold, 30% Nano-hydroxyapatite chitosan, as a therapeutic application for bone healing in the induced tibia defect in the rabbit. SUBJECT AND METHODS: hAF-MSCs proliferation and culture expansion was done in vitro, and osteogenic differentiation characterisation was performed by Alizarin Red staining after 14 & 28 days. Expression of the surface markers of hAF-MSCs was assessed using Flow Cytometer with the following fluorescein-labelled antibodies: CD34-PE, CD73-APC, CD90-FITC, and HLA-DR-FITC. Ten rabbits were used as an animal model with an induced defect in the tibia to evaluate the therapeutic potential of osteogenic differentiation of hAF-MSCs seeded on 3D scaffold, 30% Nano-hydroxyapatite chitosan. The osteogenic differentiated hAF-MSCs/scaffold composite system applied and fitted in the defect region and non-seeded scaffold was used as control. The histopathological investigation was performed at 2, 3, & 4 weeks post-transplantation and scanning electron microscope (SEM) was assessed at 2 & 4 weeks post-transplantation to evaluate the bone healing potential in the rabbit tibia defect. RESULTS: Culture and expansion of 2nd-trimester hAF-MSCs presented high proliferative and osteogenic potential in vitro. Histopathological examination for the transplanted hAF-MSCs seeded on the 3D scaffold, 30% Nano-hydroxyapatite chitosan, demonstrated new bone formation in the defect site at 2 & 3 weeks post-transplantation as compared to the control (non-seeded scaffold). Interestingly, the scaffold accelerated the osteogenic differentiation of AF-MSCs and showed complete bone healing of the defect site as compared to the control (non-seeded scaffold) at 4 weeks post-transplantation. Furthermore, the SEM analysis confirmed these findings. CONCLUSION: The combination of the 2nd-trimester hAF-MSCs and 3D scaffold, 30% Nano-hydroxyapatite chitosan, have a therapeutic perspective for large bone defect and could be used effectively in bone tissue engineering and regenerative medicine.

Spectroscopic Characterization of Dust-Fall Samples Collected from Greater Cairo, Egypt.

This work aimed to characterize dust-fall samples collected from street's trees in Greater Cairo (GC), Egypt, and its surroundings by different spectroscopic techniques, namely; X-ray diffraction (XRD), attenuated total-reflection Fourier transform infrared (ATR-FTIR), particle-size analyzer, and scanning electron microscopy (SEM) combined with energy dispersive X-ray measurements. Samples were collected from 19 different locations inside and outside of GC. Quantitative phase analysis of the dust-fall samples was performed using the Rietveld method. Results showed that the most frequently observed phases in the dust-fall samples were calcite (CaCO3), dolomite (CaMg(CO3)2), gypsum (CaSO4·2H2O), and quartz (SiO2) with average concentrations of 39 ± 16, 8 ± 7, 22 ± 13, and 33 ± 14 wt%, respectively. The occurrence of these constituents referred to a combination of different anthropogenic and natural sources. The ATR-FTIR results are in good agreements with XRD data of the different observed phases. Based on the SEM and particle-size measurements, quantitative determination of the particle-size distribution was described. It was found that not only the large-sized particles are deposited but also the small-sized ones (PM10 and PM2.5). In addition, the particle size of the collected dust-fall samples varied from 0.1 to 200 µm with an average particle size of 17.36 µm; however, the particle size ranged from 2.5 to 40 µm predominated in all of the dust-fall samples.

The influence of low power microwave on the properties of DPPC vesicles.

The effect of microwave exposure on liposome at non-thermal level are studied. Dipalmitoyl phosphatidylcholine (DPPC) liposomes were exposed to 950 MHz at power densities of 2.5 mW/cm(2), which is equivalent to specific absorption rate (SAR) of 0.238 W/K. The interaction of microwave with liposomes was investigated by membrane solubilization measurements using a non-ionic detergent, octylglucoside (OG), as well as Fourier transform infrared (FTIR) spectroscopy and flow activation energy measurements. The amount of detergent needed to completely solubilize the liposomal membrane was increased after exposure of liposomes to microwave irradiation, indicating an increased membrane resistance to the detergent and hence a change in the natural membrane permeation properties. In the analysis of FTIR spectra the symmetric and antisymmetric CH(2) (at 2070 cm(-1)) band and the CO (at 1640 cm(-1)) stretching bands were investigated after liposomal exposure to microwave irradiation. It is clearly shown from the flow activation energy measurements, that low-power microwave induce changes in the liposomes deformability (decreases the liposome fluidity and increases the liposome rigidity). Finally it could be concluded that low-power microwave of 950 MHz induced structural and functional changes in liposomes as a membrane model system.

Use of FT-Raman Spectroscopy to Determine the Degree of Polymerization of Dental Composite Resin Cured with a New Light Source.

OBJECTIVES: To use the FT-Raman spectroscopy for evaluation the degree of polymerization of dental composite as a result of photo curing with a new light source in comparison to the conventional halogen light. MATERIALS AND METHODS: In this study a new light source, based on a metal-halide lamp (TOPSPOT G12) was developed at NRC-Egypt for curing dental composites. Two groups of 108 composite samples each were cured using both the new light source and a conventional halogen source, as a control source. Different samples' sizes (2x2, 3x3 and 6x3 mm(2)) were cured for different periods of time (2, 4, 8, 12, 20, and 40 seconds). The spectroscopic data were analyzed statistically by ANOVA and Duncan's multiple range test (P< .05). RESULTS: The results showed that the samples cured by the new metal-halide source produced higher polymerization rates than those cured by the halogen source. The polymerization rate was directly proportional to the exposure time and inversely proportional to the sample size, irrespective to the light source used. The results also showed that 12 seconds of metal-halide light curing produced polymerization rate comparable to or even higher than that produced by 40 seconds halogen light curing. CONCLUSIONS: The new light source produced a satisfactory degree of polymerization in a remarkable shorter curing time and it can be recommended for clinical use.