Brajadulal Chattopadhyay

Bacterial (BKH1) assisted silica nanoparticles from silica rich substrates: A facile and green approach for biotechnological applications

A green technique of silica nanoparticles (SiO2-NPs) formation by using a thermophilic bacterium (BKH1) as biological template is demonstrated here. SiO2-NPs are synthesized from inorganic (magnesium tri-silicate), and organic (tetraethyl orthosilicate) precursor with the help of BKH1 bacteria. BKH1 derived SiO2-NPs are subjected to Atomic Force Microscopy, Transmission Electron Microscopy, and Field Emission Scanning Electron Microscopy equipped with Energy Dispersive X-ray Analyzer to establish nanoparticle morphology. In addition, Infrared Spectroscopy reveals the presence of chemical and functional groups in SiO2-NPs samples and X-ray diffraction, the amorphous nature. The Zeta potential (ζ) reveals substantial stability of bacteria derived SiO2-NPs in the aqueous environment. Presence of two intense luminescence peaks in the UV and visible regions merits the bacteria derived SiO2-NPs for use as an optical probe in biomedical applications. This novel mode of bacteria derived SiO2-NPs formation is eco-friendly and ambient temperature synthesis approach. It avoids the complex protocol of multi-steps synthesis of silica nanoparticles, hence likely to be cost-effective. In-depth translation research is suggested for the synthesis of silica nanoparticles in large quantities using thermophilic BKH1 template.

Epigenetic regulation of DNMT1 gene in mouse model of asthma disease.

Asthma is a complex genetic disease, which arises from the interaction of multiple genes and environmental stimuli. These influences are important to asthma pathogenesis. These can be mechanically explained by the Epigenetic phenomenon, which consists of the chromatin and its modifications, as well as a covalent modification of cytosines residing at the dinucleotide sequence CG in DNA by methylation. This reaction is catalyzed by a family of DNA methyltransferase enzyme (DNMTs). DNMT1 is one of them which maintained the methylation status during replication and also critical for the development, differentiation and regulation of Th1 and Th2 cells. Therefore we studied the DNMT1 mRNA expression profiling as well as CpG methylation status in promoter region. For these studies we developed asthma mouse model, and used Flow cytometer, qRT2-PCR, Methylation specific PCR, bisulfate conversion and BiQ analyzer. We found that DNMT1 expression level was low in all the tissues (lung, trachea and BALF cells) of asthmatic in comparison to normal mice. This was due to the methylation of regulatory sites of DNMT1 promoter region at cytosine residue. As the incidence of asthma is increasing globally and in world, this study assumes greater significance in designing and developing therapeutic means.

Development of an improved E. coli bacterial strain for green and sustainable concrete technology

Development of smart bioconcrete materials has recently become an emerging area of research for construction. Here, the silica leaching attribute transferred to an E. coli bacterial strain, has been utilized for higher strength and more durable concrete structures. The silica leaching gene was fished out from the BKH2 bacterium (GenBank accession no.: KP231522), amplified by the PCR technique and cloned into E. coli bacteria via a suitable T-vector to develop a bio-engineered E. coli strain. The transformed bacterial cells when incorporated directly into mortar specimens produced high performance biocomposite materials. Improvements on the compressive strength (>30%), ultrasonic pulse velocity (>5%), and decrease in the water absorption capacity were noted in the bacteria amended mortars. FESEM analysis revealed rod-like crystalline structures within the mortar matrices, and XRD analysis confirmed the development of a new silicate phase (gehlenite). The bioengineered E. coli cells can be directly explored for green and sustainable high performance composites in the near future.

Protein dependent fate of hepatic cells under nicotine induced stress and curcumin ameliorated condition.

Nicotine is mainly metabolized in liver. Its abuse elicits acute phase response by activating macrophages to produce pro-inflammatory cytokines, which play critical role in apoptosis or cell proliferation. The protective pharmacological mechanism of curcumin against nicotine-induced toxicity on protein malnourished liver is still remaining unclear. This study investigated the ameliorative mechanism of curcumin against nicotine-induced toxicity and also fate of liver particularly under protein restricted condition. Female Albino-rats maintained under normal/protein-restricted diets, were subcutaneously injected with nicotine tartrate (2.5 mg/kg body weight/day) and orally supplemented with curcumin (80 mg/kg body weight/day) for 21 days. The animals were then sacrificed to dissect out liver and proceed with further experiments. Interactions of nicotine with DNA both in vivo and in vitro were observed by thermal denaturation and DNA laddering assays. Effects of nicotine on hepatic cells were monitored by differential staining, comet assay, cytokine profiling, mRNA and protein expression. Nicotine caused more intense DNA damage, promoted hepatic cell death through up-regulating pro-apoptotic proteins and signaling molecules in protein malnourished individuals. Through up-regulation of anti-apoptotic proteins and proliferation promoting molecules, nicotine dysregulated homeostasis in normal protein condition. Curcumin significantly ameliorated the nicotine-induced toxicity in both conditions and regulated the imbalance between cell survival and death induced by nicotine. The protein content present in the nicotine induced hepatic cell decides either cell-survival pathway or cytotoxic pathway.

Ameliorative effect of sesame lignans on nicotine toxicity in rats.

Nicotine causes oxidative and genotoxic damages in the tissues leading to several diseases. Any strategy through natural diet that prevents or slows the progression and severity of nicotine toxicity has a significant health impact. This work is designed to investigate natural antioxidants that play effective protective role against nicotine-induced toxicity. Experiments were conducted on male albino rats by injecting nicotine tartrate (3.5 mg/kg body wt./day for 15 days) subcutaneously and thereby supplementing sesame lignans (0.1 g/100g diet and 0.2 g/100g diet) orally to them. Significant (P<0.01) increase of total cholesterol, triglyceride, LDL-cholesterol, VLDL-cholesterol, decrease of HDL-cholesterol, decrease in antioxidant enzymes and increase in concentration of lipid peroxidative product has been observed in plasma due to nicotine toxicity. Significant (P<0.01) decrease of total DNA contents and highly significant (P<0.001) DNA damage of liver tissue is also observed on nicotine treatment. Sesame lignans minimizes the above mentioned effects. The nicotine-induced oxidative and genotoxic damages on the tissues can be effectively attenuated by sesame lignans supplemented diet.

Genetically-enriched microbe-facilitated self-healing concrete – a sustainable material for a new generation of construction technology

The fundamentals of engineering and structural properties such as mechanical strength, durability, bond strength, and self-healing behaviour of a genetically-enriched microbe-incorporated construction material have been explored in the present study. The alkaliphilic Bacillus subtilis bacterium is able to survive inside the concrete/mortar matrices for an extended period due to its spore forming ability. The bioremediase-like gene of a thermophilic anaerobic bacterium BKH2 (GenBank accession no. KP231522) was thus transferred to the bacillus strain to develop a true self-healing biological agent. Incorporation of the transformed bacterial cells at different concentrations in the bio-concrete/mortar exhibited higher mechanical strengths and improved durability of the samples in comparison to the normal cement–sand mortar/concretes. Microstructural analyses confirmed the formation of a novel gehlenite (Ca2Al2SiO7) phase besides calcite deposition inside the matrices of the transformed Bacillus subtilis-amended cementitious materials. The gradual development of nano rod-shaped gehlenite composite within the bio-mortar matrices was due to the biochemical activity of the bioremediase-like protein expressed within the incorporated bacterial cells. This development significantly increased the true self-healing property as well as enhanced the mechanical strength of the bio-concrete/mortar material which was sustained for a prolonged period. This study demonstrates a new approach towards the enhancement of structural properties and true self-healing activity by genetically-enriched spore-forming Bacillus sp. with advancement towards sustainable and green construction technology.

Anti-microbial efficiency of nano silver–silica modified geopolymer mortar for eco-friendly green construction technology

A silver–silica nano composite based geopolymer mortar has been developed by simple adsorption of silver in a suitable amount of a colloidal silica suspension for anti-bacterial property development. The silver nanoparticles (3–7 nm) were attached on the surface of 20–50 nm sized silica nanoparticles. The silver–silica nano-composite was characterized by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and energy dispersive X-ray spectral analysis. Mechanical strength, durability and mechanistic anti-bacterial activity of the silver–silica nano composite modified geopolymer mortar (GMAg–Si) were investigated and compared to nano silica modified geopolymer mortar (GMSi) and control cement mortar (CM). To accesses the anti-microbial efficacy of the samples, 99% mortality for Gram positive and Gram negative bacteria was calculated. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values were determined from batch cultures. The addition of 6% (w/w) of the silver–silica nano composite in the geopolymer mortar cured at ambient temperature shows substantial improvement in mechanical strength, durability and anti-bacterial property. Reactive Oxygen Species (ROS) generation and cell wall rupture as observed from fluorescence microscopy and Field Emission Scanning Electron Microscopy (FESEM) may be possible reasons behind the anti-bacterial efficacy of silver–silica nano composite modified geopolymer mortar.

Pentavalent outer membrane vesicles of Vibrio cholerae induce adaptive immune response and protective efficacy in both adult and passive suckling mice models.

Recently, we demonstrated oral immunizations with single serotype outer membrane vesicles of Vibrio cholerae induced serogroup specific protective immunity in the RITARD model. In our present study, we advanced our research by formulating multi-serotype outer membrane vesicles, mixing the OMVs of five virulent V. cholerae strains. Four doses of oral immunization with cholera pentavalent outer membrane vesicles (CPMVs) induced V. cholerae specific B and T cell responses. CPMVs-immunized mice generated long lasting serum IgG, IgA, IgM as well as mucosal sIgA and also elicited a higher percentage of CD4+ T cell distribution in spleen. Our study revealed that in vitro CPMVs-activated dendritic cells were secreting T cell polarizing cytokines, IL-12p40, IL-4, IL-6 and IL-1β. Moreover, purified splenic CD4+ T cells of immunized mice also secreted IL-4, IL-13 and IL-17 cytokines, indicating the initiation of Th2 and Th17 cell mediated immune responses. CPMVs immunized adult female mice and their offspring were significantly protected from heterologous challenge with wild type V. cholerae. CPMVs could be exploited for the development of a novel non-living vaccine against circulating cholera in near future.

DNA methyltransferase 1(DNMT1) induced the expression of suppressors of cytokine signaling3 (Socs3) in a mouse model of asthma

DNMT1 is the most important methyltransferase enzyme, involved in the regulation of gene expression and appropriate histone modification. It interact with proliferating cell nuclear antigen (PCNA), SNF2 family member ATP-dependent chromatin remodeling enzyme, cyclin dependent kinases inhibitor, E2F1 transcription factor and HDACs to form a repressor complex known as HDAC complexes. The interaction of DNMT1 with numerous protein suppressors of promoters suggests that the enzyme is a crucial element of the transcription suppression complex. Since the mechanism behind over expression of Socs3 in Asthma is unclear, we study the Epigenetic mode of overexpression of Socs3 in terms of methylation/acetylation/inactivation of HDACs/activation of HATs enzymes in a mouse model of asthma. The results show that low expression of DNMT1 might indirectly induce the expression of Socs3 and HAT, and inhibit the expression of HDACs family. Furthermore knockdown of DNMT1 by siRNA induced expression of Socs3 while knock down of Socs3 by siRNA has no effect on DNMT1 expression. Our result suggests that the over expression of Socs3 is due to the inhibition of HDACs complex and hyperacetylation of histones molecule along with down regulation of DNMT1 gene. In depth study on DNMT1 might be useful for the development of therapeutic drug against asthma/allergic diseases.

Comparative analysis of microbial diversity in two hot springs of Bakreshwar, West Bengal, India

Various aspects of hot springs at Bakreshwar (Lat. 23°52′48″N; Long. 87°22′40″E) in West Bengal, India have been investigated since the middle of 20th century, but comprehending the complete diversity and the complexity of the microbial population therein has been in the continuing process. Some of these microorganisms are found to have immense industrial importance. Microbes generally exist in milieus of varying complexities and diversities. Attempting the usually employed cultivation-based techniques in experimentation with those microbes had confronted various limitations. To overcome these limitations a strategy based on high-throughput sequencing of 16S rRNA gene amplicon analysis was employed for studying the differential diversity and the detailed nature of microbial population of the two hot springs of Bakreshwar (54 °C & 65 °C). Paired-end libraries of amplified V-3 hyper-variable 16S rDNA fragments from sets of samples that varied in their contents, ranging from a single bacterium to highly complex communities were sequenced. The comparison revealed the differential aspects in the two hot spring waters; the samples at 54 °C showed the bacterial phylum Firmicutes (65.85%) and Synergistetes (27.24%) predominating and those from hot spring water at 65 °C showed the abundance of the phyla Firmicutes (96.10%) and Proteobacteria (3.36%). The presence of Archaea in the hot springs could not be ascertained.