Jiwaji University

ACC deaminase is a pyridoxal phosphate-dependent enzyme that is highly prevalent in the plant-associated bacteria and fungi and is vital to the regulation of plant responses to abiotic stress. ACC deaminase reduces the stress-induced ethylene production, which otherwise suppresses plant growth and development. ACC deaminase degrade ACC, the immediate precursor of ethylene, into ammonia and 2-ketobutyrate. The acdS gene encodes the enzyme, which is highly regulated by complex transcriptional regimes containing regulatory elements including acdR (LRP family) and other related factors which respond to environmental factors. Evidence indicates that rhizobacteria with ACC deaminase activity increase root structure, nutrient uptake and salinity, drought, and heavy metal tolerance due to the coordinated hormonal regulation, antioxidant mobilization and rhizosphere interactions. Phylogenetic studies indicate that acdS is widely distributed among different bacteria and fungi. This study aims to discusses available knowledge, mechanism of action, genetics, distribution of ACC deaminase among various species, ecological role of ACC deaminase and, future research direction in developing transgenic plants through expression of foreign AcdS gene to survive biotic and abiotic stresses. ACC deaminase represents a key functional trait in soil–plant–microbe interactions with strong potential for sustainable agriculture, although further research is required to ensure reliable field-level applications.

The escalating global climate crisis necessitates the development of sustainable energy solutions, driving research into vacancy-ordered double perovskites Cs2MBr6 (M = Re4+, W4+, Ru4+, Os4+) for photocatalytic and thermoelectric applications. This study employs density functional theory (DFT) within the WIEN2k framework, integrating the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential and spin-orbit coupling (SOC), to investigate the structural, electronic, optical, mechanical, photocatalytic, and thermoelectric properties of these materials. The cubic Fm-3 m structure, featuring isolated [MBr6] octahedral units, ensures stability, with lattice constants ranging from 10.58 & Aring; (Cs2RuBr6) to 10.71 & Aring; (Cs2WBr6) and bulk moduli from 32.06 GPa to 46.68 GPa. Band gaps (1.66-3.06 eV) and half-metallic ferromagnetic behavior, enhanced by SOC, support applications in spintronics and energy conversion. Optical properties reveal absorption coefficients up to 22 x 105 cm-1 and exciton binding energies of 14.3-19.4 meV, while photocatalytic assessments confirm water splitting and CO2 reduction capabilities, notably for Cs2WBr6 (-0.72 V ECB) and Cs2ReBr6. Thermoelectric figure of merit (ZT) values exceed 1.3 at 1000 K, with Cs2WBr6 reaching 1.387, highlighting their potential for waste heat recovery. Ab-initio molecular dynamics at 300 K validates structural stability, positioning Cs2MBr6 as a robust platform for addressing energy and environmental challenges.

We present a comprehensive density functional theory investigation of the layered rare-earth nickelates Sm4Ni3O8 and Eu4Ni3O8 to elucidate their structural, electronic, magnetic, and thermodynamic properties. Calculations were performed within the PBE-GGA framework, with electronic corrections introduced using the modified Becke Johnson (mBJ) potential and on-site Coulomb interactions treated through the DFT + U approach to accurately describe localized Ni-3d and rare-earth 4f electrons. Both compounds exhibit metallic behaviour, as confirmed by spin-resolved band structures without a band gap in either spin channel. Density of states analysis reveals strong Ni-3d-O-2p hybridization, while Sm-4f and Eu-4f states contribute significantly near the Fermi level, governing electronic transport and magnetic characteristics. Charge density analysis indicates stronger covalent bonding in Sm4Ni3O8, whereas Eu4Ni3O8 displays a more ionic nature. Magnetic moment analysis shows dominant contributions from rare-earth atoms, supported by moderate Ni moments. Thermodynamic properties were evaluated using the quasi-harmonic Debye model over temperatures from 0 to 900 K and pressures up to 50 GPa. The specific heat approaches the Dulong Petit limit at elevated temperatures, while increasing pressure enhances the Debye temperature and bulk modulus, indicating increased lattice stiffness. These results highlight the potential of these metallic layered nickelates for magnetic and thermoelectric applications.

Five novel transition metal complexes [Ni(H2aeth)2(Pic)2] (1), [Co(H2aeth)2(Pic)2] (2), [Ni(H2aeth)2(Pic)(HPic)] ClO4 (3), [Co(H2aeth)2(Pic)(HPic)]ClO4 (4) and [Zn(H2aeth)2 (Pic)(HPic)]ClO4 (5) were synthesized using a 2amino-5-ethylthio-1,3,4-thiadiazole (H2aeth) and picolinic acid (HPic) as co-ligands. These complexes were characterized by FT-IR, UV-Vis., X-ray photoelectron spectroscopy, TG-DTA, and single-crystal X-ray techniques. Crystallographic analysis confirmed distorted octahedral geometries around the metal centers with extensive hydrogen bonding networks promoting supramolecular assembly in the solid state. X-ray photoelectron spectroscopy (XPS), validated the +2 oxidation state of each metal center. Thermal studies indicated multistep decomposition processes resulting in the formation of metal oxides. Density functional theory (DFT) and timedependent DFT calculations were employed to explore electronic structures and predict UV-Vis. transitions, which showed good agreement with experimental data. Frontier molecular orbital (FMO) analysis revealed that Ni(II) complexes 1 and 3 are softer and more reactive, consistent with their observed biological activity. The anticancer potential of complexes 1-5 was evaluated in vitro using the MCF-7 human breast cancer cell line and the MTT assay. Complex 1 exhibited the strongest cytotoxicity (IC50 = 26.5 mu g/mL) followed by complexes 3 (34.9 mu g/mL), 4 (46.4 mu g/mL), 2 (81.1 mu g/mL), and 5 (103.3 mu g/mL). The observed activity trends correlate with metal identity and coordination environment, underlining the role of electronic and structural factors in modulating bioactivity. These findings suggest that thiadiazole-picolinate metal complexes, particularly those based on Ni (II), are promising scaffolds for anticancer drug development.

Plant growth promoting rhizobacteria (PGPR) are beneficial microorganisms that play a crucial role in enhancing crop growth, productivity and resilience to environmental stresses. They colonize the root zone of plants, forming a symbiotic relationship that benefits both the plants and the microorganisms. In recent years, understanding the mechanisms by which PGPR influence plant growth and exploring their potential in sustainable agricultural practices has been the center of attention for the scientific community. Acting as bioinoculants, PGPR improve plant health through various mechanisms, including nutrient solubilization, hormone production and induction of systemic resistance against pathogens. PGPR are receiving a considerable attention because of the beneficial effects they offer, which can replace the utilization of chemical fertilizers, harmful pesticides and other supplements that are not appropriate for crop plants. Soil microbial communities are said to be a boon for agriculture because they play a pivotal role in the colonization of root-soil environments and carry out a wide variety of interactive activities. Furthermore, PGPR can alleviate biotic and abiotic stresses and help plants to survive, grow and develop under adverse conditions. This comprehensive review explores the multifaceted applications of PGPR in promoting crop development, increasing yield and improving stress tolerance, with a focus on drought, salinity and nutrient deficiency. In addition, the role of PGPR in advancing sustainable agriculture is discussed, highlighting its potential as an eco-friendly alternative to chemical fertilizers and pesticides. This review also examines the current challenges in PGPR application and suggests future research directions to optimize their use in modern farming systems. By integrating PGPR into sustainable agricultural practices, we can address global food security challenges while minimizing their environmental impacts.