Antimicrobial Protein Produced by Vaginal Lactobacillus acidophilus that inhibits Gardnerella vaginalis

Alla A. Aroutcheva, Jose A. Simoes, and Sebastian Faro
Department of Obstetrics and Gynecology, Rush-Presbyterian-St. Luke's Medical Center, 1653W. Congress Pkwy, 720 Pav., Chicago, IL, 60612, USA,
Infect Dis Obstet Gynecol 2001;9:33–39

Objective: The objective of this study was to develop a simple method for recovery and purification of the antimicrobial protein produced by endogenous vaginal L. acidophilus. Obtaining a pure bacteriocin will permit investigations leading to a better understanding of the interaction between the endogenous bacteria of the vagina..

All nine isolates of Gardnerella were inhibited by the bacteriocin isolated from L. acidophilus 160.
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.

Lactobacilli, through the antagonistic interaction
with pathogenic bacteria, maintain the vaginal ecosystem in a healthy state.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

Lactobacilli, through the antagonistic interaction with pathogenic bacteria, maintain the vaginal ecosystem in a healthy state. Regulatory processes are carried out by species of Lactobacillus that produce antibacterial compounds, such as lactic and other organic acids, H2O2, and bacteriocins. Bacteriocins are biologically active, lowmolecular-weight proteins or peptides that inhibit the growth of a variety of bacteria.

The bacteriocin activity includes other species of lactobacilli, as well as a variety of Gram-positive and Gram-negative aerobic, facultative, and obligate anaerobic bacteria. It is significant that one species of Lactobacillus will produce a bacteriocin that inhibits the growth of other lactobacilli. This may be one mechanism that allows Lactobacillus to dominate the ecosystem by suppressing not only other bacteria but also other lactobacilli. This in turn reduces competition within an ecosystem.

Abstract: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1784632

Full text: http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1784632&blobtype=pdf

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