Duraisamy Kalpana

Synthesis and characterization of bactericidal silver nanoparticles using cultural filtrate of simulated microgravity grown Klebsiella pneumoniae.

Silver nanoparticles were synthesized by biological method using cultural filtrate of Klebsiella pneumoniae cultured under simulated microgravity and silver nitrate solution as precursor. The nanoparticles exhibited typical plasmon absorption maximum of silver nanoparticles between 405 and 407 nm. Spherical silver nanoparticles were found to have size between 15 and 37 nm by TEM analysis. XRD pattern corresponding to planes (111), (200), (220) (311) revealed the crystalline nature of the biosynthesized silver nanoparticles. FTIR spectrum proposed stabilization of silver nanoparticles by the protein molecules present in the cultural filtrate. The silver nanoparticles exhibited high bactericidal activity against Salmonella enterica, Escherichia coli and moderate bactericidal activity against Streptococcus pyogenes.

Bioremediation of the heavy metal complex dye Isolan Dark Blue 2SGL-01 by white rot fungus Irpex lacteus.

The present study was conducted to evaluate the decolorization and degradation of the chromium metal complex dye Isolan Dark Blue 2SGL-01 by Irpex lacteus, a white rot lignolytic fungus. I. lacteus effectively decolorized the sulphonated reactive dye at a high concentration of 250 mg/l over a wide range of pH values of 5-9 and temperatures between 20 and 35°C. Complete (100%) decolorization occurred within 96h, and I. lacteus demonstrated resistance to the metallic dye. UV-vis spectroscopy, HPLC, GC-MS, and FT-IR analyses of the extracted metabolites confirmed that the decolorization process occurred due to degradation of the dye and not merely by adsorption. GC-MS analysis indicated the formation of 1(2H)-naphthalenone, 3,4-dihydro- and 2-naphthalenol as the main metabolite. ICP analysis demonstrated the removal of 13.49% chromium, and phytotoxicity studies using germinated seeds of Vigna radiata and Brassica juncea demonstrated the nontoxic nature of the metabolites formed during the degradation of Isolan Dark Blue 2SGL-01 dye.

Influence of antimicrobial additives on the formation of rosin nanofibers via electrospinning

In this study, we describe the influence of antimicrobial additives on the formation of rosin fibers by using electrospinning technique. Systematic experiments were performed to fabricate the rosin fibers via electrospinning and we tried to reduce the size of the fibers by mixing some additives such as triethylbenzylammonium chloride (TEBAC), chitosan and silver nitrate in the rosin polymer solution. The morphology, structure and thermal properties of the electrospun rosin fibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy and thermogravimetry (TGA). Rosin fibers with a diameter of the order of nanoscale were achieved by the use of TEBAC additive. The antimicrobial activity of the resultant fibers was checked by the antimicrobial disc diffusion test. All the rosin fibers showed excellent antibacterial activity against the gram negative bacteria and feeble activity against the gram positive bacteria. The present study demonstrated that the electrospun rosin fibers can be utilized for potential antimicrobial products.

Phylogenetic analysis of culturable marine bacteria in sediments from South Korean Yellow Sea

Biogeochemical and microbiological characterization of marine sediments taken from the Yellow Sea of South Korea was carried out. One hundred and thirty six bacterial strains were isolated, characterized and phylogenetic relationship was evaluated. The gene sequences of 16S rDNA regions were examined to study the phylogenetic analysis of bacterial community in the marine sediments. Among 136 isolates, 5 bacterial isolates were identified as novel members, remaining 131 isolates were fall into 5 major linkages of bacterial phyla represented as follows: Firmicutes,, -@Proteobacteria, High G + C and Bacteroidetes. Bacterial community in sediments mainly dominated by Firmicute (58.77%) and followed by @-Proteobacteria (38.16%). @-Proteobacteria domain highly diverged and mainly consists of the genera Vibrio, Marinobacterium, Photobacterium, Pseudoalteromonas, Oceanisphaera, Halomonas, Alteromonas, Stenotrophomas and Pseudomonas. Total N and Organic matter content in Yellow Sea of South Korea were relatively high. The Total-N content in the sediments was varied from 177.31 to 1974.96 (mg/kg) and organic matter ranged from 0.82 to 4.23 (g/100 g−1). The current research work provides clear explanation obtained for the phylogenetic affiliation of the culturable bacterial community in sediments of South Korean Yellow Sea and revealed the relationship with biogeochemical characteristics of the sediments.

Synthesis, characterization and In vitro cytotoxicity of gold nanoparticles using cultural filtrate of low shear modeled microgravity and normal gravity cultured K. pneumoniae

AbstractThe cultural filtrates of Klebsiella pneumoniae cultured under normal gravity and low shear modeled microgravity were potentially used to biosynthesize gold nanoparticles using the precursor gold III chloride trihydrate. The gold nanoparticles produced were spherical, of size between 16–36 and 24–50 nm with the cultural filtrates of normal and low shear modeled microgravity respectively. The characteristic plasmon resonance of gold nanoparticles occurred between 535–550 nm in the spectral analysis. XRD reflections (1 1 1), (2 0 0), (2 2 0), (3 1 1) indicate the face centered cubic and crystalline nature of the biosynthesized gold nanoparticles. The FTIR study proposes that proteins excreted into the cultural filtrate were involved in the synthesis and stabilization of gold nanoparticles. The in vitro cytotoxicity on 3T3L1, H9c2 and HepG2 cell lines showed the nontoxic and biocompatible nature of biosynthesized gold nanoparticles.

Multipurpose polyurethane antimicrobial metal composite films via wet cast technology

AbstractWe report on the preparation and characterization of polyurethane (PU) film containing metal particles and their antibacterial activity. The utilized PU films containing metal particles were prepared by a simple solvent evaporation method. The surface morphology, structure and optical properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and UV-vis spectroscopy. The antibacterial activity was tested against four common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae by minimum inhibitory concentration (MIC) method. Our results demonstrated that no bactericidal activity was detected for the pristine PU film. Further on, antibacterial activity was observed to be more pronounced for the PU films containing metal particles which were attributed to the presence of metal in the PU thin films. Overall, this study demonstrates the fabrication of cheap, stable and effective material with excellent antimicrobial activity that can be utilized to inhibit the microbial growth associated with food stuff.

Growth, Morphology, Cross Stress Resistance and Antibiotic Susceptibility of K. pneumoniae Under Simulated Microgravity

Spaceflights results in the reduction of immune status of human beings and increase in the virulence of microorganisms, especially gram negative bacteria. The growth of Klebsiella pneumoniae is enhanced by catecholamines and during spaceflight, elevation in the levels of cortisols occurs. So it is necessary to know the changes in physiology, virulence, antibiotic resistance and gene expression of K. pneumoniae under microgravity conditions. The present study was undertaken to study effect of simulated microgravity on growth, morphology, antibiotic resistance and cross stress resistance of K. pneumoniae to various stresses. The susceptibility of simulated microgravity grown K. pneumoniae to ampicillin, penicillin, streptomycin, kanamycin, hygromycin and rifampicin were evaluated. The growth of bacteria was found to be fast compared with normal gravity grown bacteria and no significant changes in the antibiotic resistance were found. The bacteria cultured under microgravity conferred cross stress resistance to acid, temperature and osmotic stress higher than the normal gravity cultured bacteria but the vice versa was found in case of oxidative stress.

Bactericidal efficacy of electrospun rosin/poly( ɛ-caprolactone) nanofibers

AbstractPoly(ɛ-caprolactone) (PCL)-containing rosin nanofibers were prepared via electrospinning technique for biomedical applications. To improve the biocompatibility properties, rosin was blended into PCL to prepare nanofibers. Nanofibers mats were prepared with different concentrations of rosin. The morphology, structure, and thermal properties of the resultant PCL/rosin nanofibers were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetry (TGA) analysis. SEM images revealed that the nanofibers were well-oriented and had good incorporation of rosin. FTIR results indicated the various bonding groups of PCL/rosin nanofibers with stable structure. TGA analysis revealed that the onset degradation temperature was decreased with increasing rosin content in the nanofibers. The bactericidal activity of PCL/rosin nanofibers was also investigated. These results indicate that the PCL blended with rosin nanofibers can be utilized as a promising candidate material for many biomedical applications.

Antimicrobial activity of electrospun polyurethane nanofibers containing composite materials

We report on the preparation and characterization of electrospun polyurethane nanofibers containing silver, cactus, rosin and Scutellariae Radix. The utilized polyurethane nanofibers containing different composite materials were prepared by a simple dip coating method. The morphology, structure and thermal characteristics of as-prepared composite nanofibers were studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared, Raman spectroscopy and thermogravimetric analysis. The antimicrobial activity of the composite nanofibers was tested against two common food borne pathogenic bacteria, Staphylococcus aureus and Escherichia coli, by the minimum inhibitory concentration method. Our results demonstrated that more pronounced antimicrobial activities were observed for the composite nanofibers. Overall, the fabrication of cheap, stable and effective material with excellent antimicrobial activity can be utilized to inhibit the microbial growth associated with food stuff.

Chemical composition and antioxidant capacity of the aqueous extract of Phellodendron amurense

The aqueous extract of Phellodendron amurense Rupr. (Amur Cork Tree) provides a rich source of antioxidants and chemical compounds, and can be used for food and wood preservative materials. In this study, we characterized the chemical composition of this extract by GC and GC/MS. The antioxidant capacity was evaluated using a variety of antioxidant assays (superoxide radical, hydroxyl radical, nitric oxide radical, and DPPH radical scavenging activity). Additionally, total polyphenolic content was determined. Phenolic acids and acetone derivatives were major compounds of the extract capable of scavenging the DPPH free radical and reducing ferric ions. DPPH and ferric ion reduction results were strongly correlated with total phenolic content of the extract which also exhibited strong nitric oxide, hydroxyl radical scavenging and superoxide anion radical scavenging activities.