The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
José P. Abad - One of the best experts on this subject based on the ideXlab platform.
-
Four Psychrophilic Bacteria from Antarctica extracellularly biosynthesize at low temperature highly stable silver nanoparticles with outstanding antimicrobial activity
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Siamak Javani, Irma Marín, Ricardo Amils, José P. AbadAbstract:Abstract Silver nanomaterials have been produced by chemical or biological methods requiring room to higher temperatures resulting in poor stable particles. Only a couple of reports use low temperature for their synthesis but, in these cases, nanoparticles aggregated in a short time. We hypothesized that Psychrophilic Bacteria could be found that produce stable nanoparticles at low temperature with antimicrobial activity that can be of use in biomedicine against pathogenic Bacteria. Isolation of several Bacteria from Antarctica was performed to obtain different Psychrophilic Bacteria, and their capability to extracellularly synthesize silver nanoparticles tested. Different conditions, including presence of sodium chloride and a low (4 °C) and a medium (30 °C) temperature, were used and the structure of the nanoparticles physicochemically characterized. The antimicrobial activity of freshly prepared and aged nanoparticles was determined against Gram-negative and Gram-positive Bacteria. Nanoparticles were synthesized by all four Psychrophilic Bacteria at 4 °C and 30 °C. NaCl highly decreased the synthesis of nanosilver particles. Depending on the Bacteria and temperature used, nanoparticles were spherical with sizes 5.0–11.1 nm, and stable after several months of incubation under light. The most stable nanoparticles were those kept at 4 °C and the highest detected activity was against Gram-positive Bacteria.
Siamak Javani - One of the best experts on this subject based on the ideXlab platform.
-
Four Psychrophilic Bacteria from Antarctica extracellularly biosynthesize at low temperature highly stable silver nanoparticles with outstanding antimicrobial activity
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Siamak Javani, Irma Marín, Ricardo Amils, José P. AbadAbstract:Abstract Silver nanomaterials have been produced by chemical or biological methods requiring room to higher temperatures resulting in poor stable particles. Only a couple of reports use low temperature for their synthesis but, in these cases, nanoparticles aggregated in a short time. We hypothesized that Psychrophilic Bacteria could be found that produce stable nanoparticles at low temperature with antimicrobial activity that can be of use in biomedicine against pathogenic Bacteria. Isolation of several Bacteria from Antarctica was performed to obtain different Psychrophilic Bacteria, and their capability to extracellularly synthesize silver nanoparticles tested. Different conditions, including presence of sodium chloride and a low (4 °C) and a medium (30 °C) temperature, were used and the structure of the nanoparticles physicochemically characterized. The antimicrobial activity of freshly prepared and aged nanoparticles was determined against Gram-negative and Gram-positive Bacteria. Nanoparticles were synthesized by all four Psychrophilic Bacteria at 4 °C and 30 °C. NaCl highly decreased the synthesis of nanosilver particles. Depending on the Bacteria and temperature used, nanoparticles were spherical with sizes 5.0–11.1 nm, and stable after several months of incubation under light. The most stable nanoparticles were those kept at 4 °C and the highest detected activity was against Gram-positive Bacteria.
Shashi Singh - One of the best experts on this subject based on the ideXlab platform.
-
Extracellular synthesis of antiBacterial silver nanoparticles using Psychrophilic Bacteria
Process Biochemistry, 2011Co-Authors: S. Shivaji, S. Madhu, Shashi SinghAbstract:Abstract Cell-free culture supernatants of five Psychrophilic Bacteria Pseudomonas antarctica, Pseudomonas proteolytica, Pseudomonas meridiana, Arthrobacter kerguelensis and Arthrobacter gangotriensis and two mesophilic Bacteria Bacillus indicus and Bacillus cecembensis have been used to synthesize silver nanoparticles (AgNPs). The AgNPs were characterized using UV–Visible spectroscopy, transmission electron microscopy and atomic force microscopy. The sizes of the AgNPs ranged from 6 to 13 nm and were stable for 8 months in the dark. The synthesis and stability of AgNPs appears to depend on the temperature, pH or the species of Bacteria (P. antarctica or A. kerguelensis) from which the supernatant is used. It was observed that the A. kerguelensis supernatant could not produce AgNPs at the temperature where the P. antarctica could synthesize AgNPs. Thus the study provides evidence that the factors in the cell-free culture supernatants that facilitate synthesis of AgNPs vary from Bacterial species to species. The AgNPs were bacteriocidal. This report presents for the first time data on the generation of AgNPs using culture supernatants of Psychrophilic Bacteria and also demonstrates that culture supernatants of species of Arthrobacter, a genus which has never been investigated earlier, can also synthesize AgNPs.
T Higashihara - One of the best experts on this subject based on the ideXlab platform.
-
Phylogenetic analysis of Psychrophilic Bacteria isolated from the Japan Trench, including a description of the deep-sea species Psychrobacter pacificensis sp. nov.
International journal of systematic and evolutionary microbiology, 2000Co-Authors: A Maruyama, D Honda, H Yamamoto, K Kitamura, T HigashiharaAbstract:Phylogenetic positions of Psychrophilic Bacteria isolated from the Japan Trench were determined by sequencing analysis of PCR-amplified Bacterial small subunit (16S) rRNA genes. Between surface and deep-sea psychrophiles, distinct positions clearly differed within the gamma-ProteoBacteria. In phylogenetic analysis using neighbour-joining, maximum-parsimony and maximum-likelihood, strains from surface seawater were inferred to be located in the Halomonas aquamarina-meridiana clade within the family Halomonadaceae. Strains from deep seawater (5000-6000 m), however, formed a novel monophyletic clade within the Moraxella-Psychrobacter branch in the family Moraxellaceae, showing separation from terrestrial and Antarctic relatives. These deep-sea strains were also discriminated from other known Psychrobacter species in phenotype, e.g. limited growth in the absence of NaCl (optimum at about 3% NaCl), positive urease activity, acid production from xylose and arabinose, and the presence of multiple fimbriae. DNA relatedness values among six deep-sea strains were > 85% in DNA-DNA hybridization experiments and > 98% in aligned 16S rDNA sequences. From this evidence, a new species, Psychrobacter pacificensis, is proposed for these deep-sea psychrophiles; the type strain of Psychrobacter pacificensis is strain NIBH P2K6T (= IFO 16270T). Occurrence of psychrobacters in cold Japan Trench deep seawater and at the Antarctic sea surface suggests that deep-sea Bacterial habitation and evolution have been mediated by global deep-ocean circulation linked to the sinking of cooled seawater in polar regions.
Irma Marín - One of the best experts on this subject based on the ideXlab platform.
-
Four Psychrophilic Bacteria from Antarctica extracellularly biosynthesize at low temperature highly stable silver nanoparticles with outstanding antimicrobial activity
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Siamak Javani, Irma Marín, Ricardo Amils, José P. AbadAbstract:Abstract Silver nanomaterials have been produced by chemical or biological methods requiring room to higher temperatures resulting in poor stable particles. Only a couple of reports use low temperature for their synthesis but, in these cases, nanoparticles aggregated in a short time. We hypothesized that Psychrophilic Bacteria could be found that produce stable nanoparticles at low temperature with antimicrobial activity that can be of use in biomedicine against pathogenic Bacteria. Isolation of several Bacteria from Antarctica was performed to obtain different Psychrophilic Bacteria, and their capability to extracellularly synthesize silver nanoparticles tested. Different conditions, including presence of sodium chloride and a low (4 °C) and a medium (30 °C) temperature, were used and the structure of the nanoparticles physicochemically characterized. The antimicrobial activity of freshly prepared and aged nanoparticles was determined against Gram-negative and Gram-positive Bacteria. Nanoparticles were synthesized by all four Psychrophilic Bacteria at 4 °C and 30 °C. NaCl highly decreased the synthesis of nanosilver particles. Depending on the Bacteria and temperature used, nanoparticles were spherical with sizes 5.0–11.1 nm, and stable after several months of incubation under light. The most stable nanoparticles were those kept at 4 °C and the highest detected activity was against Gram-positive Bacteria.