Identification of antimicrobial activity from goat cervical epithelium.

1. In mammals, antimicrobial peptides are present in epithelial cells of the respiratory, gastrointestinal and urinogenital tracts. In the present study, we report the identification and partial characterization of an antimicrobial peptide in extracts prepared from goat cervical epithelial tissue. 2. The bioactivity, as determined by radial and disc diffusion assays, was identified in a peptide of molecular mass 4.5 kDa purified by cation exchange and gel filtration techniques. The purified peptide exhibited antibacterial activity against Escherichia coli (Gram-negative) as well as Bacillus subtilis (Gram-positive) bacteria. 3. The minimum inhibitory concentration of the peptide estimated by liquid broth assay for E. coli and B. subtilis suspensions was 31 and 50 microg/mL, respectively, a result implying that the peptide is more efficient in inhibiting Gram-negative than Gram-positive bacteria. 4. Because the peptide has no spermicidal activity, we propose that it is responsible for protecting the female genital tract against bacteria. 5. Whether the peptide has potentials for use in the cryopreservation, storage and transport of semen remains to be determined.