Browsing by Author "Thakur, Indu Shekhar"

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Draft genome sequence of Zhihengliuella sp. strain ISTPL4, a psychrotolerant and halotolerant bacterium isolated from pangong lake, India
(American Society for Microbiology, 2018) Mishra, Arti; Jha, Gopaljee; Thakur, Indu Shekhar
Zhihengliuella sp. strain ISTPL4, a psychrotolerant bacterium, was isolated from brackish water of the high-altitude Pangong Lake in India. In this study, we report its draft genome sequence, which contains 3,529,629 bp with a G+C content of 69.84%. The genome is enriched in genes associated with cold adaptation and plant growth promotion.
Genome sequence of carbon dioxide-sequestering serratia sp. strain ISTD04 isolated from marble mining rocks
(American Society for Microbiology, 2016) Kumar, Manish; Gazara, Rajesh Kumar; Verma, Sandhya; Kumar, Madan; Verma, Praveen K.; Thakur, Indu Shekhar
The Serratia sp. strain ISTD04 has been identified as a carbon dioxide (CO2)-sequestering bacterium isolated from marble mining rocks in the Umra area, Rajasthan, India. This strain grows chemolithotrophically on media that contain sodium bicarbonate (NaHCO3) as the sole carbon source. Here, we report the genome sequence of 5.07 Mb Serratia sp. ISTD04.
Genome sequence of pandoraea sp. ISTKB, a lignin-degrading betaproteobacterium, isolated from rhizospheric soil
(American Society for Microbiology, 2016) Kumar, Madan; Gazara, Rajesh Kumar; Verma, Sandhya; Kumar, Manish; Verma, Praveen K.; Thakur, Indu Shekhar
We report here the genome sequence of Pandoraea sp. ISTKB, a betaproteobacterium isolated from rhizospheric soil in the backwaters of Alappuzha, Kerala, India. The strain is alkalotolerant and grows on medium containing lignin as a sole carbon source. Genes and pathways related to lignin degradation were complemented by genomic analysis.
Genomic and proteomic analysis of lignin degrading and polyhydroxyalkanoate accumulating beta-proteobacterium Pandoraea sp ISTKB
(BioMed Central Ltd, 2018) Kumar, Madan; Verma, Sandhya; Gazara, Rajesh Kumar; Kumar, Manish; Pandey, Ashok; Verma, Praveen K.; Thakur, Indu Shekhar
Background: Lignin is a major component of plant biomass and is recalcitrant to degradation due to its complex and heterogeneous aromatic structure. The biomass-based research mainly focuses on polysaccharides component of biomass and lignin is discarded as waste with very limited usage. The sustainability and success of plant polysaccharide-based biorefinery can be possible if lignin is utilized in improved ways and with minimal waste generation. Discovering new microbial strains and understanding their enzyme system for lignin degradation are necessary for its conversion into fuel and chemicals. The Pandoraea sp. ISTKB was previously characterized for lignin degradation and successfully applied for pretreatment of sugarcane bagasse and polyhydroxyalkanoate (PHA) production. In this study, genomic analysis and proteomics on aromatic polymer kraft lignin and vanillic acid are performed to find the important enzymes for polymer utilization. Results: Genomic analysis of Pandoraea sp. ISTKB revealed the presence of strong lignin degradation machinery and identified various candidate genes responsible for lignin degradation and PHA production. We also applied label-free quantitative proteomic approach to identify the expression profile on monoaromatic compound vanillic acid (VA) and polyaromatic kraft lignin (KL). Genomic and proteomic analysis simultaneously discovered Dyp-type peroxidase, peroxidases, glycolate oxidase, aldehyde oxidase, GMC oxidoreductase, laccases, quinone oxidoreductase, dioxygenases, monooxygenases, glutathione-dependent etherases, dehydrogenases, reductases, and methyltransferases and various other recently reported enzyme systems such as superoxide dismutases or catalase-peroxidase for lignin degradation. A strong stress response and detoxification mechanism was discovered. The two important gene clusters for lignin degradation and three PHA polymerase spanning gene clusters were identified and all the clusters were functionally active on KL-VA Conclusions: The unusual aerobic'-CoA'-mediated degradation pathway of phenylacetate and benzoate (reported only in 16 and 4-5% of total seguenced bacterial genomes), peroxidase-accessory enzyme system, and fenton chemistry based are the major pathways observed for lignin degradation. Both ortho and meta ring cleavage pathways for aromatic compound degradation were observed in expression profile. Genomic and proteomic approaches providedvalidation to this strain's robust machinery for the metabolism of recalcitrant compounds and PHA production and provide an opportunity to target important enzymes for lignin valorization in future.
Involvement of plasmid in degradation of pentachlorophenol by Pseudomonoas sp. from a chemostat
(Elsevier B.V., 2001) Thakur, Indu Shekhar; Verma, Praveen K.; Upadhaya, Kailash C.
Pseudomonas sp. strain IST103 obtained from a stable bacterial consortium was capable of utilizing pentachlorophenol (PCP) as sole carbon and energy source. The consortium was developed by continuous enrichment in a chemostat. The degradation of PCP by bacterial strain proceeded through an oxidative route as indicated by accumulation of tetrachlorop-hydroquinone and chlorohydroquinone determined by high performance liquid chromatography (HPLC), and chloride molecules released in culture medium. Two different molecular size plasmids, of approximately 80 and 4 kilobase, were found to be responsible for carrying genes for degradation of PCP. This was evidenced by mutants produced by curing of plasmid by treatment of ethidium bromide. The derivatives were not able to utilize PCP, however, transformation of low molecular size plasmid of Pseudomonas sp. strain 103 into E. coli JM109 utilized PCP, indicated a possible involvement of plasmid in degradation of pentachlorophenol
Molecular cloning and characterization of pentachlorophenol-degrading monooxygenase genes of Pseudomonas sp. from the chemostat
(Elsevier B.V., 2002) Thakur, Indu Shekhar; Verma, Praveen K.; Upadhayaya, Kailash
Pseudomonas sp. strain IST 103 (PCP103) capable of utilizing pentachlorophenol (PCP) was determined by utilization of a carbon source and release of the hydroxylating enzyme PCP-4 monooxygenase. The metabolites were extracted from the culture medium and analyzed by high-performance liquid chromatography. The enzyme purified to apparent homogeneity from an extract of PCP-grown cells indicated that a fraction of DEAE-cellulose ion exchange chromatogra- phy of molecular size of 30,000 kDa determined by gel filtration chromatography and SDS–polyacrylamide gel electrophoresis was responsible for dechlorination of PCP. The plasmid isolated from the bacterium was subjected to Shotgun cloning by restriction digestion by BamHI, HindIII, and SalI, ligated to pUC19 vector, and transformed into Escherichia coli XLBlue1(alpha). The recombinant clones having higher potentiality to de- grade PCP were selected by utilization of a carbon source and release of intermediary metabolites during degradation of PCP as the sole source of carbon and energy. The recombinant clones, which contained an insert of 3.0 kb of SalI and HindIII sites, were sequenced and compared with gene sequences deposited in GenBank by BLAST search; this indicated homology with the thdf gene of monooxygenase of thiophene and furan. Southern blot analysis performed by developing gene probes indicated the presence of the PCP monooxygenase gene in plasmids of the bacterium.
Production and characterization of polyhydroxyalkanoate from lignin derivatives by Pandoraea sp. ISTKB
(American Chemical Society, 2017) Kumar, Madan; Singhal, Anjali; Verma, Praveen Kumar; Thakur, Indu Shekhar
The present study investigates polyhydroxyalkanoate (PHA) production from lignin and its derivatives by a previously reported lignin-degrading bacterial strain Pandoraea sp. ISTKB. PHA production was screened by fluorescence microscopy and flow cytometry using a Nile red stain. PHA and biomass accumulation, while screening, was found to be maximum on 4-hydroxybenzoic acid followed by p-coumaric acid, vanillic acid, 2,6-dimethoxyphenol, and kraft lignin after 96 h. Monomer composition was analyzed by gas chromatography–mass spectrometry (GC–MS) and was followed by Fourier transform infrared and 1H NMR analysis, indicating PHA to be a copolymer of P(hydroxybutyrate-co-hydroxyvalerate). Genomic analysis of Pandoraea sp. ISTKB also complemented the results of GC–MS and NMR, and the relevant genes responsible for the synthesis of small chain length PHA were discovered in the genome. Process parameters were optimized by response surface methodology for enhanced production of PHA and biomass on 4-hydroxybenzoate. Optimization results showed 30 and 66% increase in the biomass and PHA production, respectively. The results obtained were promising and indicated that if lignin is depolymerized into low-molecular-weight intermediates, then it can easily be utilized and converted into value-added products like PHA by microbes.