Ecophysiological and Phylogenetic Studies ofNevskia ramosa in Pure Culture

1998 ◽  
Vol 64 (5) ◽  
pp. 1890-1894 ◽  
Author(s):  
Heike St�rmeyer ◽  
J�rg Overmann ◽  
Hans-Dietrich Babenzien ◽  
Heribert Cypionka
Keyword(s):  
Nitrogenase Activity ◽  
Hydrophobic Surface ◽  
Surface Films ◽  
Organic Substrates ◽  
Water Interface ◽  
Phylogenetic Studies ◽  
Air Water Interface ◽  
Pure Cultures ◽  
Close Relatives ◽  
First Time

ABSTRACT During the last 100 years, the neuston bacterium Nevskia ramosa has been described several times. This bacterium forms conspicuous rosette-like microcolonies at the air-water interface. In this study, pure cultures of Nevskia ramosawere obtained for the first time, from a bog lake (strain Soe1, DSMZ 11499T) and a freshwater ditch (strain OL1, DSMZ 11500). The isolates showed special adaptations to life in the epineuston. They formed hydrophobic surface films with a dull appearance. N. ramosa is sensitive to UV radiation but revealed a very effective photorepair mechanism. Exposure to light at a wavelength of 350 nm after UV treatment raised the number of surviving cells by several orders of magnitude. The isolates grew with a broad range of organic substrates. Surface films were formed only in the absence of combined nitrogen; however, nitrogenase activity was not detected. It appears that during growth at the air-water interface the cells benefit from trapping ammonia from the air. The G+C content of the DNA was 67.8 and 69.0 mol% for strains Soe1 and OL1, respectively. The slight difference was confirmed by enterobacterial repetitive intergenic consensus PCR. The 16S rRNA sequences revealed 99.2% similarity. Thus, both isolates belong to the same species. The phylogenetic analysis indicated that Nevskia is a member of the gamma-subclass Proteobacteria that has no known close relatives.

Sampling and analysis of the air-water interface with SEM and EDS of microlayers

1989 ◽  
Vol 47 ◽  
pp. 1004-1005
Author(s):  
Randall W. Smith ◽  
John Dash
Keyword(s):  
Heavy Metals ◽  
Surface Microlayer ◽  
Surface Films ◽  
Water Interface ◽  
Physical Processes ◽  
Infrared Spectroscopic Analysis ◽  
Eds Analysis ◽  
Air Water Interface ◽  
Significant Area ◽  
Bulk Chemical

The structure of the air-water interface forms a boundary layer that involves biological ,chemical geological and physical processes in its formation. Freshwater and sea surface microlayers form at the air-water interface and include a diverse assemblage of organic matter, detritus, microorganisms, plankton and heavy metals. The sampling of microlayers and the examination of components is presently a significant area of study because of the input of anthropogenic materials and their accumulation at the air-water interface. The neustonic organisms present in this environment may be sensitive to the toxic components of these inputs. Hardy reports that over 20 different methods have been developed for sampling of microlayers, primarily for bulk chemical analysis. We report here the examination of microlayer films for the documentation of structure and composition.Baier and Gucinski reported the use of Langmuir-Blogett films obtained on germanium prisms for infrared spectroscopic analysis (IR-ATR) of components. The sampling of microlayers has been done by collecting fi1ms on glass plates and teflon drums, We found that microlayers could be collected on 11 mm glass cover slips by pulling a Langmuir-Blogett film from a surface microlayer. Comparative collections were made on methylcel1ulose filter pads. The films could be air-dried or preserved in Lugol's Iodine Several slicks or surface films were sampled in September, 1987 in Chesapeake Bay, Maryland and in August, 1988 in Sequim Bay, Washington, For glass coverslips the films were air-dried, mounted on SEM pegs, ringed with colloidal silver, and sputter coated with Au-Pd, The Langmuir-Blogett film technique maintained the structure of the microlayer intact for examination, SEM observation and EDS analysis were then used to determine organisms and relative concentrations of heavy metals, using a Link AN 10000 EDS system with an ISI SS40 SEM unit. Typical heavy microlayer films are shown in Figure 3.

scholarly journals Nanoparticle interaction with model lung surfactant monolayers

2009 ◽  
Vol 7 (suppl_1) ◽  
Author(s):  
Rakesh Kumar Harishchandra ◽  
Mohammed Saleem ◽  
Hans-Joachim Galla
Keyword(s):  
Surface Properties ◽  
Self Assembly ◽  
Current Knowledge ◽  
Surface Film ◽  
Lung Surfactant ◽  
Hydrophobic Surface ◽  
Surface Pattern ◽  
Lipid Monolayers ◽  
Water Interface ◽  
Air Water Interface

One of the most important functions of the lung surfactant monolayer is to form the first line of defence against inhaled aerosols such as nanoparticles (NPs), which remains largely unexplored. We report here, for the first time, the interaction of polyorganosiloxane NPs (AmorSil20: 22 nm in diameter) with lipid monolayers characteristic of alveolar surfactant. To enable a better understanding, the current knowledge about an established model surface film that mimics the surface properties of the lung is reviewed and major results originating from our group are summarized. The pure lipid components dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol have been used to study the biophysical behaviour of their monolayer films spread at the air–water interface in the presence of NPs. Film balance measurements combined with video-enhanced fluorescence microscopy have been used to investigate the formation of domain structures and the changes in the surface pattern induced by NPs. We are able to show that NPs are incorporated into lipid monolayers with a clear preference for defect structures at the fluid–crystalline interface leading to a considerable monolayer expansion and fluidization. NPs remain at the air–water interface probably by coating themselves with lipids in a self-assembly process, thereby exhibiting hydrophobic surface properties. We also show that the domain structure in lipid layers containing surfactant protein C, which is potentially responsible for the proper functioning of surfactant material, is considerably affected by NPs.

scholarly journals Crystalline-like structures and multilayering in Langmuir films of ionic liquids at the air–water interface

2016 ◽  
Vol 52 (32) ◽  
pp. 5585-5588 ◽  
Author(s):  
Eduardo. J. M. Filipe ◽  
Pedro Morgado ◽  
Miguel Teixeira ◽  
Karina Shimizu ◽  
Nathalie Bonatout ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Langmuir Films ◽  
Water Interface ◽  
Air Water Interface ◽  
Reversible Formation ◽  
First Time

Langmuir films of [C18mim][NTf2] ionic liquid exhibited, for the first time, the reversible formation of crystalline-like structures at the surface of water, compatible with the formation of multilayers.

Role of the Air-Water-Solid Interface in Bacteriophage Sorption Experiments

1998 ◽  
Vol 64 (1) ◽  
pp. 304-309 ◽  
Author(s):  
Shawn S. Thompson ◽  
Markus Flury ◽  
Marylynn V. Yates ◽  
William A. Jury
Keyword(s):  
Liquid Phase ◽  
Freundlich Isotherm ◽  
Hydrophobic Surface ◽  
Water Interface ◽  
Batch Experiments ◽  
Batch Sorption ◽  
Solid Interface ◽  
Phage Adsorption ◽  
Air Water Interface

ABSTRACT Batch sorption experiments were carried out with the bacteriophages MS2 and φX174. Two types of reactor vessels, polypropylene and glass, were used. Consistently lower concentrations of MS2 were found in the liquid phase in the absence of soil (control blanks) than in the presence of soil after mixing. High levels of MS2 inactivation (∼99.9%) were observed in control tubes made of polypropylene (PP), with comparatively little loss of virus seen in PP tubes when soil was present. Minimal inactivation of MS2 was observed when the air-water interface was completely eliminated from PP control blanks during mixing. All batch experiments performed with reactor tubes made of glass demonstrated no substantial inactivation of MS2. In similar experiments, bacteriophage φX174 did not undergo inactivation in either PP or glass control blanks, implying that this virus is not affected by the same factors which led to inactivation of MS2 in the PP control tubes. When possible, phage adsorption to soil was calculated by the Freundlich isotherm. Our data suggest that forces associated with the air-water-solid interface (where the solid is a hydrophobic surface) are responsible for inactivation of MS2 in the PP control tubes. The influence of air-water interfacial forces should be carefully considered when batch sorption experiments are conducted with certain viruses.

Multi-Layers Thin Films of Acetalized Poly(Vinyl Alcohol) Derivatives Obtained by the LB Method and Their Opto-Electronic Properties

1989 ◽  
Vol 175 ◽  
Author(s):  
Kiyoshi Oguchi ◽  
Yasuhiko Yokoh ◽  
Kohei Sanui ◽  
Naoya Ogata
Keyword(s):  
Vinyl Alcohol ◽  
Second Harmonic ◽  
Repeat Unit ◽  
Single Layer ◽  
Degree Of Polymerization ◽  
Poly Vinyl Alcohol ◽  
Surface Films ◽  
Water Interface ◽  
Number Of Layers ◽  
Air Water Interface

AbstractThe formation of surface films of acetalized poly(vinyl alcohol)s at the air/water interface has been investigated in terms of the structure of the transferred films, after transfer of these surface films to solid substrates by means of the Langmuir-Blodgett technique. Furthermore, their electron beam exposure characteristics and non-linear optical properties were measured. It was found that the monolayers of acetalized poly(vinyl alcohol)s having aliphatic side chaines gave stable surface films with a limiting area of ca. 0.3nm2/average repeat unit, irrespective of the side-chain length and the degree of polymerization of the starting poly(vinyl alcohol). The surface films could be deposited onto various substrates with deposition ratios of 1.0. The resulting multilayers were Y type. The thickness of the multilayers was proportional to the number of layers, and the single-layer thickness increased with increasing sidechain length. The surface wettability of the multilayers changed alternatingly, depending on whether the number of layers was even or odd. These results indicated that the surface films were monolayers of polymers, with hydrophilic main chains spread over the air/water interface and hydrophobic side chains directed approximately normal to the interface. The transferred films maintained the oriented structure of the monolayers at the interface. The acetalized poly(vinyl alcohol)s prepared by the LB technique is adaptable as a high resolution negative-type EB resist. And the second harmonic generation (SHG) of some acetalized poly(vinyl alcohol)s was observed by LB method and by electric field poling method.

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