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Antimicrobial effect of simple lipids and the effect of pH and positive ions
Abstract:
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.
Insights
Branched fatty acids inhibit fungi and bacteria. Univalent ions like sodium and potassium enhance this effect, while calcium ions reduce it, particularly at high pH levels.
Area of Science:
- Microbiology
- Biochemistry
- Membrane Biophysics
Background:
- Branched fatty acids, especially iso-fatty acids, exhibit fungistatic and bacteriostatic properties.
- Previous research suggested these effects stem from increased plasma membrane permeability, observed via swelling of Fusarium roseum hyphae.
Purpose of the Study:
- To investigate the influence of pH and specific counter ions (K+, Na+, Ca2+) on the antimicrobial activity of branched fatty acids.
- To understand how ion interactions affect fatty acid solubilization within cell membranes.
Main Methods:
- Studying the fungistatic and bacteriostatic effects of iso-tetradecanoic acid under varying pH conditions.
- Assessing the impact of potassium (K+), sodium (Na+), and calcium (Ca2+) ions on antimicrobial activity.
- Evaluating the combined effect of fatty acids and tetramethylthiuramdisulfide with varying KCl concentrations.
Main Results:
- Univalent ions (Na+, K+) significantly enhanced the fungistatic effect of iso-tetradecanoic acid.
- The divalent ion (Ca2+) exhibited an opposite effect, reducing the antimicrobial activity.
- These ionic effects were more pronounced at higher pH values.
- Antimicrobial efficacy was notably boosted when fatty acids were combined with tetramethylthiuramdisulfide in the presence of 0.1% and 0.2% KCl.
Conclusions:
- The antimicrobial activity of branched fatty acids is modulated by pH and the type of counter ion present.
- Monovalent cations enhance, while divalent cations antagonize, the membrane-disrupting effects of these fatty acids.
- Ionic strength and composition are critical factors in optimizing the antimicrobial potential of fatty acids and their synergistic combinations.