Sanjiv K. Mishra

Resonance energy transfer approach and a new ratiometric probe for Hg2+ in aqueous media and living organism.

Resonance energy transfer from dansyl to the rhodamine moiety in a newly synthesized chemosensor L(2) has been utilized successfully for detection of Hg(2+) in aqueous solution and living cells such as Pseudomonas putida.

Specific Recognition and Sensing of CN− in Sodium Cyanide Solution

Specific recognition of CN(-) in sodium cyanide solution was achieved using two imidazole-based receptors (A and B). Visually detectable color changes were associated with the formation of hydrogen bonded adducts, A.CN(-) and B.CN(-). Ratiometric fluorescence response was achieved for receptor A on binding to CN(-), and this reagent was used for imaging bacterial cells pre-exposed to 1.42 microM CN(-) solution.

Isolation of promising bacterial strains from soil and marine environment for polyhydroxyalkanoates (PHAs) production utilizing Jatropha biodiesel byproduct.

PHAs are biodegradable and environmentally friendly thermoplastics. The major contributor to PHA production cost is carbon substrate cost, therefore it is desirable to produce PHA from waste/byproducts like Jatropha biodiesel byproducts. This study was done using Jatropha biodiesel byproduct as carbon source, to decrease production cost for PHAs. Total 41 isolates from soil and marine source were able to utilize Jatropha biodiesel byproduct. Nine bacteria were selected for further studies, which were found positive for Nile red viable colony screening. Two bacterial isolates SM-P-1S and SM-P-3M isolated from soil and marine environment respectively, were found promising for PHA production. PHA accumulation for SM-P-1S and SM-P-3M was 71.8% and 75% PHA/CDW respectively and identified as Bacillus sonorensis and Halomonas hydrothermalis by MTCC. The PHA obtained from SM-P-1S and SM-P-3M was analyzed by FTIR and NMR as polyhydroxybutyrate (PHB).

Rapid quantification of microalgal lipids in aqueous medium by a simple colorimetric method.

Identification of novel microalgal strains with high lipid productivity is one of the most important research topics in renewable biofuel research. However, the major bottleneck in the strain screening process is that currently known methods for the estimation of microalgal lipid are laborious and time-consuming. The present study successfully employed sulpho-phospho-vanillin (SPV) colorimetric method for direct quantitative measurement of lipids within liquid microalgal culture. The SPV reacts with lipids to produce a distinct pink color, and its intensity can be quantified using spectrophotometric methods by measuring absorbance at 530nm. This method was employed for a rapid quantification of intracellular lipid contents within Chlorella sp., Monoraphidium sp., Ettlia sp. and Nannochloropsis sp., all of which were found to have lipid contents ranging in between 10% and 30%. Subsequent analysis of the biomass using gas chromatography confirmed that our protocol is highly accurate (R(2)=0.99).

Purification and characterization of haloalkaline thermoactive, solvent stable and SDS-induced protease from Bacillus sp.: A potential additive for laundry detergents

An extracellular haloalkaline, thermoactive, solvent stable, SDS-induced serine protease was purified and characterized from an alkali-thermo tolerant strain Bacillus sp. SM2014 isolated from reverse osmosis reject. The enzyme was purified to homogeneity with recovery of 54.4% and purity fold of 64. The purified enzyme was composed of single polypeptide of molecular mass about 71 kDa. The enzyme showed optimum activity at alkaline pH 10 and temperature 60°C. The km and Vmax for the enzyme was 0.57 mg/ml and 445.23 U/ml respectively. The enzyme showed novel catalytic ability at high pH (10), temperature (60°C) and salinity (3M). Moreover, the stability of enzyme in organic solvents (50% v/v) of logP ≥ 2 signified the prospective of this enzyme for peptide synthesis. The compatibility of the enzyme with surfactants and various detergent matrices together with wash performance test confirmed its potential applicability in laundry industry.

Polyhydroxyalkanoate (PHA) synthesis by Spirulina subsalsa from Gujarat coast of India

Cyanobacteria have many unexploited potential for natural products with a huge variability in structure and biological activity. Their products are species specific and substrate+growth condition specific. Under stress conditions they are reported to produce biopolymers like EPS and PHA, which can be produced extracellularly and intracellularly, respectively. Polyhydroxyalkanoates are polymers of biological origin, they are also capable of being completely broken down to water and carbon dioxide by microorganisms found in a wide range of environments, such as soil, water, and sewage. We have studied marine cyanobacteria Spirulina subsalsa from Veraval coast, Gujarat, India, producing PHA under increased sodium chloride (NaCl) concentration (5% enhancement to the ASNIII medium), The biopolymer was chemically characterized through FTIR, NMR, TGA, and DSC. The present study shows increased PHA accumulation in S. subsalsa by twofold increased NaCl concentration in the growth media.

Recognition of Hg(2+) using diametrically disubstituted cyclam unit.

A newly synthesized 1,4,8,11-tetraazacyclotetradecane derivative (L), functionalized with a diazo moiety as the reporter functionality, is found to bind specifically to Hg(2+) with an associated change in color that could be visually detected. With biologically benign β-CD, it forms an inclusion complex (L·2β-CD), which shows a much higher solubility in water, and this helps in developing a more intense color on binding to Hg(2+) in a CH(3)CN-HEPES buffer medium. The nontoxic nature of L was checked with the living cells of a Gram negative bacterium, Pseudomonas putida . Further, experiments revealed that these two reagents could be used as staining agents for the detection of Hg(2+) present in this microorganism.

An effective, cost-efficient extraction method of biomass from wet microalgae with a functional polymeric membrane

For energy-efficient extraction of biomass from microalgae, it is essential to extract the intracellular lipid directly from wet microalgae without drying the microalgal biomass. In this work, a novel, highly efficient cell disruption process was devised using a functional membrane coated with a cationic polymer. The proposed mechanism of cell disruption involves the perturbation of the local electrostatic equilibrium of the amphiphilic microalgal cell membrane caused by the direct contact with the tertiary-amine cations on the surface of the membrane. A tert-amine-containing polymer, poly-dimethylaminomethylstyrene (pDMAMS) film was conformally deposited on a nylon membrane by a vapor-phase polymerization process, termed as initiated chemical vapor deposition (iCVD). For the wet extraction with this membrane, the pDMAMS-coated membrane was immersed in a microalgal culture of Aurantiochytrium sp. KRS101. The microalgal culture was simply shaken together with the membrane to prompt the contact with the pDMAMS-coated membrane. With this ultimately simple procedure, the bursting of cells was clearly observed. Surprisingly, by this simple, energy-efficient process, a significantly high disruption yield of 25.6 ± 2.18% was achieved. The membrane-based extraction process is highly desirable in that (1) the process does not require an energy-consuming drying procedure, and (2) the proposed cell disruption method with a functional membrane is extremely simple and highly efficient.

The detection of Hg2+ by cyanobacteria in aqueous media

A tetrapyrrole-based chromophore was obtained through the methanolysis of C-phycocyanin extracted from Spirulina platensis, and was found to act as a selective receptor for Hg(2+) at physiological pH conditions.

Zn(II)−Cyclam Based Chromogenic Sensors for Recognition of ATP in Aqueous Solution Under Physiological Conditions and Their Application as Viable Staining Agents for Microorganism

Two chromogenic complexes, L.Zn (where L is (E)-4-((4-(1,4,8,11-tetraazacyclotetradecan-1-ylsulfonyl)phenyl)diazenyl)-N,N-dimethylaniline) and its [2]pseudorotaxane form (α-CD.L.Zn), were found to bind preferentially to adenosine triphosphate (ATP), among all other common anions and biologically important phosphate (AMP, ADP, pyrophosphate, and phosphate) ions in aqueous HEPES buffer medium of pH 7.2. Studies with live cell cultures of prokaryotic microbes revealed that binding of these two reagents to intercellular ATP, produced in situ, could be used in delineating the gram-positive and the gram-negative bacteria. More importantly, these dyes were found to be nontoxic to living microbes (eukaryotes and prokaryotes) and could be used for studying the cell growth dynamics. Binding to these two viable staining agents to intercellular ATP was also confirmed by spectroscopic studies on cell growth in the presence of different respiratory inhibitors that influence the intercellular ATP generation.