Biological and chemical aspects of the aquatic lipid surface microlayer.
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Bacteria↗
Biomedical subjects
B Norén
Publications and source records attributed to B Norén.
Intake system using glass ampoules for gas chromatographic analysis of volatile compounds of biological origin.
A gas chromatographic intake system using 1 ml glass ampoules is described. Examples of analyses of gases and volatile organic compounds produced by soil and soil organisms incubated in the ampoules are given. The gas chromatographic system was used to analyze permanent gases produced by germinating Fusarium conidia and by an agricultural soil as well as to study the respiration of Panagrellus nematodes. A comparison of the gas chromatograms of volatile organic compounds present in a beech forest soil and an agricultural soil indicates that the chromatograms represent "finger prints" of the two soils. Results obtained with the intake system described are compared to those obtained using a conventional head space technique.
Chromatography, Gas↗
Antimicrobial effect of simple lipids and the effect of pH and positive ions.
Various branched fatty acids, particularly those of iso-configuration, have been shown to possess fungistatic and bacteriostatic properties. On the basis of their swelling effect on hyphae of Fusarium roseum it was suggested that this is due to an increase in the permeability of the plasma membrane. The solubilization of fatty acids in membranes should be expected to be influenced by the degree of dissociation and the presence of counter ions. Therefore, the effects of pH and K(+), Na(+), and Ca(2+) ions were studied. It is demonstrated that the presence of the univalent ions, Na(+) and K(+), markedly enhances the fungistatic effect of iso-tetradecanoic acid, whereas the opposite effect is noted for the divalent ion, Ca(2+). The effects are particularly pronounced at high pH. Furthermore, the antimicrobial effect obtained from the combination of fatty acid and tetramethylthiuramdisulfide is significantly enhanced in the presence of 0.1 and 0.2% KCl.
Anti-Infective Agents↗
Antimicrobial effect of simple lipids with different branches at the methyl end group.
Various fatty acids of branched nature possess fungistatic and bacteriostatic properties. Some of these, particularly those of iso-configuration, strongly enhance the effect of conventional antimicrobial agents that act inside the cell membrane. A relation between this biological effect and the collapse properties of the corresponding monomolecular surface film on water has been observed. In this work, a series of fatty acids with a slightly smaller end group than iso-propyl, the omega-cyclopropane fatty acids, as well as one possessing a somewhat larger end group, the neo-branched fatty acids, have been examined. The omega-cyclopropane fatty acids were found to be more fungistatic than the iso-acids studied earlier. Furthermore, both cyclopropane and neo-fatty acids of short chain lengths exhibited synergistic effects in combination with tetramethylthiuramdisulfide.
Anti-Bacterial Agents↗