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Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and ?-ray brightness levels
In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and ?-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to ?-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and ?-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates. 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. -
Effect of age and gender on dietary patterns, mindful eating, body image and confidence
The emergence of Diet Culture came into existence with the era of pop culture, which emphasized the idea of body improvement by embracing the portrayal of unrealistic beauty standards set by the thin-ideal media. This growing and trending culture gained its popularity in India with the COVID pandemic and the imposed lockdown, wherein the prevalence of obesity and binge eating resulted from counter-regulatory eating behaviors and restrictive food intake to a greater extent of skipping meals to achieve the desired body type. The present empirical investigation focuses on understanding the gender and age-based differences (between the ages 18 to 55) among Indian population on dietary patterns, body image, mindful eating and physical appearance confidence using 2 3 factorial design. The tools used were Eating Behavior Pattern Questionnaire (EBPQ) [43], Body Self- image Questionnaire (BSIQ) [40], Mindful Eating Questionnaire (MEQ) [18] and Personal Evaluation Inventory (PEI) [44] were administered on a sample size of 120, selected using convenience sampling technique. The collected data was analyzed using SPSS Version 20.0. Results of the study reveal non-significant age and gender differences for mindful eating and appearance confidence. Significant age- differences were observed for Snacking and convenience F(2,114) = 6.22, p <.05; social dependence F(2,114) = 3.87, p <.05 and height dissatisfaction F(2,114) = 8.79, p <.05. And, significant gender differences were observed for Meal Skipping F(1,114) = 6.46, P <.05; snacking and convenience F(1,114) = 4.19, p <.05; fatness evaluation F(1,114) = 5.94, p <.05 and fitness evaluation F(1,114) = 5.33, p <.05. The only significant interaction effect observed was for social dependence dimension F(2, 114) = 3.96, p <.05. Thus, high exposure to social media and diet-related content contributed significantly to changing dietary patterns, and how they look, feel or perceive their body. 2023, BioMed Central Ltd., part of Springer Nature. -
Did the Economic Reforms Change the Macroeconomic Drivers of the Indian Economy in the Post-Reform Era? An ARDL Bounds Test Approach
Purpose: The purpose of this study is to investigate the macroeconomic forces that have been driving the Indian economy during both the pre-reform and post-reform eras, that is, from 1950-1951 to 1990-1991 and from 1991-1992 to 2022-2023 respectively. Problem: The Indian economy underwent significant economic and financial sector reforms in 1991-92, with the goal of reviving its stagnant growth. These reforms are intended to spur the economic growth of India. What were the main forces behind the Indian economy before and after the reforms? Is the research question. The goal of the current study is to determine if the economic reforms shifted or maintained the pre-reform eras driving forces for the Indian economy in the post-reform era. Design/Methodology/Approach: The gross domestic product (GDP), the gross domestic savings (GDS), the private consumption expenditure (PFCE), the government final consumption expenditure (GFCE), the inflation rate, the exchange rate, the exports, the imports, the internal and external borrowings of the government, personal remittances, foreign direct investment (FDI), and foreign portfolio investments (FPI) are all taken into consideration in order to fill the research gap that has been identified as a result of the comprehensive review of the literature. Following an analysis of the selected variables' fundamental characteristics, an econometric model is developed using the Autoregressive Distributed Lag (ARDL) Bounds Test Model. Findings: There is no evidence of long-run causation and association between the variables, but the findings of the ARDL Bounds Test showed that in the pre-reform period, PFCE is the major driver of the GDP in the short-run, with strong support from imports. However, since the reform, PFCE, GDS, and Exports are the primary short-and long-term contributors to GDP. Practical Implication: These findings indicate that India's macroeconomic system is shifting. The Indian economy has undergone a dramatic shift, moving away from a reliance on imports and toward one that is consumer-driven and export-driven. As savings and consumer expenditures are the main drivers of the Indian economys growth in the post-reform era, policies should be designed to increase savings and consumption as well as increase exports. 2023, ASERS Publishing House. All rights reserved. -
How does geopolitical risk affect CO2 emissions? The role of natural resource rents
In a panel dataset of 38 developing and industrialized countries from 1970 to 2021, this study investigates how geopolitical risk and resource rents affect CO2 emissions. After implementing diagnostics, the paper observes significant relationships among CO2 emissions, geopolitical risk, natural resource rents, per capita income, and share of renewable energy in the long run. The panel data estimations show that geopolitical risk, natural resource rents, and per capita income increase CO2 emissions. However, the share of renewable energy is negatively associated with it. The mediation effect of geopolitical risk and natural resource rents on CO2 emissions is also positive. Potential policy repercussions are also discussed. 2023 Elsevier Ltd -
The rise of new age social media influencers and their impact on the consumers' reaction and purchase intention
The internet revolution and digitisation have created innovative platforms and spokespersons for brands beyond traditional media. The marketing landscape for brands and customers is evolving towards a more personal and authentic approach; adopting various social media platforms and influencers creates more brand engagement. Influencers are the new third-party endorsers, catering to and recommending products to their loyal community of followers. The influencer and their fans/followers are a brands new storytellers. However, selecting the right influencer for a brands promotional strategy requires careful consideration of several factors. This paper aims to study the impact/effect of these variables, namely, endorsers credibility and corporate credibility, on consumers attitudes towards the brand and its impact on purchase intention, with respect to the millennial era. In the present study, 14 Likert-based questions were designed, asking the respondents to rank their choice of agreement on a scale of 1 to 5. The results were obtained through statistical analysis, including measuring the relationship between variables using confirmatory factor analysis and regression techniques. And the study found that corporate credibility has a significantly higher impact (approximately 90%) than individual endorsements (including those by celebrities) in enhancing customers brand perception. Copyright 2024 Inderscience Enterprises Ltd. -
Revisiting the trade opennessunemployment nexus: anapplication of the novel JKS panel causality test with static anddynamic panel models
Purpose: This paper documents a robust empirical regularity: higher trade openness is associated with a lower unemployment rate. This paper also examines whether or not the effects of trade liberalisation depend on countries' income levels. Further, the dynamic causation between trade openness and unemployment is also examined. Design/methodology/approach: In order to obtain insight into the opennessunemployment nexus, following empirical methods were utilised - static panel models, dynamic panel models and a novel panel Granger causality approach proposed by Juodis etal. (2021). Findings: Results suggest that openness negatively affects unemployment; the extent to which trade liberalisation affects unemployment depends on the income level of each country. The Juodis, Karavias, and Sarafidis (JKS) test confirmed that the past values of trade openness, inflation, foreign direct investment and gross domestic product per capita contain information that helps to predict unemployment in a more robust manner. To simply put, opening upto trade may eventually become a requirement for creating more job opportunities, but this alone may not be enough. The extent to which nations benefit from trade liberalisation is largely dependent on the overall economic conditions and their capability to move up the income scale. Originality/value: A major difference between this study and those performed previously is that this study does not only examine the impact of trade openness on unemployment, but also investigates whether the unemployment effect of liberalisation is affected by countries' income levels an issue that has received little attention in the past. Additionally, the unique panel non-causality approach put forth by Juodis etal. (2021) is used in the first instance to look into the causal link between trade openness and unemployment. This method has advantages in that the method enables capturing Granger-causality in homogeneous or heterogeneous panels amongst multiple variables. 2023, Emerald Publishing Limited. -
Experimental and Theoretical Approach of Evaluating Chitosan Ferulic Acid Amide as an Effective Corrosion Inhibitor
Phenolic acid grafted chitosan has widespread drug delivery applications, as bio adsorbent, packing material, etc., due to its excellent antioxidant and antimicrobial properties. However, for the first time, the anticorrosive efficiency of ferulic acid modified chitosan has been investigated. The prepared chitosan derivative is characterized using spectral methods, thermal analytical methods, surface charge, and particle size analysis. The evaluation of corrosion inhibition potential showed a highest value of 95.96% at 303K. Thermodynamic activation and adsorption parameters endorse a mixed adsorption process involving an initial electrostatic interaction followed by chemisorption. Electrochemical studies gave results which agreed well with the gravimetric studies. Surface morphological studies were performed using contact angle measurements, FESEM, EDAX, AFM, optical profilometric and UV spectral techniques. Computational studies involving quantum chemical calculations, Monte Carlo and molecular dynamic simulation studies, and radial distribution function analysis are further done to validate the experimental results. Graphical Abstract: [Figure not available: see fulltext.] 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG. -
A critical assessment of technical advances in pharmaceutical removal from wastewater A critical review
Use of pharmaceutical products has seen a tremendous increase in the recent decades. It has been observed that more than thirty million tons of pharmaceuticals are consumed worldwide. The used pharmaceutical products are not completely metabolized in human and animal body. Therefore, they are excreted to the environment and remain there as persistent organic chemicals. These compounds emerge as toxic contaminants in water and affect the human metabolism directly or indirectly. This literature review is an endeavour to understand the origin, applications and current advancement in the removal of pharmaceuticals from the environment. It discusses about the pharmaceuticals used in medical applications such diagnosis and disease treatment. In addition, it discusses about the recent approaches applied in pharmaceutical removal including microbial fuel cells, biofiltration, and bio nanotechnology approaches. Moreover, the challenges associated with pharmaceutical removal are presented considering biological and environmental factors. The review suggest the potential recommendations on pharmaceutical removal. 2023 The Authors -
Optical spectroscopy of Gaia detected protostars with DOT: Can we probe protostellar photospheres?
Optical spectroscopy offers the most direct view of the stellar properties and the accretion indicators. Standard accretion tracers, such as H ? , H ? and Ca II triplet lines, and most photospheric features fall in the optical wavelengths. However, these tracers are not readily observable from deeply embedded protostars because of the large line of sight extinction (Av? 50 100 mag) toward them. In some cases, however, it is possible to observe protostars at optical wavelengths if the outflow cavity is aligned along the line-of-sight that allows observations of the photosphere, or the envelope is very tenuous and thin, such that the extinction is low. In such cases, we not only detect these protostars at optical wavelengths, but also follow up spectroscopically. We have used the HOPS catalog (Furlan et al. in 2016) of protostars in Orion to search for optical counterparts for protostars in the Gaia DR3 survey. Out of the 330 protostars in the HOPS sample, an optical counterpart within 2 ? ? is detected for 62 of the protostars. For 17 out of 62 optically detected protostars, we obtained optical spectra (between 5500 and 8900 using nt Object Spectrograph and Camera (ADFOSC) on the 3.6-m Devasthal Optical Telescope (DOT) and Hanle Faint Object Spectrograph Camera (HFOSC) on 2-m Himalayan Chandra Telescope (HCT). We detect strong photospheric features, such as the TiO bands in the spectra (of 4 protostars), hinting that photospheres can form early in the star-formation process. We further determined the spectral types of protostars, which show photospheres similar to a late M-type. Mass accretion rates derived for the protostars are similar to those found for T-Tauri stars, in the range of 10 - 7 10 - 8M? yr - 1 . 2023, Indian Academy of Sciences. -
Prediction of DDoS attacks in agriculture 4.0 with the help of prairie dog optimization algorithm with IDSNet
Integrating cutting-edge technology with conventional farming practices has been dubbed smart agriculture or the agricultural internet of things. Agriculture 4.0, made possible by the merging of Industry 4.0 and Intelligent Agriculture, is the next generation after industrial farming. Agriculture 4.0 introduces several additional risks, but thousands of IoT devices are left vulnerable after deployment. Security investigators are working in this area to ensure the safety of the agricultural apparatus, which may launch several DDoS attacks to render a service inaccessible and then insert bogus data to convince us that the agricultural apparatus is secure when, in fact, it has been stolen. In this paper, we provide an IDS for DDoS attacks that is built on one-dimensional convolutional neural networks (IDSNet). We employed prairie dog optimization (PDO) to fine-tune the IDSNet training settings. The proposed model's efficiency is compared to those already in use using two newly published real-world traffic datasets, CIC-DDoS attacks. 2023, Springer Nature Limited. -
Fault Analysis and Clearance in FL-APC DC-AC Converter; [Analyse et imination des dauts dans le convertisseur CC-CA FL-APC]
The traditional active neutral-point-clamped (APC) dc-ac converter maintains great common-mode voltage with high-frequency (CMV-HF) reduction capability, so it has limited voltage gain. This article presents a new five-level APC (FL-APC) dc-ac converter capable of voltage step-up in a single-stage inversion. In the suggested design, a common ground not only reduces the CMV-HF but also improves dc-link voltage usage. While comparing with traditional two-stage FL-APC dc-ac converter, the proposed design has lower voltage stresses and greater uniformity. While improving overall efficiency, the suggested clamped dc-ac converter saves three power switches and a capacitor. Modeling and actual tests have proven the suggested APC inverter's overall operation, efficacy, and achievability. The proposed circuit is finally tested with fault clearance capability. 2023 IEEE. -
Enhancement of the thermal conductivity of a near room temperature magnetocaloric composite using graphene-like hybrid nanosheets derived from organic waste
Polymer matrix composites, fabricated to counter the inherent brittleness of magnetocaloric Heusler alloys, suffer from low thermal conductivity. Here, we demonstrate a low-cost, scalable route towards developing thermally conductive, mechanically robust near-room-temperature magnetocaloric composites by incorporating graphene-like hybrid nanostructures chemically synthesized from discarded sugarcane. Micron-sized particles obtained by manually grinding Ni50.2Mn36.7Sn13 ribbons possessing a strong magnetostructural transformation near room-temperature were chosen as the active magnetocaloric fillers. Both the functional fillers were incorporated into a polysulfone matrix by solution casting. Large values of isothermal entropy change ? 0.43 and -0.46 J/kg.K were observed for a ?H = 2T, driven by two successive first and second-order transformations within the alloy fillers. Additionally, an enhanced value of the in-plane thermal conductivity ? 3.06 0.4 W/m.K was observed in the composites owing to the formation of efficient thermal bridges/pathways by the graphene-like hybrid nanostructures, rendering them promising candidates for magnetic refrigeration applications. 2023 Acta Materialia Inc. -
Morphology-dependent supercapacitive properties of Co3O4 nanomaterials synthesized via coprecipitation and hydrothermal methods
The supercapacitive properties of Co3O4 nanocrystalline powders with two different morphologies synthesized by coprecipitation (referred to as Co3O4C) and hydrothermal (referred to as Co3O4-H) methods were compared and studied. The samples were analyzed for their phase purity, crystal structure, surface morphology, and surface area. Both samples were found to be single-phase nanostructures with a normal spinel-type cubic crystal structure (space group Fd3m), as indicated by Raman and XRD (X-ray diffraction) data analyses. TEM (Transmission electron microscopy) images clearly show that the Co3O4C sample exhibits spherical particles with a mean size of 10 nm. On the other hand, the Co3O4H sample shows a flower-like assembly of particles. The Co3O4C sample has a higher specific surface area than the Co3O4-H sample due to its smaller particle size. XPS (X-ray photoelectron spectroscopy) data were collected to analyze the chemical states and cation distribution of the samples, revealing a 2:1 ratio of Co3+ and Co2+ in both samples. Both samples displayed pseudocapacitive behaviour in CV (cyclic voltammetry) and GCD (galvanostatic chargedischarge) analyses. Despite having a smaller surface area, the Co3O4H electrode exhibited a higher CS (specific capacitance) compared to the Co3O4C electrode at all current densities when tested using 1 M KOH electrolyte. At a specific current density (0.5 A/g), the Cs values for Co3O4C and Co3O4H are found to be 366 F/g and 233 F/g, respectively. As the current density increases, the specific capacitance of both electrodes decreases, but this reduction is more prominent for Co3O4-C than Co3O4-H. The study indicates that besides surface area, the morphology of the sample also plays a crucial role in determining the capacitance of a material. 2023 Elsevier B.V. -
Indian spectroscopic and imaging space telescope (INSIST): An optics design trade-off study
Large ground and space-based surveys in optical and near-infrared (NIR) wavelengths will revolutionize astronomy in the coming decade. Unfortunately, no ultraviolet (UV) facilities are planned to complement these surveys, which is crucial for studying the most active phase of the Universe that includes star formation in galaxies, active galactic nuclei (AGN), galaxy clusters, etc. A dedicated UV mission, the Indian Spectroscopic and Imaging Space Telescope (INSIST), is proposed to observe the UV sky. The compelling science objectives defined a set of high-level mission requirements. According to which, the INSIST is to have a wide field-of-view (FoV ? 0.25 square degree) comparable to Indias Ultraviolet Imaging Telescope (UVIT) and about two orders of magnitude larger than that of the Hubble Space Telescope, simultaneous imaging of the FoV in UV (150300nm), u (300400nm) and g (400550nm) bands, a Multi-Object-Slit medium resolution spectroscopy in a narrow FoV in UV and a simultaneous slitless spectroscopic capability in UV and u bands. To achieve these requirements, several optical design configurations were explored. Here, we present an optical design trade study conducted on various optical design configurations to achieve a sensitivity limit of mAB> 26 mag, in the UV band and a spatial resolution better than 0.2 ? , using a 1-m size telescope aperture. We also present results from our fabrication and alignment tolerance analysis of the selected optical designs, and the design performance that meets the design requirements. Critical parameters like the encircled energy concentration, point spread function (its stability over the field), effects of the spiders supporting the secondary, etc., are explored during the design phase. Based on the trade study conducted in reference to various performance matrices, we down-selected the most optimal optical design for the INSIST. 2023, Indian Academy of Sciences. -
Role of management education in adapting the Indian public sector to market-based economic reforms
Purpose: In 1991, India embarked on market-based economic reforms initiatives pillared on liberalization, privatization and globalization (LPG). The reforms exposed the public sector enterprises to competitive market forces, raising the need to identify and develop the competencies necessary for survival. Executive training programs were initiated to prepare public enterprises for the market-based reforms. Three decades later, the reforms especially privatization is witnessing renewed interest under the current administration. In this context, the article takes a closer look at the structure of management education provided to public sector officers in India. The article also identifies barriers for implementing the learnings from the management courses in the workplaces and suggests approaches for closing the gap. Design/methodology/approach: The study follows a thematic approach based on unstructured interviews of senior executives of Indian public sector enterprises covering oil and gas, aeronautical, power and transportation sectors. New public management (NPM) is used as a yardstick of business-like characteristics of public sector enterprises. Findings: Despite heavy investment, trainings have had only partial success in implementing the core objective of NPM, i.e. to provide quality services in a professional manner to meet citizen requirements. The study found that though concepts of NPM are introduced at multiple management training programs, thepublic enterprises lag in the implementation of NPM. The ingrained hierarchical and procedural culture of the enterprises was often highlighted as the challenge to its implementation. Practical implications: The study will be of significance to Indian policymakers in designing management education programs to public sector employees. It brings out (1) various models of management education provided to public servants across industries, (2) provide evidence on the extent of NPM implementation, (3) identify barriers for transitioning the learnings from the management courses to workplace and (4) suggest changes for improving effectiveness. Originality/value: The existing research on LPG in India covers the economic transformation post-implementation and the factors contributing to the success of its implementation. This study adds to the limited literature available on the management education of public servants in the country. 2023, Emerald Publishing Limited. -
Identifying the population of T-Tauri stars in Taurus: UVoptical synergy
With the third data release of the Gaia mission, Gaia DR3 with its precise photometry and astrometry, it is now possible to study the behavior of stars at a scale never seen before. In this paper, we developed new criteria to identify T-Tauri stars (TTS) candidates using UV and optical color-magnitude diagrams (CMDs) by combining the GALEX and Gaia surveys. We found 19 TTS candidates and five of them are newly identified TTS in the Taurus molecular cloud (TMC), not cataloged before as TMC members. For some of the TTS candidates, we also obtained optical spectra from several Indian telescopes. We also present the analysis of distance and proper motion of young stars in the Taurus using data from Gaia DR3. We found that the stars in Taurus show a bimodal distribution with distance, having peaks at 130.17-1.241.31 pc and 156.25-5.001.86 pc. The reason for this bimodality, we think, is due to the fact that different clouds in the TMC region are at different distances. We further showed that the two populations have similar ages and proper motion distribution. Using the Gaia DR3 CMD, we showed that the age of Taurus is consistent with 1Myr. 2023, Indian Academy of Sciences. -
Effects of activation energy and chemical reaction on unsteady MHD dissipative DarcyForchheimer squeezed flow of Casson fluid over horizontal channel
The impact of chemical reaction and activation energy plays a vital role in the analysis of fluid dynamics and its thermal properties. The application of the flow of fluid is significantly considered in nuclear reactors, automobiles, manufacturing setups, electronic appliances etc. This study explores the impacts of activation energy and chemical reaction on the magnetohydrodynamic DarcyForchheimer squeezed Casson fluid flow through a porous material across the horizontal channel where the two parallel plates are assumed to be in motion. By using similarity variables, partial differential equations are converted to ordinary differential equations. Numerical method is applied using MATLAB to solve the problems and acquire the data for velocity field, thermal distribution, and concentration distribution. The graphs indicate that fluid velocity and temperature increases as the plates are brought closer. In addition, there was a correlation between a rise in the Hartmann number and a decrease in the fluid's velocity because of the existence of strong Lorentz forces. The temperature and the concentration of the liquid will increase due to the Brownian motion. When the DarcyForchheimer and activation energy parameters are both increased, the velocity and concentration decreases. 2023, The Author(s). -
A Reflection on the Current Status of Animal-Assisted Therapy in India
The field of animal-assisted therapy is advancing quickly throughout the world gaining popularity as a complementary therapy. Several countries, especially in the East, are still in their nascent phase in utilizing animal-assisted therapy and a more realistic presentation of their status should drive them towards effective initiatives to promote the field. The primary objective of this paper is to throw light on the current scenario of animal-assisted therapy in India. The relevant databases such as Scopus, Google Scholar, Proquest, PubMed, and JSTOR were searched to identify the research literature. The organizational websites, news, and blog articles, as well as institutional repositories, were explored to maximize the evidence. A total of 24 articles were found which included published research articles as well as unpublished conference papers. Results found a dearth of practice and research throughout the country indicating an urgent need to direct steps in promoting the growth of the field. The contemporary issues in the implementation of animal-assisted therapy such as cultural and religious beliefs, lack of awareness, lack of practising organizations and therapists warrant immediate attention. Reducing the research and practice gap alongside focusing on creating awareness, changing public perception, introducing coursework in educational institutions, the publication of evidence-based research will help in the acceptance and growth of this novel therapeutic field. 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG. -
Copper oxide modified biphasic titania for enhanced hydrogen production through photocatalytic water splitting
Recently, TiO2(B) has been extensively used in catalytic and energy fields owing to its exceptional crystal structure. But being a metastable state, TiO2(B) is transformed easily into other stable crystalline forms like anatase or rutile phase, and the low crystallinity limits the application of the material in catalysis. A combination of TiO2(B) with anatase, which is benefitted by a homojunction, is proven to be blessed with high activity. Herein, hydrogen production via photocatalytic water-splitting is presented using Cu modified biphasic titania nanotubes achieved by a facile hydrothermal procedure. The systems are well characterized using SEM, TEM, XRD analysis, N2 adsorption study, FTIR, DR-UV, Raman, Photoluminescence, and X-ray photoelectron spectral analysis. The homo-junction developed in titania due to anatase TiO2 (B), as well as the heterojunction created by the co-catalyst, tune the photocatalytic activity of TiO2 nanotubes positively, as evident from the enhanced hydrogen production over the system. 2023 -
Endophytic bacteria Klebsiella spp. and Bacillus spp. from Alternanthera philoxeroides in Madiwala Lake exhibit additive plant growth-promoting and biocontrol activities
Background: The worldwide increase in human population and environmental damage has put immense pressure on the overall global crop production making it inadequate to feed the entire population. Therefore, the need for sustainable and environment-friendly practices to enhance agricultural productivity is a pressing priority. Endophytic bacteria with plant growth-promoting ability and biocontrol activity can strongly enhance plant growth under changing environmental biotic and abiotic conditions. Herein, we isolated halotolerant endophytic bacteria from an aquatic plant, Alternanthera philoxeroides, from the polluted waters of Madiwala Lake in Bangalore and studied their plant growth promotion (PGP) and biocontrol ability for use as bioinoculant. Results: The isolated bacterial endophytes were screened for salt tolerance ranging from 5 to 15% NaCl concentration. Klebsiella pneumoniae showed halotolerant up to 10% NaCl and Bacillus amyloliquefaciens and Bacillus subtilis showed up to 15%. All three strains demonstrated good PGP abilities such as aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, phosphate solubilization, ammonia production, and nitrogen fixation. In addition, K. pneumoniae also exhibited high indoleacetic acid (IAA) production (195.66 2.51g/ml) and potassium solubilization (2.13 0.07ppm). B. amyloliquefaciens and B. subtilis showed good extracellular enzyme production against cellulase, lipase, protease, and amylase. Both the isolates showed a broad spectrum of antimicrobial activity against the tested organisms. The optimization of IAA production by K. pneumoniae was done by the response surface methodology (RSM) tool. Characterization of IAA produced by the isolate was done by gas chromatography-mass spectrometry (GCMS) analysis. The enhanced plant growth-promoting ability of K. pneumoniae was also demonstrated using various growth parameters in a pot trial experiment using the seeds of Vigna unguiculata. Conclusion: The isolated bacterial endophytes reported in this study can be utilized as PGP promotion and biocontrol agents in agricultural applications, to enhance crop yield under salinity stress. The isolate K. pneumoniae may be used as a biofertilizer in sustainable agriculture and more work can be done to optimize the best formulations for its application as a microbial inoculant for crops. 2023, The Author(s).