Biswanath Mahanty

Biosynthesis of hematite nanoparticles and its cytotoxic effect on HepG2 cancer cells.

Iron oxide nanoparticles were gaining significant importance in a variety of applications due to its paramagnetic properties and biocompatibility. Various chemical methods were employed for hematite nanoparticle synthesis which require special equipment or a complex production process. In this study, protein capped crystalline hexagonal hematite (α-Fe2O3) nanoparticles were synthesized by green approach using culture supernatant of a newly isolated bacterium, Bacillus cereus SVK1 at ambient conditions. The synthesized nanoparticles were characterized by electron microscopy, X-ray diffraction, UV-visible spectroscopy and Fourier transform infrared spectroscopic analysis. Nanoparticles were evaluated for its possible anticancer activity against HepG2 liver cancer cells by MTT assay. Hematite nanoparticles with an average diameter of 30.2 nm, exhibited a significant cytotoxicity toward HepG2 cells in a concentration-dependent manner (CTC50=704 ng/ml).

Production and Properties of a Biosurfactant Applied to Polycyclic Aromatic Hydrocarbon Solubilization

Microorganisms isolated from a soil sample collected from a gasoline filling station (located in Guwahati) were tested for their pyrene- and anthracene-degrading potential. Preliminary studies showed the ability of the organism to grow on carbon-free mineral medium (CFMM) supplemented with pyrene as the sole source of carbon. The organisms were found to produce a bioemulsifier when grown on CFMM with glucose or glycerol and/or pyrene as the carbon source. The organisms could also utilize anthracene when grown on mineral salt medium along with 2% glycerol. Within 2 d, anthracene concentration dropped less than 30% of the original concentration. Approximately 100 mg of the emulsifier was isolated from 25 mL of the 5-d-grown culture. The emulsifier was tested to produce emulsion with both an aliphatic and an aromatic group of hydrocarbons and resulting emulsions were found to be stable for a long period of time when keptat 10–15°C. The emulsifier was also quite stable in a pH range of 3.0–11.0. In a concentration range of 0.5–10 mg/mL, it resulted in a linear increment of apparent pyrene and anthracene solubility in water.

Optimization of co-digestion of various industrial sludges for biogas production and sludge treatment: methane production potential experiments and modeling.

Optimal biogas production and sludge treatment were studied by co-digestion experiments and modeling using five different wastewater sludges generated from paper, chemical, petrochemical, automobile, and food processing industries situated in Ulsan Industrial Complex, Ulsan, South Korea. The biomethane production potential test was conducted in simplex-centroid mixture design, fitted to regression equation, and some optimal co-digestion scenarios were given by combined desirability function based multi-objective optimization technique for both methane yield and the quantity of sludge digested. The co-digestion model incorporating main and interaction effects among sludges were utilized to predict the maximum possible methane yield. The optimization routine for methane production with different industrial sludges in batches were repeated with the left-over sludge of earlier cycle, till all sludges have been completely treated. Among the possible scenarios, a maximum methane yield of 1161.53 m(3) is anticipated in three batches followed by 1130.33 m(3) and 1045.65 m(3) in five and two batches, respectively. This study shows a scientific approach to find a practical solution to utilize diverse industrial sludges in both treatment and biogas production perspectives.

Understanding the Complexity and Strategic Evolution in PAH Remediation Research

The development and improvement of society through industrialization and urbanization comes with the cost of consistent deterioration and degradation of the natural environment through generation of toxic and hazardous pollutants. Polycyclic aromatic compounds (PAHs) are a major class of such persistent organic pollutants, posing serous threat to terrestrial and aquatic ecosystems due to their intrinsic low aqueous solubility, higher binding affinity toward soil organic matters, and higher chemical stability, making them less susceptible toward remediation process. Two key issues are covered in the review. First, the severity of contamination and its implications are addressed with reference to source, distribution, and toxicity of PAHs. Second, a detailed overview on significant and systematic changes that have ever been observed in remediation methodology of PAH contaminants in past decades is presented. The remediation and treatment time, contaminant composition and load, site characteristics, and desired degree of cleanup are the decisive factors guiding selection of proper in situ or ex situ remediation technology. It has generally been observed chemical oxidation is the method of choice for rapid reduction (within minutes to couple of hours) of recalcitrant PAHs (e.g., benzo[a]pyrene) load in a more heterogeneous system (e.g., soil) with an efficiency from ∼10% to 100%. On the other hand phytoremediation can effectively handle 3- and 4-ring PAHs (phenanthrene, pyrene) in aged and spiked contaminated soil and sediment system with a similar degree of conversion, but in a long or extended period of time (a couple of months to years). The times scale for ex situ microbial remediation systems in liquid phase are in days to weeks and contaminant load that can effectively be treated varies with the nature and concentration of additives (e.g., surfactants, solvents). Finally, the authors offer general insight about biological treatment methods, with a wider focus into the recent developments in the process.

SYNCHRONOUS FLUORESCENCE AS A SELECTIVE METHOD FOR MONITORING PYRENE IN BIODEGRADATION STUDIES

A simple and effective method based on synchronous fluorescence spectroscopy for quantifying pyrene and its metabolites in a biodegradation study using Mycobacterium frederiksbergense is reported in this work. An optimum excitation-emission wavelength offset of 39 nm and a corresponding excitation wavelength of 335 nm was found to be suitable for the determination of pyrene. Interference due to naphthalene and anthracene in the analysis were found to be 11 and 4.7%, respectively. Batch biodegradation experiments in a 3L fermentor revealed a high pyrene degradation rate of 10.22 mg L− 1 d− 1 by the mycobacterium in presence of the surfactant tween 20. Tween 20 was, however, found preferentially utilized over pyrene, which resulted in a lag of 120 h in pyrene degradation by the culture. In the absence of the surfactant, pyrene degradation rate was found to be only 6.1 mg L− 1 d− 1, but without any lag in its degradation.

PYRENE ENCAPSULATED ALGINATE BEAD TYPE FOR SUSTAINED RELEASE IN BIODEGRADATION: PREPARATION AND CHARACTERISTICS

A novel method for preparation of pyrene encapsulated alginate beads for controlled release delivery of pyrene is reported in this study. Five different bead types that varied on the organic phase for pyrene delivery, presence or absence of polyvinyl alcohol (PVA) and boric acid treatment were prepared. Based on the pyrene release profile, silicone oil encapsulated in PVA-alginate bead was selected where encapsulation efficiency was more than 99% without any solvent leakage. Silicone oil encapsulation was further confirmed in microscopy observations. Pyrene release behavior from the beads was explained by a diffusion controlled first order release (R2 > 0.96). Reusability of this bead was demonstrated, where pyrene was loaded from an external medium in a non-destructive way. Application of the system was finally established in a biodegradation study using Mycobacterium frederiksbergense, where simultaneous release and removal of pyrene along with appearance of pyrene metabolites was observed.

Characterization of co-digestion of industrial sludges for biogas production by artificial neural network and statistical regression models.

The characteristics and impact of industrial sludges of paper, chemical, petrochemical, automobile, and food industries situated in the Ulsan Industrial Complex, Ulsan, Republic of Korea in co-digestion for biogas production were assessed by artificial neural network (ANN) and statistical regression models. The regression model was based on a simplex-centroid mixture design and the ANN was based on a resilient back-propagation algorithm (topology 5-7-1). Using connection weights and bias of the trained ANN model, the impact of each sludge of co-digestion was assessed using Garsons’ algorithm. Results suggested that the modelling and predictability of ANN were superior to the regression model with accuracy (A f) 1.01, bias (B f) 1.00, root mean square error 3.56, and standard error of prediction 2.51%. Sludge from the chemical industry showed the highest impact on specific methane yield (SMYvs) with a relative importance of 28.59% followed by sludges from paper (20.07%), food (19.59%), petrochemical (15.92%), and automobile (15.82%) industries. The interactions between diverse industrial sludges were successfully modelled and partitioned into various synergistic and antagonistic effects on SMYvs. Synergistic interactions between the chemical industry sludge and either petrochemical or food industry sludges on SMYvs were detected. However, strong negative interaction between automobile sludge and other sludges was observed. This study indicates that though the ANN model performed better in prediction and impact assessments, the regression model reveals the synergistic and antagonistic interactions among sludges.

Substrate Inhibition Growth Kinetics for Cutinase Producing Pseudomonas cepacia Using Tomato-peel Extracted Cutin

Cutinase [EC 3.1.1.74] is a key enzyme known to hydrolyze cutin – a water insoluble polymeric network of esterified hydroxyl and epoxy fatty acids (C16 and C18), and the predominant component embedded in plant cuticles1 protecting it from desiccation as well as microbial and insect attack. Cutinase is believed to belong to a group of intermediate enzymes between lipase and esterase, which are able to hydrolyze cutin polymer, soluble esters and emulsified triacylglycerol – as efficiently as pancreatic lipases.2 The absence of any significant structural rearrangements upon binding to a non-hydrolysable substrate analogue represents an important feature of cutinase.3 Because of no or little interfacial activation and being active on both soluble and emulsified triglycerides, this enzyme is gaining more attention over lipases in recent years.1

Degradation of the long-resistant pharmaceutical compounds carbamazepine and diatrizoate using mixed microbial culture

ABSTRACT The microbial degradation of two recalcitrant pharmaceutical compounds, carbamazepine (CBZ) and diatrizoate (DTZ), was studied in laboratory batch experiments. We used a defined mixed microbial culture comprising four distinct microbial species that were previously known to have high decomposition capacity toward recalcitrant substances. Biological decomposition in liquid phase cultures for either CBZ or DTZ, or in a combination of the two, was conducted for 12 days. DTZ and CBZ were degraded by 43.2% and 60%, respectively from an initial concentration of 100 µg L−1. When degradation was assessed using a mixture of the two compounds, the initial degradation rates of CBZ and DTZ were lower than those observed in the single-compound study. However, the final cumulative removal efficiency was very similar. The extent of dissolved organic carbon (DOC) removal was correlated with the degradation of the pharmaceuticals.

Activity of a Methanotrophic Consortium Isolated from Landfill Cover Soil: Response to Temperature, pH, CO2, and Porous Adsorbent

ABSTRACT A robust, naturally evolving methanotrophic community in landfill cover soil (LFCS) can be the simplest way to mitigate landfill methane emission. In this study, bacterial community composition in LFCS and methane oxidation potential of enriched methanotrophic consortium, in comparison to that of axenic Methylosinus sporium, was investigated. Growth and methane oxidation of the consortium was studied in liquid phase batch experiments under varying temperature (20–40°C), pH (5–10), headspace CO2, and in presence of porous adsorbent (1.3 cm3 sponge cubes). The 16S rRNA gene analysis revealed presence of both type-I and type-II methanotrophs along with few obligate methylotroph in LFCS. Though the optimal growth condition of the consortium was at 30°C and pH 7, it was more resilient in comparison to M. sporium. With increasing availability of porous adsorbent, methane consumption by the consortium was significantly improved (p < 0.001) reaching a maximum specific methane oxidation rate of 11.4 μmol mg−1 biomass h−1. Thus, inducing naturally thriving methanotrophs in LFCS is a better alternative to axenic methanotrophic culture in methane emission management.