Apurba Dey

Decolorization and biodegradation of congo red dye by a novel white rot fungus Alternaria alternata CMERI F6

A novel white rot fungus Alternaria alternata CMERI F6 decolorized 99.99% of 600 mg/L congo red within 48 h in yeast extract-glucose medium at 25 °C, pH 5 and 150 rpm. Physicochemical parameters like carbon and nitrogen sources, temperature, pH and aeration were optimized to develop faster decolorization process. Dye decolorization rate was maximal (20.21 mg/L h) at 25 °C, pH 5, 150 rpm and 800 mg/L dye, giving 78% final decolorization efficiency. Scanning electron microscopy and X-ray Diffraction analysis revealed that the fungus become amorphous after dye adsorption. HPLC and FTIR analysis of the extracted metabolites suggested that the decolorization occurred through biosorption and biodegradation. Thermogravimetric analysis (TGA), differential thermal analysis (DTA) and acid-alkali and 70% ethanol treatment revealed the efficient dye retention capability of the fungus. The foregoing results justify the applicability of the strain in removal of congo red from textile wastewaters and their safe disposal.

Potential use of polyphenol oxidases (PPO) in the bioremediation of phenolic contaminants containing industrial wastewater

The present review emphasizes on the use of Polyphenol oxidase (PPO) enzyme in the bioremediation of phenolic contaminants from industrial wastewater. PPO is a group of enzyme that mainly exists in two forms; tyrosinase (E.C. 1.14.18.1) and laccase (E.C. 1.10.3.1) which are widely distributed among microorganisms, plants and animals. These oxidoreductive enzymes remain effective in a wide range of pH and temperature, particularly if they are immobilized on some carrier or matrices, and they can degrade a wide variety of mono and/or diphenolic compounds. However, high production costs inhibit the widespread use of these enzymes for remediation in industrial scale. Nevertheless, bench studies and field studies have shown enzymatic wastewater treatment to be feasible options for biodegradation of phenols through biological route. Nanomaterials-PPO conjugates have been also applied for removal of phenols which has successfully lower down the drawbacks of enzymatic water treatment. Therefore in this article various approaches and current state of use of PPO in the bioremediation of wastewater, as well as the benefits and disadvantages associated with the use of such enzymes have been overviewed.

Application of Central Composite Design approach for removal of chromium (VI) from aqueous solution using weakly anionic resin: Modeling, optimization, and study of interactive variables

In this paper, response surface methodology (RSM) approach using Central Composite Design (CCD) is applied to develop mathematical model and optimize process parameters for Cr (VI) removal from aqueous streams using weakly anionic resin Amberlite IRA 96. The individual and combined effect of four process parameters, i.e. contact time, initial solution pH, initial Cr (VI) concentration and resin dose on Cr adsorption were studied. Analysis of variance (ANOVA) showed the relative significance of process parameters in removal process. Initial solution pH and resin dose were found to be more significant than contact time and initial Cr (VI) concentration. The second-order regression model was developed to predict the removal efficiency using Design Expert software. The optimal conditions to remove Cr from aqueous solution at constant temperature of 30°C and stirring speed of 250 rpm were found to be contact time 62.5 min, pH 1.96, initial Cr (VI) concentration 145.4 mg/L, and resin dose 8.51 g/L. At these conditions, high removal efficiency (93.26%) was achieved. FTIR and EDX analysis were conducted to interpret the functional groups involved during the Cr-resin interaction.

Batch removal of chromium (VI) from aqueous solutions using wheat shell as adsorbent: process optimization using response surface methodology

Abstract The biosorption potential of wheat (Triticum aestivum) shells to remove hexavalent Chromium (Cr+6) ions from aqueous solutions was investigated in batch mode experiments. The equilibrium adsorption level was determined and it was observed that equilibrium adsorption of chromium was function of the solution contact time and initial metal concentration. The effect of solution pH on biosorption was also studied. From experimental results it was observed that the biosorptive capacity of the shell was dependent on the pH and initial Cr (VI) ions concentration. The Freundlich and Langmuir constants for biosorption of chromium (VI) on wheat shells were determined and it was observed that the adsorption data fi t well with the Langmuir isotherm model. To optimization of this process response surface methodology (RSM) was utilized. The regression equation was obtained using Design Expert 7.0 software. Predicted values thus obtained were closed to experimental value indicating suitability of the model.

Effect of pH and temperature on stability and kinetics of novel extracellular serine alkaline protease (70 kDa).

A novel extracellular serine protease (70 kDa by SDS-PAGE) was purified and characterized. This enzyme retained more than 93% of its initial activity after preincubation for 30 min at 37 °C in the presence of 25% (v/v) tested organic solvents and showed feather degradation activity. The purified enzyme was deactivated at various combinations of pH and temperature to examine the interactive effect of them on enzyme activity. The deactivation process was modeled as first-order kinetics and the deactivation rate constant (k(d)) was found to be minimum at pH 9 and 37 °C. The kinetic analysis of enzyme over a range of pH values indicated two pK values at 6.21 and at 10.92. The lower pK value was likely due to the catalytic histidine in the free enzyme and higher pK value likely reflected deprotonation of the proline moiety of the substrate but ionization of the active site serine is another possibility. Inhibition kinetic showed that enzyme is serine protease because enzyme was competitively inhibited by antipain and aprotinin as these compounds are known to be competitive inhibitors of serine protease. The organic solvent, thermal and pH tolerances of enzyme suggested that it may have potential for use as a biocatalyst in industry.

An integrated approach to remove Cr(VI) using immobilized Chlorella minutissima grown in nutrient rich sewage wastewater.

The potential of an integrated system for sewage wastewater treatment and biosorption of chromium(VI) was evaluated using immobilized Chlorella minutissima cells. Immobilized algal cells were grown in sewage wastewater in designed photobioreactor for 48 h and then subjected to removal of Cr(VI) from synthetic wastewater. The effect of pH, Cr(VI) concentration, biosorbent dose on Cr(VI) removal was investigated. C. minutissima showed a higher NH(4)(+)-N and PO(4)(3-)-P removal efficiency (above 99% removal) than the NO(3)(2-)-N (58% removal) in 48 h. Biosorption of Cr(VI) was found to be highly dependent on solution pH, biosorbent dose and initial Cr(VI) concentration. Maximum Cr(VI) uptake 57.33 mg Cr(VI)/g dry biosorbent/L of solution was observed at pH2 with 20% (w/v) biosorbent. Further more than 90% of total Cr adsorbed could be recovered using 0.5 M NaOH as desorption medium.

Statistical Approach for Optimization of Physiochemical Requirements on Alkaline Protease Production from Bacillus licheniformis NCIM 2042.

The optimization of physiochemical parameters for alkaline protease production using Bacillus licheniformis NCIM 2042 were carried out by Plackett-Burman design and response surface methodology (RSM). The model was validated experimentally and the maximum protease production was found 315.28 U using optimum culture conditions. The protease was purified using ammonium sulphate (60%) precipitation technique. The HPLC analysis of dialyzed sample showed that the retention time is 1.84 min with 73.5% purity. This enzyme retained more than 92% of its initial activity after preincubation for 30 min at 37°C in the presence of 25% v/v DMSO, methanol, ethanol, ACN, 2-propanol, benzene, toluene, and hexane. In addition, partially purified enzyme showed remarkable stability for 60 min at room temperature, in the presence of anionic detergent (Tween-80 and Triton X-100), surfactant (SDS), bleaching agent (sodium perborate and hydrogen peroxide), and anti-redeposition agents (Na2CMC, Na2CO3). Purified enzyme containing 10% w/v PEG 4000 showed better thermal, surfactant, and local detergent stability.

MEGA biocentric software for sequence and phylogenetic analysis: a review

Biocomputing has moved into central position in molecular biology research. Enormous improvements in genetic engineering have led to the accumulation of a vast amount of biological information. With the advent of this extensive repertoire of raw sequence information, the next major challenge for a modern researcher is to interpret this biological information. Molecular Evolutionary Genetic Analysis (MEGA) is bio-computational software to fill the vacuum between data development and analysis. In this paper, an attempt to review the evolution of MEGA software, working and application has been made. Moreover, data analysis, implementation and advantages over other bioinformatics software have been discussed systematically.

Optimization of culture condition for growth and phenol degradation by Alcaligenes faecalis JF339228 using Taguchi Methodology

Abstract The optimization of five process parameters such as pH, agitation, temperature, inoculum percentage and incubation time were optimized by Taguchi robust design method for obtaining enhanced biomass and phenol degradation by the isolated Alcaligenes faecalis JF339228 from Durgapur steel industry (DSP), India. About 18 experiments were conducted with a different combination of factors and the results obtained in terms of growth of specific bacterial strain and phenol degradation rates were processed in the Qualitek-4 software to study the main effect of individual factors. The main effect, interaction effects and optimal levels of the process factors were determined using signal-to-noise (S/N) ratio. The effect of factors has been studied for bacterial growth and phenol degradation by A. faecalis JF339228. Optimization of the said parameters has been evaluated by Taguchi method and analysed by analysis of variance. Predicted results showed enhanced process performance such as biomass (131.78%) and ...

Optimization of physicochemical parameters for phenol biodegradation by Candida tropicalis PHB5 using Taguchi Methodology

AbstractThe Taguchi orthogonal array (OA) design of experiments methodology, a quality optimization tool, was used to improve the phenol biodegradation potential of the yeast Candida tropicalis PHB5. At three levels, an OA was selected to analyze the effects of the different physicochemical process factors. Experiments were undertaken to confirm the effectiveness of this method and the main factors affecting the growth of C. tropicalis on phenol and its subsequent degradation were found, together with the optimal factor levels. Predicted results showed that biomass yield could be increased from 1,051.96 to 2,495.74 mg/l and the subsequent amount of phenol degraded could be increased from 879.42 to 2,386.43 mg/l. Based on Taguchi methodology, an overall enhancement of growth by 137.24% and phenol degradation by 171.49% could be attained. Validation experiments showed that the growth and phenol biodegradation was significantly improved by up to 132.4% and 165.64%, respectively.