Showing papers by "Ruma Pal published in 2012"

Screening of different algae for green synthesis of gold nanoparticles

Abstract: The cyanobacteria Phormidium valderianum, P. tenue and Microcoleus chthonoplastes and the green algae Rhizoclonium fontinale, Ulva intestinalis, Chara zeylanica and Pithophora oedogoniana were exposed to hydrogen tetrachloroaurate solution and were screened for their suitability for producing nano‐gold. All three cyanobacteria genera and two of the green algae (Rhizoclonium fontinale and Ulva intestinalis) produced gold nanoparticles intracellularly, confirmed by purple colouration of the thallus within 72 h of treatment at 20°C. Extracted nanoparticle solutions were examined by UV‐vis spectroscopy, transmission electron microscopy (TEM) and X‐ray diffractometry (XRD). XRD confirmed the reduction of Au (III) to Au (0). UV‐vis spectroscopy and TEM studies indicated the production of nanoparticles having different shapes and sizes. Phormidium valderianum synthesized mostly spherical nanoparticles, along with hexagonal and triangular nanoparticles, at basic and neutral pHs (pH 9 and pH 7, respectively). Medi...

Gold nanorod production by cyanobacteria—a green chemistry approach

Abstract: Intracellular bioconversion of auric ion (Au3+) to gold nanorod (Au0) by the cyanobacterium Nostoc ellipsosporum has been observed for the first time in laboratory condition. The nanorods were produced within the cell after exposing the healthy growing filaments to 15 mg L−1 gold (III) solution (pH 4.5) for 48 h at 20°C. The gold nanoparticles were extracted with sodium citrate solution and were subjected to UV–Visible spectroscopy. The characteristic surface-multiple plasmon bands at 560, 610, and 670 nm were observed. The nature and size of the particles were determined by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and zeta potential studies. The nanorod size ranged from 137 to 209 nm in length and 33 to 69 nm in diameter. DLS study revealed the average hydrodynamic size as 435 nm and XRD study indicated the reduction of Au3+ to Au0. Methods of extraction and preservation of gold nanorod particles have also been studied.

Mapping Algae of Sundarban Origin as Lipid Feedstock for Potential Biodiesel Application

Abstract: Six Cyanobacterial and fifteen other algal taxa from Sundarban mangrove forest of South East Asia have been analyzed for total lipid estimation and fatty acid profiling to search for a suitable feedstock for algal biodiesel production. Total lipid content varied from 7 – 23 % for the studied genera. GCMS analysis revealed that Palmitic (16:0) and Oleic (18:1) as major fatty acids from the taxa collected from freshwater, brackish water and marine habitat of Sundarban with variable salinity (0-23psu). A few microalgae from cyanophyceae like, Lyngbya majuscula, Phormidium valderianum, Synechocystis pevalekii and chlorophycean genera viz. Rhizoclonium riparium, Rhizoclonium africanum, Pithophora cleveana, Spirogyra orientalis and Cladophora crystallina, having suitable fatty acid composition were identified for biodiesel production. Fatty acid profile showed more diversification in unsaturated fatty acid in fresh water region, indicating more variable environment in upstream fresh water regions of Sundarban.

Scope of phycoremediation of Arsenic using Phormidium tenue with special reference to modulation in cellular biochemistry

Abstract: Phormidium tenue (Meneghini) Gomont , a microscopic filamentous cyanobacterium was exposed to 5ppm Na-arsenate (sub lethal dose) for different time intervals (1h, 3h and 24h) at a pH variation of 5.5, 7.0 and 8.5 to study the accumulation pattern of toxic metalloid arsenic. It was observed that arsenic accumulation of P. tenue increased with time and maximum accumulation was recorded in pH-7 after 24h exposure (80.51 mg. g 1 ). In another experiment P. tenue was treated with different concentrations of Sodium arsenate (0.1, 1, 5, 10, 25, 50 and 100ppm) in pH-7 to study the growth pattern and changes in biochemical parameters like, chlorophyll a , carotenoids, phycobiliproteins, total protein and carbohydrate content in control and arsenic exposed biomass. This study was done to assess primarily the ability of the cyanobacteria for arsenic removal and to study the cellular biochemistry of arsenic exposed biomass for a longer period of time. From the study it was evident that P. tenue responded differently in different doses of arsenic and showed optimum growth even when exposed to 50ppm arsenic for 60 days indicating arsenic resistance.

Morphotaxonomic account of some common seaweeds from Indian Sundarbans mangrove forest and inner island area

Abstract: The taxonomic study of marine seaweeds from Indian Sundarbans mangrove forest reveals the presence of nine taxa belonging to the class Chlorophyceae and Rhodophyceae. The present paper deals the morphotaxonomic description of nine taxa of which two from Chlorophyceae and seven from Rhodophyceae were recorded. Among the Chlorophyceae two species of Ulva viz. U. lactuca and U. intestinalis were found. The Rhodophycean taxa belongs to Catenella with two species viz. C. repens and C. nipae, Polysiphonia, Bostrychia, Compsopogon, Gelidium and Ceramium. The temperature (oC), pH and salinity were also studied at the time of collection of seaweeds.

Chemical characterization and the stress induced changes of the extracellular polysaccharide of the marine cyanobacterium, Phormidium tenue

Abstract: The cyanobacterial strain Phormidium tenue was subjected to different stress conditions like culture aging, phosphate and nitrate depleted condition, excess nitrate (10mM) and salinity (0.9M NaCl). Excess nitrate and salinity used were just the double amount, required for normal concentration. Growth was monitored by Chlorophyll content and total protein level in relation to polysaccharide production. Remarkable increase in EPS contents were noted in all stresses given, which were almost 1.7, 2, 3 and 4 times more in excess nitrate condition, phosphate depleted, nitrate depleted and high salinity respectively. It was also observed that aging is an important factor for increasing EPS production. Exocellular polysaccharide (EPS) from this marine cyanobacterium was characterized using GLCMS and stress induced variation in total production was studied in batch culture mode. The neutral sugar composition of Phormidium biomass was identified by gas liquid chromatography showing monosaccharide composition as Rhamnose, Fucose, Xylose, Mannose, Glucose and Galactose. It was evident from the study that the structural architecture of the extra cellular polysaccharide of Phormidium is highly complex in nature as common in algal system.