Molecular analyses of methanogen diversity associated with cattle dung

Methanogen communities were characterized in cattle dung of different ages by using a culture-independent approach. Community structures were determined by the phylogenetic analyses of methyl-coenzyme M reductase A (mcrA) clones of fresh, 8-month-old, and 24-month-old-dry dung samples. The clones in the mcrA libraries of fresh and 8-month old dung samples were identified as belonging to Methanomicrobiales, Methanobacteriales, and Methanosarcinales. However, clones in the library of 24-month-old dung were not affiliated to Methanomicrobiales. Anaerobic digestion of 2-month-old dung produced only 15% less methane compared to fresh dung which indicated the possibility of using dry dung to fuel the biogas plants in areas where unavailability of fresh dung hinders their continuous functioning. Our results first time showed the presence of viable methanogens in dry cattle dung stored for prolonged periods of time.     

Soil carbon sequestration: an innovative strategy for reducing atmospheric carbon dioxide concentration

Global warming due to increasing greenhouse gases emission and the subsequent climatic changes are the most serious environmental challenges faced by environmental scientists, academicians, regulatory agencies and policy makers worldwide. Among the various greenhouse gases, CO₂ constitutes a major share and its concentration is increasing rapidly. Therefore, there is perhaps an urgent need to formulate suitable policies and programs that can firmly reduce and sequester CO₂ emissions in a sustainable way. In order to combat the predicted disaster due to rising CO₂ level, several CO₂ capture and storage technologies and medium are being widely pursued and deliberated. Among them soil carbon sequestration (SCS) is gaining global attention because of its stability and role in long-term surface reservoir, natural low cost and eco-friendly means to combat climate change. Apart from the carbon capturing, the process of soil carbon stabilization also provides other tangible benefits that includes achieving food security, by improving soil quality, wasteland reclamation and preventing soil erosion. The present article aimed to address all these concerns and provide strategies and critical research needs to implement SCS as a mitigation option for increasing atmospheric CO₂ level and its future directions.     

Structural and Functional Characterization of the PaaI Thioesterase from Streptococcus pneumoniae Reveals a Dual Specificity for Phenylacetyl-CoA and Medium-chain Fatty Acyl-CoAs and a Novel CoA-induced Fit Mechanism

PaaI thioesterases are members of the TE13 thioesterase family that catalyze the hydrolysis of thioester bonds between coenzyme A and phenylacetyl-CoA. In this study we characterize the PaaI thioesterase from Streptococcus pneumoniae (SpPaaI), including structural analysis based on crystal diffraction data to 1.8-Å resolution, to reveal two double hotdog domains arranged in a back to back configuration. Consistent with the crystallography data, both size exclusion chromatography and small angle x-ray scattering data support a tetrameric arrangement of thioesterase domains in solution. Assessment of SpPaaI activity against a range of acyl-CoA substrates showed activity for both phenylacetyl-CoA and medium-chain fatty-acyl CoA substrates. Mutagenesis of putative active site residues reveals Asn³⁷, Asp⁵², and Thr⁶⁸ are important for catalysis, and size exclusion chromatography analysis and x-ray crystallography confirm that these mutants retain the same tertiary and quaternary structures, establishing that the reduced activity is not a result of structural perturbations. Interestingly, the structure of SpPaaI in the presence of CoA provides a structural basis for the observed substrate specificity, accommodating a 10-carbon fatty acid chain, and a large conformational change of up to 38 Å in the N terminus, and a loop region involving Tyr³⁸-Tyr³⁹. This is the first time PaaI thioesterases have displayed a dual specificity for medium-chain acyl-CoAs substrates and phenylacetyl-CoA substrates, and we provide a structural basis for this specificity, highlighting a novel induced fit mechanism that is likely to be conserved within members of this enzyme family.     

Four marine-derived fungi for bioremediation of raw textile mill effluents

Textile dye effluents pose environmental hazards because of color and toxicity. Bioremediation of these has been widely attempted. However, their widely differing characteristics and high salt contents have required application of different microorganisms and high dilutions. We report here decolorization and detoxification of two raw textile effluents, with extreme variations in their pH and dye composition, used at 20–90% concentrations by each of the four marine-derived fungi. Textile effluent A (TEA) contained an azo dye and had a pH of 8.9 and textile effluent B (TEB) with a pH of 2.5 contained a mixture of eight reactive dyes. The fungi isolated from mangroves and identified by 18S and ITS sequencing corresponded to two ascomycetes and two basidiomycetes. Each of these fungi decolorized TEA by 30–60% and TEB by 33–80% used at 20–90% concentrations and salinity of 15 ppt within 6 days. This was accompanied by two to threefold reduction in toxicity as measured by LC₅₀ values against Artemia larvae and 70–80% reduction in chemical oxygen demand and total phenolics. Mass spectrometric scan of effluents after fungal treatment revealed degradation of most of the components. The ascomycetes appeared to remove color primarily by adsorption, whereas laccase played a major role in decolorization by basidiomycetes. A process consisting of a combination of sorption by fungal biomass of an ascomycete and biodegradation by laccase from a basidiomycete was used in two separate steps or simultaneously for bioremediation of these two effluents.     

Plant Regeneration from Leaf Explants of Three Grain Legumes on Same Medium

The regeneration potential of leaves of moth bean, pigeonpea and grass pea was studied on Murashige and Skoog’s (MS) medium supplemented with various combinations of auxins and cytokinins. Regeneration of shoots was obtained mainly on MS medium supplemented with high auxin and low cytokinin levels. However, frequency of response varied not only in the three legume species but also in their varieties studied. Roots were induced on regenerated shoots by transferring them to MS basal medium. Complete plant regeneration was observed in the three legumes in a short duration of 60–70 days.     

An Efficient Multigram Synthesis of Monomers for the Preparation of Novel Oligonucleotides Containing Isosteric Non-Phosphorous Backbones

Abstract

The facile preparation of two novel classes of nucleoside analogs for the inclusion as dimeric non-phosphorous containing subunits in chimeric backbones has been accomplished. The concise preparation of 3′-formylnucleosides and 5′-O-(N-methylhydroxylamino)-nucleosides is reported.     

Combinatorial Approach Through In Vitro Regeneration and Phytochemical Profiling of Ceropegia media (Huber) Ans.: A Potential Way Forward in the Conservation of an Endangered Medicinal Plant from the Western Ghats in India

Journal of Plant Growth Regulation - Ceropegia media is an endemic and endangered plant as its propagation through seeds is unreliable due to low germination, slow growth and seedling decay under...