Purification and characterization of a thermoalkaline, cellulase free thermostable xylanase from a newly isolated Anoxybacillus sp. Ip-C from hot spring of Ladakh

An alkaline, highly thermostable cellulase free xylanase was purified from a thermophilic Anoxybacillus sp. Ip-C, newly isolated from hot spring of Ladakh. The enzyme was purified using ammonia sulphate precipitation followed by Sephadex G-75. The molecular weight of the xylanase was about 45 kDa, as analyzed by SDS-PAGE. The enzyme had optimum activity at pH 9.0 and 70ºC temperature; the enzyme retained 90% of its original activity for 96 hrs at 70 ºC. Vmax and Km of the enzyme were found to be 13.5 µmol min-1 mg-1 protein and 4.59 mg ml-1, respectively. Metal ions, Ca+2, Fe+2 and Mg+2 highly enhance the enzyme activity to 122.45, 119.06 and 118.98% respectively; whereas SDS and Hg+2 completely inhibit (0 U/ml) the enzyme activity. TLC analysis of enzymatic hydrolysis products showed that this xylanase is an endoxylanase, and generates xylooligosaccharides. Thus, it provides a potential thermostable alkaline xylanase for industrial applications

Bacterial biofilms: role of quorum sensing and quorum quenching

Bacterial biofilms provide an adjustable strategy to manage themselves in the existing conditions. Biofilms of pathogenic bacteria act as a reservoir for various device and non-device related diseases which are tough to cure. Exposure to a high dose of antibiotics is not an appropriate solution to this problem as high antibiotic concentrations lead to the generation of Multi-drug resistant strains as well as affect the human body. So, it is needed to bypass the use of antibiotics to prevent bacterial biofilms. In this context, Quorum Sensing (QS) may be a potential target since biofilm formation is regulated by QS. N-acyl homoserine lactones (N-AHL) act as predominant QS signal molecules in Gram-negative bacteria. Counteraction of the QS-regulated activities using quorum quenching may be an alternative way to combat biofilm formation in bacteria. Quorum sensing inhibitors (QSIs) and QQ enzymes play a significant role in this regard either by interference with the signal generation, perception, or by degradation, and chemical modification, respectively. Many quorum quenching enzymes have been reported from bacteria. Extremophilic bacteria have also been reported to produce potent quorum quenching enzymes which can effectively break down N-AHLs

Sensitive and fluorescent Schiff base chemosensor for pico molar level fluoride detection: In vitro study and mimic of logic gate function

Modification of the side arm of two newly synthesized organic chemosensor acts as a ‘key’ for opening the ‘lock’ at pico molar level fluoride (F−) sensing by fluorescence ‘turn on’ phenomenon in different environmental water samples (drinking water) collected from rural parts of several districts of West Bengal, India. Intracellular fluoride detection in Candida albicans and pollens of Techoma stans, incubated in pico molar (10−12 M) fluoride contaminated hand pump water collected from Bankura, West Bengal has been successful under fluorescence microscope. The interesting fluorescence spectral responses mimics several different logic operations (XOR, OR, AND, NOT and NOR) with ‘Write-Read-Erase-Read’ option

Recognition of fluoride anions at low ppm level inside living cells and from fluorosis affected tooth and saliva samples

A simple Schiff base chemosensor 2-((2-(2,4-dinitro phenyl)hydrazono)methyl)-4-nitrophenol (L) has been developed as a colorimetric and fluorimetric ‘turn on’ sensor for fluoride (F−). F− recognition at ppm levels from mouth rinses and a toothpaste water solution has been successful. Significantly, L can detect F− from fluorosis affected tooth and saliva samples by similar colorimetric changes. A test kit for F− detection from a DMSO–water (1 : 1) mixture is also engineered. Intracellular F− from pollen grains of Techoma stans and Candida albicans (a diploid fungus), grown in 10−6 (M) F− contaminated water has been successfully detected under a fluorescence microscope

Intracellular Fluorometric Recognition of Explosive and Mutagenic Nitroaromatics by a Luminescent Phenanthrene-Naphthalene Sulfone

Novel phenanthrene-naphthalene sulfone based luminescent chemosensor has been synthesized for recognition of explosive and mutagenic 2,4,6-Trinitrophenolby fluorescence quenching with binding constant (1.93×105 M−1) and LOD (100 nM) that are better than reported sensory materials. Keeping in mind the toxic nature of 2,4,6-Trinitrophenol by, in vitro detection has been performed inside living organism like pollen cells of Tecoma Stans, Peperomia roots and Candida albicans. Luminescent phenanthrene-naphthalene sulfone has been synthesized having phenanthrene and naphthalene as antenna center with an aim of fluorogenic in vitro detection of highly mutagenic NACs, which are hitherto less explored. The chemosensor could detect NACs selectively over NALs of which TNP detection is highly selective by a swing in fluorescence spectrum from 405 to ∼475 nm with extremely high quenching constant 1.93×105 M−1 and LOD 100 nM. Fluorometric recognition of TNP was explained through a combined complex PET-RET-ACQ-CT pathway. DFT calculation has been performed to obtain the low energy configuration of the host⋅⋅⋅guest adduct. NMR titration reveals the chemical stability of the host in presence of TNP, suggests that the interaction belongs to supramolecular realm that supports the utilization of the chemosensor forin vitro detection of TNP within pollens of Tecoma Stans, Peperomia roots and Candida Albicans, indeed establishes the scaffold as a biocompatible chemosensor

Intracellular Fluorometric Recognition of Explosive and Mutagenic Nitroaromatics by a Luminescent Phenanthrene‐Naphthalene Sulfone

Novel phenanthrene-naphthalene sulfone based luminescent chemosensor has been synthesized for recognition of explosive and mutagenic 2,4,6-Trinitrophenolby fluorescence quenching with binding constant (1.93×105 M−1) and LOD (100 nM) that are better than reported sensory materials. Keeping in mind the toxic nature of 2,4,6-Trinitrophenol by, in vitro detection has been performed inside living organism like pollen cells of Tecoma Stans, Peperomia roots and Candida albicans. Luminescent phenanthrene-naphthalene sulfone has been synthesized having phenanthrene and naphthalene as antenna center with an aim of fluorogenic in vitro detection of highly mutagenic NACs, which are hitherto less explored. The chemosensor could detect NACs selectively over NALs of which TNP detection is highly selective by a swing in fluorescence spectrum from 405 to ∼475 nm with extremely high quenching constant 1.93×105 M−1 and LOD 100 nM. Fluorometric recognition of TNP was explained through a combined complex PET-RET-ACQ-CT pathway. DFT calculation has been performed to obtain the low energy configuration of the host⋅⋅⋅guest adduct. NMR titration reveals the chemical stability of the host in presence of TNP, suggests that the interaction belongs to supramolecular realm that supports the utilization of the chemosensor forin vitro detection of TNP within pollens of Tecoma Stans, Peperomia roots and Candida Albicans, indeed establishes the scaffold as a biocompatible chemosensor

Nanomolar level detection of explosive and pollutant TNP by fluorescent aryl naphthalene sulfones: DFT study, in vitro detection and portable prototype fabrication

Luminescent Aryl Naphthalene Sulfones have been prepared via Garratt-Braverman cyclization of γ-substituted bis-propargyl sulfones for explosive and pollutant 2,4,6-Tri nitrophenol (TNP) recognition in aqueous medium by fluorescence quenching. The quenching can be explained through AIE-ACQ-RET-ICT based mechanisms. In vitro detection of TNP has been performed inside pollen cells. In real time stepping, paper strip and pocket solution kit has been fabricated for on spot detection of TNP. Moreover as an analytical application TNP has been detected from several surface water specimens collected throughout West Bengal, India. The limit of detection has been found as low as 10 nM together with quenching constant as 6.8 × 105 M−1, which is even superior to the recently published sensor materials

Molecular evidence for the occurrence of Japanese encephalitis virus genotype I and III infection associated with acute Encephalitis in Patients of West Bengal, India, 2010

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis virus (JEV), a mosquito-borne zoonotic pathogen, is the sole etiologic agent of Japanese Encephalitis (JE); a neurotropic killer disease which is one of the major causes of viral encephalitis worldwide with prime public health concern. JE was first reported in the state of West Bengal, India in 1973. Since then it is being reported every year from different districts of the state, though the vaccination has already been done. Therefore, it indicates that there might be either partial coverage of the vaccine or the emergence of mutated/new strain of JEV. Considering this fact, to understand the JEV genotype distribution, we conducted a molecular epidemiological study on a total of 135 serum/cerebrospinal fluid (CSF) samples referred and/or collected from the clinically suspected patients with Acute encephalitis syndrome (AES), admitted in different district hospitals of West Bengal, India, 2010.</p> <p>Findings</p> <p>JEV etiology was confirmed in 36/135 (26.6%) and 13/61 (21.3%) 2–15 days’ febrile illness samples from AES cases by analyzing Mac-ELISA followed by RT-PCR test respectively. Phylogenetic analysis based on complete envelope gene sequences of 13 isolates showed the emergence of JEV genotype I (GI), co-circulating with genotype III (GIII).</p> <p>Conclusion</p> <p>This study represents the first report of JEV GI with GIII, co-circulating in West Bengal. The efficacy of the vaccine (derived from JEV GIII strain SA-14-14-2) to protect against emerging JEV GI needs careful evaluation. In future, JE outbreak is quite likely in the state, if this vaccine fails to protect sufficiently against GI of JEV.</p

Nanomolar-level selective dual channel sensing of Cu2+ and CN− from an aqueous medium by an opto-electronic chemoreceptor

A dual-channel chromogenic and fluorogenic fused-aromatic-system-based chemoreceptor (2-(benzo[d]thiazol-2-yl)-1-((pyren-8-yl)methylene)hydrazine) (TyM) was designed for ditopic sensitivity towards heavy and transition metal ions (HTMs), such as Cu2+, in an aqueous medium and lethal CN− in a semi-aqueous medium. The chemoreceptor displayed proclivity towards the targeted analytes with a distinct optical response (yellow to colourless in the case of Cu2+ and yellow to bright red for CN−). TyM formed a 2 : 1 adduct with Cu2+ with a detection limit of 40 nM. A 1 : 1 binding stoichiometry was confirmed with the chemoreceptor TyM with CN− in sub-nano molar limit of detection. In addition to sophisticated spectroscopic analysis, such as UV-vis, fluorescence, FTIR, 1H-NMR, 13C-NMR, ESI-MS, and HRMS, the plausible mechanistic course of sensing was also established from a theoretical perspective. The reversible UV-vis response of the chemoreceptor TyM towards CN− and H+ can mimic different molecular logic functions and therefore can be exploited for designing several complex electronic circuits principally based on Boolean Algebra. In vitro fluorescence imaging in male microspores of seed plants (Bohonia Nigalandra) and Monilia Albicans (diploid fungus) with TyM and Cu2+ confirmed the permeability of the chemoreceptor TyM at the cellular level as well as its ability to investigate transition metals, such as Cu2+, in biological samples