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Papers by Simran Jit

Figure S1A Figure S1A. Experimental (circles) and theoretical (curves) formamide dissociation pro... more Figure S1A Figure S1A. Experimental (circles) and theoretical (curves) formamide dissociation profiles of 100 randomly selected probes from Length set (Table 2). The labels (upper right corner of each graph) indicate probe name (top), Imax (bottom, first number), err[FA]1/2 value (bottom, second number). See main manuscript for the descriptions of probe names and Imax and err[FA]1/2 values. x-axis, formamide concentration; y-axis, normalized signal intensity; error bars, standard deviations. Probes 1-8:

Biodegradation, 2016

Hexachlorocyclohexane (HCH) contaminated soils were treated for a period of up to 64 days in situ... more Hexachlorocyclohexane (HCH) contaminated soils were treated for a period of up to 64 days in situ (HCH dumpsite, Lucknow) and ex situ (University of Delhi) in line with three bioremediation approaches. The first approach, biostimulation, involved addition of ammonium phosphate and molasses, while the second approach, bioaugmentation, involved addition of a microbial consortium consisting of a group of HCH-degrading sphingomonads that were isolated from HCH contaminated sites. The third approach involved a combination of biostimulation and bioaugmentation. The efficiency of the consortium was investigated in laboratory scale experiments, in a pot scale study, and in a full-scale field trial. It turned out that the approach of combining biostimulation and bioaugmentation was most effective in achieving reduction in the levels of α- and β-HCH and that the application of a bacterial consortium as compared to the action of a single HCH-degrading bacterial strain was more successful. Although further degradation of β- and δ-tetrachlorocyclohexane-1,4-diol, the terminal metabolites of β- and δ-HCH, respectively, did not occur by the strains comprising the consortium, these metabolites turned out to be less toxic than the parental HCH isomers.

AIP Conference Proceedings, 2013

ABSTRACT The present work focuses on Figure-of-merit (FOM) of strained-Si-on-Silicon-Germanium-on... more ABSTRACT The present work focuses on Figure-of-merit (FOM) of strained-Si-on-Silicon-Germanium-on-Insulator (SSGOI) MOSFETs with back gate configuration in terms of drain-induced-barrier-lowering (DIBL) and subthreshold swing (S). The theoretical model is developed by solving the 2D Poisson’s equation with suitable boundary conditions using evanescent mode analysis technique in both the strained-Si and relaxed Si1-xGex layers. We have studied the effect of buried oxide thickness on DIBL and subthreshold swing. The validity of analytical model is verified by using ATLASTM, a 2D device simulator from Silvaco.

Journal of Basic Microbiology, 2013

The disposal of hexachlorocyclohexane (HCH) muck has created large number of HCH dumpsites all ov... more The disposal of hexachlorocyclohexane (HCH) muck has created large number of HCH dumpsites all over the world from where the harmful HCH isomers are leaking into the environment. Bacteria have evolved at such contaminated sites that have the ability to degrade HCH. Degradation of various HCH isomers in bacterial strains is mediated primarily by two genes: linA and linB which encode dehydrochlorinase and haloalkane dehalogenase respectively. In this study we explored one such highly contaminated HCH dumpsite located in Lucknow, Uttar Pradesh, India. To assess the biostimulation potential of the contaminated site, microbial diversity study and real-time PCR based quantification of lin genes was carried out. The soil samples from dumpsite and surrounding areas were found to be highly contaminated with HCH residue levels as high as 1.8 Â 10 5 mg kg À1. The residues were detected in areas upto 13 km from the dumpsite. Sphingomonads, Chromohalobacter, and Marinobacter were the dominant genera present at the dumpsite. Role of Sphingomonads in HCH degradation has been well documented. The highest copy numbers of linA and linB genes as determined using real-time PCR were 6.2 Â 10 4 and 5.3 Â 10 5 , respectively, were found in sample from the dump site. The presence of Sphingomonads, linA, and linB genes from HCH contaminated soil indicates the presence of indigenous bacterial communities capable of HCH degradation. : Additional supporting information may be found in the online version of this article at the publisher's web-site.

Journal of Applied Microbiology, 2009

Aims: To locate a high-dose point hexachlorocyclohexane (HCH)-contaminated site, to identify HCH-... more Aims: To locate a high-dose point hexachlorocyclohexane (HCH)-contaminated site, to identify HCH-degrading bacteria in it and assay HCH-decontamination by biostimulation. Methods and Results: Bacteria were isolated by serial dilution method from HCH-contaminated soil samples collected from areas near an HCH-manufacturing unit and its dumpsite in North India. After confirming the presence of indigenous HCH-degraders (seven of 24 strains), an ex situ biostimulation experiment was conducted. For this, residue levels in soil were diluted by mixing with pristine garden soil and aeration, moisture and nutrients were provided intermittently. This soil was monitored for reduction in R-HCH (sum of a-, b-, c-and d-HCH) levels and stimulation of HCH-degraders. Experiments were conducted twice, in March-April (c. 75 lg R-HCH g)1 soil) and October-November 2006 (c. 280 lg R-HCH g)1 soil) at 26-30°C. R-HCH levels were reduced to <30% of the original in 24 days and <3% in 240 days in the experimental pits. Terminal restriction fragment length polymorphism analysis reflected changes in microbial community structure during the course of experiment. Conclusions: Our results show presence of HCH-degrading sphingomonads at a high-dose point HCH-contaminated site and presents biostimulation as an effective approach for its decontamination via aeration, addition of nutrients and moisture, of the indigenous population. Significance and Impact of the Study: The study demonstrates that biostimulation of indigenous HCH-degrading microbial population can be used for decontamination of chronically HCH-contaminated sites.

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2009

A yellow-pigmented, hexachlorocyclohexane (HCH)-degrading bacterium, strain IP26 T , was isolated... more A yellow-pigmented, hexachlorocyclohexane (HCH)-degrading bacterium, strain IP26 T , was isolated from an HCH dumpsite and subjected to a polyphasic analysis in order to determine its taxonomic position. Strain IP26 T showed maximum 16S rRNA gene sequence similarity with Sphingobium francense Sp+ T (98.5 %), Sphingobium japonicum UT26 T (98.4 %) and Sphingobium indicum B90A T (98.2 %). Phylogenetic analysis based on 16S rRNA gene sequences also showed that strain IP26 T formed a cluster with these three HCH-degrading strains. Chemotaxonomic data (major polyamine, spermidine; major quinone, ubiquinone with ten isoprene units; major polar lipids, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, diphosphatidylglycerol, phosphotidylcholine; and presence of 2-hydroxy fatty acid) supported inclusion of strain IP26 T in the genus Sphingobium. However, the results of DNA-DNA hybridization and morphological and biochemical tests clearly allowed phenotypic and genotypic differentiation of strain IP26 T from recognized species of the genus Sphingobium. Strain IP26 T thus represents a novel species of the genus Sphingobium for which the name Sphingobium chinhatense sp. nov. is proposed. The type strain is IP26 T (5MTCC8598 T 5CCM 7432 T).

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2008

A Gram-negative, non-spore-forming, cream-yellow-pigmented bacterial strain, IP-10 T , was isolat... more A Gram-negative, non-spore-forming, cream-yellow-pigmented bacterial strain, IP-10 T , was isolated from soil samples from a waste site highly contaminated with hexachlorocyclohexane in Ummari village, India. The organism showed the highest 16S rRNA gene sequence similarity of 92.7 % with Flavobacterium soli KCTC 12542 T and levels of 87-92 % with the type strains of other recognized species of the genus Flavobacterium. The DNA G+C content of strain IP-10 T was 31 mol%. The predominant fatty acids were iso-C 15 : 0 (22.1 %), iso-C 17 : 0 3-OH (18.5 %) and summed feature 3 (comprising C 16 : 1 v7c and/or iso-C 15 : 0 2-OH; 13.2 %). Strain IP-10 T could be differentiated from recognized species of the genus Flavobacterium based on a number of phenotypic features. Strain IP-10 T is therefore considered to represent a novel species of the genus Flavobacterium, for which the name Flavobacterium lindanitolerans sp. nov. is proposed. The type strain is IP-10 T (5MTCC 8597 T 5CCM 7424 T).

International Journal of Systematic and Evolutionary Microbiology, 2009

A Gram-negative, non-spore-forming, cream-coloured bacterial strain, UM2T, was isolated from an o... more A Gram-negative, non-spore-forming, cream-coloured bacterial strain, UM2T, was isolated from an open hexachlorocyclohexane (HCH) dump site at Ummari village in Lucknow, India. Data generated from a polyphasic approach including phenotypic, genotypic and chemotaxonomic analyses confirmed that strain UM2T belonged to the genus Sphingomonas. The highest similarity found to the 16S rRNA gene sequence of strain UM2T was 99.4 %, with Sphingomonas wittichii DSM 6014T, whereas the DNA–DNA relatedness value between these strains was 31 %, indicating that they represent separate species. The DNA G+C content of UM2T was 66.9 mol%. The respiratory pigment ubiquinone Q-10 was present. The predominant fatty acids were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c; 32.9 %), C19 : 0 cyclo ω8c (15.5 %) and C16 : 0 (12.1 %). The major polar lipids were phosphatidylcholine, phosphatidylglycerol and phosphatidyldimethylethanolamine. sym-Homospermidine was the major polyamine observed. On the basis o...

Indian Journal of Microbiology, 2007

Classification of microorganisms on the basis of fi traditional microbiological methods (morpholo... more Classification of microorganisms on the basis of fi traditional microbiological methods (morphological, physiological and biochemical) creates a blurred image about their taxonomic status and thus needs further clarification. It fi should be based on a more pragmatic approach of deploying a number of methods for the complete characterization of microbes. Hence, the methods now employed for bacterial systematics include, the complete 16S rRNA gene sequencing and its comparative analysis by phylogenetic trees, DNA-DNA hybridization studies with related organisms, analyses of molecular markers and signature pattern(s), biochemical assays, physiological and morphological tests. Collectively these genotypic, chemotaxonomic and phenotypic methods for determining taxonomic position of microbes constitute what is known as the 'polyphasic approach' for bacterial systematics. This approach is currently the most popular choice for classifying bacteria and several microbes, which were previously placed under invalid taxa have now been resolved into new genera and species. This has been possible owing to rapid development in molecular biological techniques, automation of DNA sequencing coupled with advances in bioinformatic tools and access to sequence databases. Several DNA-based typing methods are known; these provide information for delineating bacteria into different genera and species and have the potential to resolve differences among the strains of a species. Therefore, newly isolated strains must be classifi ed fi on the basis of the polyphasic approach. Also previously classifi ed organisms, as and when required, can be reclas-fi sified on this ground in order to obtain information about fi their accurate position in the microbial world. Thus, current techniques enable microbiologists to decipher the natural phylogenetic relationships between microbes.

Indian Journal of Microbiology, 2008

The unusual process of production of hexachlorocyclohexane (HCH) and extensive use of technical H... more The unusual process of production of hexachlorocyclohexane (HCH) and extensive use of technical HCH and lindane has created a very serious problem of HCH contamination. While the use of technical HCH and lindane has been banned all over the world, India still continues producing lindane. Bacteria, especially Sphingomonads have been isolated that can degrade HCH isomers. Among all the bacterial strains isolated so far, Sphingobium indicum B90A that was isolated form HCH treated rhizosphere soil appears to have a better potential for HCH degradation. This conclusion is based on studies on the organization of lin genes and degradation ability of B90A. This strain perhaps can be used for HCH decontamination through bioaugmentation.

Environmental Science and Pollution Research, 2010

Purpose α-Hexachlorocyclohexane (HCH), β-HCH, and lindane (γ-HCH) were listed as persistent organ... more Purpose α-Hexachlorocyclohexane (HCH), β-HCH, and lindane (γ-HCH) were listed as persistent organic pollutants by the Stockholm Convention in 2009 and hence must be phased out and their wastes/stockpiles eliminated. At the last operating lindane manufacturing unit, we conducted a preliminary evaluation of HCH contamination levels in soil and water samples collected around the production area and the vicinity of a major dumpsite to inform the design of processes for an appropriate implementation of the Convention. Methods Soil and water samples on and around the production site and a major waste dumpsite were measured for HCH levels. Results All soil samples taken at the lindane production facility and dumpsite and in their vicinity were contaminated with an isomer pattern characteristic of HCH production waste. At the dumpsite surface samples contained up to 450 gkg −1 Σ HCH suggesting that the waste HCH isomers were simply dumped at this location. Ground water in the vicinity and river water was found to be contaminated with 0.2 to 0.4 mgl −1 of HCH waste isomers. The total quantity of deposited HCH wastes from the lindane production unit was estimated at between 36,000 and 54,000 t. Conclusions The contamination levels in ground and river water suggest significant runoff from the dumped HCH wastes and contamination of drinking water resources. The extent of dumping urgently needs to be assessed regarding the risks to human and ecosystem health. A plan for securing the waste isomers needs to be developed and implemented together with a plan for their final elimination.