Browsing by Author "Arun Kumar Mishra"

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A grobacterium-mediated gene transfer: recent advancements and layered immunity in plants
(Springer Science and Business Media Deutschland GmbH, 2022) Madhu Tiwari; Arun Kumar Mishra; Debasis Chakrabarty
Main conclusion: Plant responds to Agrobacterium via three-layered immunity that determines its susceptibility or resistance to Agrobacterium infection. Abstract: Agrobacterium tumefaciens is a soil-borne Gram-negative bacterium that causes crown gall disease in plants. The remarkable feat of interkingdom gene transfer has been extensively utilised in plant biotechnology to transform plant as well as non-host systems. In the past two decades, the molecular mode of the pathogenesis of A. tumefaciens has been extensively studied. Agrobacterium has also been utilised as a premier model to understand the defence response of plants during plant–Agrobacterium interaction. Nonetheless, the threat of Agrobacterium-mediated crown gall disease persists and is associated with a huge loss of plant vigour in agriculture. Understanding the molecular dialogues between these two interkingdom species might provide a cure for crown gall disease. Plants respond to A. tumefaciens by mounting a three-layered immune response, which is manipulated by Agrobacterium via its virulence effector proteins. Comparative studies on plant defence proteins versus the counter-defence of Agrobacterium have shed light on plant susceptibility and tolerance. It is possible to manipulate a plant’s immune system to overcome the crown gall disease and increase its competence via A. tumefaciens-mediated transformation. This review summarises the recent advances in the molecular mode of Agrobacterium pathogenesis as well as the three-layered immune response of plants against Agrobacterium infection. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
A new species of Scytonema isolated from Bilaspur, Chhattisgarh, India
(Wiley-Liss Inc., 2016) Prashant Singh; Robin Anigo Minj; Kikku Kunui; Zaid Muneef Shaikh; Archana Suradkar; Yogesh S Shouche; Arun Kumar Mishra; Satya Shila Singh
Filamentous cyanobacterium (strain 10C-PS) isolated from a fresh water body of Bilaspur, Chhattisgarh, India is being described as new species of the polyphyletic genus Scytonema. Phenotypic, molecular and phylogenetic characterization was performed and the combined results validated the strain as a new species. Careful observations of the filaments, presence of a distinctly textured sheath throughout the length of the trichome, differences in the shape and dimensions of the vegetative cells, and heterocytes provided reliable morphological signals that the strain differed from rest of the closely related species. Sequencing of the 16S rRNA gene showed 96.89% sequence similarity with Scytonema hofmanni PCC 7110 while rbcl and psbA sequencing showed 95% and 92% similarities with Scytonema hofmanni PCC 7110 and Nostoc sp. PCC 7524 respectively while the nifD gene sequence similarity was found to be 96% with Scytonema hofmanni PCC 7110. The PC-IGS region was sequenced and concatenated cpcB, IGS and cpcA regions indicated 97% closest similarity with Scytonema sp. PCC 7110 and Scytonema bohnerii Ind24. Subsequent phylogenetic analyses gave a strong pattern of distinct clustering in case of all the molecular markers. The phenotypic, genetic and phylogenetic observations prove conclusively that the strain 10C-PS is a new species in the genus Scytonema with the name proposed being Scytonema bilaspurensis. © 2016 Institute of Botany, Chinese Academy of Sciences
A tau class glutathione-S-transferase (OsGSTU5) confers tolerance against arsenic toxicity in rice by accumulating more arsenic in root
(Elsevier B.V., 2022) Madhu Tiwari; Maria Kidwai; Prasanna Dutta; Shiv Narayan; Neelam Gautam; Khushboo Chawda; Pramod Arvind Shirke; Arun Kumar Mishra; Debasis Chakrabarty
Arsenic (As) considered as one of the hazardous metalloid that hampers various physiological activities in rice. To study the mechanism of As tolerance in rice, one differentially expressed tau class glutathione-S-transferase (OsGSTU5) has been selected and transgenic rice plants with knockdown (KD) and overexpressing (OE) OsGSTU5 were generated. Our results suggested that KD lines became less tolerant to As stress than WT plants, while OE lines showed enhanced tolerance to As. Under As toxicity, OE and KD lines showed enhanced and reduced antioxidant activities such as, SOD, PRX and catalase, respectively indicating its role in ROS homeostasis. In addition, higher malondialdehyde content, poor photosynthetic parameters and higher reactive oxygen species (ROS) in KD plant, suggests that knockdown of OsGSTU5 renders KD plants more susceptible to oxidative damage. Also, the relative expression profile of various transporters such as OsABCC1 (As sequestration), Lsi2 and Lsi6 (As translocaters) and GSH dependent activity of GSTU5 suggests that GSTU5 might help in chelation of As with GSH and sequester it into the root vacuole using OsABCC1 transporter and thus limits the upward translocation of As towards shoot. This study suggests the importance of GSTU5 as a good target to improve the As tolerance in rice © 2021 Elsevier B.V.
A tau class GST, OsGSTU5, interacts with VirE2 and modulates the Agrobacterium-mediated transformation in rice
(Springer Science and Business Media Deutschland GmbH, 2022) Madhu Tiwari; Neelam Gautam; Yuvraj Indoliya; Maria Kidwai; Arun Kumar Mishra; Debasis Chakrabarty
Key message: OsGSTU5 interacts and glutathionylates the VirE2 protein of Agrobacterium and its (OsGSTU5) overexpression and downregulation showed a low and high AMT efficiency in rice, respectively. Abstract: During Agrobacterium-mediated transformation (AMT), T-DNA along with several virulence proteins such as VirD2, VirE2, VirE3, VirD5, and VirF enter the plant cytoplasm. VirE2 serves as a single-stranded DNA binding (SSB) protein that assists the cytoplasmic trafficking of T-DNA inside the host cell. Though the regulatory roles of VirE2 have been established, the cellular reaction of their host, especially in monocots, has not been characterized in detail. This study identified a cellular interactor of VirE2 from the cDNA library of rice. The identified plant protein encoded by the gene cloned from rice was designated OsGSTU5, it interacted specifically with VirE2 in the host cytoplasm. OsGSTU5 was upregulated during Agrobacterium infection and involved in the post-translational glutathionylation of VirE2 (gVirE2). Interestingly, the in silico analysis showed that the ‘gVirE2 + ssDNA’ complex was structurally less stable than the ‘VirE2 + ssDNA’ complex. The gel shift assay also confirmed the attenuated SSB property of gVirE2 over VirE2. Moreover, knock-down and overexpression of OsGSTU5 in rice showed increased and decreased T-DNA expression, respectively after Agrobacterium infection. The present finding establishes the role of OsGSTU5 as an important target for modulation of AMT efficiency in rice. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Aluminium Toxicity and Defence Mechanisms in Plants
(Nova Science Publishers, Inc., 2017) Sindhunath Chakraborty; Satya Shila Singh; Ekta Verma; Balkrishna Tiwari; Arun Kumar Mishra
In recent days, aluminium toxicity is a serious threat to agriculture all over the world. Aluminium (Al) being the most dominant metal in the Earth’s crust exhibits highly toxic effects on the plants grown in acid soils (pH below 5.0). Initially, aluminium toxicity symptoms become apparent in the apical region of the root because of its extreme sensitivity to aluminium. Cell wall rigidification, cell membrane depolarization and cytoskeletal damages are the important primary events that take place under Al stress condition. Adverse impacts of Al on these cellular components cause reduction in cell expansion, decreased nutrient uptake, organeller dysfunctioning and subsequent rapid production of reactive oxygen species (ROS).Transient generation of ROS further induces damage to the nuclear membrane and nucleic acids which ultimately lead to cell apoptosis. In the other hand, mechanisms such as release of organic acids from the root and their binding to Al extracellularly, organic acid mediated intracellular chelation and vacuolar sequestration of Al ions, synthesis of enzymatic and non-enzymatic antioxidants contribute to the Al detoxification process. Understanding the important aspects of Al phytotoxicity and mechanisms of its tolerance would be certainly beneficial to sustain agricultural productivity in acid soils by developing traits with higher resistance against aluminium. So, this article reviews the biochemistry and physiology of Al toxicity along with the various different mechanisms that are used by the plants to detoxify Al. However, emphasis has been given to the mechanisms of Al detoxification. © 2017 by Nova Science Publishers, Inc. All rights reserved.
An overview on bacteriophages: A natural nanostructured antibacterial agent
(Bentham Science Publishers B.V., 2016) Vaibhav Rastogi; Pragya; Navneet Verma; Arun Kumar Mishra; Gopal Nath; Praveen Kumar Gaur; Anurag Verma
Recent advances in the field of bionanomedicine not only enable us to produce biomaterials but also to manipulate them at molecular level. Viruses particularly bacteriophages are a promising nanomaterial that can be functionalized with great precision. Bacteriophages are the natural antimicrobial agents that fight against antibiotic resistant bacteria which cause infections in animals, humans, or in crops of agricultural value. The idea of utilizing bacteriophages as therapeutic agents is due to their ability to kill bacteria at the end of the infectious cycle. This paper reviewed the general biology of bacteriophages and the presence of receptors on the bacteria which are necessary for the recognition and adsorption of bacteriophages. Pharmacokinetics and therapeutic potential of bacteriophages administered through various routes in treating diverse bacterial infections is also reviewed along with the problems associated with bacteriophage therapy. Among various routes of administration, parenteral route is found to be the most thriving route for the treatment of systemic infections whereas oral route is meant to treat gastrointestinal infections and; local delivery (skin, nasal, ears) of phages has proven its potency to treat topical infections. © 2016 Bentham Science Publishers.
Antimicrobial Compounds From Actinobacteria: Synthetic Pathways and Applications
(Elsevier, 2018) Ekta Verma; Sindhunath Chakraborty; Balkrishna Tiwari; Arun Kumar Mishra
Actinobacteria, bearing the characteristics of both bacteria and fungus, are considered as one of the most medicinally important candidates because of their tremendous ability to produce various bioactive compounds. Members of actinobacteria are strictly gram positive in nature and represent the most efficient group of prokaryotes capable of producing novel metabolites. The metabolites produced by actinobacteria exhibit inhibitory effects against different pathogens such as MDR bacterial strains, fungi, viruses, protozoa, and other parasites. Numerous antimicrobial compounds such as beta-lactams, tetracyclines, phenazine, aminoglycosides, etc. have already been isolated and characterized from several actinobacteria and are used as drugs to control diverse human diseases. Two individual pathways, i.e., nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS I and II), are thought to be responsible for the synthesis of these compounds in actinobacteria. This review demonstrates the diversity, chemistry, and bioactivity of actinobacterial metabolites along with the biochemical and genetic basis of their production. © 2018 Elsevier B.V. All rights reserved.
Assessing the stimulatory effect of indole-3-acetic acid on growth and sustenance of yeasts isolated from traditional fermentative sources maintained by six ethnic communities of Asssam, North-east India
(Journal of Pure and Applied Microbiology, 2019) Bhaskar Jyoti Nath; Deep Prakash Parasar; Ekta Verma; Hridip Kumar Sarma; Arun Kumar Mishra
In this investigation, growth promoting role of indole-3-acetic acid (IAA) was assessed on yeasts representing three genera and four species viz Wickerhamomyces anomalus, Saccharomyces cerevisiae, Candida tropicalis and Candida glabrata isolated from traditional fermentative starter materials of Ahom, Rabha, Bodo, Karbi, Kachari and Mishing communities of Assam, India. Isolates were first assessed for their ability to synthesize IAA in presence and absence of external tryptophan and was examined for stimulatory effect of growth on the tested isolates. Tryptophan dependent IAA synthesis was observed in 92% of isolates while 72% of isolates could synthesize IAA in absence of exogenous tryptophan. Candida glabrata KC3X could synthesize maximum IAA while Saccharomyces cerevisiae KR5.6 did not synthesize IAA in presence of external tryptophan. 3 out of 14 Wickerhamomyces isolates and the sole Saccharomyces isolate KR4.10 were found to synthesize significant amount of IAA in absence of tryptophan. Treatment of exogenous IAA on the growth of tested yeasts revealed that Saccharomyces isolates were more pronounced than others. Wickerhamomyces anomalus, Candida tropicalis and Candida glabrata did not show any significant response of growth in presence of exogenous IAA. This study concludes that plant condiments present in starter materials may aid in accelerated growth of Saccharomyces yeasts compared to non-Saccharomyces ones. Yeasts capable of synthesizing IAA but unable to show appreciable growth in presence of IAA may presumably facilitate sustenance of Saccharomyces spp. in fermentative consortia. © The Author(s) 2019.
Biodegradation and rapid removal of methyl parathion by the paddy field cyanobacterium Fischerella sp.
(Elsevier B.V., 2017) Balkrishna Tiwari; Sindhunath Chakraborty; Alok Kumar Srivastava; Arun Kumar Mishra
A paddy field cyanobacterial isolate that is capable of degrading and utilizing the organophosphorus pesticide methyl parathion (MP) as a phosphate source has been characterized as Fischerella sp. To investigate the MP removal and degradation capabilities of this cyanobacterium along with the mechanism it has adopted to combat the pesticide's toxicity, different doses of MP (0, 5, 10, 20 and 30 mg L− 1) were applied to the cyanobacterial culture. At 20 mg L− 1 of MP, the cyanobacterium efficiently modulated its antioxidative defense system and its fatty acid and hydrocarbon profiles to support growth. The initial rapid removal of methyl parathion (~ 80%) was due to the adsorption of the pesticide onto the cyanobacterial surface. Fourier transform infrared (FTIR) spectral analysis revealed that MP interacts with the [sbnd]OH group on the cell surface, and this chemical interaction may lead to chemisorptions. The initial removal pattern has followed the pseudo-second-order kinetics model of biosorption that also defines the chemisorptions mechanism. The appearance of p-nitrophenol in the medium coupled with modulation of the physiological indices of this cyanobacterium has indicated that biosorption followed by the simultaneous bioaccumulation and biodegradation of MP led to its complete removal from the medium. Under phosphorus-deficient conditions, MP exposure induced the growth and intracellular alkaline phosphatase activity of the cyanobacterium, which both support the view that the organism can use this pesticide as a phosphorus source. Thus, due to its tremendous efficiency in degrading and removing the organophosphorus pesticide MP, the isolated cyanobacterium Fischerella sp. can be used as a potent bioremediation agent. © 2017 Elsevier B.V.
Carbon Catabolite Repression of Methyl Parathion Degradation in a Bacterial Isolate Characterized as a Cupriavidus sp. LMGR1
(Springer, 2020) Balkrishna Tiwari; Vandana Sindhu; Arun Kumar Mishra; Satya Shila Singh
Among the mixture of carbon compounds, bacteria have the ability to select energetically efficient substrate as a preferred carbon source. This specific behavior often limits the use of pollutants as a secondary carbon source by bacteria grown with preferred carbon source and the pollutants. Therefore, to develop an efficient bioremediation technology for removal/degradation of organophosphorus pesticide methyl parathion (MP) from agricultural soils, a soil bacterial strain (LMGR1) capable of degrading MP and p-nitrophenol was isolated and identified as a Cupriavidus oxalaticus based on biochemical (carbon utilization pattern) and molecular analysis (16S rRNA gene sequence), but the phylogenetic analysis revealed a distinct position, and the name was designated as Cupriavidus sp. LMGR1. The effect of preferred carbon source on degradation was also investigated. The bacterium assimilated the pesticide as a sole source of carbon and consumes about 100 mg L−1 of MP within 6 to 7 h of incubation. Furthermore, the methyl parathion hydrolase (MPH) enzyme (localized in the periplasm of bacterium) activity was induced by the carbon deficiency instead of substrate. Determination of kinetic parameters, i.e., Vmax and Km for MPH enzyme in the extracted periplasmic protein indicated significant higher affinity towards the substrate. The reduced MPH activity in the bacterium grown in presence of preferred carbon source indicated the role of carbon catabolite repression in regulation of pesticide degradation. Thus, the bacterium has prodigious capability to be used as a bioremediation agent, but the availability of preferred carbon source may affect its potential in field application. © 2020, Springer Nature Switzerland AG.
Cell Death in Photoautotrophs
(Springer Nature, 2024) Samujjal Bhattacharjee; Prashansa Singh; Alka Bhardwaj; Arun Kumar Mishra
Programmed cell death (PCD) is a genetically controlled mechanism regulating cellular demise. Though commonly associated with multicellular organisms, it has also been observed in unicellular organisms such as photoautotrophs, which are organisms proficient in generating their sustenance through photosynthesis. This chapter delves into the fundamental role of programmed cell death in photoautotrophs, elucidating its pivotal contributions to growth, development, and adaptive responses to environmental challenges. The exploration unveils the sophisticated mechanisms these organisms have evolved to ensure survival and reproductive success amid changing conditions. Through an in-depth analysis of distinct mechanisms and regulatory pathways governing PCD in photoautotrophs, this chapter provides valuable insights into the broader understanding of cell death processes. It accentuates unique features, specific pathways, molecular players, and regulatory elements that PCD in photoautotrophs apart from other systems, particularly animals. Key discoveries underscore the significance of PCD in sculpting the life cycle of photoautotrophs, resonating with implications for plant biology, ecological dynamics, and beyond. Comparative analyses with PCD in diverse organisms shed light on the evolutionary dimensions of cell death mechanisms. The presented findings not only propel our comprehension of PCD in photoautotrophs but also pave the way for future research, unraveling the intricate interplay between cellular life and death in these vital organisms. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Characterization of frankial strains isolated from Hippophae salicifolia D. Don, based on physiological, SDS-PAGE of whole cell proteins and RAPD PCR analyses
(2010) Satya Shila Singh; Anju Singh; Amrita Srivastava; Prashant Singh; Anumeha Singh; Arun Kumar Mishra
Different Frankia strains (HsIi2, HsIi4, HsIi5, HsIi8, HsIi9, HsIi10, HsIi11, HsIi12, HsIi13, HsIi14) nodulating Hippophae salicifolia D. Don, were characterized on the basis of physiological, biochemical and molecular attributes. Results suggest that the physiological approaches i. e., nitrogenase activity, glutamine synthetase (GS) activity and ammonia excretion are strain specific. The highest rate of nitrogen fixation and maximum production of ammonia with low GS makes the strain HsIi11, a suitable biofertilizer as compared to other strains. Analysis of total protein pattern (SDS-PAGE) revealed that the most closely related strains HsIi10 and HsIi4 were found to be most distantly related to the most similar strains HsIi14, HsIi5, HsIi13, HsIi11 and HsIi12. RAPD PCR analyses with an arbitrary primer 1253 produced distinct, unique and specific DNA fingerprints for each of the Frankia strain and 100% polymorphism was observed which uncovers the genetic diversity. These approaches might be helpful in rapid identification, in designing the marker for the specific strains as well as in improving nitrogen fixation in agroforestry. © Springer Science+Business Media B.V. 2009.
Chemotaxonomy of heterocystous cyanobacteria using FAME profiling as species markers
(2012) Ekta Shukla; Satya Shila Singh; Prashant Singh; Arun Kumar Mishra
The fatty acid methyl ester (FAME) analysis of the 12 heterocystous cyanobacterial strains showed different fatty acid profiling based on the presence/absence and the percentage of 13 different types of fatty acids. The major fatty acids viz. palmitic acid (16:0), hexadecadienoic acid (16:2), stearic acid (18:0), oleic acid (18:1), linoleic (18:2), and linolenic acid (18:3) were present among all the strains except Cylindrospermum musicola where oleic acid (18:1) was absent. All the strains showed high levels of polyunsaturated fatty acid (PUFAs; 41-68. 35%) followed by saturated fatty acid (SAFAs; 1. 82-40. 66%) and monounsaturated fatty acid (0. 85-24. 98%). Highest percentage of PUFAs and essential fatty acid (linolenic acid; 18:3) was reported in Scytonema bohnerii which can be used as fatty acid supplement in medical and biotechnological purpose. The cluster analysis based on FAME profiling suggests the presence of two distinct clusters with Euclidean distance ranging from 0 to 25. S. bohnerii of cluster I was distantly related to the other strains of cluster II. The genotypes of cluster II were further divided into two subclusters, i. e., IIa with C. musicola showing great divergence with the other genotypes of IIb which was further subdivided into two groups. Subsubcluster IIb 1 was represented by a genotype, Anabaena sp. whereas subsubcluster IIb 2 was distinguished by two groups, i. e., one group having significant similarity among their three genotypes showed distant relation with the other group having closely related six genotypes. To test the validity of the fatty acid profiles as a marker, cluster analysis has also been generated on the basis of morphological attributes. Our results suggest that FAME profiling might be used as species markers in the study of polyphasic approach based taxonomy and phylogenetic relationship. © 2011 Springer-Verlag.
Comparative Analysis of Paddy Soil Denitrifying Bacteria with Soil Phospholipid Fatty Acid Profile
(Bellwether Publishing, Ltd., 2021) Meenakshi Srivastava; Arun Kumar Mishra
To characterize the metabolic versatility of denitrifying bacterial communities residing in the paddy soil, phospholipid fatty acid (PLFA) analyses were done along with nosZ encoding nitrous oxide reductase gene-based PCR-DGGE and real-time Q-PCR analysis. In this study, we have analyzed the abundance of nitrous oxide reductase (nosZ) genes and DGGE-based denitrifier community assessment was found to be correlated with soil PLFA profile in terms of their pattern analysis. Among all detected denitrifying bacteria, Ochrobactrum sp. represented a major fraction following Cupriavidus and uncultured bacteria. The data related to nosZ gene abundance were found to show similar pattern with PLFA-based lipid profile. Greater amount of lipid content (C18-C20) and denitrifiers diversity was apparently visible at Chandauli of Eastern UP, India and thus positively impact each other in the soil. Our study suggests that the nosZ-based DGGE and gene abundance data were increased in response to soil PLFA profiles. Subsequently, the presence of an increased lipid content of soil samples with increased abundance and diversity of denitrifying bacteria could be helpful in managing nutrient dynamics as well as microbial dynamics of paddy soil ecosystem. © 2021 Informa UK Limited, trading as Taylor & Francis Group.
Comparative responses of diazotrophic abundance and community structure to the chemical composition of paddy soil
(Springer Verlag, 2018) Meenakshi Srivastava; Arun Kumar Mishra
Diazotrophy is considered as one of the most crucial and dynamic phenomena in the rice field and also a major source of nitrogen input. The objective of this study was to elucidate possible interactions between diverse and dominant diazotrophic bacterial community and organic carbon composition of the paddy soil. Our results suggest that most abundantly found diazotrophs belong to a proteobacteria group and uncultured bacterial forms. A gene abundance study clearly showed significantly higher diazotrophic abundance (P < 0.01) at Chandauli (CHN) as compared to Varanasi (VNS) and Ghazipur (GHJ) districts of Eastern Uttar Pradesh, India, with nitrogenase reductase (nifH) copy number between 1.44 × 103 and 3.34 × 103 copy g−1 soil. Fourier-transform infrared (FT-IR) spectroscopy data identified –CO–, C=O (NH2− and –NH–), CH2−, and OH– as dominant organic functional groups in the paddy soil. Multivariate analysis was performed to get a clear and more accurate picture of interactions between free-living diazotrophs and abiotic soil factors. Regression analysis suggested a similar trend of distribution of different functional groups along each site. Relative abundance and diversity of diazotrophic population increased in response to FT-IR-based soil organic fractions. Maximum number of FT-IR spectral peak at sites in the Chandauli district augmented its bacterial diazotrophic diversity and abundance. Taken together, the present study sheds light on the substrate-driven composition of the microbial population of selected paddy areas. © 2017, Springer-Verlag GmbH Germany.
Cyanobacteria
(Elsevier, 2023) Arun Kumar Mishra; Satya Shila Singh
Cyanobacteria: Metabolisms to Molecules covers diversity, fundamental metabolisms, crucial metabolities, their synthesis, and bioinformatics topics surrounding cyanobacteria, an organism regarded as the most important organism to sustain life on the planet during ancient times. Cyanobacteria are among the first pioneering communities on various harsh habitat, hydrarch or xerarch, which finally facilitate the emergence of vast communities including higher plants. Being the progenitor of chloroplast, the cyanobacterial metabolisms has always fascinated microbiologists. Additionally, the ability of these prokaryotes to produce valuable and prolific sources of natural products signified their role in an array of industrial sectors. Therefore, in this book, the book's authors accumulate the current knowledge of cyanobacterial metabolisms and molecules as a valuable asset for students, researchers, and biotechnologists. © 2024 Elsevier Inc. All rights reserved.
Cyanobacteria: a key player in nutrient cycling
(Elsevier, 2023) Alka Bhardwaj; Prashansa Singh; Neha Gupta; Samujjal Bhattacharjee; Ankit Srivastava; Anirbana Parida; Arun Kumar Mishra
Cyanobacteria are photosynthetic prokaryotic organisms that are found in various aquatic and terrestrial environments. They are one of the oldest and most primitive forms of life on Earth, playing critical role in the biological nutrient cycling of different habitats. The phenomenon of nutrient cycling delineates the continual recycling of essential elements, which are rendered accessible to the biota of an ecosystem. Cyanobacteria possess the ability to fixate atmospheric nitrogen and transform it into a bioavailable form, which can be utilized by other organisms in the ecosystem. This process is called nitrogen fixation, and it helps to increase the availability of nitrogen in the ecosystem, which is an essential nutrient for the growth of different life forms. They also play a key role in carbon cycling by capturing carbon dioxide through photosynthesis and releasing oxygen into the atmosphere. Indeed, cyanobacteria played a significant role in making the early environment aerobic by producing oxygen through photosynthesis. This process helps to regulate the amount of carbon dioxide in the atmosphere, which is important for mitigating the effects of climate change. Additionally, cyanobacteria can contribute to the cycling of other nutrients, such as phosphorus and sulfur, by releasing them from organic matter and making them available for other organisms to use. Overall, cyanobacteria are crucial for the cycling of different nutrients, including nitrogen, carbon, phosphorus, and sulfur, and their impact on the health of the ecosystem cannot be overstated. The presence of these microorganisms is essential for ensuring a stable and thriving environment, and their involvement in nutrient cycling and oxygenic photosynthesis has constituted a critical component in the evolutionary history of life on Earth. © 2024 Elsevier Inc. All rights reserved.
Cyanobacterial bioactive compound EMTAHDCA recovers splenomegaly, affects protein profile of E. coli and spleen of lymphoma bearing mice
(Springer Netherlands, 2019) Niveshika; Shashank Kumar Maurya; Balkrishna Tiwari; Sindhunath Chakraborty; Ekta Verma; Rajnikant Mishra; Arun Kumar Mishra
The antibacterial and anticancerous properties of EMTAHDCA have already been reported in our previous study. However, mode of action of EMTAHDCA is still elusive. The present study was aimed to investigate the molecular targets in Escherichia coli and spleen of lymphoma-bearing mice in response to cyanocompound 9-ethyliminomethyl-12 (morpholin-4-ylmethoxy)-5, 8, 13, 16-tetraaza -hexacene-2, 3- dicarboxylic acid (EMTAHDCA) isolated from fresh water cyanobacterium Nostoc sp. MGL001. Differential expressions of proteins were observed in both E. coli and spleen of lymphoma-bearing mice after EMTAHDCA treatment. In continuation of our previous study, the present study revealed that the antibacterial agent, EMTAHDCA causes the drastic reduction in synthesis of proteins related to replication, transcription, translation and transportation in E. coli. Probably the direct or indirect interaction of this compound with these important metabolic processes led to the reduction in growth and cell death. Furthermore, the anticancerous property of the compound EMTAHDCA reflected as down regulation in proteins of cell cycle, cellular metabolism, signalling, transcription and transport together with up regulation of apoptosis, DNA damage and immunoprotection related proteins in spleen of lymphoma-bearing mice. In this study the EMTAHDCA induced modulations in expression of proteins of key metabolic pathways in E. coli and spleen cells of lymphoma bearing mice helped in understanding the mechanism underlying the antibacterial and anti-cancerous property. © 2019, Springer Nature B.V.
Cyanophages: interacting mechanism and evolutionary significance
(Elsevier, 2023) Ankit Srivastava; Neha Gupta; Arun Kumar Mishra
Cyanophages are viruses that exhibit a highly specific interaction mechanism with their host cyanobacteria. This specificity is driven by the recognition of host cell surface receptors by the phage tail fibers, which allows for the injection of the phage DNA into the host cell. Once inside the host cell, the phage DNA is replicated and transcribed, leading to the production of new phage particles. The evolutionary significance of cyanophages is multifaceted that lies in their role in shaping microbial communities and biogeochemical cycles in aquatic ecosystems. On one hand, cyanophages act as important regulators of cyanobacterial populations in aquatic ecosystems. These viruses have been shown to impact the growth, abundance, and diversity of cyanobacteria, which in turn can affect the functioning of the ecosystem as a whole. On the other hand, the study of cyanophages also provides insight into the coevolution of viruses and their hosts. The transfer of genetic material between cyanophages and cyanobacteria can occur through a variety of mechanisms, including lysogeny, transduction, and horizontal gene transfer. Understanding the mechanisms and evolutionary dynamics of virus–host interactions is therefore crucial for predicting the response of aquatic ecosystems to changing environmental conditions. Therefore cyanophages provide a window into the complex relationships between viruses and their hosts, and the important role of viruses in shaping aquatic ecosystems. Overall, this chapter presents valuable insights into the complex relationships between viruses and cyanobacteria, and the important role of viruses in shaping microbial communities and aquatic ecosystems. © 2024 Elsevier Inc. All rights reserved.
Deciphering salinity tolerance in the cyanobacterium Anabaena sphaerica: an evaluation of physiological and biochemical adjustments
(Institute for Ionics, 2022) Surbhi Kharwar; Samujjal Bhattacharjee; Arun Kumar Mishra
Besides being a determinant of species distribution around the globe, salinity over the threshold limit imparts detrimental effects on life forms. The present study deciphered the tolerance of heterocytous cyanobacterium Anabaena sphaerica to 77.5, 100, and 200 mM NaCl by analyzing physiological and biochemical adjustments within the cells. Exposing the cyanobacterium to high NaCl reduces growth dynamics, photosynthesis, and membrane stability. Intracellular Na+ accumulation not only induces ionic imbalances by increasing Na+/Mg2+ and Na+/K+ ratios, but also causes oxidative burst in the cell. Moreover increased glutathione, proline, and sucrose contents along with higher enzymatic antioxidants such as superoxide dismutase and catalase, delineated cyanobacterial resilience against both osmotic and oxidative stresses. Additionally, Fourier-transform infrared (FTIR) spectroscopy exhibited carbohydrate accumulation in the stressed cells as a function of reprogrammed carbon allocation, which might also occur as an adaptive measure. However, escalation in the activities of nitrate reductase and nitrite reductase at 77.5 and 100 mM NaCl depicted an increase in nitrate assimilation, indicating the ability of cyanobacterium to withstand at least 100 mM NaCl in the surrounding. Hence, A. sphaerica displays significant tolerance to salinity and, thus, can play a crucial role in ameliorating salinity from salt-affected paddy fields. © 2022, The Author(s) under exclusive licence to Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.