Anupama Shrivastav

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.

A rhodamine-based chemosensor that works in the biological system.

A new rhodamine-based reversible chemosensor (L1 ) is reported, which could bind Hg2+ and Cu2+ in aqueous methanol solution with detectable change in color. Cu2+ and Hg2+ ions responded differently toward the fluorescence output signals on binding to L1.L1 could also be used as a selective probe for monitoring Hg2+ adsorbed on bacteria using an optical microscope.

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).

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.

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.

Biosorption of Methylene Blue by De-Oiled Algal Biomass: Equilibrium, Kinetics and Artificial Neural Network Modelling

The main objective of the present study is to effectively utilize the de-oiled algal biomass (DAB) to minimize the waste streams from algal biofuel by using it as an adsorbent. Methylene blue (MB) was used as a sorbate for evaluating the potential of DAB as a biosorbent. The DAB was characterized by SEM, FTIR, pHPZC, particle size, pore volume and pore diameter to understand the biosorption mechanism. The equilibrium studies were carried out by variation in different parameters, i.e., pH (2–9), temperature (293.16–323.16 K), biosorbent dosage (1–10 g L−1), contact time (0–1,440 min), agitation speed (0–150 rpm) and dye concentration (25–2,500 mg L−1). MB removal was greater than 90% in both acidic and basic pH. The optimum result of MB removal was found at 5–7 g L−1 DAB concentration. DAB removes 86% dye in 5 minutes under static conditions and nearly 100% in 24 hours when agitated at 150 rpm. The highest adsorption capacity was found 139.11 mg g−1 at 2,000 mg L−1 initial MB concentration. The process attained equilibrium in 24 hours. It is an endothermic process whose spontaneity increases with temperature. MB biosorption by DAB follows pseudo-second order kinetics. Artificial neural network (ANN) model also validates the experimental dye removal efficiency (R2 = 0.97) corresponding with theoretically predicted values. Sensitivity analysis suggests that temperature and agitation speed affect the process most with 23.62% and 21.08% influence on MB biosorption, respectively. Dye adsorption capacity of DAB in fixed bed column was 107.57 mg g−1 in preliminary study while it went up to 139.11 mg g−1 in batch studies. The probable mechanism for biosorption in this study is chemisorptions via surface active charges in the initial phase followed by physical sorption by occupying pores of DAB.

Effect of light quality on the C-phycoerythrin production in marine cyanobacteria Pseudanabaena sp. isolated from Gujarat coast, India

The isolated cyanobacterium containing biopigments like chlorophyll-a, phycoerythrin, phycocyanin, and carotenoid was cultured under different quality of light modes to ascertain biomass and pigment productivity. On the basis of 16S rRNA gene sequence, the isolate was identified as Pseudanabaena sp. Maximum biomass concentration obtained in white-, blue-, and green-light was 0.82, 0.94, and 0.89 g/L, respectively. It was observed that maximum phycoerythrin production was in green light (39.2 mg/L), ensued by blue light (32.2 mg/L), while phycocyanin production was maximum in red light (10.9 mg/L). In yellow light, pigment production as well as the growth rate gradually declined after 12 days. Carotenoid production decreased in blue-, white-, and red-light after 15 days, while in green light it had increased gradually. The present communication suggests that Pseudanabaena sp. can be used for commercial production of phycoerythrin when grown under green light.

Effect of preservatives for food grade C-Phycoerythrin, isolated from marine cyanobacteria Pseudanabaena sp.

C-Phycoerythrin is water soluble red color chromo-protein, which is used as a natural food colorant. The effect of selected edible preservatives like citric acid, sodium chloride, sucrose and calcium chloride on the stability of C-Phycoerythrin at 0±5°C and 35±5°C was studied in aqueous solution. Experiment was carried out to select a stabilizing agent having Hofmeister series behavior acting on hydrophobic interactions. The denaturation of phycoerythrin with urea as denaturant and effect of different pH on C-Phycoerythrin was studied. Citric acid (4 mg/ml) was observed to be one of the best preservative for C-Phycoerythrin at 35±5°C and 0±5°C in aqueous solution for 45 days. Citric acid was able to maintain the stability of C-Phycoerythrin in the solution. The amount of C-Phycoerythrin left in the solution containing citric acid after 30 and 45 days was 46 and 37.8% respectively at higher temperature.

Preparation of highly purified C-phycoerythrin from marine cyanobacterium Pseudanabaena sp.

C-phycoerythrin was isolated and purified from marine Pseudanabaena sp. using two step chromatographic methods. Phycobiliproteins in the marine Pseudanabaena was extracted in 100 mM phosphate buffer (pH 7.2) and precipitated by salting out. The precipitated C-phycoerythrin was purified by gel filtration with Sephadex G-150, and then it was purified by ion exchange chromatography on DEAE cellulose, which was developed by linear ionic strength gradients. Purified phycoerythrin showed absorption maxima at 568 and 541 nm, and displayed a fluorescence maximum at 578 nm. The absorbance ratio A₅₆₈/A₂₈₀, a criterion for purity (purity ratio) achieved was 6.86. It showed a single band on examination by polyacrylamide gel electrophoresis (PAGE). The polypeptide analysis of the purified C-phycoerythrin by SDS-PAGE demonstrated that it contained two chromophore-carrying subunits. The yield of purified C-phycoerythrin obtained was 13.6 mg/g of the cell dry weight with 47% of yield. Obtaining highly pure C-phycoerythrin allows one to evaluate its fluorescence properties for future applications in biochemical and biomedical research.