Anasuya Ganguly

Isolation of hydrocarbonoclastic bacteria from bilge oil contaminated water

Two bacterial strains, i.e. Pseudomonas mendocina and Ochrobactrum sp. were isolated from bilge oil contaminated water of Mormugao harbour, Goa, India and grown in a culture medium with hexadecane as the sole carbon source. Pseudomonas mendocina was used in further studies as it was the dominant strain. This strain effectively degraded tetradecane, hexadecane and octadecane leaving a residual concentration of about 73 %, 54 % and 40 % respectively in 120 h. Sequence analysis of the dominant bands from the denaturing gradient gel electrophoresis profiles revealed the differences between the genera of bilge oil contaminated sea water and its enrichment culture on hexadecane indicating a shift in community structure based on the type of substrate available. Pseudomonas mendocina amplified for the following catabolic genes namely C23O, nid and ndo. Based on the catabolic gene study the potential of the bacterial strain isolated, i.e. Pseudomonas mendocina seems to be interesting as it will be able to degrade polyaromatic hydrocarbons as well. Physicochemical properties of Pseudomonas mendocina indicates production of exopolysaccharides based on the value of its isoelectric point.

A PEGylated-rhodamine based sensor for “turn-on” fluorimetric and colorimetric detection of Hg2+ ions in aqueous media

A water soluble turn-on fluorescent probe for the detection of mercury ions in water is developed by appending a water-compatible PEG-unit onto a rhodamine derivative. The probe, Rh1 responds to Hg2+ ions with an intense pink colour and orange fluorescence due to Hg2+ ion-induced opening of the spirolactam ring with high selectivity and sensitivity. The Jobs plot reveals that a 1 : 1 stoichiometry was most favourable for the binding mode of Hg2+ and the probe. Preliminary studies revealed that the probe molecule is fairly non-toxic and can successfully penetrate the cell surface of HeLa cells and interact with intercellular Hg2+ ions, indicating its usefulness for monitoring Hg2+ ions in biological samples as well. The probe is highly efficient, cost-effective and shows a low detection limit of 0.14 ppm.

The cell cycle of Entamoeba invadens during vegetative growth and differentiation

The cell division cycle of Entamoeba invadens was studied during vegetative growth of trophozoites and during their differentiation into cysts. During vegetative growth of trophozoites, it was observed that DNA synthesis typically continued after one genome content had been duplicated. During encystation, DNA synthesis was arrested after 4n genome content had been synthesised. Using multi-parameter flow cytometry, the light scattering properties of cysts and trophozoites were studied. The cytoplasmic granularity, reflected by the side scatter of light, was proportional to DNA content of trophozoites, whereas cysts with similar DNA contents showed heterogeneity in their cytoplasmic granularity. Dynamic changes in the intracellular calcium pools were observed during differentiation of trophozoites to cysts. Comparison of E. invadens and Entamoeba histolytica cell cycles suggest that both organisms may have similar regulatory processes during cell division and differentiation. Since E. histolytica cannot be induced to encyst in axenic culture, analysis of the E. invadens cell cycle during encystation may be useful for identifying homologous processes in E.histolytica.

d-Glucose derived novel gemini surfactants: synthesis and study of their surface properties, interaction with DNA, and cytotoxicity

Four new D-glucose derived m-s-m type gemini surfactants with variable spacer and tail length have been synthesized by a simple and efficient synthetic methodology utilizing the free C-3 hydroxy group of diisopropylidene glucose. The synthetic route to these gemini surfactants with a quaternary ammonium group as polar head group involves a sequence of simple reactions including alkylation, imine formation, quaternization of amine etc. The surface properties of the new geminis were evaluated by surface tension and conductivity measurements. These gemini surfactants showed low cytotoxicity by MTT assay on HeLa cell line. The DNA binding capabilities of these surfactants were determined by agarose gel electrophoresis, fluorescence titration, and DLS experiments. The preliminary studies by agarose gel electrophoresis indicated chain length dependent DNA binding abilities, further supported by ethidium bromide exclusion experiments. Two of the D-glucose derived gemini surfactants showed effective binding with pET-28a plasmid DNA (pDNA) at relatively low N/P ratio (i.e., cationic nitrogen/DNA phosphate molar ratio).

Biochemical Methane Potential of Agro Wastes

The focus of our work is on anaerobic digestion of locally available agro wastes like coconut oil cake, cashew apple waste, and grass from lawn cuttings. The most productive agro waste, in terms of methane yield, was coconut oil cake and grass. The results showed that the initial volatile solids concentration significantly affected the biogas production. The methane yield from coconut oil cake was found to be 383 ml CH4/g VS and 277 ml CH4/g VS added at 4 and 4.5 g VS/l. In case of grass the biogas production increased with increasing VS concentrations with methane yield of 199, 250, 256, 284, and 332 ml CH4/g VS at 3, 3.5, 4, 4.5, and 5.0 g VS/l. For cashew apple waste single-stage fermentation inhibited biogas production. However, phase separation showed methane yield of 60.7 ml CH4/g VS and 64.6 ml CH4/g VS at 3.5 and 4.0 g VS/l, respectively. The anaerobic biodegradability of coconut oil cake was evaluated in fed batch mode in a 5 L anaerobic reactor at 4 g VS/L per batch, and the maximum methane yield was found to be 320 ml CH4/g VS.

Green synthesis of a benzothiazole based ‘turn-on’ type fluorimetric probe and its use for the selective detection of thiophenols in environmental samples and living cells

We have developed an efficient turn-on type fluorescent chemodosimeter for the detection of aromatic thiols in aqueous media. The probe was successfully synthesized by condensation of 2-aminothiophenol with salicylaldehyde followed by SNAr with 2,4-dinitrochlorobenzene in one-pot in a micellar medium. The function of the probe is attributed to the thiol driven cleavage of the dinitrophenyl ether linkage of probe 1 to release 2-(2-hydroxyphenyl)benzothiazole (2) which shows strong greenish fluorescence by excited-state intramolecular proton transfer (ESIPT). The probe is highly selective for aromatic thiols in the presence of several aliphatic thiols, including biologically important thiol-containing amino acids. The utility of the probe was successfully demonstrated in the detection of thiophenols in real samples and in living cells. A hazardless synthetic procedure, cost effective single-step synthesis, high selectivity and sensitivity, fast signal transduction and low limit of detection (3.3 ppb) are some of the key merits of this analytical tool.

Aggregation-Induced Emission-Based Chemodosimeter Approach for Selective Sensing and Imaging of Hg(II) and Methylmercury Species

Methylmercury (CH3Hg+) is the common form of organic mercury and is more toxic than its inorganic or elemental forms. Mercury is emanated in the course of various natural events and human activities and converts to methylmercury by anaerobic organisms. CH3Hg+ are ingested by fish and subsequently bioaccumulated in their tissue and, eventually, enter the human diet, causing serious health issues. Therefore, selective and sensitive detection of bioaccumulated CH3Hg+ in fish samples is essential. Herein, the development of a simple, highly sensitive and selective aggregation-induced emission (AIE)-based turn-on probe for both inorganic mercury ions and organicmercury species is reported. The probes function is based on mercury ion-promoted transmetalation reaction of aryl boronic acid. The probe, a tetraphenylethylene (TPE)-monoboronic acid (1), was successfully utilized for AIE-based fluorescence imaging study on methylmercury-contaminated live cells and zebrafish for the first time. Both Hg(II) and CH3Hg+ ensued a fast transmetalation of TPE-boronic acid causing drastic reduction in the solubility of the resulting product (TPE-HgCl/TPE-HgMe) in the working solvent system. At the dispersed phase, the aggregated form of TPE-mercury ions recovers planarity because of restricted rotational freedom promoting aggregation-induced emission. Simple design, cost-effective synthesis, high selectivity, inexpensive instrumentation, fast signal transduction, and low limit of detection (0.12 ppm) are some of the key merits of this analytical tool.

The combined effect of PDX1, epidermal growth factor and poly-L-ornithine on human amnion epithelial cells' differentiation.

BackgroundIt has been suggested that the ectopic expression of PDX1, a dominant pancreatic transcription factor, plays a critical role in the developmental programming of the pancreas even from cells of unrelated tissues such as keratinocytes and amniotic fluid stem cells. In this study we have chosen to drive pancreatic development in human amnion epithelial cells by inducing endogenous PDX1 expression. Further, we have investigated the role of Epidermal Growth Factor (EGF) and Poly-L-Ornithine (PLO) on this differentiation process.ResultsHuman amnion epithelial cells expressed high levels of endogenous PDX1 upon transduction with an adenoviral vector expressing murine Pdx1. Other markers of various stages of pancreatic differentiation such as NKX6.1, SOX17, RFX6, FOXA2, CFTR, NEUROD1, PAX4 and PPY were also expressed upon Pdx1 transduction.Although initial expression of pancreatic progenitor markers was higher in culture conditions lacking EGF, for a sustained and increased expression EGF was required. Culture on PLO further increased the positive impact of EGF.ConclusionPancreatic marker expression subsequent to mPdx1 transduction suggests that this approach may facilitate the in vitro differentiation of hAECs into cells of the endocrine pancreas. This result may have important implications in diabetes therapy.

Effect of caffeine and saponin on anaerobic digestion of food waste

Food waste is the single largest component of the waste stream by weight. In the present work, we attempted to study the effect of caffeine and saponin on anaerobic fermentation of food waste to examine their potential influence on biogas production at 8% total solids (TS) content. Addition of caffeine at 50, 100, and 150 ppm to the food waste on the first day resulted in biogas production in 24 hours which normally comes on 4th day. The maximum biogas production of 408.5 ml/g TS was found at 100 ppm caffeine whereas 50 ppm and 150 ppm caffeine produced 359 ml and 336 ml in comparison with the control which showed 182 ml/g TS. This is the first study of effect of caffeine as stimulants in anaerobic environments. Addition of saponin had no beneficial effect; on the other hand, it inhibited the biogas production at 50, 100 and 150 ppm.

Biocompatible agarose-chitosan coated silver nanoparticle composite for soft tissue engineering applications.

Abstract With increasing gap in the demand and supply of vital organs for transplantation there is a pressing need to bridge the gap with substitutes. One way to make substitutes is by tissue engineering which involves combining several types of synthetic or biomaterials, cells and growth factors cross-linked together to synthesize a functional scaffold for repair or replacement of non-functional organs. Nanoparticle based composites are gaining importance in tissue engineering due to their ability to enhance cell attachment and proliferation. The current study focuses on synthesizing agarose composites embedded with chitosan-coated silver nanoparticles using glutaraldehyde as the cross-linker. The synthesis of chitosan coated silver nanoparticles within the scaffold was confirmed with UV-visible spectroscopy. Physical and chemical characterization of the synthesized nanoparticles were done by XRD, FTIR, TGA and SEM. DMA showed higher mechanical strength of the scaffolds. The scaffolds showed degradation of ∼37% within a span of four weeks. The higher physical support provided by the synthesized scaffolds was shown by in-vitro cell viability assay. Broad spectrum anti-bacterial activity and superior hemocompatibility further showed the advantage it offered for growing cells. Thus a biopolymer based nanocomposite was synthesized, with intended widespread use as scaffold for engineering of soft tissues due to its enhanced biocompatibility and greater surface area for cell growth.