Coexisting Kondo hybridization and itinerant f-electron ferromagnetism in UGe2

Kondo hybridization in partially filled f-electron systems conveys significant amount of electronic states sharply near the Fermi energy leading to various instabilities from superconductivity to exotic electronic orders. UGe2 is a 5f heavy fermion system, where the Kondo hybridization is interrupted by the formation of two ferromagnetic phases below a 2nd order transition Tc ~ 52 K and a crossover transition Tx ~ 32 K. These two ferromagnetic phases are concomitantly related to a spin-triplet superconductivity that only emerges and persists inside the magnetically ordered phase at high pressure. The origin of the two ferromagnetic phases and how they form within a Kondo-lattice remain ambiguous. Using scanning tunneling microscopy and spectroscopy, we probe the spatial electronic states in the UGe2 as a function of temperature. We find a Kondo resonance and sharp 5f-electron states near the chemical potential that form at high temperatures above Tc in accordance with our density functional theory (DFT) + Gutzwiller calculations. As temperature is lowered below Tc, the resonance narrows and eventually splits below Tx dumping itinerant f-electron spectral weight right at the Fermi energy. Our findings suggest a Stoner mechanism forming the highly polarized ferromagnetic phase below Tx that itself sets the stage for the emergence of unconventional superconductivity at high pressure

Low-Abundance Members of the Firmicutes Facilitate Bioremediation of Soil Impacted by Highly Acidic Mine Drainage From the Malanjkhand Copper Project, India

Sulfate- and iron-reducing heterotrophic bacteria represented minor proportion of the indigenous microbial community of highly acidic, oligotrophic acid mine drainage (AMD), but they can be successfully stimulated for in situ bioremediation of an AMD impacted soil (AIS). These anaerobic microorganisms although played central role in sulfate- and metal-removal, they remained inactive in the AIS due to the paucity of organic carbon and extreme acidity of the local environment. The present study investigated the scope for increasing the abundance and activity of inhabitant sulfate- and iron-reducing bacterial populations of an AIS from Malanjkhand Copper Project. An AIS of pH 3.5, high soluble SO42− (7838 mg/l) and Fe (179 mg/l) content was amended with nutrients (cysteine and lactate). Thorough geochemical analysis, 16S rRNA gene amplicon sequencing and qPCR highlighted the intrinsic metabolic abilities of native bacteria in AMD bioremediation. Following 180 days incubation, the nutrient amended AIS showed marked increase in pH (to 6.6) and reduction in soluble -SO42− (95%), -Fe (50%) and other heavy metals. Concomitant to physicochemical changes a vivid shift in microbial community composition was observed. Members of the Firmicutes present as a minor group (1.5% of total community) in AIS emerged as the single most abundant taxon (∼56%) following nutrient amendments. Organisms affiliated to Clostridiaceae, Peptococcaceae, Veillonellaceae, Christensenellaceae, Lachnospiraceae, Bacillaceae, etc. known for their fermentative, iron and sulfate reducing abilities were prevailed in the amended samples. qPCR data corroborated with this change and further revealed an increase in abundance of dissimilatory sulfite reductase gene (dsrB) and specific bacterial taxa. Involvement of these enhanced populations in reductive processes was validated by further enrichments and growth in sulfate- and iron-reducing media. Amplicon sequencing of these enrichments confirmed growth of Firmicutes members and proved their sulfate- and iron-reduction abilities. This study provided a better insight on ecological perspective of Firmicutes members within the AMD impacted sites, particularly their involvement in sulfate- and iron-reduction processes, in situ pH management and bioremediation

Microbial Diversity in Uranium Deposits from Jaduguda and Bagjata Uranium Mines, India as Revealed by Clone Library and Denaturing Gradient Gel Electrophoresis Analyses

<div><p>Microbial communities within subsurface uranium (U) deposits were explored to understand the nature of community composition and their potential role in biogeochemical cycle and bioremediation. Geochemical analysis revealed that the U ores were mainly hosted on metamorphosed chlorite-biotite schists, containing varied organic carbon and elevated level of several heavy metals (U, Cu, Cr, Zn, etc.). Microbial diversity as explored by 16S rRNA gene clone library and DGGE analyses revealed predominance of <i>Proteobacteria</i>, <i>Acidobacteria</i>, <i>Bacteroidetes</i> along with <i>Firmicutes</i> and candidate division OP9 within the domain <i>Bacteria</i> and <i>Euryarchaeota</i> within the domain <i>Archaea</i>. Among the physiochemical parameters, level of organic carbon showed considerable impact on influencing community diversity and composition. Samples from Jaduguda with high organic carbon showed abundance of bacteria known for metabolizing different carbon compounds and affiliated to unclassified uncultured members of <i>Chitnophagaceae</i> (<i>Bacteroidetes</i>), Gp4 of <i>Acidobacteria</i> and unclassified β-<i>Proteobacteria</i> and halophilic, nitrate-reducing γ-<i>Proteobacteria</i>. A relatively diverse assemblage of species capable of autotrophic/heterotrophic N₂ fixation, CH₄ utilization, H₂(0)/Fe(II)/Mn(II)/S(0) oxidation, NO₃/Fe(III) reduction, U and other metal precipitation/mineralization and affiliated to families <i>Rhizobiaceae, Bradyrhizobiaceae, Caulobacteraceae</i>, <i>Comamonadaceae</i> and genera <i>Acinetobacter, Marinobacter</i> and <i>Alcanivorax</i> constituted the Bagjata samples. Distribution and interrelations among abundance of various bacterial groups detected in other U mines/radioactive waste sites were compared with our data. Overall, the study reported distinct compositions of indigenous microbial communities among the samples from two mines and provided a better insight in geomicrobiology of U deposits.</p></div

The assessment of microbial ecology : a special emphasis on the Indian scenario

This special issue dedicated to the state of microbial ecology highlights some of the key academic research topics in the current scenario with special emphasis on India. To sum up this issue, we have provided a brief description about the articles published in the ‘Environmental Microbiology and Environmental Microbiology Reports’

Genome sequencing reveals the potential of an indigenous arsenotrophic bacterium; Achromobacter sp. KAs 3-5 for sub-surface arsenic mobilization and strategies for bioremediation

Prevalence of toxic arsenic (As) oxyanion species in oligotrophic groundwater of south-east Asiatic regions (India and Bangladesh) has threatened the health of millions of people. As-transforming bacteria alter the mobility, speciation and bioavailability of As in the aquifer ecosystem, hence play important roles in the biogeochemical cycling of As. Till date, only 19 cultivable As-transforming bacterial strains have been reported but with no description on their detail genomic and physiological perspective of As homeostasis. In this study, the draft genome (5.7 Mbp) of an As-transforming, aromatic hydrocarbon utilizing and iron disproportioning indigenous groundwater bacterium KAs 3-5 has been obtained by Ion-Torrent sequencing revealed 65% genomic GC content, 5100 protein coding genes, and taxonomic affiliation to the members of genus Achromobacter, with &gt;85% of genomic completeness. Phylogenomic signatures like MLST of 10 house-keeping genes, cut-off of &lt;95% of average nucleotide/amino acid identity (ANI/OrthoANI/AAI), &lt;0.99 of tetra-nucleotide correlations, and &lt;70% value of DNA-DNA homology with nearest phylogenetic neighbors exhibited its species distinctiveness among all the described Achromobacter sp. members. Pan-genomic analysis confirmed the strain’s potential to adapt wide array of environmental stresses with a higher abundance of unique genes for metabolism of amino acids, polyketide, xenobiotics, nitroso compounds, aromatic hydrocarbons and most necessarily complete operon cluster for As-resistance/transformation/detoxification, as well as genes for transport, and signal transduction mechanisms. The genome analysis also highlighted its genetic determinants for loss of functions for antibiotic resistance, pathogenicity regulations, and gain of new/acquired functions for Fe-transport, fatty acids uptake-metabolism, motility, heavy metal (Cu-Zn-Co) metabolism and several putative/hypothetical proteins owing to its capacity to acquired desired traits through horizontal gene transfer events. The ability of the organism to metabolize mono-poly aromatics like benzene, toluene, naphthalene, anthracene, etc. (by catechol, homogentisate pathways) coupled to As reduction (through arsHBC, arsC, ACR3) found to be well validated by genomic observations. X-ray absorption fine structure (XANES) also enabled us to decipher detailed Fe-based reductive As release process from sediment and its interaction. The obtained genome data provide us with a better understanding of sub-surface mechanisms of hydrocarbon (organic matter) driven As release, which may contribute to the future design of rational strategies for bioremediation of As/other heavy metal contaminated environments

Metagenomic exploration of microbial community in mine tailings of Malanjkhand copper project, India

Mine tailings from copper mines are considered as one of the sources of highly hazardous acid mine drainage (AMD) due to bio-oxidation of its sulfidic constituents. This study was designed to understand microbial community composition and potential for acid generation using samples from mine tailings of Malanjkhand copper project (MCP), India through 16S rRNA gene based amplicon sequencing approach (targeting V4 region). Three tailings samples (T1, T2 and T3) with varied physiochemical properties selected for the study revealed distinct microbial assemblages. Sample (T3) with most extreme nature (pH 3.0) exhibited abundance of Proteobacteria, Fimicutes, Actinobacteria and/or Nitrospirae. Metagenomic sequences are available under the BioProject ID PRJNA361456

Extracellular Polysaccharides of a Copper-Sensitive and a Copper-Resistant Pseudomonas Aeruginosa Strain: Synthesis, Chemical Nature and Copper Binding

Extracellular polysaccharides (EPS) of a copper-sensitive (Cus) and a copper-resistant (Cur) Pseudomonas aeruginosa strain were investigated in terms of their production, chemical nature and response towards copper exposure. The extent of EPS synthesis by the resistant strain (4.78 mg mg)1 cell dry wt.) was considerably higher over its sensitive counterpart (2.78 mg mg)1 dry wt.). FTIR-spectroscopy and gas chromatography revealed that both the polymers were acidic in nature, containing alginate as the major component along with various neutraland amino-sugars. Acid content in the Cur EPS (480.54 mg g)1) was greater than that in the Cus EPS (442.0mg g)1). Presence of Cu2þ in the growth medium caused a dramatic stimulation (approximately 4-fold) in EPS synthesis by the Cur strain, while in a similar condition, the Cus failed to exhibit such response. The polymer of the resistant strain showed elevated Cu2þ binding (320mg g)1 EPS) compared to that of the sensitive type (270mg g)1). The overall observations show the potential of the Cur EPS for its deployment in metal bioremediation

Perspectives on CCUS deployment on large scale in India: Insights for low carbon pathways

The energy and industrial sectors' most recent extraordinarily quick expansion has resulted in a substantial rise in stationary CO2 sources. As a result, many questions have been raised concerning how to stop global warming and implement methods to mitigate its effects by 2050 to create a low-carbon and sustainable future. Over the last three decades, India's CO2 emissions have increased at a growth rate of 3.1 % mainly consumption of fossil fuels. In this global and Indian situation, the best method, besides renewable energy sources, is Carbon capture, utilization, and storage (CCUS), which will make it possible to achieve net-zero emissions targets within this century. Given this, a brief review and discussion that aims to study India's development in CCUS deployment and its importance for sustainable development were conducted. The review highlights the current energy scenario of India and the world, the CO2 increase trend, and its consequences globally. Furthermore, a brief discussion on the present status of several areas of carbon capture, utilization, and storage (CCUS) technologies have been done. To clearly define the maturity of each important component of the CCUS system with a commercialization direction route, we focused on determining the technological readiness level (TRL) from India's perspective. Further, we identified important data of different sizes from the biggest R&D schemes, policies, regulations and initiatives taken by the government across the country. Lastly, our study seeks to provide a guide for the successful implementation of CCUS in India