Ruma Pal

Bio: Ruma Pal is an academic researcher from University of Calcutta. The author has contributed to research in topics: Rhizoclonium & Phytoplankton. The author has an hindex of 19, co-authored 75 publications receiving 1256 citations.

An Overview of Cyanobacterial Exopolysaccharides: Features, Composition and Effects of Stress Exposure

Abstract: Cyanobacterial polysaccharides have been topic of current research interests for quite some time. Most of the cyanobacteria are observed to secrete a somewhat slimy material which is either loosely bound to or released to the medium. These extracellular polysaccharidic materials are of high molecular weight and consist of either one or different sugar residues. The presence of more than one uronic acids and/or acetylated amino sugars, phosphate, lactate etc. are thought to be one of the main reasons of the structural complexity of these materials. The structural composition and productivity of cyanobacterial polysaccharides are usually changed during different stress exposure including aging. This unique property can play a vital role in the possible biotechnological exploitation in various fields. Though ample data are there, still there is a large gap between the information on hand and the technology needed to meet the demand of the industrial sectors on the other. In the current review article an attempt has been taken to compile the information available about the main features, structural composition, varied roles and to highlight the thrust areas in a detail approach. DOI: http://dx.doi.org/10.3126/ijls.v8i4.10891

Rapid Accumulation of Total Lipid in Rhizoclonium africanum Kutzing as Biodiesel Feedstock under Nutrient Limitations and the Associated Changes at Cellular Level.

Abstract: Increase of total lipid and the proportion of the favorable fatty acids in marine green filamentous macroalga Rhizoclonium africanum (Chlorophyceae) was studied under nitrate and phosphate limitations. These stresses were given by both eliminating and doubling the required amounts of nitrate and phosphate salts in the growth media. A significant twofold increase in total lipid (193.03 mg/g) was achieved in cells in absence of nitrate in the culture medium, followed by phosphate limitation (142.65 mg/g). The intracellular accumulation of neutral lipids was observed by fluorescence microscopy. The scanning electron microscopic study showed the major structural changes under nutrient starvation. Fourier transform infrared spectroscopy (FTIR) revealed the presence of ester (C-O-C stretching), ketone (C-C stretching), carboxylic acid (O-H bending), phosphine (P-H stretching), aromatic (C-H stretching and bending), and alcohol (O-H stretching and bending) groups in the treated cells indicating the high accumulation of lipid hydrocarbons in the treated cells. Elevated levels of fatty acids favorable for biodiesel production, that is, C16:0, C16:1, C18:1, and C20:1, were identified under nitrate- and phosphate-deficient conditions. This study shows that the manipulation of cultural conditions could affect the biosynthetic pathways leading to increased lipid production while increasing the proportion of fatty acids suitable for biodiesel production.

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.

Synthesis of silver nanoparticles: chemical, physical and biological methods.

Abstract: Silver nanoparticles (NPs) have been the subjects of researchers because of their unique properties (e.g., size and shape depending optical, antimicrobial, and electrical properties). A variety of preparation techniques have been reported for the synthesis of silver NPs; notable examples include, laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods. This review presents an overview of silver nanoparticle preparation by physical, chemical, and biological synthesis. The aim of this review article is, therefore, to reflect on the current state and future prospects, especially the potentials and limitations of the above mentioned techniques for industries.

Synthesis and biological characterization of silver nanoparticles derived from the cyanobacterium Oscillatoria limnetica.

Abstract: Using aqueous cyanobacterial extracts in the synthesis of silver nanoparticle is looked as green, ecofriendly, low priced biotechnology that gives advancement over both chemical and physical methods. In the current study, an aqueous extract of Oscillatoria limnetica fresh biomass was used for the green synthesis of Ag-NPs, since O. limnetica extract plays a dual part in both reducing and stabilizing Oscillatoria-silver nanoparticles (O-AgNPs). The UV-Visible absorption spectrum, Fourier transforms infrared (FT-IR), transmission electron microscopy (TEM) and scanning electron microscope (SEM) were achieved for confirming and characterizing the biosynthesized O-AgNPs. TEM images detected the quasi-spherical Ag-NPs shape with diverse size ranged within 3.30–17.97 nm. FT-IR analysis demonstrated the presence of free amino groups in addition to sulfur containing amino acid derivatives acting as stabilizing agents as well as the presence of either sulfur or phosphorus functional groups which possibly attaches silver. In this study, synthesized Ag-NPs exhibited strong antibacterial activity against multidrug-resistant bacteria (Escherichia coli and Bacillus cereus) as well as cytotoxic effects against both human breast (MCF-7) cell line giving IC50 (6.147 µg/ml) and human colon cancer (HCT-116) cell line giving IC50 (5.369 µg/ml). Hemolytic activity of Ag-NPs was investigated and confirmed as being non- toxic to human RBCs in low concentrations.