Tris(hydroxymethyl)aminomethane buffer modification of Escherichia coli outer membrane permeability

Area of Science:

• Microbiology
• Biochemistry
• Cell Biology

Background:

• The outer membrane of Gram-negative bacteria like Escherichia coli acts as a barrier.
• Understanding factors affecting outer membrane permeability is crucial for drug delivery and studying bacterial physiology.
• Tris buffer is commonly used in biological experiments, often assumed to be inert.

Purpose of the Study:

• To investigate the effect of tris(hydroxymethyl)aminomethane (Tris) buffer on the outer membrane permeability of Escherichia coli.
• To determine if Tris buffer affects bacterial strains with different lipopolysaccharide (LPS) structures.
• To assess the physiological inertness of Tris buffer in microbiological studies.

Main Methods:

• Examined Tris buffer's effect on outer membrane permeability in smooth (D280) and heptose-deficient LPS (F515) strains of E. coli O8.
• Assessed permeability by measuring alkaline phosphatase activity (Vo) and lysozyme sensitivity.
• Analyzed alkaline phosphatase localization and cell envelope component release.

Main Results:

• Tris buffer (pH 8.00) significantly increased outer membrane permeability in both E. coli strains.
• Increased permeability correlated with Tris concentration and exposure duration.
• The observed effects were specific to Tris buffer and not due to allosteric activation of enzymes.

Conclusions:

• Tris buffer is not physiologically inert and can alter bacterial outer membrane permeability.
• Researchers using Tris buffer should consider its potential impact on experimental systems.
• Tris buffer can lead to the release of cell envelope components, necessitating caution in its application.