Smita S. Kumar

Methane production, oxidation and mitigation: A mechanistic understanding and comprehensive evaluation of influencing factors.

Methane is one of the critical greenhouse gases, which absorb long wavelength radiation, affects the chemistry of atmosphere and contributes to global climate change. Rice ecosystem is one of the major anthropogenic sources of methane. The anaerobic waterlogged soil in rice field provides an ideal environment to methanogens for methanogenesis. However, the rate of methanogenesis differs according to rice cultivation regions due to a number of biological, environmental and physical factors like carbon sources, pH, Eh, temperature etc. The interplay between the different conditions and factors may also convert the rice fields into sink from source temporarily. Mechanistic understanding and comprehensive evaluation of these variations and responsible factors are urgently required for designing new mitigation options and evaluation of reported option in different climatic conditions. The objective of this review paper is to develop conclusive understanding on the methane production, oxidation, and emission and methane measurement techniques from rice field along with its mitigation/abatement mechanism to explore the possible reduction techniques from rice ecosystem.

Bioelectricity generation using sulphate-reducing bacteria as anodic and microalgae as cathodic biocatalysts

ABSTRACT Because microalgal species carry out oxygenic photosynthesis, they can be employed in the cathode chamber of microbial fuel cells, thus negating the need for mechanical aeration for oxygen reduction reactions. A conventional H-shaped configuration is used for comparative analysis of bioelectricity generation using pure and mixed microalgal cultures. Three reactors are simultaneously inoculated with sulphate-reducing bacteria as anodic and mixed culture of microalgae (MA#1) and two pure species in the cathodic chamber in separate reactors (MA#2; MA#3). Maximum open circuit potentials of 670, 476 and 529 mV are achieved with MA#3, MA#2 and MA#1, respectively. Power densities on the order of 442.5, 69 and 135 mW/m3 are obtained for microalgal cultures MA#3, MA#2 and MA#1, respectively. The highest power and current density values are obtained with MA#3 inoculated with pure algal species. The algal species are also examined for their lipid content with the use of Fourier transform infrared spectroscopy, Nile red spectroscopy and lipid content analysis. A good amount of lipid content is shown in spectroscopy images. Biomass content is highest for the algal consortium (MA#1) whereas lipid content is best in the case of pure algal species (MA#2).

Biogenesis of copper oxide nanoparticles (CuONPs) using Sida acuta and their incorporation over cotton fabrics to prevent the pathogenicity of Gram negative and Gram positive bacteria

Textile industry is a major sector providing global financial and employment support to different countries of the world. The major problems of the textile industry are dirt and microbial contaminants affecting the quality of cotton fabrics. Recently, nanoparticles such as silver, chitosan, silicon dioxide, titanium dioxide and zinc oxide have gained attraction in textile industries to avoid the contamination of fabrics through microbes. The necessity to develop an ecofriendly, efficient and cost effective method for the synthesis of nanoparticles is under the radar. Plant extracts serve as potential reducing and coating agents due to the presence of bioactive molecules such as phenols, lipids, carbohydrates, enzymes, protein molecules etc., which endow effective antimicrobial activity to the nanoparticles. In the present study, biological synthesis of Copper oxide nanoparticles (CuONPs) was performed using S. acuta leaf extract. CuONPs were synthesized and characterized using UV-vis, FTIR, SEM and TEM analyses. The antimicrobial property of CuONPs was tested against Gram negative (Escherichia coli and Proteus vulgaris) and Gram positive (Staphylococcus aureus) pathogens, which showed zones of inhibition at different concentrations. As the final part of the study, CuONPs were coated over cotton fabrics showing longer stability, which prevented the growth of infectious pathogens. Apart from the antimicrobial activity, CuONPs synthesized using S. acuta possessed effective photocatalytic activity against commercial dyes.

Phytoremediation and Rhizoremediation: Uptake, Mobilization and Sequestration of Heavy Metals by Plants

Microorganisms residing over the rhizosphere have the capability to catalyse metal uptake in a symbiotic relationship with the roots. This syntrophic relationship enhances the bioavailability of heavy metals and encourages the root adsorption capacity for vital in addition to non-essential metal. It also changes their chemical properties that ultimately have an effect on metal dissolution. Molecular level understanding of the physiological and evolutionary mechanism along with genetics and biochemistry principles underlying the uptake, transportation, translocation and storage of heavy metals (HMs) in model plant species thus allowing alteration to the HM stress can loan much to our comprehension of the fundamental segments of HM metabolism. A lucid understanding of molecular level changes is necessary for plant biotechnologist, regarding changes provoked in plants because of HM stress. It is also helpful to develop stress-resistant cultivars and species with superior phytoremediation capacity through cell and genetic engineering technologies. We hereby summarize the present understanding of HM uptake by plants and also provide a brief study related to their biochemical characteristics of take-up, transport and assortment plus injury and defence mechanism against HM. In this review chapter, we have also focused over the future prospect of research to enhance the discriminate perspective of the basic phytoremediation components specifically rhizoremediation of HMs.

Uses of peroxide on the formation of chlorinated phenolics by gas chromatography technique in nonwood pulps to reduce toxicity in paper manufacturing

ECF technology has been established itself as the most preferred process worldwide. Peroxide addition minimizes the effluent color. The study deals with the bleaching of Bamboo and Jute Cady pulps with chlorine and peroxide treatment and identification of various chlorophenolics compounds. The results show that quantity of the total chlorophenolic compounds formed decreases up to 54% in total chlorophenolic compound in the CEH effluent and the COD and color values are reduced by 35% and 33% respectively as E stage is changed to Ep stage in Bamboo pulp. And there is a reduction of 52% in total chlorophenolic compound in the CEH effluent when E stage is changed to Ep. and the COD and color values are reduced by 30% and 33% respectively as E stage is changed to Ep stage in Jute Cady pulp