Browsing by Author "Siddhartha Singh"

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Effect of unusual dust event on meteorological parameters & aerosol optical and radiative properties
(India Meteorological Department, 2018) V.K. Soni; Sanjay Bist; R. Bhatla; S.C. Bhan; Gajendra Kumar; M. Sateesh; Siddhartha Singh; D.R. Pattanaik
A very unusual dust plume generated from dust-storm activities over the Arabian Peninsula and Southwest Asia affected the north-west region of India between March 20 and 23, 2012, causing significant reductions in air quality and consequently changes in meteorological parameters. Ground based measurements of aerosol optical depth at 500 nm reached 1.015 ± 0.24 and 0.837 ± 0.042 at Jodhpur while Angstrom exponent dropped to-0.030 and-0.065 on March 20 and 21, 2012 respectively. The AOD reached 0.959 in Delhi while Angstrom exponent dropped to 0.006 on March 21, 2012. PM10 concentration peaked at an unusually high value of more than 1800 μgm-3 during dust storm hours of March 20, 2012 at Delhi. Moderate Resolution Imaging Spectrometer (MODIS) retrieved aerosol optical depth also exhibited high values as well along the path of dust storm and dust plume. The intensity of the dust plume was such that it caused significant cooling at the surface. The large reduction in the radiative flux at the surface level had caused a drop in surface temperature by approximately 2-10 °C. Shortwave and longwave Direct Aerosol Radiative Forcing was calculated using SBDART during the dust period. © 2018, India Meteorological Department. All rights reserved.
Identification and characterization of cellular locus of limonin biotransforming enzyme in Pseudomonas putida
(2010) Jay Prakash Verma; Siddhartha Singh; Moushumi Ghosh; Pramod Kumar Srivastava
Limonin is a highly oxygenated triterpene derivative of class of limonoids which causes delayed bitterness in citrus. Pseudomonas putida (P. putida) is able to reduce 47% and 63% of limonin from juice serum extract and standard limonin, respectively. Biochemical studies with P. putida indicate that probably two metabolic pathways viz. 17-dehydrolimonoid and deoxylimonoid pathway exists in the test organism. Experimental results indicate that the enzyme limonoate dehydrogenase which is found to be localized in periplasmic space of P. putida plays a major role in conversion of limonin to 17-dehydrolimonoate A-ring lactone. Enzymatic studies have shown a 72% reduction in limonin. The experimental results show 9 folds reduction in limonin content in presence of NAD as cofactor. The molecular weight of one of its polypeptide is found to be 66 kDa. The optimum pH and temperature for enzyme activity is 8.5 and 30°C, respectively. © 2010 The Authors. Journal compilation © 2010 Institute of Food Science and Technology.
Immobilization and applications of glucose-6-phosphate dehydrogenase: A review
(2013) Pramod Kumar Srivastava; Siddhartha Singh
Immobilized enzymes have been used extensively in the fields of food industry, materials processing, textiles, detergents, biochemical and chemical industries, biotechnology, and pharmaceuticals. Studies on immobilization of glucose-6-phosphate dehydrogenase have been less extensive than those for other industrially applicable enzymes. Immobilization of glucose-6-phosphate dehydrogenase has been carried out for the formation of biosensors for the estimation of glucose, ATP, phosphate, and so on. The present review deals with the attempts made for immobilization of glucose-6-phosphate dehydrogenase and its applications for various purposes. © 2013 Taylor & Francis Group, LLC.
Improvement strategies, cost effective production, and potential applications of fungal glucose oxidase (GOD): Current updates
(Frontiers Media S.A., 2017) Manish K. Dubey; Andleeb Zehra; Mohd Aamir; Mukesh Meena; Laxmi Ahirwal; Siddhartha Singh; Shruti Shukla; Ram S. Upadhyay; Ruben Bueno-Mari; Vivek K. Bajpai
Fungal glucose oxidase (GOD) is widely employed in the different sectors of food industries for use in baking products, dry egg powder, beverages, and gluconic acid production. GOD also has several other novel applications in chemical, pharmaceutical, textile, and other biotechnological industries. The electrochemical suitability of GOD catalyzed reactions has enabled its successful use in bioelectronic devices, particularly biofuel cells, and biosensors. Other crucial aspects of GOD such as improved feeding efficiency in response to GOD supplemental diet, roles in antimicrobial activities, and enhancing pathogen defense response, thereby providing induced resistance in plants have also been reported. Moreover, the medical science, another emerging branch where GOD was recently reported to induce several apoptosis characteristics as well as cellular senescence by downregulating Klotho gene expression. These widespread applications of GOD have led to increased demand for more extensive research to improve its production, characterization, and enhanced stability to enable long term usages. Currently, GOD is mainly produced and purified from Aspergillus niger and Penicillium species, but the yield is relatively low and the purification process is troublesome. It is practical to build an excellent GOD-producing strain. Therefore, the present review describes innovative methods of enhancing fungal GOD production by using genetic and non-genetic approaches in-depth along with purification techniques. The review also highlights current research progress in the cost effective production of GOD, including key advances, potential applications and limitations. Therefore, there is an extensive need to commercialize these processes by developing and optimizing novel strategies for cost effective GOD production. © 2017 Dubey, Zehra, Aamir, Meena, Ahirwal, Singh, Shukla, Upadhyay, Bueno-Mari and Bajpai.
In vivo immunomodulatory effects of the methanolic leaf extract of Gymnema sylvestre in Swiss albino mice
(Institut za Bioloska Istrazivanja, 2015) Laxmi Ahirwal; Siddhartha Singh; Manish Kumar Dubey; Vandana Bharti; Archana Mehta; Shruti Shukla
In the present study we performed a comparative phytochemical analysis of the immunomodulating activities of the methanol leaf extract of Gymnema sylvestre (MLEGS) in Swiss albino mice. The phytochemical screening conducted on MLEGS revealed the presence of several phytoconstituents, including saponins, alkaloids, glycosides, phenols, tannins, and flavonoids. Immunomodulatory activities were determined by hemagglutination antibody (HA) titer and delayed-type hypersensitivity (DTH) tests for determining specific and non-specific immune responses. Flow cytometric techniques were performed for the estimation of B lymphocytes (CD3 and CD19) and Th2 cytokines (IL-2, IFN-γ and IL-4). The response produced by oral administration of MLEGS elicited a significant reduction in a dose-related manner in the primary and secondary antibody response and DTH response. The response produced by oral administration of MLEGS caused a significant reduction in a dose-related manner in the primary and secondary antibody and DTH responses, with maximum reduction observed at 200 mg/kg-body wt. The maximal reductions in the production of CD3, CD19, IL-2, IFN-γ and IL-4 were 31.59, 32.12, 29.51, 32.45 and 33.53%, respectively, at 200 mg/kg body weight. This study demonstrates that G. sylvestre exerts immunosuppressive effects on the components of the immune system of mice, and points to its significant immunomodulatory potential.