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Antibacterial activity of methylated egg white proteins against pathogenic G(+) and G(-) bacteria matching
Seham Abdel-Shafi1, Ali Osman2, Gamal Enan1
1Botany Department, Faculty of Science, Zagazig University, Zagazig, 44519 Egypt.
Abstract:
Native egg white protein with high level of acidic amino acid residues (pI = 4.8) and hydrophilic nature was transformed into its methylated derivative (MEW), acquiring rather hydrophobic and basic character (pI = 8). The MIC of MEW against ten studied bacteria (G(+) and G(-)) ranged between 0.5 and 1 μg/disc matching or excelling the comparative values of some known specific antibiotics (ranging from 1 to 7.5 μg/disc). Combinations of MEW (1 MIC) and different ready-made disc concentrations of antibiotics indicated either nil, antagonistic or synergistic antimicrobial effect. Replacing the antibiotic Ciprofloxacin by gradual levels of MEW (20-100 %) proportionally increased the potentiality to induce bigger sized inhibition zones. MEW (1 MIC) could inhibit the growth of 6 G(+) and 4 G(-) pathogenic bacteria in their liquid broth media during 24 h at 37 °C, indicating its broad and wide specificity. TEM examination indicated the susceptibility of the two types of bacteria (G(+) and G(-)) to the antimicrobial action of MEW as manifested in different signs of cellular deformations, confirming its broad specificity and its mode of action was rather targeting the cell wall and cell membrane.
Insights
Methylated egg white protein (MEW) exhibits potent broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria. MEW demonstrates efficacy comparable to or exceeding certain antibiotics, suggesting potential as a novel antimicrobial agent.
Area of Science:
- Biochemistry
- Microbiology
- Materials Science
Background:
- Egg white protein is hydrophilic with acidic residues (pI=4.8).
- Modification can alter protein properties for new applications.
- Understanding protein derivatives' antimicrobial potential is crucial.
Purpose of the Study:
- To methylate native egg white protein, creating a hydrophobic and basic derivative (MEW).
- To evaluate the antimicrobial activity of MEW against a panel of Gram-positive and Gram-negative bacteria.
- To investigate the synergistic or antagonistic effects of MEW in combination with antibiotics.
Main Methods:
- Protein methylation to produce MEW with altered physicochemical properties (pI=8).
- Determination of Minimum Inhibitory Concentration (MIC) of MEW against ten bacterial strains.
- Testing combinations of MEW and antibiotics, and evaluating MEW as a replacement for ciprofloxacin.
- Transmission Electron Microscopy (TEM) to visualize bacterial cell damage.
Main Results:
- MEW displayed potent antimicrobial activity, with MIC values between 0.5-1 μg/disc against all tested bacteria.
- MEW's efficacy matched or surpassed that of specific antibiotics (1-7.5 μg/disc).
- Combinations with antibiotics showed varied effects (nil, antagonistic, synergistic), while MEW substitution enhanced inhibition zones.
- MEW inhibited 6 Gram-positive and 4 Gram-negative bacteria in broth culture within 24h.
- TEM revealed cellular deformations in bacteria treated with MEW, indicating cell wall and membrane damage.
Conclusions:
- Methylated egg white protein (MEW) possesses significant broad-spectrum antimicrobial properties.
- MEW is effective against both Gram-positive and Gram-negative pathogenic bacteria.
- The mode of action involves targeting the bacterial cell wall and membrane, with potential applications as a novel antimicrobial agent.
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