Mausam Verma

Green approach for nanoparticle biosynthesis by fungi: current trends and applications.

In recent years, the green approach of nanoparticle synthesis by biological entities has been gaining great interest over various other physico-chemical methods, which are laden with many disadvantages. The important challenging issues in current nanotechnology include the development of reliable experimental techniques for the synthesis of nanoparticles of different compositions and sizes along with high monodispersity. Biological systems offer unique promising features to tailor nanomaterials with predefined properties. Fungi are the favorite choice of microorganisms due to the wide variety of advantages they offer over bacteria, yeast, actinomycetes, plants, and other physico-chemical techniques. The use of microorganisms for the deliberate synthesis of nanoparticles is a fairly new and exciting area of research with considerable potential for further development. This review describes an overview of the current green approaches for the synthesis of nanoparticles with particular emphasis on fungi, which are gaining worldwide popularity as nano-factories for the green synthesis of nanoparticles.

Extraction and Analysis of Polyphenols: Recent trends

In recent years, there has been an increasing interest in diets rich in fruits and vegetables and this is mostly due to their presumed role in the prevention of various degenerative diseases, such as cancer and cardiovascular diseases. This is mainly due to the presence of bioactive compounds, such as polyphenols, carotenoids, among others. Polyphenols are one of the main classes of secondary metabolites derived from plants offering several health benefits resulting in their use as functional foods. Prior to the use of these polyphenols in specific applications, such as food, pharmaceutical, and the cosmetic industries, they need to be extracted from the natural matrices, then analyzed and characterized. The development of an efficient procedure for the extraction, proper analysis, and characterization of phenolic compounds from different sources is a challenging task due to the structural diversity of phenolic compounds, a complex matrix, and their interaction with other cellular components. In this light, this review discusses different methods of extraction, analysis, and the structural characterization of polyphenolic compounds.

Membrane processes for removal of pharmaceutically active compounds (PhACs) from water and wastewaters

Pharmaceutically active compounds (PhACs), which find their way easily into the water sources, are emerging as a major concern for drinking water quality and aquatic species. Therefore, their removal from water sources is a priority from environmental point of view. During the past decade, different methods including membrane separation, adsorption systems and chemical transformation have been evaluated for removal of these compounds. This paper reviews different aspects of PhAC removal by using membrane separation processes, as they have been conventionally known to show high potential in the production of superior quality drinking and industrial water. In brief, osmosis membranes can efficiently remove almost all PhACs though its operational cost is relatively high and nanofiltration (NF) membranes are highly influenced by electrostatic and hydrophobic interaction. Moreover, the efficiency of membrane bioreactors (MBRs) is difficult to predict due to the complex interaction of compounds with microorganisms. To improve the performance and robustness of membrane technology, it is suggested to combine membranes with other systems, such as activated carbon and enzymatic degradation.

Diclofenac and its transformation products: Environmental occurrence and toxicity - A review

Diclofenac (DCF) is a prevalent anti-inflammatory drug used throughout the world. Intensive researches carried out in the past few decades have confirmed the global ubiquity of DCF in various environmental compartments. Its frequent occurrence in freshwater environments and its potential toxicity towards several organisms such as fish and mussels makes DCF an emerging environmental contaminant. At typical detected environmental concentrations, the drug does not exhibit toxic effects towards living organisms, albeit chronic exposure may lead to severe effects. For DCF, about 30-70% removal has been obtained through the conventional treatment system in wastewater treatment plant being the major primary sink. Thus, the untreated DCF will pass to surface water. DCF can interact with other inorganic contaminants in the environment particularly in wastewater treatment plant, such as metals, organic contaminants and even with DCF metabolites. This process may lead to the creation of another possible emerging contaminant. In the present context, environmental fate of DCF in different compartments such as soil and water has been addressed with an overview of current treatment methods. In addition, the toxicity concerns regarding DCF in aquatic as well as terrestrial environment along with an introduction to the metabolites of DCF through consumption as well as abiotic degradation routes are also discussed. Further studies are required to better assess the fate and toxicological effects of DCF and its metabolites and must consider the possible interaction of DCF with other contaminants to develop an effective treatment method for DCF and its traces.

Green synthesis approach: extraction of chitosan from fungus mycelia

Chitosan, copolymer of glucosamine and N-acetyl glucosamine is mainly derived from chitin, which is present in cell walls of crustaceans and some other microorganisms, such as fungi. Chitosan is emerging as an important biopolymer having a broad range of applications in different fields. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal sources. The methods used for extraction of chitosan are laden with many disadvantages. Alternative options of producing chitosan from fungal biomass exist, in fact with superior physico-chemical properties. Researchers around the globe are attempting to commercialize chitosan production and extraction from fungal sources. Chitosan extracted from fungal sources has the potential to completely replace crustacean-derived chitosan. In this context, the present review discusses the potential of fungal biomass resulting from various biotechnological industries or grown on negative/low cost agricultural and industrial wastes and their by-products as an inexpensive source of chitosan. Biologically derived fungal chitosan offers promising advantages over the chitosan obtained from crustacean shells with respect to different physico-chemical attributes. The different aspects of fungal chitosan extraction methods and various parameters having an effect on the yield of chitosan are discussed in detail. This review also deals with essential attributes of chitosan for high value-added applications in different fields.

Behavior and characterization of titanium dioxide and silver nanoparticles in soils

The presence and transport of emerging Engineered Nano Particles (ENPs) in the environment is driven by combination of multiple factors comprising their size, charge and aggregation/agglomeration rate along with interactions with different soil types. Due to the complexity of the soil, it is difficult to associate an exact concentration with the possible transport pathways, interactions and transformation mechanisms. Major uncertainties arise with the increased number of extraction and filtration steps required for determining the exact toxicity doses of ENPs. Due to these issues, TiO2 and Ag behavior, characterization, transport, and environmental effects in soils are still not clear. In soils, TiO2 and Ag have been mainly reported to be present in the surroundings of point sources and are driven by their aggregation/agglomeration rate in combination with different soil types. TiO2 and Ag are mainly transported by interstitial water depending on their zeta-potential in the local soil. Along the transport route, TiO2 and Ag undergo alteration in dissolution, corrosion, redox reaction and coatings with the soil matrix. Their mobility is better across mineral soil in comparison to soil rich in organic colloids. The bioavailability gets modified and, in consequence, they are retained until complete degradation of the organic matrix. Depending on the soil matrix composition in terms of water content, minerals, and biological structure, the current most used methods for TiO2 and Ag characterization are FFFF and UV spectroscopy coupled with ICP-MS and LCMS/MS. The increased flux of TiO2 and Ag across soil is significant in understanding/accessing the viable threats, in particular their release affects the natural ecosystem.

Biohydrogen production by co-fermentation of crude glycerol and apple pomace hydrolysate using co-culture of Enterobacter aerogenes and Clostridium butyricum

Co-substrate utilization of various wastes with complementary characteristics can provide a complete medium for higher hydrogen production. This study evaluated potential of apple pomace hydrolysate (APH) co-fermented with crude glycerol (CG) for increased H2 production and decreased by-products formation. The central composite design (CCD) along with response surface methodology (RSM) was used as tool for optimization and 15 g/L of CG, 5 g/L of APH and 15% (v/v) inoculum were found to be optimum to produce as high as 26.07 ± 1.57 mmol H2/L of medium. The p-value of 0.0017 indicated that APH at lower concentration had a significant effect on H2 production. By using CG as sole carbon source, reductive pathway of glycerol metabolism was favored with 19.46 mmol H2/L. However, with APH, oxidative pathway was favored with higher H2 production (26.07 ± 1.57 mmol/L) and decrease in reduced by-products (1,3-propanediol and ethanol) formation. APH inclusion enhanced H2 production, and decreased substrate inhibition.

Adsorption of methylene blue on biochar microparticles derived from different waste materials

Biochar microparticles were prepared from three different types of biochar, derived from waste materials, such as pine wood (BC-PW), pig manure (BC-PM) and cardboard (BC-PD) under various pyrolysis conditions. The microparticles were prepared by dry grinding and sequential sieving through various ASTM sieves. Particle size and specific surface area were analyzed using laser particle size analyzer. The particles were further characterized using scanning electron microscope (SEM). The adsorption capacity of each class of adsorbent was determined by methylene blue adsorption tests in comparison with commercially available activated carbon. Experimental results showed that dye adsorption increased with initial concentration of the adsorbate and biochar dosage. Biochar microparticles prepared from different sources exhibited improvement in adsorption capacity (7.8±0.5 mg g(-1) to 25±1.3 mg g(-1)) in comparison with raw biochar and commercially available activated carbon. The adsorption capacity varied with source material and method of production of biochar. The maximum adsorption capacity was 25 mg g(-1) for BC-PM microparticles at 25°C for an adsorbate concentration of 500 mg L(-1) in comparison with 48.30±3.6 mg g(-1) for activated carbon. The equilibrium adsorption data were best described by Langmuir model for BC-PM and BC-PD and Freundlich model for BC-PW.

Bisphenol A degradation in water by ligninolytic enzymes

Many endocrine disruptor compounds, such as bisphenol A (BPA) are used today and released into the environment at low doses but they are barely degraded in wastewater treatment plants. One of the potential alternatives to effectively degrade endocrine disruptor compounds is based on the use of the oxidative action of extracellular fungal enzymes. The aim of this work is to study the ability of free and encapsulated enzymes (manganese peroxidase, lignin peroxidase and laccase) to degrade BPA. Higher degradation of BPA (90%) by ligninolytic enzymes encapsulated on polyacrylamide hydrogel and pectin after 8h was obtained. The degradation of BPA while using the free enzyme (26%) was lower than the value obtained with encapsulated enzymes. The presence of pectin in the formulation significantly (p>0.05) enhanced the activity of enzymes. Kinetics of BPA degradation showed an increase in Vm, while Km remained constant when enzymes were encapsulated. Hence, encapsulation protected the enzymes from non-competitive inhibition.

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by fungal enzymes: A review

Polycyclic aromatic hydrocarbons (PAHs) are a large group of chemicals. They represent an important concern due to their widespread distribution in the environment, their resistance to biodegradation, their potential to bioaccumulate and their harmful effects. Several pilot treatments have been implemented to prevent economic consequences and deterioration of soil and water quality. As a promising option, fungal enzymes are regarded as a powerful choice for degradation of PAHs. Phanerochaete chrysosporium, Pleurotus ostreatus and Bjerkandera adusta are most commonly used for the degradation of such compounds due to their production of ligninolytic enzymes such as lignin peroxidase, manganese peroxidase and laccase. The rate of biodegradation depends on many culture conditions, such as temperature, oxygen, accessibility of nutrients and agitated or shallow culture. Moreover, the addition of biosurfactants can strongly modify the enzyme activity. The removal of PAHs is dependent on the ionization potential. The study of the kinetics is not completely comprehended, and it becomes more challenging when fungi are applied for bioremediation. Degradation studies in soil are much more complicated than liquid cultures because of the heterogeneity of soil, thus, many factors should be considered when studying soil bioremediation, such as desorption and bioavailability of PAHs. Different degradation pathways can be suggested. The peroxidases are heme-containing enzymes having common catalytic cycles. One molecule of hydrogen peroxide oxidizes the resting enzyme withdrawing two electrons. Subsequently, the peroxidase is reduced back in two steps of one electron oxidation. Laccases are copper-containing oxidases. They reduce molecular oxygen to water and oxidize phenolic compounds.