Browsing by Author "Alok Kumar Srivastava"

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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.
Differential physiological, oxidative and antioxidative responses of cyanobacterium Anabaena sphaerica to attenuate malathion pesticide toxicity
(Elsevier Ltd, 2017) Sindhunath Chakraborty; Balkrishna Tiwari; Satya Shila Singh; Alok Kumar Srivastava; Arun Kumar Mishra
Malathion, a synthetic organophosphorus pesticide, is very frequently utilized in the paddy fields to overcome crop loss caused by pest invasion. Importance and association of cyanobacteria with paddy fields creates an interesting new perspective to investigate the physiological and biochemical alterations in the paddy field cyanobacterium namely Anabaena sphaerica at different levels of malathion (5, 10, 20 and 30 µg ml−1). Malathion at 5 µg ml−1 increased the growth and exerted no adverse impact on the physiological and biochemical indices but the higher dose, 30 µg ml−1, exhibited detrimental effects on the cell growth, total pigment content, total protein content, carbohydrate content, photosynthetic efficiency and protein profile of the cyanobacterium through relentless generation of reactive oxygen species (ROS). However, enhanced level of antioxidative enzyme activity (SOD, CAT and APX) coupled with increased production of phenolics and flavonoids reflected their involvement in the ROS detoxification mechanism and in small reduction of growth at sublethal doses (10 and 20 µg ml−1). Possession of almost equal amount of total carbohydrate content and the simultaneous production of higher level of non-enzymatic antioxidants (carotenoids, phenolics and flavonoid) at sublethal doses of malathion appeared to be an additional effective detoxification system in A. sphaerica. © 2017 Elsevier Ltd
Microbial biofilm: An advanced eco-friendly approach for bioremediation
(Elsevier, 2019) Anjney Sharma; Hena Jamali; Anukool Vaishnav; Balendu Shekhar Giri; Alok Kumar Srivastava
Microbial biofilm is a new emerging subject for microbiologists to work in the areas of environment, industry, agriculture, and health. Biofilms enhance the proliferation and colonization of microbes on surface and protect cells in an adverse environment. The potential of microbes surrounded by biofilms has recently been realized for bioremediation processes. The mutually beneficial interaction of multiple microorganisms in biofilms attracts attention toward xenobiotics and their uses in industrial plants to degrade pollutants. Microbial biofilms are using in different bioreactors and biofilters for pollutant degradation on a large scale. Although limited information is are available on bioremediation through microbial biofilms, this chapter presents the fundamental aspects of biofilms and their application in the bioremediation field. A better understanding of the role of microbial mechanisms in pollutant tolerance and their degradation can be beneficial for bioremediation strategies. Understanding the mechanisms and genes involved in biofilm formation will help to develop new strategies for bioremediation. © 2020 Elsevier B.V. All rights reserved.
Phylogeny and evolutionary genetics of Frankia strains based on 16S rRNA and nifD-K gene sequences
(Wiley-VCH Verlag, 2015) Arun Kumar Mishra; Pawan Kumar Singh; Prashant Singh; Anumeha Singh; Satya Shila Singh; Amrita Srivastava; Alok Kumar Srivastava; Hridip Kumar Sarma
16S rRNA and nifD-nifK sequences were used to study the molecular phylogeny and evolutionary genetics of Frankia strains isolated from Hippöphae salicifolia D. Don growing at different altitudes (ecologically classified as riverside and hillside isolates) of the Eastern Himalayan region of North Sikkim, India. Genetic information for the small subunit rRNA (16S rRNA) revealed that the riverside Frankia isolates markedly differed from the hillside isolates suggesting that the riverside isolates are genetically compact. Further, for enhanced resolutions, the partial sequence of nifD (3′ end), nifK (5′ end) and nifD-K IGS region have been investigated. The sequences obtained, failed to separate riverside isolates and hillside isolates, thus suggesting a possible role of genetic transfer events either from hillside to riverside or vice versa. The evolutionary genetic analyses using evogenomic extrapolations of gene sequence data obtained from 16S rRNA and nifD-K provided differing equations with the pace of evolution being more appropriately, intermediate. Values of recombination frequency (R), nucleotide diversity per site (Pi), and DNA divergence estimates supported the existence of an intermixed zone where spatial isolations occurred in sync with the temporal estimates. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Tolerance strategies in cyanobacterium Fischerella sp. under pesticide stress and possible role of a carbohydrate-binding protein in the metabolism of methyl parathion (MP)
(Elsevier Ltd, 2018) Balkrishna Tiwari; Ekta Verma; Sindhunath Chakraborty; Alok Kumar Srivastava; Arun Kumar Mishra
The tolerance strategy of cyanobacterium Fischerella sp. under methyl parathion (MP) stress was investigated through proteomics analysis using 2-DE technique coupled with MALDI- TOF MS/MS. Proteomic study of the cyanobacterium treated with or without MP for two and eight days exhibited differential expressions of proteins related to photosynthesis, energy and protein metabolism, redox homeostasis, signal transduction and cellular defence. Inhibitory effect of MP on the growth of the test organism was more pronounced after the 2nd day of treatment and the majority of the proteins, except those involved in the protein metabolism (DnaK, Ef-Tu and proteases), were downregulated. However, the growth of the cyanobacterium was significantly less affected after the 8th day of MP treatment and a number of proteins, viz., antioxidative enzymes, signalling protein, chaperones, were induced. Transcript analyses of the genes of few upregulated and downregulated proteins, i.e., phycocyanin α subunit (cpcA), ribulose bisphosphate carboxylase (rbcl), F0F1 ATP synthase subunit α, F0F1 ATP synthase subunit β, SOD (sod), NifH (nif H), DnaK (dnaK) and Peptidase S8 showed similar results after the 8th day of MP treatment. Furthermore, some hypothetical proteins were also found to be upregulated in the cyanobacterium under MP stress. Functional prediction of four of these hypothetical proteins using bioinformatic tools revealed their roles in signalling and carbohydrate metabolism. Interestingly, one hypothetical protein was homologous to lectin and found to possess a binding pocket for MP. Therefore, this lectin-type protein of the cyanobacterium might have a crucial role in the removal and degradation of MP. © 2017 Elsevier Ltd