Enhancement of electro-optical response of photonic crystal fibers infiltrated with ferroelectric liquid crystal doped with titanium dioxide nanoparticles.

Light propagation has been studied in photonic crystal fibers (PCFs) doped with W212 ferroelectric liquid crystal (FLC) composites with titanium dioxide nanoparticles (TiO2 NPs) of low concentrations between 0.2 and 1 wt. % in the FLC matrix. Optical microscopy observations indicated a slight increase of transition temperature to the isotropic phase by ∼1-2°C compared to the undoped FLC sample, and the TiO2 admixture was found to decrease free ionic charge impurities in the FLC, thus improving its electro-optical parameters. The switching time measurements in the PLCFs clearly indicate that TiO2 NPs reduce switching times for low electric field intensity, even by 32% compared to the undoped PLCF.

Microalgal competence in urban wastewater management: phycoremediation and lipid production.

The present study was conducted to assess the strain aptness, phycoremediation potential and lipid yield in microalgae Chloroccocum humicola and Oscillatoria sp. Results revealed that microalgae treated with different concentration of wastewater (25%, 50%, 75% and 100%) recovered nutrients (Nitrogen: 50.55-85.90%, Phosphorus: 69.98-93.72%) and removed heavy metals (24.17-88.10%) from wastewater. Microalgae C. humicola showed significant reduction in physico-chemical parameters of wastewater at 25% and 50% respectively with considerable increase in lipid production (1.61 folds) at 50% wastewater concentration. In order to counterbalance the wastewater induced toxicity, both microalgae exhibited stimulated antioxidants viz., proline (1.26-4.04 folds), ascorbic acid (1.01-9.21 folds), cysteine (1.44-4.92 folds), catalase (0.99-3.63 folds), superoxide dismutase (1.15-1.43 folds) and glutathione reductase (1.43-6.67 folds) at different wastewater concentrations. Further, Fourier transforms infrared spectroscopy spectral elucidation of Chloroccocum humicola at 50% reflected high lipid peak in the regions 3000-2800 cm-1 as compared to Oscillatoria sp. Thus, growth characteristics, biochemical responses and lipid yield presented the suitability of the Chloroccocum humicola to be used in phycoremedation, resource recovery as well as lipid production, which may be further utilized as potent feedstock for third generation energy demand.

Ameliorating Effect of Bicarbonate on Salinity Induced Changes in the Growth, Nutrient Status, Cell Constituents and Photosynthetic Attributes of Microalga Chlorella vulgaris.

The cells of Chlorella vulgaris exhibited NaCl (0-400 mM) induced decrease in the growth, protein, chlorophyll, carbohydrate and total organic carbon, whereas total lipid and proline content increased with rising level of NaCl. Addition of NaHCO3 (20 mM) exhibited antagonistic effect against the adverse effect of salinity on the growth, level of macromolecules except proline. The SEM-EDS analysis of NaCl treated cells exhibited morphological variations as well as reduced accumulation of Na and Cl due to the presence of NaHCO3. The results on chlorophyll fluorescence induction kinetics revealed NaCl induced decline in the photosynthetic performance and quantum yield, while non-photochemical quenching of chlorophyll was enhanced, particularly at lower concentrations of NaCl. Addition of NaHCO3 to NaCl treated cells exhibited further increase in the non-photochemical quenching values. Thus, these results demonstrated that adverse impact of NaCl on the C. vulgaris cells was significantly mitigated in the presence of bicarbonate.

Understanding the Role of Litter Decomposition in Restoration of Fly Ash Ecosystem.

Plant species possess a huge potential in restoration of fly ash ecosystem. Litter deposition and its decomposition in the ash deposited sites are two important processes of the fly ash ecosystem. In order to identify the biological potential of a plant species to aid restoration of fly ash deposited sites, it is needed to assess leaf litter decomposition as well as nutrient release pattern. In the present investigation, we studied the leaf litter decomposition of the plant species (Leucaena leucocephala, Pithecellobium dolce and Prosopis juliflora) and mix plantation in the fly ash ecosystem. The litter bag experiment was conducted in the area of plantation on the fly ash deposited site during a period of 365 days. Percentage of C and N was higher in L. leucocephala > P. dolce >Mix Plantation > P. juliflora while C/N ratio was higher in P. juliflora >Mix Plantation > L. leucocephala > P. dolce. L. leucocephala and P. dolce showed relatively fast decomposition rates (k = 1.27, 1.17), respectively while mix plantation (k = 0.82) and P. juliflora (k = 0.73) exhibited relatively slower decomposition rates. Thus, we noted that the decomposition rate of L. leucocephala was greater than the other selected species. This shows that the species having faster decomposition rate and nutrient release could be a factual choice for rehabilitation of fly ash deposited sites.

Bioaccumulation and Toxicity of As in the Alga Chlorococcum sp.: Prospects for As Bioremediation.

Ubiquitous distribution, fast growth rate and manifold relevance has credited algae a potential bioresource in current state of affairs of environmental degradation. In the present study, green alga Chlorococcum sp. has been collected from waste water, isolated and cultured to assess their accumulation and toxicity responses at different As(III) concentration. Results revealed that Chlorococcum sp. treated with 10 µM As(III) showed a minimal reduction (21%) in chlorophyll concentration with high proline and carotenoids content indicating its adaptive tolerance potential against As(III). The EC50 of As(III) for inhibiting growth of the microalgae after 10 days of experiment was 9.4 µM. Further, Chlorococcum sp. accumulated 239.09 µg g- 1 dw As at the concentration of 10 µM of As(III) after 10 days of treatment. Concentration dependent accumulation pattern and antioxidant responses in Chlorococcum sp. could be a used as a potential bioindicator and bioremediator of As from waste water.

Kinetic and thermodynamic characterization of novel alkaline lipase from halotolerant Bacillus gibsonii.

A halotolerant bacterial strain isolated and identified as Bacillus gibsonii was used for extracellular lipase production. The bacterial strain was able to grow up to 1200 mM salt concentration and showed maximum growth at 600 mM NaCl concentration. The present study includes production of extracellular lipase enzyme and characterization of partially purified lipase with respect to its kinetic and thermodynamic behaviour. Maximum lipase activity was observed at 60 °C under alkaline pH (9.0) condition. The kinetic parameters such as Vmax, Km and Kcat were calculated as 158.73 U/mL, 0.539 mM and 483.93 min-1 at 60 °C, respectively, suggested thermostable nature of the enzyme. The thermal inactivation energy [Ea(d)] was calculated as 66.98 kJ/mol. The values of Gibb's free energy (86.31 kJ/mol), enthalpy (64.26 kJ/mol) and entropy (- 66.21 × 10-3 kJ/mol/K) for the enzyme inactivation obtained at 60 °C corroborated the assumption that 60 °C was the optimum temperature. Further, the deactivation rate constant (kd) values calculated at 60 °C and 80 °C were found to be 0.0907 and 0.182 min-1, respectively, which suggested that enzyme was more stable at 60 °C and it was partly inactivated at 80 °C.

Heat stroke-related deaths in India: An analysis of natural causes of deaths, associated with the regional heatwave.

Soaring temperatures cause deaths in large numbers in various parts of India. The number of deaths vary with region and are influenced by the demographics and socioeconomic characteristics of the region. This study tried to estimate the number of deaths associated with exposure to heat in the different states of India. Secondary data was used, which was collected from the website data.gov.in, an Open Government Data (OGD) Platform of the Indian government. Descriptive statistics were applied using Microsoft Excel-10. It was found that there 3014 men died from heat-related causes in 2001-05, which increased to 5157 in the period 2011-15. For women the number of deaths in the corresponding periods were 849 and 1254 respectively. Deaths caused by heatwaves were found to be higher than those resulting from avalanches, exposure to cold, cyclone, tornado, starvation due to natural calamity, earthquake, epidemic, flood, landslide, torrential rain and forest fire. The study revealed that there are regional variations in the number deaths due to heatstroke. From the perspective of disaster preparedness, it is important to note that deaths from heat strokes occur every year. With rising temperatures, the numbers are likely to increase. The findings of the study highlight this concern. Therefore, there is a need for targeted region-specific interventions for reducing the number of deaths due to heatwaves.

Phytoremediation ability of naturally growing plant species on the electroplating wastewater-contaminated site.

The presence of heavy metal in soil and water resources has serious impact on human health. The study was designed to examine the phytoremediation ability of plant species that are growing naturally on the Zn-contaminated site. For the study, six plant species and their rhizospheric soil as well as non-rhizospheric soil samples were collected from different parts of the industrial sites for chemical and biological characterization. Visual observations and highest importance value index (IVI) through biodiversity study revealed potential plants as effective ecological tools for the restoration of the contaminated site. Among the plants, almost all were the most efficient in accumulating Fe, Mn, Cu and Zn in its shoots and roots, while Cynodon dactylon, Chloris virgata and Desmostachya bipinnata were found to be stabilizing Cr, Pb and Cd (bioconcentration factor in root = 7.95, 6.28 and 1.98 as well as translocation factor = 0.48, 0.46 and 0.78), respectively. Thus, the results of this study showed that the naturally growing plant species have phytoremediation potential to remediate the electroplating wastewater-contaminated site. These plant species are successful phytoremediators with their efficient metal stabilizing and well-evolved tolerance to heavy metal toxicity.

Molecular p-doping in organic liquid crystalline semiconductors: influence of the charge transfer complex on the properties of mesophase and bulk charge transport.

We explore the molecular nature of doping in organic semiconductors (OSCs) by employing a liquid crystalline organic semiconductor based on phenyl naphthalene as a model. The mesophase nature of composites that include a charge transfer complex (CTC) between the OSC (8-PNP-O12) and an electron acceptor (F4TCNQ) has been investigated by means of differential scanning calorimetry, polarized optical microscopy and X-ray scattering. Optical and vibrational spectroscopies allow us to explore the characteristics and the amount of charge transfer in the CTC and expose some properties that appear only in the complexed state. We have found this system to exhibit partial charge transfer, which manifests itself in all the phase states of the host 8-PNP-O12, as well as in solution. Due to the lowering of molecular symmetry as a result of the charge transfer, one of the previously IR-only vibrational bands of the nitrile group is found to be now active in the Raman spectrum. We have also made an attempt to further investigate the influence of dopant introduction on the bulk hole mobility of 8-PNP-O12. It is found that the presence of the CTC promotes the hole transport in the Smectic B mesophase, however it seems to have a somewhat negative influence in the less ordered smectic A mesophase. This work aims to establish the link between the inevitable change of molecular geometry that occurs on charge transfer with the results obtained by spectroscopic techniques and electronic charge carrier mobility measurements.

Synergistic action of adsorption and reductive properties of ash derived from distilled Mentha piperita plant waste in removal of Cr(VI) from aqueous solution.

Adsorption behavior of Mentha Plant Ash (MPA) in removal of Cr(VI) from aqueous solution was analyzed as a function of different pH (3.0-8.0), different concentration of Cr(VI) (10-50 mg L-1), contact time (0-90 min) and doses of adsorbent (0.1-0.5 g/100 mL). Adsorption of Cr(VI) onto MPA was found to be dependent on pH condition of the solution and showed maximum removal of Cr(VI) at pH 3.0. The study of adsorption kinetics on Cr(VI) removal by MPA showed that pseudo-second order kinetic model was more suitable to describe the Cr(VI) removal by adsorption onto MPA. Results on Cyclic Voltammetry study of MPA treated with Cr(VI) solution revealed the reduction of Cr(VI) to Cr(III) and Cr(II) by MPA particles through multi-step electron transfer reactions. A combined effect of adsorption and reduction properties of MPA was particularly responsible for removal and transformation of Cr(VI). These attributes of MPA were contributed by many active Cr(VI) binding and electron donating ligands present on the MPA surface as evident from FTIR and XPS analysis of MPA.

Nitrogen-dependent metabolic regulation of lipid production in microalga Scenedesmus vacuolatus.

Microalga Scenedesmus vacuolatus exhibited maximum growth, protein and carbohydrate contents at 10.0 mM concentration of nitrate, 1.0 mM of glutamate nitrogen and at C/N ratio (12 mM acetate+10 mM nitrate). However, these cell constituents showed the highest values in the C+N grown cells, but the lipid content was found to be the highest glutamate grown cells. FTIR analysis of Lipid/Carbohydrate and Lipid/Protein ratio and flow cytometric analysis of neutral lipids revealed higher lipid content in the glutamate grown cells than in the nitrogen starved, nitrate and C+N grown cells. The nitrate reductase activity was the highest in the C+ N grown cells and the lowest activity was found in the glutamate grown cells. A corollary of these results suggested that suppression of nitrogen assimilatory system, whether by glutamate or by nitrogen deprivation, was the most suitable physiological condition for enhanced lipid synthesis and biofuel production in microalgal cells.

Lactobacillus plantarum MTCC 9510 supplementation protects from chronic unpredictable and sleep deprivation-induced behaviour, biochemical and selected gut microbial aberrations in mice.

AIM: Here, we evaluated any beneficial effects of a potential probiotic bacterial strain (Lactobacillus plantarum MTCC 9510) in two different stress paradigms in mice. METHODS AND RESULTS: Lactobacillus plantarum MTCC 9510 (2 × 1010 CFU per mice) was supplemented to male Swiss albino mice either subjected to chronic unpredictable mild stress or sleep deprivation (SD) stress. Various behavioural and biochemical tests along with selected gut bacterial abundances were determined. Lactobacillus plantarum MTCC 9510 supplementation prevented stress-induced behavioural despair (depression, anxiety, learning and memory, stereotypic behaviour), oxidative stress markers and inflammatory cytokines in brain and serum. Its supplementation also improved gut and blood brain barrier integrity. It also affected caecal short-chain fatty acids along with the promotion of Lactobacillus sp. and reduction in Enterobacteriaceae abundances. We also observed that two different stresses variably affected various behavioural and biochemical changes but L. plantarum MTCC 9510 supplementation most effectively prevented all these changes. CONCLUSION: We provide evidence that positive modulation of the selected beneficial gut microbial population could serve as a viable strategy to neutralize day-to-day and SD stress-induced pathological alterations. SIGNIFICANCE AND IMPACT OF THE STUDY: Therapeutic potential of this/other probiotic strains in tackling the deleterious neurobiological effects on exposure to various stress-related conditions can be explored.

Regulation of oxidative stress and mineral nutrient status by selenium in arsenic treated crop plant Oryza sativa.

The present study was conducted to examine the impact of selenium (Se) on mineral nutrient status and oxidative stress in crop plant Oryza sativa treated with arsenic (As). Scanning electron microscopy (SEM) coupled with Energy dispersive x-ray spectroscopy (EDS) study revealed the morphological deformities in leaf veins along with granular deposition on the leaf surface. The EDS analysis exhibited loss of elements (S, Si, Cl, K, Ca, Fe and Cu) in As(III) treatment in rice roots as compared to untreated root. In the case of As(III) treated shoot, changes in elements content in term of percent atomic weight was K (1.17-0.90%), Cl (1.04-24.75%), Na (0.65-3.52%) and S (0.49-2.52%) when compared with untreated shoot. The result of EDS analysis showed that As limits the concentration of important mineral elements present in the rice root and shoot. Rice plant treated with Se (10µM) and sub lethal dose of As(III) (60µM) showed better growth responses in term of root, shoot length (11.4% and 10.71%, respectively), biomass (11.7%), reduced malonyldialdehyde content (35.14%) and stimulated antioxidant level indicating better As tolerance potential against As. Further, a selenium dependent significant reduction in As accumulation was also observed in root (14.24%) and shoot (23.78%) of rice plant when compared with plant treated with As alone. This study highlights the potential of Se to ameliorate the ecotoxicological risks associated with the As buildup in agricultural land.

Decolourization of malachite green dye by mentha plant biochar (MPB): a combined action of adsorption and electrochemical reduction processes.

Adsorption behavior of mentha (mint) plant biochar (MPB) in removal of malachite green (MG) dye from aqueous solution was analyzed as a function of different pH (4.0-10.0), initial dye concentration (20-100 mg/L), contact time (0-45 min) and dose of adsorbent (0.05-0.3 g/100 mL). The zeta potential of the MPB particles was found to be -37.9 mV, indicating a negatively charged sorption surface of MPB particles. MPB was found to be more effective in removal of MG dye at pH 6.0 due to combined action of physico-chemisorption and a reductive electron transfer reaction. Results on the Brunauer-Emmett-Teller (BET) analysis of the N2 adsorption-desorption isotherm of MPB as adsorbent showed sigmoidal shape similar to the type IV isotherm and mesoporous nature. The cyclic voltammetric analysis of MG dye showed a reversible, coupled redox reaction at the interface of dye molecules and MPB particles. The maximum monolayer adsorption capacity (qmax) of MPB was found to be 322.58 mg g-1. The separation factor (RL) value was between 0 and 1, indicating a favourable adsorption of MG dye onto MPB. The results fitted well to a pseudo-second-order kinetic model. Further results from desorption experiments showed recovery of MG dye by about 50% in the presence of 1 N HCl.

A novel cobiotic-based preventive approach against high-fat diet-induced adiposity, nonalcoholic fatty liver and gut derangement in mice.

BACKGROUND: High-fat diets (HFDs) induce systemic inflammation, gut microbial derangements and disturb metabolic homeostasis, resulting in weight gain, insulin resistance and nonalcoholic fatty liver (NAFL). Numerous antioxidants and prebiotic/probiotics per se may prevent HFD-associated comorbidities, but there are no reports related to their combination. OBJECTIVE: In the present study, we aim to evaluate a cobiotic combination of lycopene (antioxidant) and isomalto-oligosaccharides (IMOs, a prebiotic) for prevention of HFD-induced alterations. DESIGN: Male Swiss albino mice were fed either normal pellet diet (NPD) or HFD and lycopene (5 and 10 mg kg(-1)), IMOs (0.5 and 1 g kg(-1)) or their combination for 12 weeks. Systemic adiposity, glucose tolerance, insulin sensitivity, feeding regulators in hypothalamus, hepatosteatosis and liver inflammation, cecal short chain fatty acids (SCFAs), serum inflammatory cytokines, gut morphology and alterations in selected gut microbes were studied. RESULTS: Lycopene, IMOs and their combination prevented weight gain, adiposity, improved adipose tissue fat mobilization and reduced insulin resistance. Hypothalamic orexigenic and anorectic genes have also been modulated by these treatments. Dietary interventions prevented NAFL-like symptoms and improved glucose homeostasis. Improvement in selected gut microbial abundance and SCFA concentration along with reduced systemic inflammation, metabolic endotoxemia and improved ileal and colonic health were observed in mice supplemented with lycopene, IMOs and their combination. Interestingly, cobiotic combination synergistically improved many of the HFD-induced alterations. CONCLUSION: The present work provide evidence that new approach based on cobiotic combination (antioxidant plus prebiotic) can be employed to develop novel class of functional foods for their application against HFD-associated pathological complications.

Experimental and kinetic studies for phycoremediation and dye removal by Chlorella pyrenoidosa from textile wastewater.

Potential of Chlorella pyrenoidosa was experimentally investigated for phycoremediation and dye removal from textile wastewater (TWW) in batch cultures. Growth of alga was observed at various concentration of textile wastewater (25%, 50%, 75% and 100%) and was found in a range of 8.1-14 µg ml(-1) day(-1). Growth study revealed that alga potentially grows up to 75% concentrated textile wastewater and reduces phosphate, nitrate and BOD by 87%, 82% and 63% respectively. Methylene blue dye (MB) removal was also observed by using dry and wet algal biomass harvested after phycoremediation. Adsorption isotherms (Langmuir and Freundlich) and kinetic models (pseudo first and second order) were applied on adsorption process. Dry algal biomass (DAB) was found more efficient biosorbent with large surface area and showed high binding affinity for MB dye in compare to wet algal biomass (WAB). The RL value for both biosorbent showed feasible adsorption process as the obtained value was between 0 and 1. Pseudo second order kinetic model with high degree of correlation coefficient and low sum of error squares (SSE %) value was found more suitable for representation of adsorption process in case of both biosorbents, however pseudo first order also showed high degree of correlation for both biosorbents.

Pathology of a H5N1, highly pathogenic avian influenza virus, in two Indian native chicken breeds and a synthetic broiler line.

In this study, susceptibility to H5N1 virus infection was studied in two Indian native chicken breeds viz. Kadaknath and Aseel (Peela) and an Indian synthetic broiler strain (Synthetic dam line (SDL-IC). Fifty birds from each genetic group were infected intra-nasally with 1000 EID50 of a highly pathogenic avian influenza virus (HPAIV) strain A/chicken/Navapur/India/7972/ 06 (H5N1) and observed for a period of 10 days. Significant differences in severity of clinical signs, gross lesions and time for onset of symptoms were observed. The overall severity of clinical signs and gross lesions was less in SDL-IC broilers as compared to the other two genetic groups. The mortality percentages were 100, 98 and 92% with Mean Death Time (MDT) of 3.12, 5.92 and 6.96 days, respectively for the two native breeds Kadaknath and Aseel (Peela), the and SDL-IC broiler strain. Comparison of histological lesions revealed differences in disease progression among the genetic groups. Vascular lesions such as disseminated intravascular coagulopathy (DIC) were predominant on 3 days post infection (dpi) in Kadaknath, and on 5 and 6 dpi in Aseel (Peela) and SDL-IC broiler. The mean log2 HA titres of the re-isolated virus from various organs of H5N1 AIV infected birds of the three genetic groups ranged from 2.32 (lung, trachea and bursa) to 5.04 (spleen) in Kadaknath; 2.32 (lung) to 6.68 (brain) in Aseel (Peela); and 2.06 (liver) to 7.01 (lungs and kidney) in SDL-IC broiler. These results suggest that the susceptibility to H5N1 highly pathogenic avian influenza virus infection differed among the three breeds; Kadaknath being highest followed by Aseel (Peela) and synthetic SDL-IC broiler. This is possibly the first report on the differences in the susceptibility of the India native breeds to H5N1 virus infection and its severity.

Comparison of three PCR-based assays for the non-invasive diagnosis of malaria: detection of Plasmodium parasites in blood and saliva.

The conventional molecular diagnosis of malaria uses 18S rRNA-based PCR assay employing blood samples. This assay presents limitation in terms of long turnaround time and increased chances of false-positive results. Here, we evaluated one-step singleplex or multiplex PCR assay based on high copy species-specific consensus repeat sequences (CRS) along with standard 18S rRNA nested PCR (18S n-PCR) assay to detect P. falciparum and P. vivax infection using blood and saliva samples from Indian febrile patients. Out of 327 patients, 187 were found to be positive for malaria parasites by microscopic examination of peripheral blood smears. Among these 130 were P. vivax and 57 were P. falciparum cases. The 18S n-PCR assay and CRS PCR assay identified 186 out of 187 cases (99.4 %). Multiplex CRS PCR assay detected Plasmodium in 176 out of 187 cases (94.1 %). Both singleplex and multiplex CRS PCR assay identified 6 mixed infection cases, while 18S n-PCR assay detected 10 mixed infection cases of P. vivax and P. falciparum, which were not recognized by microscopy. Non-invasive Plasmodium detection rate with DNA derived from saliva samples was highest for 18S n-PCR (87.36 %), followed by singleplex CRS (81 %) and multiplex CRS PCR assay (70.5 %). Specificity for P. vivax and P. falciparum detection for all assays was 98.48 % and 100 % respectively. Detection rate for P. vivax in saliva correlated with parasite density for CRS target-based assays. The species-specific CRS PCR, either as a singleplex or multiplex assay, can have an impact on diagnosis and epidemiological studies in malaria.

Biotransformation of arsenic by bacterial strains mediated by oxido-reductase enzyme system.

The present study deals with the enzyme mediated biotransformation of arsenic in five arsenic tolerant strains (Bacillus subtilis, Bacillus megaterium, Bacillus pumilus, Paenibacillus macerans and Escherichia coli). Biotransformation ability of these isolates was evaluated by monitoring arsenite oxidase and arsenate reductase activity. Results showed that arsenic oxidase activity was exclusively present in P. macerans and B. pumilus while B. subtilis, B. megaterium and E. coli strains showed presence of Arsenic oxido-reductase enzyme. The reversible nature of arsenic oxido- reductase suggested that same enzyme can carry out oxidation and reduction of arsenic depending upon the relative concentration of arsenic species. Lineweaver-Burk plot of the arsenite oxidase activity in P. macerans showed highest Km value (Km- 200 µM) and lower Vmax (0.012 µmol mg-1 protein min-1) indicating lowest affinity of the enzyme for arsenite. On the contrary, E. coli showed the lower Km value ( Km- 38.46 µM) and higher Vmax (0.044 µmol mg-1 protein min-1) suggesting for higher affinity for the arsenite. Lineweaver-Burk plot of arsenate reductase activity showed the presence of this enzyme in B. subtilis, B. megaterium and E. coli which were in the range of 200-360 µM Km and Vmax value between 0.256- 0.129 mmol mg-1 protein min-1. These results suggested that affinity of the as reductase enzyme is lowest for arsenate than that for the arsenite. Thus, arsenite oxidase system appears to be a predominant mechanism of cellular defense in these bacterial strains.

Removal of Cr (VI) by a halotolerant bacterium Halomonas sp. CSB 5 isolated from sambhar salt lake Rajastha (India).

A halotolerant chromate reducing bacterium CSB 5 isolated from the Sambhar Salt Lake (Rajasthan) was identified as Halomonas sp. CSB 5 by 16SrDNA sequence analysis. The isolate could tolerate up to 25% NaCl (w/v) and100 µg mL-1of Chromium hexavalent in the complex medium (CM). Removal of Cr (VI) at concentration of 20, 40 and 60 µg mL-1 was found to be 98%, 90.2%, and 65.7% within a period of 60 hour.Effect of factors like pH and temperature on the total removal of Cr (VI) at 60µg mL-1concentration showed maximum removal at pH 8.0 (77.9 %) and temperature 35°C (82.6%) in 60 hour. The maximum intracellular uptake and surface adsorption (3.22 ± 0.09 and 14.16 ± 0.49 µg mg-1 dry wt.) in CMB 5 bacterium was observed at 75 µg mL-1 of Cr (VI) concentration in 45 min.The results showed that contribution of surface binding was about 4-5 fold higher than the intracellular uptake. Bacterium showed concentration dependent increase in the chromate reductase activity with saturating rate at 60 µg mL-1 concentration of chromium. The values of Km and Vmax with NADH of the bacterium was found to be 0.818 µg mL-1 and 0.085 µg mL-1.min-1.mg-1 protein, respectively. Fourier Transform Infrared Spectroscopy (FTIR) analysis of Cr (VI) binding on membrane surface showed changes in wavenumber between 3300-2800 cm-1due to involvement of proteins and fatty acids in the binding of Cr (VI). The absorption peaks at wavenumbers 1654.9, 1580.3 cm-1, 1248 and 1085.6 cm-1 shifted to lower frequencies due to interaction of Cr (VI) with functional groups like amides and phosphodiester. These results suggested that the isolated CSB 5 bacterium can be used as potential bioremediating agent for removal of Cr (VI) in salt loaded waste water.