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Specific solute effects on Staphylococcus aureus cells subjected to reduced water activity
S A Ballesteros1, J Chirife, J P Bozzini
1Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
International Journal of Food Microbiology
|November 1, 1993
Summary
Lowering water activity (aw) with solutes like sodium chloride and sucrose inhibited Staphylococcus aureus by reducing water availability. Other solutes showed specific antibacterial effects, potentially by attacking the cell wall.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Staphylococcus aureus is a significant human pathogen.
- Understanding bacterial responses to environmental stressors like low water activity is crucial for controlling infections.
- Various solutes can lower water activity, impacting microbial growth.
Purpose of the Study:
- To investigate the effects of different solutes on Staphylococcus aureus behavior at lowered water activity (aw).
- To differentiate between general water activity-lowering effects and specific solute toxicity.
- To explore potential mechanisms of antibacterial action.
Main Methods:
- Transmission electron microscopy was used to observe Staphylococcus aureus cell morphology.
- Various solutes (sodium chloride, sucrose, glycols) were added to growth media to lower aw.
- Physical properties of the growth medium were theoretically estimated.
Main Results:
- Sodium chloride and sucrose primarily inhibited S. aureus by reducing water activity, with no specific solute effects observed.
- Propylene glycol, butylene glycol, and polyethylene glycols exhibited specific antibacterial activity against S. aureus.
- The physical properties of the medium did not correlate with the observed biological responses.
Conclusions:
- The inhibitory effects of NaCl and sucrose on S. aureus are mainly due to water activity reduction.
- Other tested solutes possess specific antibacterial properties against S. aureus.
- Cell wall damage is a potential mechanism for the specific antibacterial activity observed.