Browsing by Author "Avinash Singh"

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Antibiotic Residues in Food: A Global Concern for Human Health
(Springer Singapore, 2020) Avinash Singh; Sonali K. Kalra; Santosh K. Singh; Amit Prasad
Presence of antimicrobial resistance bacteria (ARBs) and antimicrobial resistance genes (ARGs) in food is a potential risk to the public health. Food animals are considered as key reservoirs of ARBs. Food can be contaminated with ARBs, ARGs and antibiotic residues in several ways, i.e. (1) by use of antibiotics during agriculture production, (2) presence of resistance genes in bacteria that are purposely added during the food processing and (3) through cross-contamination with ARBs during food processing. Contaminated food products without undergoing prior processing or preservation can be consumed, which poses a potential risk for transfer of antimicrobial resistance to humans. In this chapter, we are evaluating the food safety concerns related to the presence of antibiotic-resistant bacteria and residues in food, their impact on human health, their detection methods and few recommendations given by international and national agencies. © Springer Nature Singapore Pte Ltd. 2020.
Cyanobacterial availability for CRISPR-based genome editing: Current and future challenges
(Elsevier, 2022) Sandeep Kumar Singh; Ajay Kumar; Avinash Chandra Rai; Mukesh Kumar Yadav; Punuri Jayasekhar Babu; Zothanpuia; Liansangmawii Chhakchhuak; Prashant Kumar Singh; Garima Singh; Naveen Chandra Joshi; Avinash Singh; Kaushalendra; Rosie Lalmuanpuii; Esther Lalnunmawii; Bendangchuchang Longchar
Cyanobacterial genetic manipulations are optimistic for producing feedstocks, fuels, valuable chemicals, and a basic understanding of stress-induced responses. Regrettably, the newly available genome manipulation tools for cyanobacteria are far from other organisms despite their significant contributions to humanity. This chapter primarily focused on genome engineering efforts available to date for synthetic biology applications and the recent advances in investigations in the development of genome editing in cyanobacteria. Moreover, in recent years, clustered regularly interspaced short palindromic repeats (CRISPR) dependent approaches rapidly gained engineering popularity in all life domains. Such techniques permit markerless genome editing, simultaneous manipulation of multiple genes, and transcriptional regulation of genes. However, the cyanobacterial genome manipulations by employing the CRISPR tool are still in infancy and limited to very few reports for its synthetic applications, even though the CRISPR drastically shortened the mutant selection time and the segregation advantages. In this chapter, we highlighted the studies that have implemented CRISPR-based tools for cyanobacteria’s metabolic engineering. © 2022 Elsevier Inc. All rights reserved.
Cyanobacterial genome editing toolboxes: recent advancement and future projections for basic and synthetic biology researches
(Elsevier, 2020) Sandeep Kumar Singh; Alok Kumar Shrivastava; Ajay Kumar; Vipin Kumar Singh; Deepanker Yadav; Arpan Modi; Wenjing Wang; Avinash Singh; Toolika Singh; Viji Sitther; Prashant Kumar Singh
Cyanobacteria are ancient photosynthetic prokaryotes and serve as a model organism for studies such as photosynthesis and earth elements cycling. Cyanobacteria also termed microbial cell factories, because of their ability to utilize carbon dioxide, as well as sunlight absorption in one way, act as primary producers of the aquatic ecosystem while on the other way the diazotrophic forms fix atmospheric nitrogen in paddy fields. Moreover, the successful invention of several fuels as well as fine chemicals from cyanobacteria is indicative of the advancement in synthetic cyanobacteriology in one hand while on the other knocking the door of the augmented application shortly. Unfortunately, the limited availability of genetic manipulation tools for either at single-gene level or pathway to the whole genome in cyanobacteria compared to other organisms handicaps the fundamental biology researches as well as further application and advancement in synthetic cyanobacteriology. However, the role of genetic tools in tuning gene expression, genome-wide manipulations, and carbon flux redirections is available in cyanobacteria. Furthermore, recently a noteworthy headway evolving to familiarizing novel and efficient genetic manipulations tools such as riboswitches, promoters, ribosome-binding site engineering, small RNA regulatory tools, genome-scale modeling strategies, and clustered regularly interspaced short palindromic repeats-associated nuclease has revolutionized the cyanobacteriology. The present chapter disapprovingly recapitulates the recent advancement on the applications and development as well as technical limitations also for the future projections of the toolboxes for genetic manipulation of cyanobacterial genes/genomes. Besides this, the chapter also briefly discusses the toolkits feasible for large-scale cultivation of cyanobacteria. © 2020 Elsevier Inc. All rights reserved.
Cyanobacterial photosynthetic reaction center in wobbly light: Modulation of light energy by orange carotenoid proteins (OCPs)
(Elsevier, 2022) Rahul Prasad Singh; Sandeep Kumar Singh; Ajay Kumar; Arpan Modi; Avinash Chandra Rai; Sandip Ghuge; Anil Kumar; Mukesh Kumar Yadav; Punuri Jayasekhar Babu; Prashant Kumar Singh; Garima Singh; Kaushalendra; Naveen Chandra Joshi; Avinash Singh; Wenjing Wang
High irradiance and fluctuating light boons substantial risk to photosynthetic life forms by summoning responsive oxygen species (ROS). To bear the high irradiance level, plants, algae, and cyanobacteria have developed mechanisms to diminution the energy hitting at reaction centers to protect it from high irradiance by a photo-defensive system. In cyanobacteria, these photoprotection systems reduce the light energy arriving at the reaction centers by reducing photosynthesis and enhancing thermal energy dissipation at the level of the phycobilisome (PB), the extra-membranous light-harvesting antenna. Fluorescence recovery proteins (FRPs) and orange carotenoid proteins (OCPs) alluded to as essential elements for this mechanism by nonphotochemical quenching (NPQ). Initially, cyanobacteria were considered not to fit for performing NPQ, and the last shreds of evidence advocated NPQ as a crucial and primary photoprotective tool. OCP comprises two domains, (1) N-terminal domain (NTD) and (2) C-terminal domain (CTD), with a solitary carotenoid as a chromophore traversing evenly in the two areas. Blue-green or high irradiance light actuates the transformation of OCP from a dormant orange state (OCPO) to a dynamic red state (OCPR). Dynamic OCP (OCPR) ties to the center of the light-harvesting antenna complex, phycobilisomes (PBs), extinguishes fluorescence, and aids dispersal abundance energy’s nonradiative pathway. OCP-intervened photoprotection mechanism effectively managed by FRP by accelerating the OCP transformation of active OCP (OCPR) to the resting state (OCPO) under light-limiting conditions. However, numerous inquiries concerning the working of FRP have stayed dubious. This chapter summarizes the current information and comprehension of the FRP and OCP in cyanobacterial photoprotection and the possibilities of exploiting these systems for plant resilience to high irradiance. © 2022 Elsevier Inc. All rights reserved.
Green single-step hydrothermal synthesis of fluorescent carbon dots from Lantana camara flower for the effective fluorescent detection of Cr(VI) and live cell imaging
(Springer Science and Business Media Deutschland GmbH, 2024) Vikky Kumar Mahto; Vikas Kumar Singh; Vipendra Kumar Singh; Avinash Singh; Savita Singh; Arjun Kumar Mehara; Naina Rajak; Anurag Mishra; Neha Garg; Akanksha Upadhyay; Abhishek Rai; Ankit Kumar Singh
Chromium is one of the heavy metal ions showing high toxicity and mutagenicity. Owing to this, selective sensing of Cr(VI) from sample metrics is a challenging and tedious process. In the present work, we have synthesized fluorescent carbon dots (FCDs) using the flower of Lantana camara through a one-step hydrothermal method. Various spectroscopic techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), EDAX, and Raman analysis well supported the successful synthesis of FCDs. The obtained FCDs revealed a bright blue color under UV-light exposure (@ 365 nm), with excellent optical properties and a fluorescence quantum yield of 29%. Furthermore, FCDs showed excellent fluorescence stability, high ionic strength, good water solubility, low cytotoxicity, and well biocompatibility. Therefore, the proposed FCDs were employed for selective turn-off sensing of toxic Cr(VI) in an aqueous medium with a limit of detection (LOD) of 0.10 µM. Interestingly, the low cytotoxicity and excellent biocompatibility enable the FCDs as a good candidate for cell imaging agents as well as intracellular turn-off sensing of Cr(VI) in HEK-293 cells. Thus, the present work significantly converts biomass of weed plants into a fluorescent probe in a simple and cost-effective way for the detection of Cr(VI) in water samples as well as in living cells. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
IAA induced biomass and lipid overproduction in microalga via two-stage cultivation strategy: Characterization using FTIR/CHNS/TGA/DTG and 1H- NMR for bioenergy potential
(Elsevier Ltd, 2024) Savita Singh; Avinash Singh; Sakshi Singh; Nitesh Prasad; Laxmi; Prabhakar Singh; Ravi Kumar Asthana
Microalgae are an excellent carbon concentrators with substantial lipid content. However, biomass production vis-à-vis lipid hyperaccumulation is a major constraint in the biofuel economy. In this regard, Dunaliella salina, an oleaginous, wall less microalga, was grown in graded concentration of indole-3-acetic acid (IAA). There was a significant increase in biomass (1.57-fold), photosynthetic efficiency (Fv/Fm = 0.72), and chlorophyll a content in 0.25 mg/L IAA supplemented cultures over the control (stage I). However, supplementation of IAA under nitrogen deprivation (stage II) led to a significant rise in the lipid content (47 % DCW), carbohydrate (18.37 %) and simultaneous reduction in the oxidative status (MDA, H2O2, O2·−, OH·) over the control. Further, 0.25 mg/L IAA supplemented cultures under nitrogen starvation were undertaken for biomass and lipid characterization. Nile red based flow cytometric analysis revealed an apparent increase in the neutral lipid fluorescence, also validated by 1H- NMR based lipidome, revealing the presence of triacylglycerol (TAG, 4.12–4.31 ppm). FTIR spectra revealed the increased absorbance at 2926 cm−1, 1740 cm−1 and 1025 cm−1, validating the increased carbohydrate and lipid, while biomass pyrolysis showed 81.42 % decomposition in the active pyrolytic zone as recorded by the TGA/DTG analysis. Interestingly, elemental analysis (CHNS) of the biomass showed an increased carbon and hydrogen %, HHV (19.94 MJ kg−1), H/C ratio (1.78), and CO2 fixation rate. Thus, the present study opens new avenues for the economic feasibility of bioenergy/biofuel production from microalgal biomass at commercial scale. © 2024 Elsevier Ltd
Indian Society of Hematology and Blood Transfusion (ISHBT) Consensus Document on Hematological Practice During COVID-19 Pandemic
(Springer, 2021) Rakhee Kar; Tuphan Kanti Dolai; Prakash Singh Shekhawat; Pankaj Malhotra; Avinash Singh; Rahul Naithani; Prakas Kumar Mandal; Prasanth Ganesan; Prabhu Manivannan; Debdatta Basu; Alok Srivastava; Reena Das; Maitreyee Bhattacharya; Manoranjan Mahapatra; Rishi Dhawan; Arihant Jain; Chandni Bhandary; Hara Prasad Pati; Tathagata Chatterjee; Vijai Tilak; Sarmila Chandra; Shrimati Dharampal Shetty; Rabindra Kumar Jena
The SARS-CoV-2 (COVID-19) pandemic is a worldwide public health emergency with widespread impact on health care delivery. Unforeseen challenges have been noted during administration of usual haematology care in these unusual COVID-19 times. Medical services have been overstretched and frontline health workers have borne the brunt of COVID-19 pandemic. Movement restrictions during lockdown prevented large sections of population from accessing health care, blood banks from holding blood drives, and disrupted delivery of diagnostic hematology services. The disruption in hematology care due to COVID-19 pandemic in India has been disproportionately higher compared to other subspecialities as hematology practice in India remains restricted to major cities. In this review we chronicle the challenges encountered in caring for hematology patients during the COVID-19 pandemic in India and put forth recommendations for minimizing their impact on provision of hematology care with special emphasis on hematology practice in lower and middle income countries (LMICs). © 2021, Indian Society of Hematology and Blood Transfusion.
Molecular biology of non-ribosomal peptide (nrp) and polyketide (pk) biosynthesis in cyanobacteria
(Springer Nature, 2023) X. Laxmi; Sweksha Singh; Avinash Singh; Ravi K. Asthana
Secondary metabolites produced by cyanobacteria are numerous and structurally diverse, with a focus on non-ribosomal peptide and polyketide structures. These compounds could have a variety of bioactivities, and some of them could be valuable in the creation of commercial medications or as biochemical research tools. Natural product gene clusters can be identified and characterized via genome mining. This has allowed for the clustering of biosynthetic genes encoding diverse substances, including non-ribosomal peptides (NRPs), polyketides (PKs), and hybrids thereof, which span a wide range of bioactive metabolites of human significance. Various bioinformatics techniques have only just been created to anticipate the outcomes of orphan gene clusters, although the cyanobacterial pathways are complex in some cases, making prediction difficult. However, this backdrop can be avoided through the heterologous expression and/or mass spectrometry. Several cyanobacterial genomes have been found to contain peptide synthetase and polyketide synthase genes, according to recent research. This information could be extremely useful in future screening initiatives aiming at detecting new bioactive chemicals. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.
Optimizing light regimes for neutral lipid accumulation in Dunaliella salina MCC 43: a study on physiological status and carbon allocation
(Springer Science and Business Media B.V., 2024) Abhishek Mohanta; Nitesh Prasad; Sk Riyazat Khadim; Prabhakar Singh; Savita Singh; Avinash Singh; A.M. Kayastha; R.K. Asthana
Dunaliella salina is a favourable source of high lipid feedstock for biofuel and medicinal chemicals. Low biomass output from microalgae is a significant barrier to industrial-scale commercialisation. The current study aimed to determine how photosynthetic efficiency, carbon fixation, macromolecular synthesis, accumulation of neutral lipids, and antioxidative defence (ROS scavenging enzyme activities) of D. salina cells were affected by different light intensities (LI) (50, 100, 200, and 400 µmol m−2 s−1). The cells when exposed to strong light (400 µmol m−2 s−1) led to reduction in chlorophyll a but the carotenoid content increased by 19% in comparison to the control (LI 100). The amount of carbohydrate changed significantly under high light and in spite of stress inflicted on the cells by high irradiation, a considerable increase in activity of carbonic anhydrase and fixation rate of CO2 were recorded, thus, preserving the biomass content. The high light exposed biomass when subjected to nitrogen-deficient medium led to increase in lipid content (59.92% of the dry cell weight). However, neutral lipid made up 78.26% of the total lipid while other lipids like phospholipid and glycolipid content decreased, showing that the lipid was redistributed in these cells under nitrogen deprivation, making the organism more appropriate for biodiesel/jet fuel use. Although D. salina cells had a relatively longer generation time (3.5 d) than other microalgal cells, an economic analysis concluded that the amount of carotenoid they produced and the quality of their lipids made them more suited for commercialization. Graphical abstract: [Figure not available: see fulltext.] © 2024, The Author(s), under exclusive licence to Springer Nature B.V.
Phytohormone augmented biomass and lipid production in Dunaliella salina under two-stage cultivation strategy: A comprehensive characterization of biomass and lipid using DLS, FTIR, CHNS and NMR for bioenergy prospects
(Elsevier Ltd, 2024) Savita Singh; Avinash Singh; Nitesh Prasad; Sakshi Singh; Ravi Kumar Asthana
Increasing population, climatic shifts, and decreasing fossil-fuels worldwide led scientists to explore microalgae as a renewable energy resource. The present study unravels the impact of gibberellic acid (GA3) on biomass production, enzymatic activities, macromolecular synthesis, and metabolome analysis of Dunaliella salina using two-stage cultivation strategy. The results indicated a marked increase in biomass (1.44-fold), photosynthetic yield (Fv/Fm 0.68), along with RuBisCO activity (1.66-fold), with an increased in absolute value of zeta potential(ζ) in cultures treated with 10 µM GA3 compared to controls (Stage I). Interestingly, 15 µM GA3-treated cells significantly enhanced lipid content (42.36 %), and carbohydrates (16.56 %) with elevated antioxidative enzymes (SOD, CAT, and APX) activities (Stage II). Enhanced lipid content was further confirmed through FTIR spectra (2928 cm-1, and 1740 cm-1) and 1H NMR signals (1.0– 2, 3.5–4.5 ppm), indicating an increase in both saturated (SFA) and polyunsaturated fatty acids (PUFAs). Elemental analysis demonstrated higher carbon and hydrogen percentages, reflected in higher heating value (HHV) and H/C ratio at 15 µM GA3. The increased lipid content was found to be significantly correlated with ACCase and GPAT activities, suggesting the allocation of carbon flux toward lipid biosynthesis pathways. To substantiate the carbon flux, HR-MS-based metabolomic analysis was performed, indicating a reduction in TCA and Calvin cycle intermediates with a significant rise in carotenoid biosynthesis, as well as metabolic shift towards fatty acid biosynthesis reflecting in the enhanced SFA and PUFAs. Thus, these findings highlighted GA3 significant role in the carbon flux allocation towards the neutral lipid biosynthesis for bioenergy prospects. © 2024 Elsevier Ltd
Tuning of aggregation enhanced emission and solid state emission from 1,8-naphthalimide derivatives: Nanoaggregates, spectra, and DFT calculations
(American Chemical Society, 2016) Ashish Kumar Srivastava; Avinash Singh; Lallan Mishra
Four new 1,8-naphthalimide based compounds, 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoic acid (LH), 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoic acid methyl ester (LMe), 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoyl chloride (LCl), and 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoic acid hydrazide (LN) are synthesized and characterized using spectral data and X-ray crystallography. They form nanoaggregates in aqueous-DMF solution and exhibited aggregation enhanced emission. The nanoaggregates are characterized using their scanning electron and atomic force microscopy images. The emission intensity follows the order as LH > LMe > LCl > LN. Their photophysical properties are recorded both in solution and in the solid-state and are correlated with the nature of benzoic acid derivatives owing to the combinatorial effect of π-π stacking and intermolecular and intramolecular interactions. The density functional theory calculations empower the understanding of their molecular and cumulative electronic behaviors. Antiparallel dimeric interactions in the solid-state extend a herringbone arrangement to LH and 2D channel and stair-like arrangement for LCl and LN, respectively. © 2016 American Chemical Society.