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Antimicrobial protein produced by vaginal Lactobacillus acidophilus that inhibits Gardnerella vaginalis
A A Aroutcheva1, J A Simoes, S Faro
1Department of Obstetrics and Gynecology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612, USA.
Objective:
To isolate bacteriocin from a vaginal strain of Lactobacillus acidophilus.
Methods:
L. acidophilus 160 was grown on two media. The first was MRS broth for 18 hours; the cells were harvested, washed, and placed into a chemically defined medium. The second medium resembled vaginal fluid minus protein. Bacteriocin was precipitated from both media using ammonium sulfate. The growth-inhibiting activity of bacteriocin was determined by a bioassay using nine different isolates of Gardnerella vaginalis.
Results:
MRS broth is not a suitable medium for extracting bacteriocin, because it binds with Tween 80. Bacteriocin was isolated, without contaminating constituents, from chemically defined medium and identified as a single band by electrophoresis. Bacteriocin has a molecular weight of 3.8 kDa. All nine isolates of Gardnerella were inhibited by the bacteriocin isolated from L. acidophilus 160.
Conclusions:
Bacteriocin produced by L. acidophilus 160 was isolated from the chemically defined medium (starvation medium) in a partially pure form. L. acidophilus 160 bacteriocin inhibited growth of all nine isolates of Gardnerella vaginalis.