Comprehensive toxicity assessment of nanodiamond on Blaps polychresta: implications and novel findings.

With the increasing development of nanomaterials, the use of nanodiamonds (NDs) has been broadly manifested in many applications. However, their high penetration into the ecosystem indubitably poses remarkable toxicological risks. This paper investigates the toxic effects of NDs on the darkling beetle, Blaps polychresta Forskal, 1775 (Coleoptera: Tenebrionidae). Survival analysis was carried out by monitoring the beetles for 30 d after the injection of four different doses of NDs. A dose of 10.0 mg NDs/g body weight, causing less than 50% mortality effect, was assigned in the analysis of the different organs of studied beetles, including testis, ovary, and midgut. Structural and ultrastructural analyses were followed using light, TEM, and SEM microscopes. In addition, a variety of stress markers and enzyme activities were assessed using spectrophotometric methods. Furthermore, cell viability and DNA damage were evaluated using cytometry and comet assay, respectively. Compared to the control group, the NDs-treated group was exposed to various abnormalities within all the studied organs as follows. Significant disturbances in enzyme activities were accompanied by an apparent dysregulation in the antioxidant system. The flow cytometry results indicated a substantial decrease of viable cells along with a rise of apoptotic and necrotic cells. The comet assay demonstrated a highly increased level of DNA damage. Likewise, histological analyses accentuated the same findings showing remarkable deformities in the studied organs. Prominently, the research findings substantially contribute for the first time to evaluating the critical effects of NDs on B. polychresta, adopted as the bioindicator in this paper.

Nitrate modulation of Bacillus sp. biofilm components: a proposed model for sustainable bioremediation.

The presence of different pollutants in wastewater hinder microbial growth, compromise enzymatic activity or compete for electrons required for bioremediation pathway. Therefore, there is a need to use a single microorganism that is capable of tolerating different toxic compounds and can perform simultaneous bioremediation. In the present study, nitrate reducing bacteria capable of decolorizing azo dye was identified as Bacillus subtillis sp. DN using protein profiling, morphological and biochemical tests X-ray diffraction pattern, Raman spectroscopy and cyclic voltammetry confirm that the bacterium under study possesses membrane-bound nitrate reductase and that is capable of direct electron transfer. The addition of nitrate concentrations (0-50 mM) resulted in increased biofilm formation with variable exopolysaccharides, protein, and eDNA. Fourier Transform Infrared spectrum revealed the presence of a biopolymer at high nitrate concentrations. Effective capacitance and conductivity of the cells grown in different nitrate concentrations suggest changes in the relative position of polar groups, their relative orientation and permeability of cell membrane as detected by dielectric spectroscopy. The increase in biofilm shifted the removal of the azo dye from biodegradation to bioadsorption. Our results indicate that nitrate modulates biofilm components. Bacillus sp. DN granular biofilm can be used for simultaneous nitrate and azo dye removal from wastewater.

In-vitro study of the radioprotective effect of palladium α-lipoic acid nano-complex on hemoglobin molecule.

This work is intended to study the radioprotective effect of palladium α-lipoic acid nano-complex (PLAC) on hemoglobin molecule in vitro. Blood samples were obtained from adult male rats weighing 120-150 g after dissection, using heparinized needles. Each blood sample was divided into four groups; the first group was kept untreated as control, palladium α-lipoic acid (PLAC) was added to the second group at concentration 2% v/v, the third group was exposed to 100 Gy gamma radiation and the forth group was irradiated with the addition of PLAC. Hemoglobin was extracted and prepared for measurement. The effects on the hemoglobin molecule were evaluated by FTIR and UV-visible spectroscopy. The results showed that PLAC increases the optical energy gap of the transition of the amino acid side chains and affects the spatial distribution of the globin part. Gamma radiation affects mainly the globin part, results in unfolding of the protein structure and perturbation in the relative orientation of the transition dipole moments. Addition of PLAC to the blood samples prior to irradiation was shown to provide protective effects which can be attributed to its ability to neutralize the free radicals.

Characterization of a biosurfactant producing electroactive Bacillus sp. for enhanced Microbial Fuel Cell dye decolourisation.

A biosurfactant producing Gram positive bacterium isolated from anodic biofilm of textile wastewater fed MFC was identified as Bacillus sp. MFC (Accession number: MT322244). Scanning Electron Microscopy of the bacterium showed appendages, the bacterium forms biofilm on Congo red agar medium. The obtained results showed that the addition of 5 mg/l endogenous biosurfactant to the bacterial cells resulted in 19-fold increase in bacterial surface-bound exopolysaccharides (EPS) and 1.94-fold increase in biofilm. However, when the biosurfactant concentration increased to 20 and 40 mg/l, EPS and biofilm decreased and the cells lost their colony forming ability. The dielectric properties of the bacterial cells showed increase in conductivity and relative permittivity with increasing biosurfactant concentrations. The shape of the voltammogram currents peak, their location and Electrochemical impedance spectroscopy (EIS) suggest the involvement of biofilm as direct electron transfer pathway. The average voltage obtained was 0.65 V as compared to 0.45 V for the control MFC. Decolourization was tested for Congo red in a double chamber Microbial Fuel Cell (MFC), the results showed 2-fold increase in decolourization when biosurfactant is added post biofilm formation. The results confirm that Bacillus sp. MFC possess electrogenic properties and that adding low concentrations of endogenous biosurfactant to 24 h biofilm accelerates electron transfer by inducing perforations in the cell wall and increasing EPS as an electron transfer transient medium. Therefore, MFC performance can be enhanced.

Promoting bacteria-anode interfacial electron transfer by palladium nano-complex in double chamber microbial fuel cell.

The slow electron transfer between microbial outer membrane and electrode surface is considered one of the limitations of Microbial Fuel Cell (MFC) performance. The aim of the present work is to assess the role of palladium α-lipoic acid nanocomplex compound (PLAC) in promoting bacteria-anode interfacial electron transfer, by studying the dielectric properties of Shewanella oneidensis WW-1 cell membrane and its contribution to biofilm formation on the anode. The results showed that adding PLAC increased bacterial cell membrane permeability and outer cell surface charge. Exopolysaccharides (EPS) and surface-bound proteins increased 2.27 and 1.14 fold, respectively upon adding 0.25% v/v PLAC. Dynamic Light Scattering (DLS) showed uniform distribution of Shewanella-PLAC biocomposite size while Zeta potential and Fourier Transform Infrared (FTIR) Spectroscopy results suggest that PLAC diffused inside the cells. Transmission Electron Microscope (TEM) images reveal Exopolysaccharide (EPS) mat around the cells when PLAC was added to the cells, also confirmed by the FTIR spectrum. Scanning Electron Microscope and Atomic Force Microscope (AFM) confirmed the thickness of biofilm in the presence of PLAC. The average voltage reached 492 mV (external resistance 1 KΩ) over 35 days using 0.25% v/v PLAC as compared to a few hours in MFCs lacking PLAC. The results suggest that the addition of PLAC assisted in interfacial direct electron transfer through enhancing biofilm formation, moreover, its hydrophilic/lipophilic nature facilitated the electron shuttling process from within the bacterial cell to the electrode surface suggesting the involvement of mediated electron transfer as well.

RNA Seq analysis of the role of calcium chloride stress and electron transport in mitochondria for malachite green decolorization by Aspergillus niger.

Aspergillus niger was previously demonstrated to decolorize the commercial dye malachite green (MG) and this process was enhanced under calcium chloride (CaCl2) treatment. Previous data also suggested that the decolorization process is related to mitochondrial cytochrome c. In the current work, we analyzed in depth the specific relationship between CaCl2 treatment and MG decolorization. Gene expression analysis (RNA Seq) using Next Generation Sequencing (NGS) revealed up-regulation of 28 genes that are directly or indirectly associated with stress response functions as early as 30min of CaCl2 treatment; these data further strengthen our previous findings that CaCl2 treatment induces a stress response in A. niger which enhances the ability to decolorize MG. A significant increase in fluorescence observed by MitoTracker dye suggests that CaCl2 treatment also increased mitochondrial membrane potential. Isolated mitochondrial membrane protein fractions obtained from A. niger grown under standard growth conditions decolorized MG in the presence of NADH and decolorization was enhanced in samples isolated from CaCl2-treated A. niger cultures. Treatment of whole mitochondrial fraction with KCN which inhibits electron transport by cytochrome c oxidase and Triton-X 100 which disrupts mitochondrial membrane integrity suggests that cyanide sensitive cytochrome c oxidase activity is a key biochemical step in MG decolorization. This suggestion was confirmed by the addition of palladium α-lipoic acid complex (PLAC) which resulted in an initial increase in decolorization. Although the role of cytochrome c and cytochrome c oxidase was confirmed at the biochemical level, changes in levels of transcripts encoding these enzymes after CaCl2 treatment were not found to be statistically significant in RNA Seq analysis. These data suggest that the regulation of cytochrome c enzymes occur predominantly at the post-transcriptional level under CaCl2 stress. Thus, using global transcriptomics and biochemical approaches, our study provides a molecular association between fungal mitochondrial electron transfer systems and MG decolorization.

A possible role of Aspergillus niger mitochondrial cytochrome c in malachite green reduction under calcium chloride stress.

In previous work, decolorization of malachite green (MG) was studied in Aspergillus niger in the presence and absence of calcium chloride stress. Decolorization took place within 24 h, and a signal transduction process that initiated MG decolorization was suggested to be involved. In the present study, further investigation of the relationship between calcium chloride stress and enhanced MG biodegradation was conducted at the sub-cellular level. MG-NADH reductase activity, a key enzyme in MG decolorization, was produced as decolorization commenced, and enzyme activity increased threefold upon exposure to calcium chloride. Inhibitors of cytochrome p450, Ca(2+) channel activity as well as activity of the signaling protein phosphoinositide 3-kinase were tested. All three activities were inhibited to different extents resulting in reduced MG decolorization. Spectral analysis of the mitochondrial fraction showed a heme signal at 405 nm and A405/A280 ratio that is characteristic of the porphoryin ring of cytochromes. There were no peaks detected for cytochromes a or b, but a shoulder appearing at 550 nm was observed, which suggested that cytochrome c is involved; the absorbance for cytochrome c doubled after calcium chloride stress supporting this idea. MG decolorization took place via a series of demethylation steps, and cytotoxicity analysis revealed a decrease in the toxicity associated with generation of leucomalachite green.

Biochemical and biophysical response to calcium chloride stress in Aspergillus niger and its role in malachite green degradation.

Filamentous fungi show great promise in remediation of environmental contaminants such as industrial dyes. In the current study, Aspergillus niger (Genbank ID: JF437542) decolorized 82 % of the test dye malachite green (MG; 50 mg/l) during cultivation for 24 h. The organism decolorized only 6 % of the MG at higher concentration (250 mg MG/l) during the same time period and growth was inhibited at this higher MG concentration. Exposing A. niger to different types of stress resulted in variable impacts on ability to decolorize MG. CaCl2 had the largest positive impact on decolorization. A. niger cultures treated with CaCl2 (1 M) decolorized 46 % of the MG (250 mg/l) in 1 h compared to 6 % in untreated control cultures. CaCl2 also increased catalase production in A. niger which strongly supported a direct relationship between stress response and decolorizing ability. Spectrophotometric measurement confirmed MG decolorization while Fourier transform infrared spectroscopy suggested that biodegradation of MG occurred. Cultures treated with CaCl2 accumulated fewer toxic MG by-products than untreated cultures. CaCl2-induced stress increased the permeability and conductivity of the fungal cell membrane. An observed increase in medium [H(+)] also suggested a change in Ca(2+)/H(+) exchange capacity in the fungal cell. Calcium ions had a pronounced effect on membrane properties and this may have had an important impact on signal transduction. We conclude that A. niger decolorizes MG and that CaCl2 enhances this process; the CaCl2 effect appears to be associated with stress response.

Radiation-induced changes in the optical properties of hemoglobin molecule.

Adult male Albino rats were exposed to different doses of gamma radiation from Cs-137 source. Hemoglobin samples were analyzed 24 h after irradiation. The UV-visible spectrum of hemoglobin molecule was measured in the range 200-700 nm. The overall spectrum of the hemoglobin molecule showed hypochromicity that increased with dose increase. To investigate the effect of radiation on the hemoglobin molecule, different parameters of the spectrum were calculated: molar absorption coefficient, absorption cross-section, transition dipole moment, dipole length, the optical energy gap and activation energy for each characteristic peak. The obtained results revealed that the radiation effect can induce rearrangement of the transition dipole moments and change molecular energy levels of the hemoglobin molecule.

Electrical behavior of stored erythrocytes after exposure to gamma radiation and the role of alpha-lipoic acid as radioprotector.

The effects of gamma rays (25, 50 and 100 Gy) on stored erythrocytes were studied by measuring their dielectric properties and observing their morphology under scanning electron microscopy. Alpha lipoic acid (a potent natural antioxidant) was introduced prior to irradiation for radioprotection. It can be concluded that the dose level of 25 Gy can be considered a safe sterile dose; however, irradiation doses of 50 and 100 Gy should be applied with the addition of alpha-acid to preserve the cell viability.

Biophysical characterization of beta-thalassemic red blood cells.

Thalassemia is the world's most common hereditary disease; therefore, more interest has been devoted for the development of the screening procedure of this disease. In beta-thalassemia major, the subject of the current study, impaired biosynthesis of beta-globin leads to accumulation of unpaired alpha-globin chain. The objective of the present study, was to examine many of the biophysical properties of beta-thalassemia major red blood cells (RBCs) and to study the possibility of use of any of them as a preliminary screening tool for beta-thalassemia. The percentage of normal hemolysis, osmotic fragility test, turbidity test, rheological properties, and dielectric properties, were studied in 20 regularly blood transfused thalassemia major patients who were under chelation therapy and their status were compared with those of 10 healthy subjects. There was an increase in the percentage of hemolysis for beta-thalassemia by 114.6% compared to the normal RBCs. The fragility curve for beta-thalassemia RBCs showed a shift toward lower NaCl concentration compared to the normal curve. The average osmotic fragility (H(50): the NaCl concentration producing 50% homolysis) for beta-thalassemia was found to be 3.21 +/- 0.67 g/l, whereas for normal RBCs it was 5.5 +/- 0.31 g/l. The turbidity curve of the beta-thalassemic RBCs showed a shift toward higher detergent concentration of the normal curve, with higher value for the average membrane solubilization (S(50)). The viscosity value of whole blood beta-thalassemia was found to be 3.916 +/- 0.56 cp whereas for normal blood was 2.516 +/- 0.36 cp. The relative permittivity, dielectric loss, and AC conductivity of RBCs decreased significantly compared to normal samples. This could be attributed to the loss of the insulating properties of the membrane and loss of its surface charge of thalassemic RBCs. As can be noticed, several factors showed clear difference between thalassemic and normal blood samples. Some of these parameters could be measured immediately after sample withdrawal and require short time to perform the measurements. This offers the advantages of being effective, low cost, and fast techniques, therefore, we suggest that these techniques could be applied for beta-thalassemia major screening purposes.