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Bacteriostatic activity of Whey Acidic Protein (WAP)
Tokuko Iwamori1, Naoko Nukumi, Kikuji Itoh
1Laboratory of Applied Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.
The Journal of Veterinary Medical Science
|December 17, 2009
Summary
Whey acidic protein (WAP) exhibits bacteriostatic activity, inhibiting Staphylococcus aureus growth by disrupting bacterial cell walls. This protein shows no effect on Escherichia coli growth.
Area of Science:
- Biochemistry
- Microbiology
- Proteomics
Background:
- Whey acidic protein (WAP) has been previously shown to inhibit mammary epithelial cell proliferation.
- The antimicrobial properties of WAP have not been extensively studied.
Purpose of the Study:
- To investigate the bacteriostatic activity of Whey Acidic Protein (WAP).
- To determine the effect of WAP on bacterial growth and cell wall integrity.
Main Methods:
- Isolation of WAP from rat milk whey using column chromatography.
- Western blot analysis for WAP identification.
- Bacterial growth inhibition assays with Staphylococcus aureus and Escherichia coli.
- Scanning electron microscopy (SEM) to visualize bacterial cell morphology after WAP treatment.
Main Results:
- WAP was successfully isolated and identified from rat milk whey.
- WAP demonstrated dose-dependent inhibition of Staphylococcus aureus JCM2413 growth.
- WAP did not inhibit the growth of Escherichia coli.
- Optimal bacteriostatic activity of WAP was observed at pH 6.6, unaffected by 150 mM NaCl.
- SEM revealed disruption of bacterial cell walls in WAP-treated Staphylococcus aureus.
Conclusions:
- Whey acidic protein possesses significant bacteriostatic activity against Staphylococcus aureus.
- WAP exerts its antimicrobial effect through the disruption of bacterial cell walls.
- WAP's activity is specific, targeting Gram-positive bacteria like S. aureus while sparing Gram-negative E. coli.
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