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Rice straw decomposition is an attractive solution to open-field burning but the traditional method has slow kinetics and takes 60-90 days to obtain mature compost. In this study, we propose to boost up the decomposition process by addition of a novel microbial consortium rich in lignocellulolytic microbes. C: N ratio of the compost reached 11.69% and degradation efficiency of cellulose and hemicellulose was found to be 64 and 87% respectively within 25 days. Lignocellulolytic activity of the microbial consortium was confirmed by plate and activity assay. These parameters clearly indicated that a mature compost was obtained in 25 days. The 16S rRNA gene amplicon sequencing and functional analysis of predicted genes indicated amino acid and carbohydrate metabolism as the major metabolic pathway during composting. The tertiary level of functional analysis revealed the major metabolic pathways in the bacterial communities as pentose phosphate pathway, glycolysis and tricarboxylic acid cycle.

The growing fossil fuel-based energy demand of the entire nation has led to numerous environmental problems that have threatened mankind. Moreover, the fast depletion of fossil fuel resources has also caused an energy crisis, therefore affecting the economy across the world. These serious issues have instigated a search for alternative sustainable energy sources, and biofuels are one such promising alternative that shows great potential as a future transportation or cooking fuel. Among all biofuels, hydrogen (H2) seems to be an attractive alternative due to its high energy content as compared to other hydrocarbon fuels. It is regarded as the cleanest fuel and is efficient for generating electricity as well as a transportation fuel. H2 is currently produced mostly from fossil fuels and biomass through energy-intensive chemical processes, which require high operating temperatures and pressures. On the contrary, the biological route of H2 production involves microbial bioprocesses that operate at ambient conditions and require modest reactor designs. This chapter discusses the advantages and limitations of various methods of microbial H2 production and the effects of different carbon sources used for its production. The major hurdle with the biological route is the lower yield of H2, and therefore this chapter also highlights various strategies to improve biological H2 production and its future perspectives.

This study reports engineering of a hypertransformable variant of C. pasteurianum for bioconversion of glycerol into hydrogen (H2). A functional glycerol-triggered hydrogen pathway was engineered based on two approaches: (1) increasing product yield by overexpression of immediate enzyme catalyzing H2 production, (2) increasing substrate uptake by overexpression of enzymes involved in glycerol utilization. The first strategy aimed at overexpression of hydA gene encoding hydrogenase, and the second one, through combination of overexpression of dhaD1 and dhaK genes encoding glycerol dehydrogenase and dihydroxyacetone kinase. These genetic manipulations resulted in two recombinant strains (hydA ++ /dhaD1K ++) capable of producing 97% H2 (v/v), with yields of 1.1 mol H2/mol glycerol in hydA overexpressed strain, and 0.93 mol H2/mol glycerol in dhaD1K overexpressed strain, which was 1.5 fold higher than wild type. Among two strains, dhaD1K ++ consumed more glycerol than hydA ++ which proves that overexpression of glycerol enzymes has enhanced glycerol intake rate.

The need for alternative source of fuel has demanded the cultivation of 3rd generation feedstock which includes microalgae, seaweed and cyanobacteria. These phototrophic organisms are unique in a sense that they utilise natural sources like sunlight, water and CO(2) for their growth and metabolism thereby producing diverse products that can be processed to produce biofuel, biochemical, nutraceuticals, feed, biofertilizer and other value added products. But due to low biomass productivity and high harvesting cost, microalgae-based production have not received much attention. Therefore, this review provides the state of the art of the microalgae based biorefinery approach to define an economical and sustainable process. The three major segments that need to be considered for economic microalgae biorefinery is low cost nutrient source, efficient harvesting methods and production of by-products with high market value. This review has outlined the use of various wastewater as nutrient source for simultaneous biomass production and bioremediation. Further, it has highlighted the common harvesting methods used for microalgae and also described various products from both raw biomass and delipidified microalgae residues in order to establish a sustainable, economical microalgae biorefinery with a touch of circular bioeconomy. This review has also discussed various challenges to be considered followed by a techno-economic analysis of the microalgae based biorefinery model.

Journal of alloys and compounds 749, 768 - 775 (2018). doi:10.1016/j.jallcom.2018.03.261, This paper demonstrates fine size-controlled synthesis of superparamagnetic carbon-encapsulated iron nanoparticles, by a supersonic plasma jet assisted rapid, bulk-production process, by manipulation of the pressure in the sample collection chamber. Transmission electron microscopy and small angle x-ray scattering measurements confirmed the formation of single-crystals with a narrow size distribution, having core average size of 5.0 nm and encapsulated by an ultrathin carbon coating, for sub-mbar pressure. VSM and Mossbauer characterization established the nanocrystallites to be superparamagnetic in nature, with saturation magnetization 67 emu/g and coercive field 7.4 Oe. Controlled plasma heating during synthesis led to the burning down of extra carbon that resulted in further enhancement of the magnetization of the product. Graphitization of the encapsulating layers also enhanced, which could successfully protect the metallic core from oxidation, as well as improved its cyto-compatibility. This purified sample could be ideal for targeted drugs delivery and water treatment applications. Another sample was processed through controlled reaction with oxygen, the as-synthesized sample having magnetic properties approaching that of the first sample, which may be more attractive especially for water treatment processes because of the simpler single-step processing of the material., Published by ScienceDirect, Amsterdam [u.a.]

This study presents kinetic and thermodynamic analysis of crude glycerol fermentation for hydrogen production. Fermentation parameters have been optimized using central composite design (CCD) of experiments as: pH = 6.7, temperature = 36 °C, crude glycerol concentration = 7.4 g/L. Kinetic and thermodynamic analysis has been done using Haldane substrate inhibition model, Arrhenius plots and Eyring equation. Kinetic parameters V max and K m increase, while K I reduces for crude glycerol, as compared to pure glycerol. Moreover, activation energy (217 kJ/mol) and Δ G (103 kJ/mol) for crude glycerol are lesser than pure glycerol. Consequently, hydrogen yield in crude glycerol fermentation (0.627 mol H 2 /mol glycerol with 44% v/v H 2 in product gas) is significantly higher than pure glycerol. Role of Na + ions in improving crude glycerol fermentation has been experimentally confirmed. Kinetic and thermodynamic parameters for crude glycerol fermentation determined in this study have quantitatively substantiated its potential for biohydrogen production.

This paper reports rapid, continuous and carbon-nanotube free synthesis of carbon encapsulated magnetic nanoparticles by thermal-plasma expansion technique, which combines the typical advantages of high-temperature plasma assisted synthesis method with efficient particle-size control. Core nanocrystals were encapsulated with few layers of graphitized carbon, which could provide protection against both oxidation and intense chemical treatment. The average iron/iron-carbide nanoparticle diameter (7.7, 9 and 10 nm) and the width of the size distribution increased with pressure in the sample collection chamber, as a result of the decreasing quenching rate of the plasma jet. This also resulted in the smaller particles remaining frozen predominantly in the high-temperature γ-Fe phases, part of which was oxidized subsequently and eliminated preferentially during the purification process. All samples could be correlated with smooth variation of magnetic properties; saturation magnetization, remnant magnetization and coercive-field enhancing with increasing chamber pressure or average particle size. The low pressure synthesized sample with smallest average particle size approached super-paramagnetic behavior (saturation magnetization = 51.8 emu/g, ratio of remnant to saturation magnetization = 4.9 and coercive field = 52 Oe), which may be ideal for biomedical applications. High-pressure samples on the other hand have a higher saturation magnetization (76.3 emu/g) and coercive fields (123 Oe).

Hypericin, a natural compound from Hypericum perforatum (St. John's wort), has been identified as a specific inhibitor of Leishmania donovani spermidine synthase (LdSS) using integrated computational and biochemical approaches. Hypericin showed in vitro inhibition of recombinant LdSS enzyme activity. The in vivo estimation of spermidine levels in Leishmania promastigotes after hypericin treatment showed significant decreases in the spermidine pools of the parasites, indicating target specificity of the inhibitor molecule. The inhibitor, hypericin, showed significant antileishmanial activity, and the mode of death showed necrosis-like features. Further, decreased trypanothione levels and increased glutathione levels with elevated reactive oxygen species (ROS) levels were observed after hypericin treatment. Supplementation with trypanothione in the medium with hypericin treatment restored in vivo trypanothione levels and ROS levels but could not prevent necrosis-like death of the parasites. However, supplementation with spermidine in the medium with hypericin treatment restored in vivo spermidine levels and parasite death was prevented to a large extent. The data overall suggest that the parasite death due to spermidine starvation as a result of LdSS inhibition is not related to elevated levels of reactive oxygen species. This suggests the involvement of spermidine in processes other than redox metabolism in Leishmania parasites. Moreover, the work provides a novel scaffold, i.e., hypericin, as a potent antileishmanial molecule.

The paper reports the application of supersonic thermal plasma expansion technique for controlled chemical synthesis of non-agglomerated, mono-dispersed nanoparticles of TiO 2 and also deposition of a nanocrystalline porous coating in a single-step, continuous process. The phase transformation of the nanoparticles was investigated as a function of feed rates of the basic reactants. The possibility of the particle charging and its consequences are also discussed. The grain structure of the coating was found to retain the characteristics of the seed nanoparticles. Optical Emission Spectroscopy performed at the injection section of the reactor identified the presence of TiO and TiCl molecules, which are suspected to be intermediates in this chemical route.

The paper reports the synthesis of nano-crystalline ceramics like titanium dioxide and titanium nitride using a plasma chemical experimental reactor powered by a multi-segment (cascaded) arc plasma torch. The precursor-laden plasma beam emerging from the torch anode section expands supersonically through a converging nozzle to a low-pressure collection chamber. This results in a uniform and controlled gas dynamic quenching ensuring rapid synthesis of pure, un-coagulated free-flowing particles with a narrow size distribution. Simple Langmuir probes and calorimetric energy balance methods are used for plasma and reactor characterization, while X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman and X-ray photoelectron spectroscopy (XPS) techniques have been used for product analysis. It is shown that size distribution of both the product particles is comparatively narrower than that found in most thermal plasma assisted laboratory synthesis studies. The expansion process was observed to produce a non-equilibrium electron population, which could charge up the particles after nucleation and hence could curb unwanted coagulation.

This paper presents investigations into mechanism of ultrasound assisted bioethanol synthesis using Parthenium hysterophorus biomass through simultaneous saccharification and fermentation (SSF) mode. Approach of coupling experimental results to mathematical model for SSF using Genetic Algorithm based optimization has been adopted. Comparison of model parameters for experiments with mechanical shaking and sonication (10% duty cycle) give an interesting mechanistic account of influence of ultrasound on SSF system. A 4-fold rise in ethanol and cell mass productivity is seen with ultrasound. The analysis reveals following facets of influence of ultrasound on SSF: increase in Monod constant for glucose for cell growth, maximal specific growth rate and inhibition constant of cell growth by glucose and reduction in specific cell death rate. Values of inhibition constant of cell growth by ethanol (K3E), and constants for growth associated (a) and non-growth associated (b) ethanol production remained unaltered with sonication. Beneficial effects of ultrasound are attributed to enhanced cellulose hydrolysis, enhanced trans-membrane transport of substrate and products as well as dilution of the toxic substances due to micro-convection induced by ultrasound. Intrinsic physiological functioning of cells remained unaffected by ultrasound as indicated by unaltered values of K3E, a and b.

This study presents mechanistic investigations in ultrasound-assisted bioethanol fermentation using Parthenium hysterophorus biomass. Ultrasound (35 kHz, 10% duty cycle) has been used for sonication. Experimental results were fitted to mathematical model; the kinetic and physiological parameters in the model were obtained using Genetic Algorithm (GA) based optimization. In control experiments (mechanical shaking), maximum ethanol titer of 10.93 g/L and cell mass concentration of 5.26 g/L was obtained after 18 h. In test experiments (mechanical shaking and intermittent sonication), ethanol titer of 12.14 g/L and cell mass concentration of 5.7 g/L was obtained in 10 h. This indicated ∼2× enhanced productivity of ethanol and cell mass with sonication. Trends in model parameters obtained after fitting of model to experimental data essentially revealed that beneficial influence of ultrasound on fermentation is a manifestation of enhanced trans-membrane transportation and dilution of toxic substances due to strong micro-convection induced by ultrasound.

We report the observation of magnetic entropy change due to martensitic phase transformations of bulk off-stoichiometric Heusler alloys with compositions Ni46Mn43Sn11, Ni44Mn43Co2Sn11, and Ni44Mn43Cu2Sn11, prepared by arc melting method. The martensitic transition of the parent ternary alloy (Ni46Mn43Sn11) shifts to lower temperatures upon Co and Cu substitution. Inverse magnetocaloric effect was observed in these alloys near the martensitic transformation temperature when subjected to an applied magnetic field. Ni46Mn43Sn11, Ni44Mn43Co2Sn11, and Ni44Mn43 Cu2Sn11 alloys exhibited maximum positive magnetic entropy change of 7.9, 11.3, and 18.8 J kg−1 K−1, respectively, under an applied magnetic field of 1.8 T.