Kandasamy Kathiresan

STUDIES ON SILVER NANOPARTICLES SYNTHESIZED BY A MARINE FUNGUS, PENICILLIUM FELLUTANUM ISOLATED FROM COASTAL MANGROVE SEDIMENT

In this work, in vitro biosynthesis of silver nanoparticles was achieved using AgNO(3) as a substrate by Penicillium fellutanum isolated from coastal mangrove sediment. The biosynthesis was faster within minutes of silver ion coming in contact with the cell filtrate. Presence of silver nanoparticles in the culture filtrate was confirmed by absorption peak at 430 nm, as well under transmission electron microscope. The biosynthesis of nanoparticles was the maximum when the culture filtrate was treated with 1.0 mM AgNO(3), maintained at 0.3% NaCl and pH 6.0, incubated at 5 degrees C for 24h. The culture filtrate, precipitated with ammonium sulphate, was proved to have a single protein band with a molecular weight of 70 kDa using polyacrylamide gel electrophoresis. The present work highlighted the possibility of using the marine fungal strain of P. fellutanum to achieve a fast rate of nanoparticles synthesis.

Anticancer Drugs from Marine Flora: An Overview

Marine floras, such as bacteria, actinobacteria, cyanobacteria, fungi, microalgae, seaweeds, mangroves, and other halophytes are extremely important oceanic resources, constituting over 90% of the oceanic biomass. They are taxonomically diverse, largely productive, biologically active, and chemically unique offering a great scope for discovery of new anticancer drugs. The marine floras are rich in medicinally potent chemicals predominantly belonging to polyphenols and sulphated polysaccharides. The chemicals have displayed an array of pharmacological properties especially antioxidant, immunostimulatory, and antitumour activities. The phytochemicals possibly activate macrophages, induce apoptosis, and prevent oxidative damage of DNA, thereby controlling carcinogenesis. In spite of vast resources enriched with chemicals, the marine floras are largely unexplored for anticancer lead compounds. Hence, this paper reviews the works so far conducted on this aspect with a view to provide a baseline information for promoting the marine flora-based anticancer research in the present context of increasing cancer incidence, deprived of the cheaper, safer, and potent medicines to challenge the dreadful human disease.

Screening and evaluation of probiotics as a biocontrol agent against pathogenic Vibrios in marine aquaculture.

Aims:  The present work aims at finding potential probionts from marine sources as a biocontrol agent against pathogenic Vibrio species in shrimp larval culture.

Amylase production by Penicillium fellutanum isolated from mangrove rhizosphere soil

Sorghum is a staple food grain in many semi-arid and tropic areas of the world, notably in Sub-Saharan Africa because of its good adaptation to hard environments and its good yield of production. Among important biochemical components for sorghum processing are levels of starch (amylose and amylopectin) and starch depolymerizing enzymes. Current research focus on identifying varieties meeting specific agricultural and food requirements from the great biodiversity of sorghums to insure food security. Results show that some sorghums are rich sources of micronutrients (minerals and vitamins) and macronutrients (carbohydrates, proteins and fat). Sorghum has a resistant starch, which makes it interesting for obese and diabetic people. In addition, sorghum may be an alternative food for people who are allergic to gluten. Malts of some sorghum varieties display

A review on biosynthesis of nanoparticles by marine organisms

Marine organisms produce remarkable nanofabricated structures in cell wall, shells, pearls and fish bones. Marine microorganisms such as bacteria (E. coli, Pseudomonas sp.), cyanobacteria (Spirulina platensis, Oscillatoria willei, Phormidium tenue), yeasts (Pichia capsulata, Rhodospiridium diobovatum), fungi (Thraustochytrium sp., Penicillium fellutanum, Aspergillus niger), and algae (Navicula atomus, Diadesmis gallica, Stauroneis sp. Sargassum wightii, Fucus vesiculosus) are reported to synthesize inorganic nanoparticles either inside or outside cells. Mangroves (Rhizophora mucronata, Xylocarpus mekongensis), salt marshes (Sesuvium portulacastrum and Suaeda sp.) and sand dune (Citrullus colocynthis) are also capable of synthesizing the nanoparticles, in addition to marine animals such as finfish and sponges. Biosynthesis of nanoparticles may be triggered by several compounds such as carbonyl groups, terpenoids, phenolics, flavonones, amines, amides, proteins, pigments, alkaloids and other reducing agents present in the biological extracts. Marine bio-nanotechnology has a great promise in nanomedicines, food stuff, pharmaceuticals and fabric industries for the future.

Antiviral properties of a mangrove plant, Rhizophora apiculata Blume, against human immunodeficiency virus.

A polysaccharide extracted from the leaf of Rhizophora apiculata (RAP) was assessed in cell culture systems, for its activity against human and simian immunodeficiency viruses. RAP inhibited HIV-1 or HIV-2 or SIV strains in various cell cultures and assay systems. It blocked the expression of HIV-1 antigen in MT-4 cells and abolished the production of HIV-1 p24 antigen in peripheral blood mononuclear cells (PBMC); the 50% effective concentration (EC50) of RAP in HIV-1 infected MT-4 cells and in PBMC was 10.7 and 25.9 microg/ml, respectively. RAP (100 microg/ml) completely blocked the binding of HIV-1 virions to MT-4 cells. RAP also reduced the production of viral mRNA when added before virus adsorption. RAP inhibited syncytium formation in cocultures of MOLT-4 cells and MOLT-4/HIV-1(IIIB) cells. RAP did not prolong activated partial thromboplastin time (APTT) up to 500 microg/ml. These properties may be advantageous should RAP be considered for further development.

Analysis of antimicrobial silver nanoparticles synthesized by coastal strains of Escherichia coli and Aspergillus niger

The present study investigated the extracellular biosynthesis of antimicrobial silver nanoparticles by Escherichia coli AUCAS 112 and Aspergillus niger AUCAS 237 derived from coastal mangrove sediment of southeast India. Both microbial species were able to produce silver nanoparticles, as confirmed by X-ray diffraction spectrum. The nanoparticles synthesized were mostly spherical, ranging in size from 5 to 20 nm for E. coli and from 5 to 35 nm for A. niger, as evident by transmission electron microscopy. Fourier transform spectroscopy revealed prominent peaks corresponding to amides I and II, indicating the presence of a protein for stabilizing the nanoparticles. Electrophoretic analysis revealed the presence of a prominent protein band with a molecular mass of 45 kDa for E. coli and 70 kDa for A. niger. The silver nanoparticles inhibited certain clinical pathogens, with antibacterial activity being more distinct than antifungal activity. The antimicrobial activity of E. coli was more pronounced than that of A. niger and was enhanced with the addition of polyvinyl alcohol as a stabilizing agent. This work highlighted the possibility of using microbes of coastal origin for synthesis of antimicrobial silver nanoparticles.

Evaluation of beneficial bacteria from mangrove soil

Abstract This paper describes some bacteria found on mangrove roots and their potential in promoting mangrove seedling growth. Forty-eight bacterial strains were isolated from rhizosphere soil of a mangrove species (Rhizophora mucronata). The strains were analyzed for their ability to (a) fix nitrogen, (b) solubilize phosphate, (c) produce ammonia and (d) produce the plant growth hormone (IAA); we also tested the effects of strains on shoot growth of R. mucronata. Two strains which doubled the growth of mangrove seedlings were identified as Azotobacter vinelandii and Bacillus megaterium. This raises the possibility of using the bacterial species to enhance the growth of mangrove seedlings.

DNA Extraction Protocol for Plants with High Levels of Secondary Metabolites and Polysaccharides without Using Liquid Nitrogen and Phenol

Mangroves and salt marsh species are known to synthesize a wide spectrum of polysaccharides and polyphenols including flavonoids and other secondary metabolites which interfere with the extraction of pure genomic DNA. Although a plethora of plant DNA isolation protocols exist, extracting DNA from mangroves and salt marsh species is a challenging task. This study describes a rapid and reliable cetyl trimethylammonium bromide (CTAB) protocol suited specifically for extracting DNA from plants which are rich in polysaccharides and secondary metabolites, and the protocol also excludes the use of expensive liquid nitrogen and toxic phenols. Purity of extracted DNA was excellent as evident by A260/A280 ratio ranging from 1.78 to 1.84 and A260/A230 ratio was >2, which also suggested that the preparations were sufficiently free of proteins and polyphenolics/polysaccharide compounds. DNA concentration ranged from 8.8 to 9.9 μg μL−1. The extracted DNA was amenable to RAPD, restriction digestion, and PCR amplification of plant barcode genes (matK and rbcl). The optimized method is suitable for both dry and fresh leaves. The success of this method in obtaining high-quality genomic DNA demonstrated the broad applicability of this method.

Antidiabetic activity of the mangrove species Ceriops decandra in alloxan-induced diabetic rats

Background:  Diabetes is a series of disorders characterized by increased fasting and postprandial glucose concentration and insulin deficiency and/or decreased insulin action. Although there are a number of commercially available drugs for the treatment of diabetes, their long‐term use may cause unwanted side effects. Consequently, many studies are underway to find natural remedies that can effectively reduce the intensity of diabetes. The aim of the present study was to evaluate the antidiabetic activity of the mangrove species Ceriops decandra.